[Characterization and therapy of ventricular arrhythmias due to transient myocardial ischemic attacks in variant...

Forty-two patients with variant angina were studied by ambulatory ECG monitoring to determine the incidence and the characteristics of ventricular arrhythmias during ischemic attacks. Twenty-six patients had no ventricular arrhythmias in 633 ischemic attacks; 16 patients had ventricular arrhythmias in 116/586 ischemic attacks. The number of ischemic attacks per day and the magnitude of ST elevation were significantly (p less than 0.05) greater in patients with ventricular arrhythmias. Ventricular arrhythmias appeared at the onset or at the peak of ST elevation (first phase) in 17 ischemic attacks, during the resolution of ST elevation (second phase) in 43 attacks, during both the phases in 9 attacks. ST alternans appeared during 6 ischemic attacks with arrhythmias. Two episodes of ventricular fibrillation and 22 runs of ventricular tachycardia occurred during the first phase, 17 episodes of ventricular tachycardia were recorded during the second phase. Ventricular tachycardia of the second phase compared with ventricular tachycardias of the first phase were significantly (p less than 0.01) slower, uniform and initiated by a late premature beat. Incidence of arrhythmias of the second phase was strictly correlated with the duration of ischemic attacks. Nine patients who showed ventricular arrhythmias during the second phase of ischemic attacks were enrolled in a cross-over study to assess the antiarrhythmic effects of nifedipine (120 mg/day) and verapamil (480 mg/day). During treatment with nifedipine, the frequency of ischemic attacks declined by 85%, while the frequency of attacks with arrhythmias declined by 97% (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)