Biventricular pacing attenuates T-wave alternans and T-wave amplitude compared to other pacing modes.
BACKGROUND
The impact of altered ventricular activation, including biventricular (BV) pacing, on T-wave alternans (TWA) and arrhythmic substrates is unclear. We studied how differing ventricular activation sequence alters TWA; the interval from peak-to-end of the T-wave (TpTe) and T-wave amplitude during right (RV), left (LV), and biventricular (BV) pacing; and right atrial (RA) pacing in patients with preexisting conduction delay.


RESULTS
We measured TWA during RA, RV, LV, and BV pacing in 33 patients receiving cardiac-resynchronization-therapy-defibrillators. TWA magnitude (V(alt)) was lower during BV than RV (P < 0.01), RA (P < 0.01), or LV pacing. As a result, BV-TWA was more often negative than RV-TWA (P < 0.01), LV-TWA, and RA-TWA, particularly when discordant between pacing modes (P < 0.01). Overall, 83% of TWA recordings were abnormal (25% indeterminate), and 17% negative. BV pacing reduced T-wave amplitude (P < 0.05) and TpTe (P < 0.005) compared to RV pacing and LV pacing (P < 0.05; P < 0.005 respectively). Notably, TWA magnitude varied linearly with T-wave amplitude for all pacing modes (P < 0.001). Over 410 +/- 252 days' follow-up, RV-TWA predicted the combined endpoint of death and ICD therapy with 86% negative predictive value (P < 0.05). BV-TWA, RA-TWA, and other repolarization indices were not predictive.


CONCLUSIONS
BV pacing attenuates TWA in tandem with reduced T-wave magnitude. In these patients with baseline QRS prolongation, RV-TWA predicted events more effectively than BV-TWA and RA-TWA. Further studies are required to understand how altered ventricular activation influences repolarization dynamics and arrhythmic tendency.
University of California and VA Medical Center, San Diego, California 92161, USA.
Daejoon
D
Anh
Uma
U
Srivatsa
Hanh M
HM
Bui
Scott
S
Vasconcellos
Sanjiv M
SM
Narayan
D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D017180:Tachycardia, Ventricular / Q000503:physiopathology* / Q000517:prevention & control*; D016896:Treatment Outcome