Electrocardiographic Predictive Factors of Long-Term Clinical Improvement With Multisite Biventricular Pacing in Advanced Heart Failure Christine Alonso, MD, Christophe Leclercq, MD, Fre ´de ´ric Victor, MD, Hassan Mansour, MD, Christian de Place, MD, Dominique Pavin, MD, Franc ¸ois Carre ´, MD, Philippe Mabo, MD, and J. Claude Daubert, MD Biventricular pacing has recently been proposed for treating patients with drug refractory heart failure and intraventricular conduction delay. The purpose is to re- store ventricular relaxation and contraction sequences as homogeneously as possible. The aim of this study was to determine if some factors could predict the long-term clinical effectiveness of that new treatment. This study included 26 patients, aged 66  7 years, with drug refractory heart failure and wide QRS. Patients were implanted with a biventricular pacemaker. The left ven- tricle was paced through a coronary sinus tributary. New York Heart Association functional class, exercise tolerance, and left ventricular (LV) ejection fraction were collected at baseline and after pacemaker implantation. Patients were divided into 2 groups: group I  respond- ers; group II  nonresponders. QRS duration and axis at baseline and during biventricular pacing, interventricu- lar conduction time, and LV and right ventricular lead positions were compared between the 2 groups. Group I patients (n  19) had a mean reduction of 1.3 in functional class and an increase in peak oxygen con- sumption rate by a mean of 50%. The only parameter that differed between the 2 groups was the QRS dura- tion during biventricular pacing, with a significantly shorter value in group I than in group II (154  17 vs 177  26 ms; p  0.016). Thus, a positive response to biventricular pacing is correlated with the quality of electrical resynchronization. The optimal positions of the right and LV leads would be those that could induce the greatest shortening of QRS duration. 1999 by Ex- cerpta Medica, Inc. (Am J Cardiol 1999;84:1417–1421) B iventricular pacing has recently been proposed for treating patients with drug refractory heart failure associating severe left ventricular (LV) systolic dys- function and intraventricular conduction delay. 1 The technique is currently in the evaluation process through randomized, controlled trials. The potential interest of biventricular pacing in heart failure is sup- ported by the high incidence of conduction disorders in dilated cardiomyopathy, as well as the natural ten- dency to deteriorate, which characterizes the progres- sion of the disease. In particular, the PR interval is prolonged and QRS is widened. 2,3 These conduction disorders are responsible for major electromechanical abnormalities, mainly affecting left atrioventricular (AV) synchrony and ventricular contraction/relaxation sequence. 4,5 In the early 1990s standard DDD pacing (right ventricular [RV] apical single pacing) was pro- posed in the treatment of AV asynchrony in patients with refractory heart failure but stable sinus rhythm. 6 These encouraging first results, however, were not confirmed by more recent studies. 7–9 The ineffective- ness of conventional DDD pacing can partially be explained by the lack of correction or even the wors- ening of ventricular asynchrony during pacing of the RV apex. 10 –12 The purpose of multisite, biventricular pacing is to restore ventricular relaxation and contrac- tion sequences as homogeneous as possible by simul- taneously pacing both ventricles at specific sites. In that technique the left ventricle is usually paced through a lead inserted in a coronary sinus tributary vein. 13 However, choosing the pacing site in each ventricle so as to ensure optimal resynchronization is still problematic. This study examines, from a pilot experiment, whether QRS modifications induced by biventricular pacing and the anatomic positioning of the leads in both ventricles could predict the clinical effectiveness of that new treatment. METHODS Inclusion criteria: This retrospective study involved all patients with end-stage heart failure who were referred to the same institution between August 1994 and June 1998 with an indication for biventricular pacemaker implantation, and underwent successful implantation. The inclusion criteria were: severe con- gestive heart failure rated as class III or IV, refractory to optimized drug treatment involving diuretics with converting enzyme inhibitors at the maximum tolera- ble dose; LV systolic dysfunction defined by radionu- clide ejection fraction 35% and LV end-diastolic From the De ´ partement de Cardiologie et Maladies Vasculaires, Centre Cardio-Pneumologique, Ho ˆpital Pontchaillou-CHU, Rennes Cedex, France. Manuscript received April 29, 1999; revised manuscript received July 14, 1999, and accepted July 17. Address for reprints: J. Claude Daubert, MD, De ´ partement de Cardiologie et Maladies Vasculaires, Centre Cardio-Pneumologique, Ho ˆpital Pontchaillou-CHU, 35033 Rennes Cedex, France. E-mail: christine.alonso@wanadoo.f. 1417 ©1999 by Excerpta Medica, Inc. All rights reserved. 0002-9149/99/$–see front matter The American Journal of Cardiology Vol. 84 December 15, 1999 PII S0002-9149(99)00588-3