 Nevertheless, NAPA does only affect the Q - T interval, while procainamide has also effect on the QRS-interval.Also the electrophysiologic properties of NAPA are a little bit different from those of procainamide and NAPA is not completely effective for suppressing ventricular dysrhythmias, but its antiarrhythmic mechanisms are similar to those of procainamide.The pharmacokinetic properties of acecainide, an active metabolite of procainamide, have been studied in healthy people and patients with cardiomyopathy in elderly and younger patients.