Noninvasive prediction of efficacy of type IA antiarrhythmic drugs by the signal-averaged electrocardiogram in patients with coronary artery disease and sustained ventricular tachycardia.
This study attempted to determine if specific changes on the signal-averaged electrocardiogram (ECG) after type IA antiarrhythmic therapy are predictive of efficacy in the treatment of ventricular tachycardia (VT). Scalar and signal-averaged ECGs were obtained at baseline and after type IA drug therapy in 15 patients with coronary artery disease and inducible VT at baseline electrophysiologic testing. Signal-averaged QRS duration, root-mean-square amplitude in the last 40 ms of signal-averaged QRS, and the duration under 40 mu v of the signal-averaged QRS (low-amplitude signal), as well as ventricular effective refractory period at electrophysiologic study, and QTc on the scalar ECG were compared. At drug study, 6 patients (group A) had persistent but slower VT, whereas 9 (group B) had VT rendered noninducible. The baseline signal-averaged QRS duration was longer in group A than in B (136 +/- 10 vs 115 +/- 13 ms; p < 0.05), as was the scalar QRS (115 +/- 19 vs 98 +/- 11 ms; p < 0.05). After antiarrhythmic therapy, group A had a greater prolongation of both signal-averaged QRS (24 +/- 10 vs 8 +/- 3 ms; p < 0.05) and low-amplitude signal (31 +/- 13 vs 3 +/- 7 ms; p < 0.05), whereas group B had a greater increase in ventricular effective refractory period (49 +/- 20 vs 20 +/- 13 ms; p < 0.05) and corrected QT interval (100 +/- 39 vs 43 +/- 23 ms; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Hopson
J R
JR
Department of Internal Medicine, University of Iowa, Iowa City.
Kienzle
M G
MG
Aschoff
A M
AM
Shirkey
D R
DR
D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D003327:Coronary Disease / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology; D004562:Electrocardiography / Q000187:drug effects / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000188:drug therapy* / Q000453:epidemiology
D000889:Anti-Arrhythmia Agents