Incidence of arrhythmias induced by isometric and dynamic exercise.

The incidence of arrhythmias during isometric sustained handgrip exercise and during dynamic graded bicycle exercise was compared in a group of 45 patients with various forms of heart disease on no antiarrhythmic therapy. Atrial arrhythmias were equally common during handgrip and bicycle exercise but ventricular arrhythmias were more frequent during handgrip exercise. Of the 45 patients, 38 per cent developed ventricular arrhythmias during isometric exercise, with ventricular tachycardia occurring in 15 per cent. During dynamic exercise 22 per cent of the 45 patients developed ventricular arrhythmias, with ventricular tachycardia occurring in 2 per cent. Patients with coronary artery disease and/or depressed left ventricular function developed twice the incidence of ventricular arrhythmias with isometric than with dynamic exercise. Thus, isometric exercise testing is of more value than dynamic exercise testing in unmasking latent ventricular arrhythmias in patients with heart disease.