The relative effects of digoxin and diltiazem upon ventricular ectopic activity in patients with chronic atrial fibrillation.

In eight patients with chronic atrial fibrillation, treatment with digoxin (plasma drug concentration 1.3 to 2.0 nmol l-1) was associated with a significantly higher incidence of ventricular premature beats (VPBs) (mean 22.8 h-1) than diltiazem 120 mg three times daily (mean 6.8 h-1) (P less than 0.05). Seven out of the eight patients showed an increase in numbers of VPBs recorded over 24 h during treatment with digoxin when compared with diltiazem. The clinical importance of these results is unclear, but atrial fibrillation and ischaemic heart disease frequently co-exist, and increases in ventricular ectopy may predispose to serious ventricular arrhythmias following myocardial infarction.