MALIGNANT PREMATURE VENTRICULAR BEATS IN AMBULATORY PATIENTS

The characteristics of premature ventricular beats [PVB] predisposing to ventricular tachycardia or fibrillation were assessed by 24 h ambulatory monitoring and maximal treadmill exercise testing in 339 cardiac patients with PVB. PVB were divided into early (Q-PVB < QT), late (within the last 20% of the cardiac cycle), and mid-cycle. Ventricular tachycardia was recorded in 45 patients and ventricular fibrillation, in 3. The frequency of ventricular tachycardia or fibrillation was 32% in patients with late, 16% in patients with early, and 7% in patients with mid-cycle PVB (P < 0.05). Patients with frequent (> 10/min) multiformed PVB had a frequency of ventricular tachycardia or fibrillation of 44%, while only 13% of patients with frequent uniformed PVB had ventricular tachycardia (P < 0.05). Ambulatory patients with ventricular tachycardia or fibrillation have frequent multiformed PVB, and the ventricular tachycardia or fibrillation is usually triggered by late PVB.