Bundle Branch Block and Acute Myocardial Infarction: Treatment and Outcome

Objective - To study early diagnosis, treatment and outcome in patients with bundle branch block and clinically suspected acute myocardial infarction. Design - A prospective multicenter study including 14 Swedish coronary care units. The study included 257 consecutive patients with bundle branch block and clinical suspicion of acute myocardial infarction. Results - Left bundle branch block was present in 62% of patients and right bundle branch block in 38%. Thrombolytic treatment of acute myocardial infarction in the left and right bundle branch block was 16% and 36%, respectively. Of those undergoing thrombolytic therapy, 20% of patients with left and 13% with right bundle branch block did not develop an acute myocardial infarction. Patients with left bundle branch block had higher mortality rates than those with right bundle branch block. After one year there was no difference in mortality rates between patients with and those without acute myocardial infarction on admission. Conclusion - Patients with bundle branch block and suspected acute myocardial infarction receive suboptimal treatment. Thus better diagnostic regimes are needed to identify those patients with bundle branch block and acute myocardial infarction who are suitable for thrombolytic treatment.