Digoxin and mortality in survivors of acute myocardial infarction: observations in patients at low and intermediate risk. The SPRINT Study Group. Secondary Prevention Reinfarction Israeli Nifedipine Trial.

Abstract

Controversy surrounds the safety of digoxin use in patients recovering from acute myocardial infarction. Previous observations yielded contradictory conclusions. To determine whether digoxin therapy is associated with increased mortality in patients recovering from acute myocardial infarction, we analyzed data from 1731 survivors of acute myocardial infarction enrolled in the Secondary Prevention Reinfarction Israeli Nifedipine Trial (SPRINT), from which patients with severe heart failure were excluded. At the time of hospital discharge, 175 patients (10%) were taking digoxin. Mortality over 1 year after infarction was significantly higher in patients treated with digoxin than in patients who were not receiving digoxin [27 of 175 (15%) vs. 60 of 1556 (4%); p < 0.0001]. Digoxin administration was associated with increased mortality in several subsets of patients. Since patients treated with digoxin had baseline characteristics predictive of mortality more frequently than their counterparts, we adjusted for these differences. Multivariate analysis performed by the Cox proportional hazards model identified treatment with digoxin as an independent determinant associated with increased death during the first year after myocardial infarction [relative risk (RR) 2.8; 90% confidence interval (CI) 1.8-4.2]. Subgroup multivariate analysis indicated digoxin as an independent predictor of first year death in 464 patients who developed heart failure during their hospital stay (RR 2.3; 90% CI 1.3-4.0), as well as among 1267 patients who did not (RR 3.4; 90% CI 1.7-6.9). The present study suggests a significant excess mortality associated with digoxin therapy after myocardial infarction. The increased mortality risk may be related to unidentified variables associated with the severity of disease in patients treated with digoxin. However, our findings raise concern that the administration of digoxin may contribute to increased mortality in survivors of acute myocardial infarction.