Effects on ventricular function of disopyramide, procainamide and quinidine as determined by radionuclide angiography

To evaluate the effects of the 3 commonly used antiarrhythmic agents--disopyramide, procainamide and quinidine--on left ventricular (LV) function, these 3 agents were administered in random sequence after control radionuclide angiography performed at rest and during exercise in 17 patients. Drug dosages were tailored to achieve therapeutic blood levels 5 minutes before and 2 to 3 hours after drug administration. The mean dose of disopyramide was 141 +/- 26 mg every 6 hours, procainamide, 441 +/- 100 mg every 4 hours, and quinidine, 401 +/- 101 mg of the gluconate preparation every 6 hours. The patients received the appropriate dosage for 7 or more days before repeat radionuclide angiography was performed. The ejection fraction at rest was: control 60 +/- 13%, disopyramide 55 +/- 11%, procainamide 58 +/- 11%, and quinidine 59 +/- 12%. The exercise ejection fraction was: control 61 +/- 14%, disopyramide 58 +/- 13%, procainamide 58 +/- 12% and quinidine 61 +/- 13%. In neither case, at rest nor during exercise was there any significant difference observed between any of the agents or between any individual agent and control. However, at rest 8 subjects had a 5% or more decrease from the control value with disopyramide, 5 had a 5% or more decrease with procainamide and 6 had a 5% or more decrease with quinidine, whereas during exercise the decreases were 8, 6 and 5%, respectively. These values were not statistically different but suggest that caution should be taken in administering all 3 agents, particularly to patients with impaired LV function, because individual sensitivity to a given agent may precipitate a significant decline in LV function.