Temporal pattern of the effect of verapamil on myocardial reinfarction. DAVIT Study Group. Danish Verapamil Infarction Trial

The purpose of this study was to compare the effects of verapamil on early versus late reinfarction after an index myocardial infarction. A total of 1775 consecutive patients < 76 years of age, with acute myocardial infarction, included in the Danish Verapamil Infarction Trial II, were followed for 18 months. Reinfarctions during the observation period were retrospectively divided into the 50% earliest occurring and the 50% latest occurring (early and late reinfarction, respectively). Cox regression analysis was applied to assess the significance of clinical baseline variables and treatment group (verapamil vs. placebo) on early, late, and total reinfarction. One hundred and ninety-one reinfarctions were registered during the 18-month observation: 96 in the first 5 months (early) and 95 in the last 13 months (late). On univariate analysis verapamil significantly reduced the rate of total reinfarction (P = 0.04, hazard ratio [HR] = 0.77; 95% confidence Interval [CI] 0.58-1.03) and early reinfarction (P = 0.007, HR 0.56; 95% CI 0.37-0.86), but not late reinfarction (P = 0.99, HR = 1.05; 95% CI 0.70-1.56). In a multivariate model, only the rate of early reinfarction was reduced by verapamil (P = 0.012, HR = 0.59, 95% CI 0.39-0.90). Additionally, predictors of early and late reinfarction were quite different in this model. After an index myocardial infarction verapamil reduces the rate of early but not late reinfarction.