Usefulness of procainamide challenge for electrophysiologic arrhythmia risk stratification.

Among 58 consecutive patients who underwent electrophysiologic testing for risk assessment and who subsequently received a third-generation implantable cardioverter-defibrillator, 39 had ventricular tachycardia induced in the baseline state and 19 had ventricular tachycardia induced only after administration of intravenous procainamide, increasing the yield of electrophysiologic risk assessment by 49%. At follow-up, ventricular arrhythmias requiring implantable cardioverter-defibrillator termination occurred in 14 of 39 patients inducible in the baseline state and in 7 of 19 patients inducible only with intravenous procainamide. The provocative use of intravenous procainamide during electrophysiologic risk assessment increases the detection rate for risk of sustained ventricular arrhythmias with no loss of positive predictive value.