Determinants of predicted efficacy of antiarrhythmic drugs in the electrophysiologic study versus electrocardiographic monitoring trial. The ESVEM Investigators.

BACKGROUND: The Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) study was designed to compare the accuracy of predictions of antiarrhythmic drug efficacy made by electrophysiological study (EPS) with those made by Holter monitoring (HM) combined with exercise testing. The present study describes the baseline characteristics and the response to drug efficacy tests of 486 randomized subjects. METHODS AND RESULTS: Patients with ventricular tachyarrhythmias were randomly assigned to undergo serial testing of up to six antiarrhythmic drugs by either EPS (EPS limb) or HM and exercise testing (HM limb). Efficacy predictions were achieved in 108 of 242 patients in the EPS limb (45%) and in 188 of 244 patients (77%) in the HM limb. Left ventricular ejection fraction (LVEF) < 0.25 and presence of coronary artery disease were negative correlates (p < 0.10) of drug efficacy predictions in the EPS limb. In the HM limb, LVEF was the lone univariate correlate of efficacy, although it was only marginally significant (p = 0.107). A multivariate model selected assessment by HM and higher LVEF as independent predictors (p < 0.05) of drug efficacy. The drug evaluation process required an actuarial median time of 25 days in the EPS limb and 10 days in the HM limb (p < 0.0001). CONCLUSIONS: 1) Drug efficacy predictions are achieved more frequently by HM than by EPS. 2) Assessment by HM and severity of left ventricular dysfunction are independent correlates for a drug efficacy prediction. 3) The duration of drug testing is considerably shorter for the HM method.