Effects of oral digoxin on ventricular ectopy and its relation to left ventricular function.

The ventricular antiarrhythmic properties of oral digoxin were examined in 13 patients with chronic ventricular ectopy using serial 24-hour electrocardiographic monitoring. Mean premature ventricular complex frequency (per 1,000 normal beats) decreased from 56 +/- 47 during the placebo period to 40 +/- 27 (p = not significant [NS]) and 25 +/- 17 (p less than 0.05) during daily administration of digoxin, 0.25 and 0.375 mg. Digoxin had no significant effect on the qualitative occurrence of complex ventricular arrhythmia patterns (multiformity, bigeminy, couplets, ventricular tachycardia). Radionuclide left ventricular (LV) ejection fraction was measured during the placebo period. Seven patients had normal (ejection fraction greater than 50%) and 6 abnormal global LV performance. In the normal group, the mean premature ventricular complex frequency decreased from 69 +/- 58 to 20 +/- 18 (p less than 0.05) and the mean couplet frequency decreased from 0.59 +/- 0.85 to 0.07 +/- 0.06 (p less than 0.04) during the placebo and 0.375 mg digoxin dosing periods, respectively. In contrast, no significant changes in either variable occurred after digoxin in subjects with depressed LV function. This study indicates that oral digoxin is moderately effective in suppressing premature ventricular complexes, and that its effects are greatest in patients with normal overall LV performance.