Right Bundle Branch Block in Acute Myocardial Infarction Treated by Primary Coronary Angioplasty and Stenting

Abstract

Patients with right bundle branch block (RBBB) in acute myocardial infarction (AMI) have a significantly higher mortality rate even with the advent of thrombolytic therapy. This study was undertaken to assess the impact of primary percutaneous transluminal coronary angioplasty (PTCA) and stenting on the outcome of patients with RBBB in AMI. A total of 600 patients with AMI who underwent primary PTCA and stenting (rate: 61%) < 12 hours of onset were studied. A 12-lead ECG was obtained at least every 6 hours. Serial creatine kinase was measured, and left ventricular ejection fraction was obtained during the hospital stay. Among 600 patients with AMI, 94 patients (15.7%) had RBBB; it was persistent in 31 (33%) and transient in 63 (67%). In-hospital mortality rate was 7.3% in patients without RBBB, 7.9% in transient RBBB, and 25.8% in persistent RBBB (p < 0.02). The incidence of heart failure was 26.5% in those without RBBB, 34.9% in transient RBBB, and 58.1% in persistent RBBB (p < 0.001). There was no significant difference among these 3 groups in ventricular arrhythmias and complete atrioventricular block. Peak creatine kinase was 3,214+/-2,293 U/L in those without RBBB, 4,558+/-3,316 U/L in transient RBBB (p < 0.001), and 5,635+/-3,920 U/L in persistent RBBB (p < 0.001). Left ventricular ejection fraction was 50+/-11% in those without RBBB, 47+/-11% in transient RBBB (p < 0.05), and 42+/-13% in persistent RBBB (p < 0.001). Patients with AMI treated by primary PTCA and stenting had an increased incidence of transient RBBB, especially following reperfusion therapy, although the clinical outcome was similar to that of those without RBBB. In contrast, there was no satisfactory improvement in clinical outcomes in those with persistent RBBB.