USEFULNESS OF THE RESPONSE TO INTRAVENOUS PROCAINAMIDE DURING ELECTROPHYSIOLOGIC STUDY IN PREDICTING THE RESPONSE TO ORAL QUINIDINE IN PATIENTS WITH INDUCIBLE SUSTAINED MONOMORPHIC VENTRICULAR-TACHYCARDIA ASSOCIATED WITH CORONARY-ARTERY DISEASE

The response to intravenous procainamide (15 to 20 mg/kg) and to oral quinidine 324 to 648 mg every 8 hours for 3 to 5 days was prospectivel y studied in 50 consecutive patients (43 men and 7 women, aged 38 to 8 3 years old [mean 64 +/- 11]) with coronary artery disease and baselin e-inducible sustained monomorphic VT. Mean procainamide and trough qui nidine serum levels were 10.5 +/- 2.6 and 2.6 +/- 0.8 mug/ml, respecti vely. Mean left ventricular ejection fraction was 37 +/-12%. Sustained monomorphic VT was suppressed by intravenous procainamide in 18 patie nts (36%); 8 of these patients (44%) also had suppression with oral qu inidine, but 10 (56%) did not. Of the 32 patients (64%) who continued to have inducibility with intravenous procainamide, 12 (38%) responded to oral quinidine and 22 (62%) did not. The overall concordant respon se rate to intravenous procainamide and oral quinidine was 56% (28 of 50 patients). It is concluded that the response (i.e., the presence or absence of inducible sustained monomorphic VT) to intravenous procain amide does not adequately predict the response to oral quinidine in pa tients with coronary artery disease and sustained monomorphic VT.