Impact of right bundle branch block in anterior ST-segment elevation myocardial infarction in the contemporary primary PCI era.

The presence of right bundle branch block (RBBB) has long been recognized as a risk factor for poor prognosis, particularly in patients with anterior ST-segment elevation myocardial infarction (STEMI). However, in the contemporary era of primary percutaneous coronary intervention (PCI), the prognostic significance of RBBB in anterior STEMI has not been fully clarified. This retrospective study aimed to investigate the association between RBBB and clinical outcomes in anterior STEMI patients treated with primary PCI. The primary endpoint was major adverse cardiovascular events (MACE), defined as a composite of all-cause death, non-fatal myocardial infarction, or readmission for heart failure. We included 632 patients and divided them into the RBBB group (n = 96) and non-RBBB group (n = 536). Patients with RBBB were older and had higher Killip class, lower systolic blood pressure, higher peak creatine kinase levels, and lower left ventricular ejection fraction. Proximal left anterior descending artery lesions and chronic total occlusion in non-culprit arteries were more frequent in the RBBB group. In-hospital MACE and mortality were significantly higher in patients with RBBB. During a median follow-up of 602 days, event-free survival was significantly lower in the RBBB group (log-rank p < 0.01). RBBB was independently associated with MACE after multivariable adjustment (hazard ratio 1.465, 95% confidence interval 1.005–2.136, p = 0.047). Even in the contemporary primary PCI era, RBBB with anterior STEMI is significantly associated with worse in-hospital and long-term outcomes. RBBB may reflect more extensive myocardial injury and serve as a practical marker for risk stratification, warranting careful management and closer follow-up.