Incidence, predictors, and outcomes of high-degree atrioventricular block complicating acute myocardial infarction treated with thrombolytic therapy

Background In the fibrinolytic era, several studies have suggested that the rate of atrioventricular block (AVB) in the setting of acute myocardial infarction (MI) is high and is associated with increased short-term mortality. We sought to delineate predictors of AVB and determine long-term mortality of patients developing AVB in the setting of ST-segment elevation MI (STEMI) treated with thrombolytic therapy. Methods We combined data on patients from 4 similar studies of STEMI. We identified independent predictors of AVB and compared the 6-month and 1-year mortality rates of patients with AVB (5251) to the rates of patients without AVB (70 742). Results The incidence of AVB was 6.9%. Significant independent predictors of AVB included inferior MI, older age, worse Killip class at presentation, female sex, enrollment in the United States, current smoking, hypertension, and diabetes. Adjusted mortality was significantly higher in patients with AVB than in patients without AVB within 30 days (OR 3.2, 95% CI 2.7-3.7), 6 months (OR 1.6, 95% CI 1.5-1.8), and 1 year (OR 1.5, 95% CI 1.3-1.6). For patients with AVB and inferior MI, mortality odds ratios (ORs) were 2.2 (95% CI 1.7-2.7), 2.6 (95% CI 2.4-2.9), and 2.4 (95% CI 2.2-2.6) within 30 days, 6 months, and 1 year, respectively. For patients with AVB and anterior MI, mortality ORs were 3.0 (95% CI 2.2-4.1), 3.5 (95% CI 3.1-3.8), and 3.3 (95% CI 3.0-3.7) within 30 days, 6 months, and 1 year, respectively. Conclusions In the thrombolytic era, AVB in the setting of STEMI is common and associated with higher mortality. Future studies should focus on determining therapies that are effective at reducing mortality rates in such patients.