The Effect of Procainamide on T Wave Alternans

• Published in: Journal of cardiovascular electrophysiology 1999-05, Vol.10 (5), p.649-654
• Main Authors: KAVESH, NEAL G., SHOROFSKY, STEPHEN R., SARANG, SAMANTHA B., GOLD, MICHAEL R.
• Format: Article
• Language: English
• Subjects: Anti-Arrhythmia Agents - pharmacology; Electrocardiography - drug effects; Female; Heart Conduction System - drug effects; Heart Conduction System - physiopathology; Heart Rate - drug effects; Humans; Male; Middle Aged; procainamide; Procainamide - pharmacology; Prospective Studies; T wave alternans; Tachycardia, Ventricular - drug therapy; Tachycardia, Ventricular - etiology; Tachycardia, Ventricular - physiopathology; ventricular tachycardia
• ISSN: 1045-3873; 1540-8167
• DOI: 10.1111/j.1540-8167.1999.tb00241.x

Procainamide and T‐Wave Alternans. Introduction: The measurement of microvolt level T wave alternans (TWA) is a technique for detecting arrhythmia vulnerability. Previous studies demonstrated that the magnitude of TWA is dependent on heart rate. However, the effects of antiarrhythmic drugs on TWA are unknown. Methods and Results: This was a prospective evaluation of intravenous procainamide on TWA in 24 subjects with inducible sustained ventricular tachycardia (VT). Measurements of TWA were performed at baseline in the drug‐free state and after procainamide loading (1,204 ± 278 mg). Recordings were made in normal sinus rhythm, and during atrial pacing at 100 heats/min and 120 heats/min. The magnitude of TWA in the vector magnitude lead was decreased by procainamide at all heart rates: 0.6 ± 0.8 to 0.3 ± 0.4 μV in sinus rhythm, 2.0 ± 1.6 to 0.7 ± 0.7 μV at 100 beats/min, and 3.0 ± 2.0 to 1.7 ± 1.8 μV at 120 beats/min (P < 0.001 by analysis of variance). The sensitivity of TWA for the induction of VT at baseline was 5% in sinus, 60% at 100 beats/min, and 87% at 120 beats/min, while it decreased with procainamide to 5%, 19%, and 60%, respectively. Decreases in TWA in response to procainamide were independent of the antiarrhythmic effects on VT inducibility. Conclusions: These results indicate that the magnitude of TWA decreases with acute procainamide loading and this effect decreases the sensitivity of TWA for the induction of sustained VT.