Evolution and Persistence of Electrocardiographic Conduction Abnormalities Following Acute Coronary Syndrome: A Prospective Observational Study

Background: Conduction abnormalities are important electrical complications of acute coronary syndrome (ACS) and may reflect ischemic or structural injury to the specialized cardiac conduction system. Their clinical course may vary according to the level of conduction-system involvement, infarct territory, ventricular function, and culprit coronary artery. Data describing the longitudinal persistence of individual conduction abnormalities after ACS remain limited. Objective: To evaluate the clinical profile, electrocardiographic spectrum, echocardiographic characteristics, angiographic correlates, in-hospital outcomes, and short-term evolution of conduction abnormalities in patients with ACS. Methods: This prospective observational study was conducted in a tertiary-care teaching hospital from January 2025 to June 2026. Consecutive eligible patients with ACS and conduction abnormalities were evaluated clinically and electrocardiographically. Echocardiography and coronary angiography were performed according to the study protocol and clinical circumstances. Conduction abnormalities were documented at baseline and their evolution was assessed at one and three months. Categorical variables were expressed as frequencies and percentages, and associations between categorical variables were assessed using the chi-square test. A two-sided P value <0.05 was considered statistically significant. The final analysed cohort comprised 177 patients. Results: The mean age was 61.83 ± 11.83 years, and 122 patients (68.9%) were male. Anterior myocardial infarction was the predominant presentation (94/177; 53.1%). LAHB was the most frequent baseline conduction abnormality (42/177; 23.7%), followed by qRBBB (37/177; 20.9%), first-degree AV block (24/177; 13.6%), and CHB (23/177; 13.0%). LVEF was 31–40% in 72 patients (40.7%), while right ventricular involvement was present in 29 (16.4%). During follow-up, all patients with junctional rhythm, sinus bradycardia, and Mobitz I AV block recovered. First-degree AV block persisted in 22/24 patients (91.7%) at one month and 20/24 (83.3%) at three months. LAHB persisted in 35/42 (83.3%) and 31/42 (73.8%), respectively, while LBBB persisted in 9/12 (75.0%) and 7/12 (58.3%). qRBBB persisted in 24/37 (64.9%) and 18/37 (48.6%). Among patients with CHB, 6/23 (26.1%) died during hospitalization and 17/23 (73.9%) recovered. Among 155 patients in the culprit-vessel analysis, LAD was the culprit artery in 95 (61.3%) and RCA in 50 (32.3%). CHB was predominantly associated with RCA involvement, whereas qRBBB and bifascicular block were associated with LAD involvement in the analysed subgroup. Conclusion: Conduction abnormalities accompanying ACS demonstrated heterogeneous clinical trajectories. Although high-grade abnormalities such as CHB were associated with substantial acute mortality, several other conduction abnormalities demonstrated marked persistence after the acute event. The specific conduction abnormality, infarct territory, ventricular function, culprit artery, and longitudinal ECG evolution should therefore be considered together when assessing patients with ACS and conduction disturbances.