The interaction between diltiazem and left ventricular function after myocardial infarction. Multicenter Diltiazem...

The interactions between diltiazem and three parameters of left ventricular function using cardiac death as the end point were investigated in 2,466 patients, aged 25-75 years, who were involved in the long-term diltiazem postinfarction trial. Indexes of left ventricular function included pulmonary congestion on chest x-ray, acute anterolateral Q wave myocardial infarction on electrocardiogram, and radionuclide ejection fraction. Pulmonary congestion and acute anterolateral infarction had significant (p less than 0.01) interactions with treatment allocation, and the third variable, ejection fraction, showed a similar trend (p less than 0.1). There was a diltiazem-related reduction in cardiac death (Cox hazard ratio, 0.76-0.86) for each of the parameters reflecting good ventricular function, and a significant diltiazem-related increase in cardiac death (Cox hazard ratio, 1.52-1.85) for each of the parameters associated with impaired function. Three-factor interactions highlighted the extremes of the favorable and adverse effects of diltiazem in subsets with unimpaired and impaired left ventricular function. These findings permit more appropriate selection of patients for the safe and effective administration of diltiazem to postinfarction patients.