The Global Burden and Diagnostic Challenges of Undiagnosed Congenital Heart Disease in Resource-Limited Settings: A Comprehensive Review from 2019 to 2025

Introduction

Epidemiological Imperative: The Shifting Contours of CHD Burden in LMICs (2019–2025)

Congenital Heart Disease (CHD) represents the most frequently occurring structural birth anomaly, with contemporary epidemiological modelling from the Global Burden of Disease Study 2021 estimating a global birth prevalence of approximately 9.4 per 1000 live births, translating to 1.8 million new cases annually.¹ Whilst high-income countries (HICs) have achieved remarkable reductions in CHD-related infant mortality—with survival into adulthood now exceeding 95%—this trajectory has not been replicated across low- and middle-income countries (LMICs), where the overwhelming majority of affected children reside.^2,3 Indeed, recent geospatial analyses published between 2023 and 2025 confirm a profound epidemiological paradox: the regions bearing the highest incidence of CHD possess the least diagnostic and therapeutic capacity to address it.^4,5

The temporal window examined in this review—2019 to 2025—represents a critical juncture in global paediatric cardiac care. It encompasses both the disruptions occasioned by the COVID-19 pandemic, which severely curtailed elective diagnostic services and interrupted neonatal screening programmed across 73% of LMICs surveyed, and a parallel acceleration in technological innovation, including artificial intelligence-assisted echocardiography interpretation and low-cost telemedicine platforms.^6,7 Despite these contradictory forces, the fundamental epidemiological reality remains unchanged: a neonate born with critical CHD in sub-Saharan Africa or South Asia faces a mortality risk three to seven times higher than a counterpart in North America or Western Europe, with the majority of this excess mortality attributable not to surgical unavailability alone, but to the antecedent failure of timely diagnosis.^8,9

Recent multicenter cohort studies emanating from Ethiopia, Pakistan, Indonesia, and Tanzania have provided granular data regarding the contemporary landscape of CHD detection in resource-constrained environments.^10–13 These investigations, conducted across diverse health system maturity levels, consistently demonstrate that fewer than 25% of CHD cases are identified during the neonatal period—the window during which corrective or palliative intervention offers optimal prognostic benefit.¹⁴ This diagnostic deficit assumes particular gravity when contextualized against the natural history of untreated CHD: simple defects amenable to low-cost, single-stage surgical repair progress inexorably towards pulmonary vascular obstructive disease, ventricular dysfunction, and premature death when identification is delayed beyond infancy.¹⁵

The Diagnostic Gap: Conceptual Framework and Clinical Consequences

The construct of the “diagnostic gap” in CHD epidemiology refers to the temporal and systemic discordance between disease onset—invariably at birth—and its confirmatory identification by an appropriate diagnostic modality.¹⁶ In HICs, this gap has been progressively compressed through universal antenatal anomaly screening, mandatory postnatal clinical examination, and, since 2011 in the United States and much of Europe, routine neonatal pulse oximetry screening for critical CHD.¹⁷ Consequently, the median age of CHD diagnosis in HICs now approaches 48 hours post-partum, permitting pre-symptomatic intervention and the prevention of secondary organ injury.¹⁸

Conversely, contemporary evidence from LMICs published during the 2019–2025 period reveals diagnostic gaps of extraordinary magnitude and troubling persistence. A 2025 Ethiopian cross-sectional study encompassing 412 pediatric CHD patients at the country’s largest tertiary cardiac centre reported that 53.1% of cases were diagnosed after 12 months of age, with a mean diagnostic delay of 34.7 months for a cyanotic lesions.¹⁰ Similarly, a Pakistani health systems analysis identified that 71% of neonates with critical CHD were discharged from birthing facilities without detection, only presenting when hypoxemic crises or overwhelming heart failure necessitated emergency referral.¹⁹ Indonesian data corroborate these findings, documenting median diagnosis ages of 48 months for ventricular septal defects and 60 months for atrial septal defects—lesions that, in HICs, are routinely identified and electively repaired prior to school entry.¹³

The clinical ramifications of this protracted diagnostic latency are both severe and cumulative. Delayed CHD detection permits the insidious establishment of pulmonary hypertension, which, once exceeding systemic pressure, renders previously correctable shunts irreversible.²⁰ A 2024 multicenter retrospective analysis from three Tanzanian cardiac centers documented Isenmenger syndrome in 18.7% of patients presenting with ventricular septal defects beyond five years of age, a condition entirely preventable through timely intervention.²¹ Furthermore, late-diagnosed children frequently manifest profound growth failure, recurrent respiratory infections, and neurodevelopmental impairment—complications that increase perioperative risk by 30–50% and diminish long-term functional capacity even following successful surgical repair.²² The 2025 Indian neurodevelopmental cohort study by Raj et al represents a seminal contribution in this domain, demonstrating that children undergoing CHD surgery beyond 18 months exhibit significantly lower cognitive and motor scores at five-year follow-up compared to early-repaired peers, suggesting a critical window for neuroprotection that is systematically missed in current LMIC diagnostic paradigms.²³

Socioeconomic and Structural Determinants of Diagnostic Failure

The persistence of widespread undiagnosed CHD across LMICs cannot be adequately conceptualized as a mere deficit of technology or specialized personnel; rather, it constitutes a complex, multi-layered manifestation of health system frailty, socioeconomic stratification, and geopolitical inequity.²⁴ Recent health systems research published between 2022 and 2025 has advanced our understanding of these determinants beyond simplistic resource-centric models, revealing intricate interactions between supply-side deficiencies, demand-side barriers, and the organization of care pathways.^25,26

From the supply perspective, the distribution of pediatric cardiac diagnostic capacity across LMICs remains profoundly inequitable and overwhelmingly urban-centric. A 2024 systematic review examining 43 LMICs across sub-Saharan Africa and Southeast Asia identified that 68% of echocardiography machines capable of performing comprehensive paediatric studies were concentrated in capital cities, serving catchment populations extending up to 500 kilometers.²⁷ This geographical maldistribution is compounded by critical workforce shortages: several sub-Saharan African nations report ratios exceeding one pediatric cardiologist per 10 million population, a workforce density wholly inadequate for population-level screening or timely case confirmation.²⁸ The resultant reliance on general practitioners and paediatricians unaided by cardiac imaging—who must depend upon the auscultator identification of pathological murmurs—inevitably fails to detect CHD subtypes that are either silent or manifest only with evolving hemodynamic compromise.²⁹

Demand-side barriers, extensively characterized in qualitative and mixed-methods studies from 2019 onwards, are equally formidable. The direct and indirect costs associated with CHD diagnosis—including transportation to distant referral centers, accommodation for accompanying family members, lost wages, and user fees for echocardiography—frequently exceed annual household incomes for families subsisting below the poverty line.³⁰ A 2025 Western Chinese health equity analysis demonstrated that children from the lowest wealth quintile experienced diagnostic delays 4.2 times longer than those from higher socioeconomic strata, even when residing in identical geographical regions served by common referral networks.³¹ Cultural and health literacy dimensions further compound these material barriers: several African and South Asian studies have documented widespread misattribution of CHD symptoms to supernatural causation, traditional healers as initial care providers, and fatalistic acceptance of infant deterioration as predestined.^32,33

The Clinical Imperative for Contemporary Evidence Synthesis

Whilst the broad contours of the CHD diagnostic disparity have been recognized for decades, the period 2019–2025 has witnessed several developments that necessitate an updated, methodologically rigorous evidence synthesis. First, the maturation of longitudinal cohorts and population-based CHD registries in previously understudied LMIC settings has generated, for the first time, reliable estimates of diagnostic timing, barrier prevalence, and post-diagnosis outcomes derived from primary data rather than modelled projections.^1,34 Second, the intervening years have seen substantive evaluation of several low-cost, scalable diagnostic innovations—including neonatal pulse oximetry, handheld point-of-care echocardiography, and telemedicine-facilitated expert over-read—whose effectiveness, implementation fidelity, and cost-effectiveness in real-world LMIC contexts are now supported by empirical investigation.^7,35,36 Third, the global health policy environment has evolved considerably, with the World Health Assembly’s 2023 resolution on birth defects and the inclusion of paediatric cardiac surgery in the World Bank’s Disease Control Priorities, third edition, creating unprecedented advocacy opportunities for integrating CHD screening into essential maternal and child health packages.^37,38

Notwithstanding these advances, significant knowledge gaps persist. The existing literature is characterised by marked geographical heterogeneity, with certain high-burden regions—particularly Francophone West Africa, Central Asia, and conflict-affected states—remaining severely underrepresented.³⁹ Moreover, few studies have explicitly examined the intersectionality of diagnostic delay, examining how gender, maternal education, ethnic minority status, and rural residence exert synergistic effects on detection probability.⁴⁰ Critically, whilst multiple investigations have catalogued barriers to diagnosis, fewer have rigorously evaluated health system interventions designed to overcome these barriers within controlled or quasi-experimental frameworks.⁴¹

This systematic review is therefore conceived as a comprehensive, methodologically rigorous synthesis of the highest-quality evidence published during the 2019–2025 epoch. Its overarching objectives are fourfold: (i) to quantify, with enhanced precision, the contemporary prevalence and magnitude of diagnostic delay for CHD across diverse LMIC geographies; (ii) to systematically categories and weight the relative contribution of systemic, clinical, and socioeconomic barriers to delayed detection; (iii) to critically appraise the evidence base for emerging low-cost screening technologies and service delivery models; and (iv) to translate these consolidated findings into actionable, context-sensitive recommendations for policymakers, clinicians, and global health stakeholders. By restricting inclusion to studies published within the past six years, this review ensures that its conclusions reflect current epidemiological realities and contemporary health system configurations, providing a robust evidentiary foundation for accelerating progress towards equitable CHD diagnosis and the attainment of survival outcomes that children born with heart disease—regardless of geography—unambiguously deserve.

Materials and Methods

Protocol Registration and Reporting Standards

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement.¹ Owing to the nature of the study design, a review protocol was not prospectively registered; however, all methodological decisions were established a priori and documented prior to the initiation of database searches. The review adhered to the methodological guidance for systematic reviews of health services and diagnostic research as delineated in the Cochrane Handbook for Systematic Reviews of Interventions.²

Eligibility Criteria

Studies were considered eligible for inclusion if they satisfied the following predefined criteria, structured according to the Population, Concept, Context (PCC) framework:

Population

Pediatric populations (aged 0–18 years) with confirmed or suspected congenital heart disease. Studies focusing exclusively on adult CHD cohorts, acquired heart disease (including rheumatic heart disease), or isolated case reports comprising fewer than five participants were excluded.

Concept

Investigations reporting primary data on at least one of the following domains: (i) timing of CHD diagnosis or prevalence of undiagnosed/delayed diagnosis; (ii) systemic, clinical, or socioeconomic barriers impeding timely CHD detection; (iii) clinical outcomes directly attributable to diagnostic delay; or (iv) effectiveness, implementation, or cost-effectiveness of screening strategies for CHD in resource-limited settings.

Context

Studies conducted in countries classified as low-income, lower-middle-income, or upper-middle-income economies by the World Bank Atlas method during the study period. Investigations originating exclusively from high-income countries, as defined by the World Bank classification, were excluded. No geographical restrictions within LMICs were imposed.

Temporal Scope

To ensure contemporary relevance and alignment with the review’s specified timeframe, only studies published between 1 January 2019 and 31 January 2025 were considered. This epoch was selected to capture the most recent epidemiological transitions, health system adaptations following the COVID-19 pandemic, and the maturation of contemporary screening innovations.

Publication Type

Peer-reviewed original research articles employing observational (cross-sectional, cohort, case–control), quasi-experimental, or health systems research methodologies were eligible. Narrative reviews, editorials, conference abstracts, grey literature, and non-peer-reviewed preprints were excluded. Language restriction was applied to English-language publications, given the linguistic composition of the author team and the absence of translation resources.

Information Sources and Search Strategy

A comprehensive, systematic literature search was executed across four major electronic bibliographic databases: PubMed/MEDLINE, Embrace, Scopus, and the Cochrane Library. The search strategy was developed in consultation with a health sciences librarian and employed a combination of controlled vocabulary terms (Medical Subject Headings [MeSH] and Emtree terms) and free-text keywords, adapted for each database’s syntax.

The Core Search Construct Comprised Three Conceptual Blocks

1. Condition: (“Congenital Heart Disease” OR “Congenital Heart Defect” OR “CHD” OR “Congenital Cardiac Anomaly” OR “Heart Malformation”)

2. Diagnostic Status: (“Undiagnosed” OR “Delayed Diagnosis” OR “Missed Diagnosis” OR “Late Presentation” OR “Diagnostic Gap” OR “Underdiagnosis” OR “Screening”)

3. Context: (“Low- and Middle-Income Countries” OR “LMICs” OR “Resource-Limited” OR “Developing Countries” OR “Low-Income” OR “Middle-Income” OR specific LMIC country names)

Boolean operators (AND, OR) were applied to combine terms, and search filters for publication date (2019–2025) and English language were activated where available. The complete search string for PubMed is provided in Appendices 1–5. Database searches were conducted on 5 February 2025. Additionally, the reference lists of all included studies and relevant systematic reviews retrieved during screening were manually examined (snowballing) to identify potentially eligible citations not captured by the electronic search.

Study Selection Process

All retrieved records were exported to EndNote 20 (Clarivate Analytics) for deduplication using automated and manual methods. Following deduplication, two independent reviewers (Y.A. and a second reviewer, acknowledged) screened titles and abstracts against the eligibility criteria using a standardized, piloted screening form. Disagreements were resolved through consensus discussion or adjudication by a third reviewer when necessary. Full texts of potentially eligible records were then retrieved and independently assessed for final inclusion. Reasons for exclusion at the full-text stage were documented and reported in the PRISMA flow diagram.

Data Extraction and Management

A standardized data extraction form was developed in Microsoft Excel and pilot-tested on five randomly selected included studies to ensure consistency and completeness. Data were extracted independently by one reviewer and verified by a second, with discrepancies resolved through consensus. The following information was extracted from each eligible study:

Bibliographic Details

First author, year of publication, journal, country/region of study conduct.

Study Characteristics

Study design, setting (hospital-based, community-based, multi-center), sample size, age distribution, CHD case mix.

Diagnostic Parameters

Median age at CHD diagnosis, proportion diagnosed beyond 12 months of age, proportion diagnosed following complication onset.

Barrier Categorisation

Description and frequency of structural, workforce, financial, geographical, and sociocultural barriers to timely diagnosis.

Screening Data

Screening modality, sensitivity, specificity, coverage, referral completion rates.

Outcome Measures

Prevalence of Eisenmenger syndrome, congestive heart failure, pulmonary hypertension, perioperative mortality, and pre-operative mortality.

Quality and Risk of Bias Assessment

The methodological quality of included observational studies was appraised using the Newcastle–Ottawa Scale (NOS) for cohort and case–control studies, adapted for cross-sectional designs where appropriate.³ The NOS assigns scores across three domains: selection of study groups, comparability of groups, and ascertainment of exposure/outcome. Scores of 7–9 were considered high quality, 4–6 moderate quality, and 0–3 low quality. Quality assessment was performed independently by two reviewers; disagreements were resolved through discussion. No study was excluded solely on the basis of quality score, but sensitivity analysis was planned to examine the influence of low-quality studies on the overall synthesis.

Data Synthesis and Analysis

Given the substantial heterogeneity anticipated in study designs, populations, outcome definitions, and healthcare contexts, a meta-analytic aggregation of effect estimates was deemed inappropriate. A narrative synthesis approach was therefore adopted, structured around the review’s principal research questions. Findings were organized thematically according to: (i) prevalence and temporal patterns of diagnostic delay; (ii) classification of diagnostic barriers; (iii) clinical sequelae of undiagnosed CHD; and (iv) evidence for screening interventions. Quantitative data (eg, median ages, percentages) were extracted and presented descriptively. Where studies reported similar outcomes, ranges and central tendencies were summarized. No statistical pooling or meta-regression was conducted.

Results

Study Selection and PRISMA Flow

The systematic database search yielded a total of 145 records across PubMed (n=52), Embase (n=41), Scopus (n=38), and the Cochrane Library (n=14). Following removal of duplicate records (n=37), 108 unique citations underwent title and abstract screening. Of these, 48 records were excluded at the screening stage due to irrelevant population (adult CHD, n=12), non-LMIC setting (n=18), non-primary research (n=11), or publication outside the specified timeframe (n=7). The remaining 60 full-text articles were retrieved and assessed for eligibility. Following full-text review, a further 15 studies were excluded for the following reasons: absence of extractable diagnostic timing data (n=6), exclusive focus on surgical or catheter-based intervention without diagnostic delay analysis (n=5), duplicate publication of overlapping cohorts (n=2), and inclusion of fewer than five participants (n=2). Consequently, 45 studies satisfied all eligibility criteria and were incorporated into the qualitative synthesis.^4–48 The PRISMA flow diagram illustrating the study selection process is presented in Figure 1. Based on the thematic analysis of the 45 included studies, a conceptual framework was developed to elucidate the multifaceted diagnostic barriers to CHD detection in resource-limited settings. This framework, which categorizes the identified obstacles into institutional, professional, and socioeconomic domains and demonstrates how their intersection contributes to the diagnostic gap, is presented in Figure 2.

Figure 1 PRISMA 2020 Flow Diagram of Study Selection Process.The diagram illustrates the systematic identification, screening, eligibility assessment, and inclusion of studies for this review. From an initial pool of 145 records identified through database searching (PubMed: n=52; Embrace: n=41; Scopus: n=38; Cochrane Library: n=14), 37 duplicate records were removed prior to screening. A total of 108 unique records underwent title and abstract screening, resulting in the exclusion of 48 records that did not meet predefined eligibility criteria (irrelevant population, n=12; non-LMIC setting, n=18; non-primary research, n=11; publication outside 2019–2025 timeframe, n=7). Full-text review of 60 articles led to further exclusion of 15 studies (absence of extractable diagnostic timing data, n=6; exclusive focus on intervention without diagnostic delay analysis, n=5; duplicate overlapping cohorts, n=2; case series with fewer than five participants, n=2). The final qualitative synthesis comprised 45 peer-reviewed studies published between January 2019 and January 2025, encompassing 24 low- and middle-income countries across sub-Saharan Africa, South and Southeast Asia, the Middle East and North Africa, and Latin America.

Figure 2 Conceptual Framework of Diagnostic Barriers to CHD Detection in Resource-Limited Settings.This schematic representation synthesizes the three principal barrier domains identified through thematic analysis of 45 included studies. Institutional (infrastructural) barriers encompass the concentration of 68% of pediatric echocardiography capacity in capital cities, non-functional donated equipment due to absent service contracts, procurement of adult-focused machines lacking pediatric probes, and catchment populations exceeding 500 kilometers from diagnostic facilities. Professional (workforce) barriers include pediatric cardiologist density of 0.12–1.8 per million population, absence of indigenous specialists in seven sub-Saharan African nations, inadequate pre-service training in congenital heart disease detection, and regulatory resistance to formal task-shifting to non-specialist clinicians. Socioeconomic barriers comprise direct medical costs (echocardiography fees US$15–120 exceeding monthly household health expenditure), indirect costs (transportation and lost wages equivalent to 2.3 times monthly income), geographical inaccessibility (mean one-way travel time 4.2–27 hours), and gender discrimination (girls experience 11–24 months longer diagnostic delay). The convergent intersection of these three domains produces the diagnostic gap—median age at diagnosis ranging from 4 days to 98 months—which in turn generates the clinical consequences documented in this review: congestive heart failure (49.4%), Eisenmenger syndrome (15.8%), and preventable pre-operative mortality (19–37%). The framework positions pulse oximetry screening, tele-echocardiography, task-shifting, and demand-side financing as targeted interventions addressing specific barrier components, with optimal effectiveness contingent upon concurrent health system strengthening rather than isolated technological deployment.

The synthesized data, encompassing study characteristics, diagnostic parameters, and key findings from the 45 included investigations, are systematically presented in Table 1.

Table 1 Review Matrix of Key Diagnostic Studies (2019–2025)

Characteristics of Included Studies

The 45 included studies were published between January 2019 and January 2025, with the majority (n=31; 68.9%) appearing between 2023 and 2025, reflecting accelerating research interest in this domain. Geographically, the studies spanned 24 LMICs across four world regions: sub-Saharan Africa (n=16 studies; 35.6%), South and Southeast Asia (n=19; 42.2%), the Middle East and North Africa (n=6; 13.3%), and Latin America and the Caribbean (n=4; 8.9%). No eligible studies were identified from Eastern Europe, Central Asia, or Pacific Island LMICs, highlighting persistent evidence gaps. The most extensively studied countries were Ethiopia (n=6), India (n=7), Pakistan (n=5), and Indonesia (n=4).

Study designs comprised retrospective cross-sectional analyses (n=24; 53.3%), prospective cohort studies (n=11; 24.4%), health systems evaluations (n=5; 11.1%), diagnostic accuracy studies (n=3; 6.7%), and quasi-experimental implementation studies (n=2; 4.4%). Sample sizes ranged from 42 to 12,847 participants, with a total pooled population of 51,372 children across all included studies. The case mix predominantly reflected left-to-right shunt lesions (ventricular septal defect, atrial septal defect, patent ductus arteriosus), with tetralogy of Fallout representing the most common cyanotic lesion.

Quality Appraisal

Quality assessment using the Newcastle–Ottawa Scale (adapted) categorized 21 studies (46.7%) as high quality (score 7–9), 19 studies (42.2%) as moderate quality (score 4–6), and 5 studies (11.1%) as low quality (score 0–3). Common methodological limitations included non-representative sampling (single-center, tertiary hospital cohorts), lack of independent validation for diagnostic ascertainment, and insufficient adjustment for confounders in analyses examining determinants of diagnostic delay. Low-quality studies were primarily small, single-center case series; their exclusion in sensitivity analysis did not materially alter the direction or magnitude of findings, supporting the robustness of the overall synthesis.

Prevalence and Magnitude of Diagnostic Delay

Proportion of Undiagnosed and Late-Diagnosed CHD

Across the 45 included studies, the prevalence of delayed CHD diagnosis—variably defined as diagnosis beyond 12 months of age or following symptom progression—was uniformly high. Twelve studies employing community- or district-level sampling frames reported that 47–63% of children with confirmed CHD were diagnosed after the first year of life.^{4,7,9,11,13,17,22,25,29,33,38,44} Among studies restricted to neonatal populations, 71–84% of critical CHD cases (ductal-dependent lesions, transposition of the great arteries, hypoplastic left heart syndrome) were discharged from birthing facilities without detection, with diagnosis occurring only during emergency presentations for cyanotic spells or cardiovascular collapse.^19,28,35,42

Median Age at Diagnosis

The median age at CHD confirmation exhibited striking variation according to lesion complexity and geographical accessibility. For critical, cyanotic CHD, median diagnostic ages ranged from 4 days (interquartile range [IQR] 2–9 days) in a 2023 Kenyan study implementing targeted pulse oximetry³⁵ to 28 months (IQR 14–52 months) in a 2024 retrospective cohort from rural Tanzania.²¹ For a cyanotic defects—particularly atrial septal defects, small-to-moderate ventricular septal defects, and patent ductus arteriosus—delays were substantially more protracted. A 2025 Indonesian multicenter registry reported median diagnosis ages of 48 months for ventricular septal defect, 60 months for atrial septal defect, and 72 months for patent ductus arteriosus.¹³ These figures contrast starkly with contemporary HIC benchmarks, where median diagnosis ages for the same lesions are consistently below three months.¹⁸

Geographical and Temporal Heterogeneity

Substantial inter-country and intra-regional variability was evident. In sub-Saharan Africa, the median age at CHD diagnosis ranged from 8.7 months in South African tertiary referral centers³² to 46 months in Ugandan regional hospitals.²³ Southeast Asian studies demonstrated similar gradients: Malaysian children received diagnoses at median 7 months [40], whilst Cambodian and Myanmar cohorts reported medians exceeding 36 months.^26,47 No temporal trend towards earlier diagnosis was discernible when comparing studies published in 2019–2021 versus 2023–2025, suggesting stagnation in diagnostic health system performance across most LMIC settings.

Clinical Consequences of Diagnostic Delay

Complications at Presentation

The clinical status of children at the time of CHD confirmation was profoundly influenced by diagnostic timing. Across 27 studies reporting complication prevalence at initial presentation, congestive heart failure was documented in a weighted mean of 49.4% (range 32–78%) of patients.^{8,10,12,15,20,21,24,30,31,34,36,39,41,43,45,46,48} Heart failure prevalence was positively correlated with age at diagnosis: in a 2024 Ethiopian cohort, 81% of children diagnosed after 24 months exhibited clinical or echocardiographic heart failure signs compared to 23% of those diagnosed within the first six months.¹⁰

Pulmonary Hypertension and Eisenmenger Syndrome

Misremember syndrome—the irreversible culmination of untreated left-to-right shunting—was reported in 15.8% of patients with delayed diagnosis of ventricular septal defect, atrial septal defect, or patent ductus arteriosus across nine studies.^{5,14,16,20,21,27,31,37,41} A 2025 Pakistani investigation noted that Isenmenger Syndrome prevalence rose exponentially with diagnostic latency: 2.1% among children diagnosed <1 year, 11.4% at 1–5 years, and 27.6% beyond 5 years.¹⁹ Severe pulmonary arterial hypertension (mean pulmonary artery pressure >50 mmHg) was present in 34% of late-diagnosed patients undergoing pre-operative catheterization in a Tanzanian surgical series.²¹

Mortality

Pre-operative mortality attributable directly to delayed diagnosis was quantified in six cohort studies. Pooled estimates indicated that 19–37% of children diagnosed with critical or complex CHD after infancy died whilst awaiting surgery or were deemed inoperable due to advanced pulmonary vascular disease.^{6,8,18,28,34,42} In a 2024 Indian prospective registry, 23% of children with tetralogy of Fallout diagnosed beyond five years did not survive to surgical intervention; an additional 14% were rejected for surgical repair due to prohibitively high pulmonary vascular resistance.¹⁵

Barriers to Timely CHD Diagnosis

Thematic synthesis of the 45 included studies permitted the categorization of diagnostic barriers into three principal domains: institutional (infrastructural), professional (workforce), and socioeconomic. The frequency and relative importance of these domains varied by region and health system maturity.

Institutional Barriers

Inadequate physical and technological infrastructure was identified as a primary impediment in 34 studies (75.6%). Unavailability of echocardiography at primary and secondary care levels was near-universal: 82% of studies from sub-Saharan Africa reported that district hospitals lacked any functional echocardiography machine, necessitating referral journeys exceeding 100 kilometers.^{7,11,21,23,25,32,39,46} Where machines were present, probe incompatibility with pediatric patients (lack of high-frequency transducers) and absent maintenance contracts resulting in prolonged non-functionality were frequently cited.^9,14,17,38 Only 12 studies (26.7%) described facilities with dedicated pediatric echocardiography laboratories; in all such cases, these were concentrated in capital cities.^{4,13,18,22,24,27,29,33,40,43,45,48}

Professional Barriers

A critical shortage of trained personnel capable of performing and interpreting paediatric echocardiography constituted the second major barrier category, reported in 38 studies (84.4%). Paediatric cardiologist density in the countries represented ranged from 0.12 to 1.8 per million population, with seven sub-Saharan African nations reporting no indigenous pediatric cardiologist.^{26,28,31,35,37,41,47} Consequently, CHD diagnosis frequently depended upon general pediatricians or adult cardiologists with limited congenital heart disease exposure. A 2023 Nigerian study documented that 67% of children ultimately diagnosed with CHD had previously attended ≥3 healthcare consultations without detection; the most common missed diagnosis was coarctation of the aorta, attributed to failure to perform four-limb blood pressure measurement.³⁰ Task-shifting to non-physician clinicians (nurses, clinical officers) was evaluated in two studies from Malawi and Kenya, demonstrating that after brief training, these cadres could achieve 74–81% sensitivity for detecting critical CHD using pulse oximetry and simplified clinical algorithms.^35,42

Socioeconomic Barriers

Financial and geographical barriers were universally cited, with 41 studies (91.1%) identifying them as major determinants of delayed presentation. Direct medical costs—echocardiography fees ranging from US$15 to US$120—exceeded median monthly household health expenditure in all LMIC settings examined.^{6,8,12,16,19,20,34,36,44} Indirect costs, particularly transportation and lost wages for accompanying caregivers, were proportionally even more burdensome; a 2025 Vietnamese study calculated that families spent 2.3 times their monthly income on a single diagnostic trip to Hanoi.⁴⁸ Geographical inaccessibility was quantified in seven studies: mean one-way travel time to the nearest facility offering pediatric echocardiography ranged from 4.2 hours in Indonesian Java to 27 hours in rural Ethiopia.^{10,13,21,23,29,32,46} Gender bias was explicitly examined in four South Asian studies, which consistently found that girls experienced significantly longer diagnostic delays than boys (median difference 11–24 months), attributable to lower parental health-seeking intent for female offspring.^4,15,19,33

Evidence for Screening Interventions

Pulse Oximetry Screening

Twelve studies published between 2020 and 2025 evaluated the performance of neonatal pulse oximetry screening (POS) for critical CHD in LMIC settings.^{11,17,22,25,28,35,38,40,42,43,45,47} Pooled sensitivity ranged from 76% to 93%, specificity consistently exceeded 99.4%, and false-positive rates (0.05–0.3%) were comparable to HIC benchmarks. However, implementation effectiveness was severely constrained by health system frailties. In a 2024 Pakistani implementation trial spanning 12 public hospitals, only 38% of neonates underwent POS prior to discharge; of those screening positive, just 41% successfully completed confirmatory echocardiography due to absent referral pathways and inability to locate families post-discharge.²⁸ Conversely, a 2025 Kenyan study that integrated POS with community health worker home visits achieved 89% screening coverage and 73% referral Completion, demonstrating feasibility when contextualized within existing maternal–child health platforms.³⁵

Emerging Technologies

Three studies explored handheld, battery-powered echocardiography devices operated by non-specialist clinicians following focused training.^7,24,41 Diagnostic accuracy for detecting moderate-to-severe CHD lesions ranged from 82% to 91% compared with comprehensive echocardiography; image interpretability was compromised in 14% of cases, predominantly due to suboptimal acoustic windows. Telemedicine-facilitated remote interpretation of echocardiograms acquired by peripheral providers was evaluated in two Indian studies, demonstrating 94% concordance with on-site expert reads and reducing mean diagnostic confirmation time from 63 days to 4 days.^18,33 Artificial intelligence (AI) algorithms for automated CHD detection from echocardiographic images were reported in one 2025 proof-of-concept study from Thailand, achieving area under the receiver operating characteristic curve (AUC) of 0.91 for binary classification of hemodynamically significant lesions; however, external validation and integration into clinical workflows remain nascent.⁴⁵

Discussion

This systematic review, synthesizing 45 peer-reviewed investigations published between 2019 and 2025, provides the most comprehensive contemporary account of undiagnosed congenital heart disease across low- and middle-income countries. The findings confirm that diagnostic delay remains not an exceptional occurrence but the prevailing norm for the majority of affected children in resource-limited settings. With median diagnostic ages extending to 48 months for simple a cyanotic lesions and the persistence of Isenmenger syndrome in nearly one-sixth of delayed left-to-right shunt presentations, the evidence collectively portrays a health system failure of profound proportions. However, beyond merely cataloguing the magnitude of this failure, the present synthesis permits—indeed demands—a deeper interrogation of the structural, professional, and socioeconomic architectures that sustain the diagnostic gap, and an appraisal of whether contemporary innovations offer genuine promise or merely perpetuate the cycle of underachievement.

The Diagnostic Gap: Interpreting the Persistence of Preventable Delay

That children in LMICs are diagnosed later than their HIC counterparts is neither novel nor, in isolation, instructive. What renders the current data deeply troubling is the absence of measurable improvement over the six-year study window. Studies published in 2024 and 2025 report diagnostic delays statistically indistinguishable from those published in 2019, despite parallel advances in portable technology, global awareness, and advocacy.^{4,13,19,21,28} This stagnation demands explanation. One interpretation—favoured in much of the grey literature—implicates insufficient resource allocation; yet the persistence of delay in upper-middle-income countries such as Indonesia and South Africa, where echocardiography machines are comparatively abundant, suggests that resource availability is necessary but not sufficient.^13,32 A more nuanced explanation emerges from the qualitative and health systems components of included studies: diagnostic pathways are fragmented, lacking explicit protocols for newborn assessment, referral, and feedback loops between primary and tertiary levels.^9,17,29,38 In essence, CHD diagnosis in LMICs operates as a passive, opportunistic event rather than an active, systematic process. Children are diagnosed not when screening occurs, but when symptoms compel families to navigate labyrinthine referral pathways, by which point irreversible complications have frequently already accrued.

This distinction between availability and accessibility is critical. An echocardiography machine stationed in a tertiary hospital 300 kilometers from a rural community is, for that community, diagnostically non-existent. The geographical maldistribution documented across 34 studies—with 68% of pediatric echocardiography capacity concentrated in capital cities—renders the concept of national “coverage” statistically true but operationally meaningless.^27,39,46 Moreover, even when families successfully reach referral centers, they encounter supply-side rationing disguised as clinical prioritization: in several cohorts, children with simple defects were placed on diagnostic waiting lists exceeding 12 months, predicated on the erroneous assumption that such lesions are “benign” and can await intervention.^6,15,34 This ignores the well-established natural history of untreated shunt lesions, wherein volume overload progressively induces myocardial dysfunction and pulmonary vascular remodeling. The diagnostic gap, therefore, is not merely a temporal interval but a therapeutic opportunity cost measured in irreversible pathology.

Comparative Analysis: Quantifying the Divide with High-Income Countries

Contextualizing LMIC diagnostic performance against HIC benchmarks illuminates the true depth of inequity. Contemporary HIC registries report median CHD diagnosis ages of 2–7 days for critical lesions and 1.5–3 months for a cyanotic defects, with population-wide newborn pulse oximetry achieving pre-discharge detection rates exceeding 90%.¹⁸ In the United Kingdom, the National Congenital Heart Disease Audit documents that 97% of children with coarctation of the aorta are diagnosed within one year; in the LMIC studies reviewed, coarctation was the lesion most frequently missed, with median diagnostic ages ranging from 14 to 48 months.^20,30,41 This disparity translates directly into differential survival. HIC infant mortality from CHD now approaches zero for most defect subtypes, whereas in LMICs, pre-operative mortality among late-diagnosed infants remains 19–37%.^8,28,42

Yet this comparative exercise is not intended merely to indict LMIC health systems. Rather, it exposes a fundamental incongruity in global health prioritization. The diagnostic technologies that underpin HIC success—pulse oximeters, handheld echocardiography, telemedicine networks—are neither expensive nor technologically sophisticated. A standard pulse oximeter costs US$250–350, and several LMIC manufacturers now produce validated devices for under US$100. Handheld echocardiography probes, costing US$4,000–8,000, approximate the price of a mid-range laptop computer. The barrier, therefore, is not the cost of the technology per se, but the absence of health system architectures capable of deploying it at scale. This reframing shifts the explanatory burden from technological scarcity to implementation failure—a failure of policy, governance, and health workforce strategy rather than of absolute poverty.

Deconstructing Barriers: Why Do They Persist and How Do They Operate?

Institutional barriers—the absence of echocardiography at peripheral levels, non-functional equipment, lack of consumables—are frequently attributed to underfunding. However, the 2019–2025 literature reveals a more complex etiology. In several West African and Southeast Asian studies, echocardiography machines donated through international aid programmed were non-operational within two years due to expired service contracts, unavailable replacement transducers, or lack of trained biomedical engineers.^14,26,47 The charitable medical device donation model, whilst well-intentioned, systematically neglects the total cost of ownership, creating a cycle of dependency and eventual obsolescence. Furthermore, procurement decisions are often made at central level without consultation with pediatric cardiology services, resulting in the purchase of adult-focused machines lacking pediatric probes or software packages for congenital lesion quantification.^9,38

Professional barriers extend beyond absolute workforce numbers to encompass skill maldistribution and inadequate pre-service training. The reported pediatric cardiologist density of 0.12–1.8 per million population in LMICs is, in isolation, an insurmountable constraint; even if every cardiologist worked exclusively on CHD diagnosis, population-level screening would be impossible.^28,38 Yet the studies reviewed demonstrate that non-specialist clinicians can be trained to perform reliable CHD screening. Kenyan and Malawian task-shifting initiatives achieved 74–81% sensitivity for critical CHD detection using pulse oximetry and simplified clinical algorithms after only two days of training.^35,42 This suggests that the bottleneck is not the impossibility of skill transfer but the resistance to formal task-shifting within professional hierarchies and regulatory frameworks. Pediatricians and adult cardiologists in several contexts expressed reluctance to delegate echocardiography acquisition to nurses or clinical officers, citing concerns regarding diagnostic accuracy and medicolegal liability—concerns that, whilst understandable, perpetuate the very diagnostic delays that tertiary specialists are too few to address individually.^11,33

Socioeconomic barriers, though universally acknowledged, are frequently conceptualized as immutable “contextual factors”. The 2019–2025 evidence challenges this passivity. Several studies demonstrate that demand-side financial interventions—voucher schemes for transportation, elimination of echocardiography user fees, conditional cash transfers—can significantly shorten diagnostic delays.^16,31,44 A 2025 Indian study reported that providing free bus passes and waiving diagnostic fees reduced mean time from referral to echocardiography from 63 to 19 days and increased completion rates from 41% to 78%.³³ Yet such interventions remain exceptional rather than institutionalized. Moreover, gender discrimination in diagnostic access—consistently documented in South Asia—is not an immutable cultural artefact but a modifiable health system inequity. When diagnostic services are made universally available without point-of-care charges, the sex differential in referral completion narrows substantially.^4,19 The persistence of socioeconomic barriers, therefore, reflects failure to design health systems that actively counteract known inequities rather than passive acceptance of them.

Critical Appraisal of Proposed Solutions: Pulse Oximetry and Tele-Echocardiography

Neonatal pulse oximetry screening has been advocated for LMIC adoption with near-evangelical fervour. The 2020–2025 evidence confirms its technical performance: sensitivity 76–93%, specificity >99.4%, and false-positive rates comparable to HIC benchmarks.^{11,17,22,25,28,35,38,40,42,43,45,47} Yet the implementation studies reveal a sobering reality: technical accuracy does not guarantee programmed effectiveness. In Pakistan, despite successful POS introduction, only 38% of eligible neonates were screened, and of those screening positive, fewer than half completed confirmatory echocardiography.²⁸ The missing component was not a better oximeter but functional referral pathways. POS identifies a neonate with possible critical CHD; it does not transport that neonate to a cardiology centre, nor does it ensure that echocardiography is available upon arrival, nor does it overcome the family’s financial constraints. The uncritical promotion of POS as a standalone intervention risks medicalizing a health system problem—reducing a complex, multi-layered failure to a technological quick fix. The Kenyan study demonstrating that POS effectiveness tripled when coupled with community health worker follow-up illustrates that screening is only as effective as the system into which it is inserted.³⁵

Tele-echocardiography has similarly attracted enthusiasm. The two Indian studies reporting 94% concordance between peripheral operator-acquired images and central expert interpretation, with reduction in diagnostic confirmation time from 63 days to 4 days, are genuinely encouraging.^18,33 Yet scalability questions persist. Tele-echocardiography requires reliable internet connectivity, a cadre of peripheral providers trained in image acquisition, and a critical mass of centrally located experts willing to provide sustained remote reporting. In the Indian studies, the peripheral providers were hospital-based physicians with prior ultrasound exposure; whether similar accuracy could be achieved by nurse-midwives in rural sub-Saharan Africa remains unknown. Furthermore, the sustainability of expert goodwill—the Indian tele-echocardiography service was provided pro bono by academic cardiologists—is uncertain outside research contexts. Nevertheless, tele-echocardiography represents a fundamentally different paradigm from POS: it does not merely flag suspected disease but provides a definitive anatomical diagnosis, enabling immediate surgical planning. As telecommunications infrastructure continues to improve across LMICs, tele-echocardiography may transition from an innovative pilot to a scalable platform.

Artificial intelligence for automated CHD detection, reported in one 2025 proof-of-concept study,⁴⁵ remains premature for policy consideration. The reported AUC of 0.91, whilst impressive, was derived from a single-center, high-prevalence cohort with substantial verification bias. External validation, regulatory approval, and integration into clinical workflows will require several additional years. However, the potential of AI to democratize echocardiography interpretation—enabling non-expert operators to obtain instantaneous, reasonably accurate diagnostic probabilities—merits sustained research investment.

Research Gaps: What Remains Unknown and Why This Review Matters

This review consolidates existing evidence but also exposes critical knowledge deficits. First, the geographical coverage of primary research is strikingly uneven. No eligible studies were identified from Central Asia, Eastern Europe, Francophone West Africa, or most of Latin America. The diagnostic experience of children with CHD in these regions remains entirely uncharacterized, impeding global advocacy and resource allocation. Second, the longitudinal outcomes of children diagnosed late in LMICs are poorly documented. Whilst several studies report pre-operative mortality, almost none provide neurodevelopmental follow-up beyond hospital discharge. The 2025 Indian cohort study demonstrating cognitive impairment in late-repaired children is a singular exception;²³ whether such deficits are ameliorable by post-operative enrichment programmed or early intervention services is unknown. Third, the cost-effectiveness of diagnostic interventions—POS, tele-echocardiography, task-shifting—has been modelled but seldom measured using empirical health system data.¹⁵ Without robust economic evaluations, Ministries of Health lack the evidence required to prioritize CHD screening against competing child health interventions. Fourth, and perhaps most fundamentally, implementation science research—studies examining not only whether an intervention works but how to embed it sustainably within fragile health systems—remains nascent. Only two of the 45 reviewed studies employed quasi-experimental designs to evaluate implementation strategies;^35,42 the remainder were observational or cross-sectional. This methodological imbalance limits the actionable guidance this review can provide beyond identifying barriers.

This review fills these gaps not by supplying missing data—it cannot—but by systematizing existing knowledge into a coherent framework that distinguishes established facts from areas of uncertainty. It demonstrates that the diagnostic gap is not a unitary phenomenon but a constellation of distinct, context-specific failures, each potentially amenable to targeted intervention. It refutes the nihilistic view that LMIC diagnostic delay is inevitable, whilst cautioning against the technological solutionism that would substitute devices for health system strengthening. It provides policymakers with a taxonomy of barriers and a menu of evidence-informed strategies—from pulse oximetry to task-shifting to demand-side financing—that can be combined according to local epidemiology, infrastructure, and workforce capacity.

Future Directions: From Description to Transformation

The trajectory of CHD diagnosis in LMICs over the next decade will be determined not by the invention of new technologies but by the political and administrative will to implement what is already known. The evidence reviewed here supports several clear imperatives. First, CHD screening must be integrated into existing maternal and child health platforms rather than established as vertical programmed. Neonatal pulse oximetry should be bundled with routine post-natal checks, growth monitoring, and immunization contacts, leveraging the high coverage of these platforms to achieve population-level reach. Second, task-shifting must be formalized through regulatory reform, competency-based training curricula, and career progression pathways for non-specialist clinicians acquiring echocardiography skills. The current model—whereby a pediatric cardiologist spends 30 minutes performing an echocardiogram that a trained nurse could acquire in 15 minutes for subsequent remote interpretation—is neither efficient nor scalable. Third, demand-side barriers must be actively dismantled through elimination of point-of-care charges for pediatric echocardiography, provision of transport subsidies, and community health worker engagement to counteract gender bias and fatalistic health beliefs. These are not welfare gestures but cost-effective investments; the cost of diagnosing a CHD case before the onset of Isenmenger syndrome is substantially lower than the cost of managing lifelong disability or providing palliative care. Fourth, national CHD registries should be established or strengthened to track diagnostic timing, surgical outcomes, and loss to follow-up, enabling continuous quality improvement and accountability.³⁶

Author’s Interpretation: Bridging the Evidence–Practice Gap

The synthesis of 45 studies reveals a recurring and troubling pattern: the persistence of diagnostic delay despite decades of awareness and the availability of low-cost screening technologies. In my interpretation, this reflects a fundamental misalignment between global health rhetoric and operational reality. The proliferation of narrative reviews and policy briefs advocating for pulse oximetry screening has not been matched by parallel investments in the health system architecture required to translate screening into diagnosis. An oximeter without a functional referral pathway, an echocardiography machine without a trained sonographer, and a donated device without a service contract are not tools—they are symbols of performative commitment.

I contend that the diagnostic gap is sustained by three interconnected failures. First, epistemic inertia: the persistent privileging of tertiary, high-technology interventions over primary care strengthening, despite evidence that task-shifting and decentralization are more cost-effective for population-level diagnosis. Second, regulatory resistance: professional hierarchies that obstruct the delegation of diagnostic tasks to non-physician clinicians, preserving specialty exclusivity at the expense of patient access. Third, donor fragmentation: the proliferation of short-term, project-based funding cycles that preclude the sustained health system strengthening necessary for durable change.

My interpretation of the evidence is that technological innovation has outpaced health system adaptation. The tools to diagnose CHD in newborns exist; what is absent is the collective will to embed them within the routine workflows of maternal and child health programmed. This review thus reframes the diagnostic gap not as a problem of discovery but as a problem of delivery.

Strengths and Limitations of This Review

This systematic review possesses several methodological strengths. It adheres to PRISMA 2020 guidelines, employs a comprehensive search strategy across four major databases, and applies transparent eligibility criteria with independent screening and data extraction. The restriction to studies published between 2019 and 2025 ensures contemporary relevance, and the inclusion of 45 studies spanning 24 LMICs across four world regions provides broad geographical representation. The use of the Newcastle–Ottawa Scale for quality assessment enhances the rigour of evidence synthesis, and the narrative approach permits integration of diverse study designs and outcome measures.

Several limitations must be acknowledged. Despite comprehensive searching, the review is restricted to English‑language publications, which may introduce language bias and exclude relevant studies published in French, Spanish, Portuguese, or Arabic. The marked geographical heterogeneity—with no eligible studies identified from Central Asia, Eastern Europe, Francophone West Africa, or most of Latin America—limits the generalizability of findings to these under‑represented regions. The majority of included studies employed cross-sectional or retrospective designs, which are susceptible to selection bias and confounding; only two quasi-experimental implementation studies were identified. Furthermore, substantial heterogeneity in outcome definitions, diagnostic delay thresholds, and barrier categorization precluded meta-analysis. Finally, the review synthesizes published data only and does not include grey literature or unpublished programmed reports, which may harbor additional implementation insights.

Conclusion

This systematic review, synthesizing 45 peer-reviewed studies published between 2019 and 2025, provides unequivocal evidence that undiagnosed congenital heart disease in low‑ and middle‑income countries represents a persistent and preventable public health crisis. The findings demonstrate that diagnostic delay remains the norm rather than the exception for the majority of affected children in resource‑limited settings, with median ages at diagnosis extending to 48 months for simple a cyanotic lesions and the prevalence of Eisenmenger syndrome—a condition almost eradicated in high‑income countries—still affecting 15.8% of patients with delayed left‑to‑right shunt repair. Pre‑operative mortality among children with critical CHD diagnosed after infancy continues to range between 19% and 37%, a tragic toll that is almost entirely avoidable.

The central contribution of this review lies in its systematic deconstruction of the diagnostic gap into three discrete, modifiable domains—institutional, professional and socioeconomic—and its critical appraisal of the evidence supporting each proposed solution. Contrary to the prevailing narrative that attributes diagnostic delay solely to absolute resource scarcity, our analysis reveals that the most formidable obstacles are health system frailties rather than technological deficits. The concentration of echocardiography capacity in urban tertiary centers, the non‑functionality of donated equipment due to absent maintenance contracts, the underutilization of non‑specialist clinicians through regulatory resistance to task‑shifting, and the toleration of point‑of‑care charges that exclude the poor are failures of policy, governance and health workforce strategy. Each of these failures is amenable to intervention.

Critically, this review demonstrates that effective, low‑cost diagnostic tools are no longer hypothetical. Neonatal pulse oximetry screening achieves sensitivity and specificity comparable to high‑income country benchmarks when coupled with functional referral pathways and community health worker follow‑up.^11,28 Tele‑echocardiography, supported by task‑shifting to trained non‑physician clinicians, can reduce diagnostic confirmation time from weeks to days and achieve diagnostic accuracy exceeding 90%.^18,33 Demand‑side financial interventions—elimination of user fees, transport subsidies, conditional cash transfers—have been shown to double referral completion rates and significantly narrow gender‑based disparities in diagnostic access.^16,19 The evidence base for what works in LMIC settings is no longer nascent; it is sufficiently mature to inform large‑scale implementation.

Nevertheless, this review also exposes critical knowledge deficits that must be addressed to accelerate progress. The absence of primary data from entire regions—including Francophone West Africa, Central Asia, Eastern Europe and most of Latin America—severely constrains global advocacy and resource allocation. The longitudinal neurodevelopmental outcomes of children who undergo late surgical repair in LMICs remain grossly under‑studied, with only a single prospective cohort examining cognitive function beyond hospital discharge.²³ Economic evaluations of screening and diagnostic interventions using empirical health system data are urgently needed to guide priority‑setting within constrained budgets. Most fundamentally, implementation science research—rigorous investigation of how to embed evidence‑based interventions into fragile health systems and sustain them at scale—remains in its infancy, with only two quasi‑experimental studies identified in this review.^11,42 Closing these knowledge gaps must be a research priority for the coming decade.

The Implications for policy and practice are unambiguous. Ministries of Health in LMICs must recognize that congenital heart disease is not a rare, esoteric condition requiring super‑specialist intervention at every level, but a common, readily detectable anomaly for which cost‑effective screening and diagnostic strategies exist. The integration of neonatal pulse oximetry into routine postnatal care, the formalization of task‑shifting through regulatory reform and competency‑based training, and the systematic removal of financial barriers to diagnostic services are not aspirational goals but achievable targets supported by high‑quality evidence. International donors and development partners must transition from episodic equipment donation to sustained health system strengthening partnerships that address total cost of ownership, workforce development and referral network functionality. Professional cardiology societies must embase task‑shifting not as a dilution of specialty standards but as the only ethically defensible strategy to extend diagnostic access to underserved populations.

The ethical Imperative is clear. Every child born with congenital heart disease, regardless of postal code, possesses the same fundamental right to timely diagnosis and curative intervention. The diagnostic gap documented in this review is not an inevitability of poverty; it is the product of specific, remediable failures in health system design and political prioritization. The technologies are affordable, the workforce strategies are validated, and the implementation models are tested. The question that remains is not whether we possess the knowledge or the tools, but whether the global health community possesses the collective resolve to deploy them with the urgency and scale that the victims of this inequity so unequivocally deserve.