Infarct size and recurrence of ventricular arrhythmias after defibrillatorimplantation

Infarct size as determined by perfusion imaging is an independent predictor of mortality after implantable cardioverter defibrillator (ICD) implantati on in patients with coronary artery disease (CAD) and life-threatening vent ricular arrhythmias (VA). However, its value as a predictor of VA recurrenc e and hospitalisation after ICD implantation is unknown. Therefore, the obj ective of this study was to evaluate whether infarct size as determined by perfusion imaging can help to identify patients who are at high risk for re currence of VA and hospitalisation after ICD implantation. We studied 56 pa tients with CAD and life-threatening VA. Before ICD implantation, all patie nts underwent a uniform study protocol including a thallium-201 stress-redi stribution perfusion study. A defect score as a measurement of infarct size was calculated using a 17-segment 5-point scoring system. Study endpoints during follow-up were documented episodes of appropriate anti-tachycardia p acing and/or shocks for VA and cardiac hospitalisation for electrical storm (defined as three or more appropriate ICD interventions within 24 h), hear t failure or angina. After a mean follow-up of 470+/-308 days, 22 patients (39%) had recurrences of VA. In univariate analysis, predictors for recurre nce were: (a) ventricular tachycardia (VT) as the initial presenting arrhyt hmia (86% vs 59% for patients without ICD therapy, P=0.04), (b) treatment w ith beta-blockers (36% vs 68%, P=0.03) and (c) a defect score (DS) greater than or equal to 20 (64% vs 32%, P=0.03). In multivariate analysis, VT as t he presenting arrhythmia (chi 2=5.51, P=0.02) and a DS greater than or equa l to 20 (chi 2=4.22, P=0.04) remained independent predictors. Cardiac hospi talisation was more frequent in patients with a DS greater than or equal to 20 (44% vs 13% for patients with DS <20, P=0.015) and this was particularl y due to more frequent hospitalisations for electrical storm (24% vs 3% for patients with DS<20, P=0.037). The extent of scarring determined by perfus ion imaging can separate patients with CAD into high- and low-risk groups f or recurrence of VA and cardiac hospitalisation after ICD implantation.