Prognostic impact of right bundle branch block in acute anterior wall STEMI: A cross-sectional study

Background: Right bundle branch block (RBBB) in acute anterior wall ST-segment elevation myocardial infarction (AW-STEMI) may indicate extensive myocardial injury, yet its independent prognostic value remains uncertain.

Methods: We conducted a cross-sectional observational study at the Punjab Institute of Cardiology, Lahore, from January 2022 to June 2023. A total of 349 patients with AW-STEMI were stratified into two groups based on the presence or absence of RBBB on initial electrocardiogram. Baseline demographics, comorbidities, and reperfusion strategies were recorded. Primary outcome was in-hospital mortality. Secondary outcomes included cardiogenic shock, cardiac arrest, arrhythmias, complete heart block (CHB), post-MI angina, and duration of hospital stay. Logistic regression was used to adjust for confounding variables.

Results: RBBB was present in 50 patients (14.3%). Baseline age and comorbidities (hypertension, diabetes, CKD, dyslipidemia, prior MI) were similar across groups. Compared with non-RBBB patients, those with RBBB had lower mean LVEF (40.9% vs 45.7%, p < 0.001) and higher peak troponin-I levels (33.5 vs 24.3 ng/mL, p < 0.001). In-hospital mortality was significantly higher with RBBB (16% vs 5.7%, OR 3.16, 95% CI 1.28–7.78, p = 0.009). Cardiogenic shock (36% vs 16.4%, OR 2.67, p = 0.003) and arrhythmias (42% vs 19.7%, OR 2.95, p = 0.001) were also significantly increased. Although rates of cardiac arrest (16% vs 11.4%), CHB (12% vs 8%), and post-MI angina (24% vs 15.4%) were higher in RBBB, these differences did not reach statistical significance. Notably, all RBBB patients managed with thrombolysis or conservative therapy died, whereas primary PCI markedly improved survival.

Conclusion: RBBB in AW-STEMI is associated with higher in-hospital mortality, cardiogenic shock, and arrhythmias, reflecting greater hemodynamic instability. Primary PCI offers a significant survival benefit in this high-risk subgroup, underscoring the importance of urgent invasive management.

To be updated shortly..