[Antiarrhythmic treatment of ventricular ectropic arrhythmies with Disopyramide]

Disopyramide (D.) is a new antiarrhythmic agent, which is not related chemically to any of the known substances. Animal experiments have shown a close similarity to quinidine action. Side effects are mainly due to anticholinergic effects. Pharmacokinetic studies with radioactive labelled D. have demonstrated that 80 per cent are elimated via the kidneys and 15 per cent through the gut. Gastrointestinal reabsorption in 90 per cent. We have studied the antiarrhythmic properties of D. in ventricular ectopic arrhythmias in twenty male patients. There were 13 myocardial infarctions, 5 cardiomyopathies, one severe oartic regurgitation with prosthetic valve replacement, one case with VPB of unknown aetiology. In ten cases the influence of D. on ventricular excitation threshold in implanted pacemakers was studied. The effects were correlated with Disopyramide-plasma levels. D. was effective in suppressing VPB. It was successful in 67 per cent, in 30 per cent the effect was unsatisfactory. Pacemaker-threshold remained unaltered. Side effects included constipation. Two deaths were observed. Their relationship to the adminstration of D. is not definitely proved. Nevertheless should the drug because of its negative inotropic action be employed with caution in cases with congestive heart failure.