The significance of myocardial ischaemia and verapamil treatment on the prevalence of supraventricular tachyarrhythmias in patients recovering from acute myocardial infarction. Danish Study Group on Verapamil in Myocardial Infarction.

Abstract

Twenty-four hour Holter monitoring and symptom-limited exercise testing were carried out prior to discharge in 157 patients recovering from acute myocardial infarction. Supraventricular arrhythmias (SVT) during Holter monitoring were recorded in 15%, and ST segment depression during exercise in 27%. No association between exercise-provoked ischaemia and SVT was found in the late hospital phase of myocardial infarction. After the tests, patients were double-blindly randomized to treatment with verapamil 120 mg t.i.d. or placebo. One month after randomization 24 h Holter monitoring was repeated in 125 patients (verapamil = 63, placebo = 62). At one month a significantly increased incidence of SVT was found in the placebo group (25%) compared to the verapamil-treated patients (9%) (P = 0.04). The increased prevalence in the placebo group was mainly due to an increased incidence of SVT in patients with exercise-induced ischaemia (P = 0.03). This increment was blurred in the verapamil group. In conclusion, the prevalence of SVT increases during the first month after myocardial infarction. The increase is most pronounced in patients with residual myocardial ischaemia and seemed to be prevented by treatment with verapamil.