THE RESPONSE TO ANTITACHYCARDIA PACING DIFFERENTIATES VENTRICULAR FROM SUPRAVENTRICULAR TACHYCARDIA

High precordial lead ECGs were performed on 161 patients (60%) and SAECGs on 187 patients (70%). ST-segment elevation at baseline on standard or high-lead ECG was present in 120 patients (45%, Type 2 63%,Type 3 21%). 47 patients (18%) had a positive procainamide challenge. Of these patients, 35 patients had STelevation at baseline including Type 2 (n1⁄422) and Type 3 ECGs (n1⁄48), and 12 patients with no ST-elevation. Predictors for a positive challenge were: ethnicity, baseline ST-elevation, borderline or abnormal SAECG (Table). The combination of abnormal SAECG and any ST-elevation at baseline resulted in an even stronger association with positive procainamide challenge (OR 7.65; p<0.001). Therewere no associationswith age, sex, personal history ofUCA, or family history of Brugada ECG/Syndrome. CONCLUSION: The yield of procainamide infusion is markedly enhanced when the baseline ECG shows ST-elevation and in the presence of a concomitant borderline or abnormal SAECG. A baseline Type 2 or 3 ECG pattern is predictive for a positive procainamide challenge.