Does acetyl strophanthidin suppress ventricular ectopic activity in patients with frequent ventricular premature beats?
Acetyl strophanthidin has a variable effect on ventricular premature beats, suppressing them in nearly half of patients likely via enhanced vagal tone, but increasing them in over a quarter of patients.
To determine the efficacy of digitalis drugs in suppressing ventricular ectopic activity, 142 patients with frequent (greater than 1 per minute) ventricular premature beats underwent acetyl strophanthidin tolerance testing. In 65 patients (46 per cent), frequency and grade were reduced during testing. In 37 (26 per cent), the ectopic activity remained unaltered; frequency increased during testing in the remaining 40 patients (28 per cent). In the group with a suppressive effect, ventricular premature beats decreased by 82 per cent, with complete abolition of arrhythmias in 46 per cent. The three groups were not distinguishable clinically by either the type or the extent of heart disease. The antiarrhythmic action of acetyl strophanthidin did not appear to depend upon its positive inotropic action. In some patients it appears to be due to an indirect reduction of Purkinje-fiber automaticity resulting from enhanced vagus-nerve activity that thereby lessens adrenergic tone on the heart.
Lown et al. (Thu,) studied this question.