Electrophysiologic effects of antiarrhythmic drug therapy in the prediction of successful suppression of induced ventricular tachycardia

• Published in: The American heart journal Vol. 129; no. 2; pp. 343 - 349
• Main Authors: Karagounis, Labros A., Anderson, Jeffrey L., Allen, Ann, Osborn, Jeffrey S.
• Format: Journal Article
• Language: English
• Published: New York, NY Mosby, Inc 01-02-1995; Elsevier
• Subjects: Adult; Aged; Analysis of Variance; Anti-Arrhythmia Agents - therapeutic use; Antiarythmic agents; Biological and medical sciences; Cardiac Pacing, Artificial - methods; Cardiac Pacing, Artificial - statistics & numerical data; Cardiovascular system; Chi-Square Distribution; Drug Evaluation; Electrocardiography - drug effects; Electrocardiography - statistics & numerical data; Electrophysiology; Female; Humans; Logistic Models; Male; Medical sciences; Middle Aged; Pharmacology. Drug treatments; Prognosis; Prospective Studies; Remission Induction; Tachycardia, Ventricular - drug therapy; Tachycardia, Ventricular - etiology; Tachycardia, Ventricular - physiopathology; Treatment Failure; Electrography; Human; Instrumental stimulation; Chemotherapy; Prognosis; Treatment; Arrhythmia; Treatment efficiency; Prediction; Cardiovascular disease; Sustained ventricular tachycardia; Antiarrhythmia agent
• ISSN: 0002-8703; 1097-6744
• DOI: 10.1016/0002-8703(95)90017-9

Predictors of a successful outcome of serial electrophysiologic (EP) and drug studies have been identified from among baseline patient characteristics but not from among measures of baseline and drug-related EP effects. Identifying such predictors would be useful in explaining the mechanism of successful drug therapy and in guiding drug development and selection. We prospectively studied EP characteristics in 159 trials in 62 patients with ventricular tachycardia or ventricular fibrillation during antiarrhythmic therapy and compared EP measures between successful (
n = 30) and failed trials (
n = 129). The average age of the patients was 64 years (range 27 to 78 years); 82% were men and 18% women; and 87% had coronary artery disease. Measurements included R-R, QRS, and QT intervals during intrinsic rhythm and during pacing at cycle lengths of 600 of 400 msec; ventricular effective refractory periods (ERP) during pacing at cycle lengths of 600 and 400 msec; and changes in these measures, comparing treatment with drug-free baseline. Univariate predictors of success (in order of significance) included
ERP
600
QRS
600
, sotalol versus other drugs,
ERP
400
QRS
400
, ΔERP
600, ΔR-R, ERP
600, QRS
400 (negative association), ΔERP
400, QRS
600 (negative association), ERP
400 (all
p < 0.1). In two separate multivariate models, one for each drive cycle length, only the ratio
ERP
600
QRS
600
(
p = 0.01) in the first model and
ERP
400
QRS
400
(
p = 0.01) in the second model were significantly and independently associated with achieving noninducibility with drug therapy. Therefore measures of greater refractoriness and lesser delays in conduction velocity (ie, greater “wavelength”) relate to drug success. These observations may assist in new drug development and, with other predictors, in drug selection for the treatment of patients.