Clinical, Electrocardiographic, Biochemical, and Echocardiographic Markers for Diagnosing Cardiac Dysfunction in Neonates with Hypoxic–Ischemic Encephalopathy: A Narrative Review

Background/Objectives: Hypoxic–ischemic encephalopathy (HIE) remains a leading cause of neonatal death and long-term neurodisability. Cardiovascular dysfunction commonly accompanies HIE and influences neurological recovery, yet it is difficult to recognize because conventional clinical signs correlate poorly with the myocardial function. This review summarizes the current evidence on cardiac dysfunction in neonates with HIE, with particular attention to the diagnostic tools used to evaluate cardiovascular function and the clinical outcomes associated with myocardial injury. Methods: We conducted a narrative review informed by a systematic, reproducible search of four databases (PubMed, Embase, Cochrane Library, and Web of Science) from 2000 to 2026, using a Population–Concept–Context framework to identify studies of term and near-term neonates (≥35 weeks gestation) with HIE or perinatal asphyxia reporting a measure of cardiac dysfunction (electrocardiographic, biomarker, echocardiographic, or clinical hemodynamic). Records were screened and selected using Covidence systematic review software; eligible studies were original, primary-data reports with a minimum sample size of 20 neonates. Findings were synthesized narratively and grouped thematically by diagnostic modality and clinical outcome. Results: Eighty-one studies met the pre-specified eligibility criteria following a systematic multi-database search and structured screening process. As a subset of included studies are secondary analyses or overlapping cohorts, an aggregate patient count is not reported. Reported prevalence of cardiac dysfunction varied widely with the definition applied, reaching 70–90% when multimodal assessment was used. Blood pressure, heart rate, urine output, and lactate were inconsistently reliable indicators of myocardial function, and ejection fraction and fractional shortening often remained normal despite injury. Tissue Doppler imaging and speckle-tracking strain appeared to be more sensitive, with impaired left ventricular global longitudinal strain associated with brain injury. The right ventricle was more commonly and severely affected, with reduced TAPSE, RV fractional area change, and RV strain associated with death or MRI-defined injury. Each additional 24 h of inotropic support was associated with increased odds of adverse short- and long-term outcomes by 14% and 12%, respectively. Conclusions: Cardiac dysfunction is common and prognostically important but remains underrecognized by the routine clinical assessment and cardiovascular monitoring. Multimodal monitoring centered on TnECHO, near infra-red spectroscopy, and specific biomarkers may enable earlier, physiology-based management.