To the Editor

Abstract

In the March 2008 issue of Heart Rhythm, Ehrlich et al 1 Ehrlich J.R. Wegener F.T. Anneken L. et al. Biventricular pacing does not affect microvolt T-wave alternans in heart failure patients. Heart Rhythm. 2008; 5: 348-352 Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar reported on the assessment of microvolt T-wave alternans (MTWA) in 30 patients with congestive heart failure using right atrial (RA), right ventricular (RV), left ventricular (LV), and biventricular (BiV) pacing via the patients' cardioverter-defibrillator and cardiac resynchronization system. They particularly sought to investigate whether BiV pacing might influence MTWA testing results. MTWA test results were nonnegative in 60%, 57%, 50%, and 57% of patients testing with RA, RV, LV, and BiV pacing, respectively, and were negative for all pacing sites in 23% of patients. Concordance of MTWA testing results for RA with RV, LV, and BiV pacing were found in 83%, 70%, and 83%, of patients, respectively. Concordance for positive and negative predictive values of nonnegative MTWA test results during RA and RV pacing was seen in 88% and 76% of patients, during RA and LV pacing in 80% and 60%, and during RA and BiV pacing in 88% and 76%, respectively. Thus, BiV pacing in congestive heart failure patients does not appear to augment or attenuate the existing arrhythmogenic risk as detected by MTWA testing. The results of this study will further stimulate the debate as to whether BiV pacing is arrhythmogenic, as suggested by the work of Medina-Ravell et al, 2 Medina-Ravell V.A. Lankipalli R.S. Yan G.X. et al. Effect of epicardial or biventricular pacing to prolong QT interval and increase transmural dispersion of repolarization: does resynchronization therapy pose a risk for patients predisposed to long QT or torsade de pointes?. Circulation. 2003; 107: 740-746 Crossref PubMed Scopus (291) Google Scholar who reported data arguing against this notion.