Ventricular arrhythmias are usually produced by excess catecholamines and vagal withdrawal and occasionally re-entry and triggered activity also plays a role. PVCs are more common (10 per cent to 40 per cent) in CAD patients than in those without CAD. Ominous PVCs increase the risk of mortality and coronary events to about twice that of the others. Ominous PVCs were defined as multifocal, multiform, repetitive and also ventricular tachycardia. It has also found that those with greater ischaemia (i.e. three vessel disease) had a higher incidence of more serious ventricular arrhythmias. Mc Henry and colleagues reported that 27 per cent of exercise induced ventricular arrhythmias occurred in CAD patients and 7 per cent in those with normal coronary arteries.
Interestingly, Califf and colleagues found a much higher incidence of ventricular arrhythmias among those on digitalis.