Biventricular Pacing Reduces the Positivity of T-Wave Alternans
Category:  09 Signal Average ECG/T-Wave Alternans
Presentation Time: Thursday, 10:15 a.m. - 11:15 a.m.
Daejoon Anh, MD, Scott Vasconcellos, MD, Uma Srivatsa, MD, Nancy McCormick, RN, CNP and Sanjiv M. Narayan, MD, PhD. Henry Ford Hospital, Detroit, MI, UCSD and VA Medical Centers, San Diego, CA
Presentation Number: P2-30
Poster Board Number: P2-30
T-wave alternans (TWA) is a promising risk stratifier for sudden death. However, TWA is usually measured during sinus tachycardia or atrial pacing, excluding patients with atrial fibrillation, AV Wenckebach or excessive ectopy from risk stratification. We hypothesized that TWA during right atrial (RA) pacing would be concordant with TWA during right (RV), left (LV) or bi (BV) ventricular pacing, and that this would remain stable over time.
Methods and Results. We studied 44 patients with implantable defibrillators (27 BV), mean age 70+9.6 years, LVEF 31+10 %, and 80% with coronary disease. TWA was measured sequentially during incremental BV, RV, LV and RA pacing, if possible, using HeartWave (Cambridge Heart). TWA measurements were then repeated at all sites in 280+177 days. Of 186 resulting TWA recordings, 21% were negative and 79% were non-negative. Non-negativity was 72% (BV), 82% (RV), 82% (LV) and 81% (RA). Notably, RA-TWA had a concordance of 94 % compared with TWA from pacing at each other site. Concordances were 82%, 86% and 71% for BV-TWA, RV-TWA and LV-TWA, respectively, compared to all other sites. Surprisingly, when BV TWA was discordant with TWA at other sites including RA, BV-TWA was significantly more likely to be negative (77% vs. 23%, p=0.05). Comparing BV-TWA and RV-TWA, concordance was 86 % but of the discordant results 77% showed negative BV yet non-negative RV (p<0.001). When measured over time, TWA reproducibility was comparable between RA (67%), BV (72 %) or RV (76%) pacing.
Conclusions. TWA is highly concordant between ‘traditional’ RA pacing and ventricular pacing, but varies between ventricular sites. Notably, our finding that negative TWA is more likely with BV than RV pacing suggests that TWA may identify patients in whom BV pacing reduces arrhythmic tendency.