Association of digitalis therapy with mortality in survivors of acute myocardial infarction: observations in the Beta-Blocker Heart Attack Trial

Abstract

The influence of digitalis therapy on survivors of acute myocardial infarction was examined in the placebo-treated patients from the Beta-Blocker Heart Attack Trial (BHAT). Two hundred fifty (13%) of the 1,921 placebo-treated patients were receiving digitalis at the time of randomization. Patients receiving digitalis differed from those not receiving digitalis in such baseline characteristics as age, prior history of heart failure, prior myocardial infarction and angina pectoris. They also experienced a higher proportion of in-hospital complications including pulmonary edema, persistent hypotension, atrial fibrillation and heart failure in addition to a greater prevalence of complex ventricular premature beats. The total mortality rate over a mean 25 month follow-up period for digitalis-treated patients was 20.4% compared with 8.2% for patients not receiving digitalis; the odds ratio was 2.87 (p less than 0.05). When the mortality rates were adjusted for heart failure and ventricular premature beat complexity, patients receiving digitalis again demonstrated a higher mortality rate, although the adjusted odds ratio was now lower (1.70). When the patients receiving or not receiving digitalis were compared by a multiple logistic regression analysis adjusting for 17 independent variables predictive of mortality, the use of digitalis was no longer independently predictive of total mortality (adjusted odds ratio 1.07). These data indicate that patients receiving digitalis had more extensive cardiovascular disease and greater morbidity than patients not receiving digitalis. Their subsequent higher mortality rate was probably related to these factors rather than to digitalis therapy.