ACUTE MYOCARDIAL-INFARCTION AND COMPLETE BUNDLE-BRANCH BLOCK AT HOSPITAL ADMISSION - CLINICAL CHARACTERISTICS AND OUTCOME IN THE THROMBOLYTIC

Objectives. We sought to assess the outcome of patients with acute myo cardial infarction (MI) and bundle branch block in the thrombolytic er a. Background. Studies of patients with acute MI and bundle branch blo ck have reported high mortality rates and poor overall prognosis. Meth ods. The North American population with acute MI and bundle branch blo ck enrolled in the Global Utilization of Streptokinase and t-PA [tissu e-type plasminogen activator] for Occluded Coronary Arteries (GUSTO-I) trial was matched by age and Killip class with an equal number of GUS TO-I patients without conduction defects. Results. Of all 26,003 North American patients in GUSTO-I, 420 (1.6%) had left (n = 131) or right (n = 289) bundle branch block. These patients had higher 30-day mortal ity rates than matched control subjects (18% vs. 11%, p = 0.003, odds ratio [OR] 1.8) and were more likely to experience cardiogenic shock ( 19% vs. 11%, p = 0.008, OR 1.78) or atrioventricular block asystole (3 0% vs. 19%, p < 0.012, OR 1.57) and to require ventricular pacing (18% vs. 11%, p = 0.006, OR 1.73). Bundle branch block also carried an ind ependent 53% higher risk for 30-day mortality, Thirty day mortality ra tes for patients with complete, partial and no reversion of the bundle branch block were 8%, 12% and 20%, respectively (two-tailed chi-squar e test for trend 5.61, p = 0.02, OR 0.34 for complete reversion, OR 0. 55 for partial reversion). Conclusions. Bundle branch block at hospita l admission in patients with acute MI predicts in hospital complicatio ns and poor short-term survival. (C) 1998 by the American College of C ardiology.