The value of warning arrhythmias in the prediction of ventricular fibrillation within one hour of coronary occlusion. Experimental studies in the baboom

Abstract

Factors associated with the development of ventricular fibrillation after coronary artery ligation were studied in a subhuman primate (Cape Chacma baboon). In 25 or 66 per cent of 38 baboons, primary ventricular fibrillation occurred within the first hour after the onset of acute myocardial infarction. Increasing age, total heart weight, and the size of the infarct were directly related to the incidence of primary ventricular fibrillation. Anterolateral infarcts had the highest risk of ventricular fibrillation. Anteroseptal and posterior infarcts had the best survival rate for the first hour. Male baboons were more prone to develop ventricular fibrillation than were females. There was no definite progression from ventricular ectopic beats to ventricular fibrillation. In the presence of ventricular tachycardia (even when brief in duration), ventricular bigeminy, or R-on-T beats, ventricular fibrillation has to be expected from the time of onset of the arrhythmia till 30, 20, or 10 minutes have elapsed, respectively. Beyond these times, ventricular fibrillation did not develop during the experimental period. Conversely, the absence of these signs could predict survival for 1 hour. The over-all efficiency of the warning signs in predicting ventricular fibrillation or survival was 85 per cent. Ventricular fibrillation occurred without any of these 3 warning signs in only 1 baboon (5 per cent of all cases). It is suggested that these warning arrhythmias could have a practical value in the management of patients with acute myocardial infarction of recent onset by anticipating the time of impending ventricular fibrillation.