Long-term prognosis in patients with bundle branch block complicating acute anteroseptal infarction.

In a previous study patients with bundle branch block complications acute anteroseptal infarction found to have a high incidence rate of sudden death and late ventricular fibrillation in the first 6 weeks after infarction. Forty-two such consecutive patients were therefore kept within the monitoring area during those 6 weeks. Eighteen (43 percent) of these 42 patients survived and were then followed up for an average of 13 months to assess long-term prognosis and to evaluate whether the in-hospital monitoring period should be extended over 6 weeks. In most of these 18 patients a bifascicular block developed in the acute stage of infarction and in 3 it progressed to transient high degree atrioventricular (A-V) block. Seven of the 18 survivors had potentially lethal complications during the first 6 weeks. Four of these seven underwent aneurysmectomy between 10 and 20 weeks after infarction, and one of them died of a surgical complication. Major cardiac events occurred in 3 of the 17 survivors. None of these patients died during the follow-up period. In one patient complete A-V block developed after aneurysm resection; this was the only patient treated with permanent pacing. Fifteen of the 17 patients were in functional class I or II. These results indicate that (1) patients with bundle branch block complicating acute anteroseptal infarction who survive the first 6 weeks after infarction have a good prognosis during the 1st year, and (2) extension of the in-hospital monitoring period is not necessary. The results further suggest that prophylactic permanent pacing does not affect prognosis in these patients.