Prevalence, characteristics and significance of ventricular tachycardia (three or more complexes) detected with ambulatory electrocardiographic recording in the late hospital phase of acute myocardial infarction.

A 24 hour electrocardiographic recording was performed before hospital discharge in 430 patients who survived the cardiac care unit phase of acute myocardial infarction. Fifty patients (11.6 percent) had ventricular tachycardia, that is, three or more consecutive ventricular complexes. In 25 (50 percent) of these 50 patients, there was only one episode of ventricular tachycardia and, in 15 patients (30 percent), the longest run of ventricular tachycardia was only three consecutive ventricular premature depolarizations. The average rate of tachycardia was 119/min. Tachycardia rarely started with R on T ventricular premature complexes (4 of 1,370 episodes in 50 patients). There was no difference between the groups with and without ventricular tachycardia with respect to age and sex, but the patients with tachycardia had a significantly greater prevalence of previous myocardial infarction, left ventricular failure in the cardiac care unit, atrial fibrillation, ventricular tachycardia or ventricular fibrillation in the cardiac care unit and significantly more frequent use of digitalis and diuretic and antiarrhythmic drugs at the time of hospital discharge. The group with tachycardia had a 38.0 percent 1 year mortality rate compared with the rate of 11.6 percent in the group without tachycardia. Ventricular tachycardia had a strong association with 1 year mortality (odds ratio = 4.7). Although ventricular tachycardia had a significantly association with many other postinfarction risk factors, it was still significantly associated with the 1 year mortality (p less than 0.05) when other important risk variables were controlled statistically using a multiple logistic regression model. The 36 month cumulative mortality rate was 54.0 percent in the group with ventricular tachycardia compared with 19.4 percent in the group without tachycardia.