Time to Reversal of Complete Heart Block Complicating Acute Inferior Wall ST-Elevation Myocardial Infarction: An Observational Study

Abstract

Objectives: To determine the time required for the resolution of complete heart block (CHB) in patients presenting with acute inferior wall myocardial infarction (IWMI), and to evaluate whether delayed permanent pacemaker (PPM) implantation can safely be avoided. Methodology: This prospective observational study was conducted over 15 months at the National Institute of Cardiovascular Diseases, Karachi, Pakistan. Patients presenting within 24 hours of symptom onset with acute IWMI complicated by CHB and narrow QRS escape rhythm were included. Although stratification based on reperfusion strategy was planned, none of the patients received thrombolysis. Daily rhythm assessment was performed for 10 days or until spontaneous conduction recovery. Results: Ninety-six patients were enrolled (74% male). Temporary pacemaker (TPM) insertion was performed in 85 (88.5%) patients. Revascularization was achieved in 86 (89.6%) patients, predominantly through percutaneous coronary intervention (PCI). The right coronary artery (RCA) was identified as the culprit vessel in 77 (89.5%) cases. Atrioventricular (AV) node conduction recovered in 94 patients (97.9%) within 10 days. Conduction was restored in 56.3% by day 2, and 92% by day 5. Only two patients required PPM implantation by day 10. Revascularized patients showed significantly faster recovery (median 2 days) compared to those who were not revascularized (median 5 days; p < 0.001). Conclusion: At 72 hours, 78% of patients had regained AV conduction. Extending observation by an additional 48 hours allowed another 14.6% to avoid unnecessary PPM. These findings support a conservative approach of watchful waiting for up to 10 days, allowing sufficient time for spontaneous recovery in CHB associated with IWMI and minimizing unwarranted pacemaker implantation.