Anh Daejoon, Srivatsa Uma, Bui Hanh M, Vasconcellos Scott, Narayan Sanjiv M
University of California and VA Medical Center, San Diego, California 92161, USA.
Pacing Clin Electrophysiol. 2008 Jun;31(6):714-21. doi: 10.1111/j.1540-8159.2008.01074.x.
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.
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.
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.
包括双心室（BV）起搏在内的心室激动改变对T波交替（TWA）和心律失常基质的影响尚不清楚。我们研究了不同的心室激动顺序如何改变TWA；右心室（RV）、左心室（LV）和双心室（BV）起搏期间从T波峰值到终点的间期（TpTe）和T波振幅；以及在已有传导延迟的患者中右心房（RA）起搏的情况。
我们在33例接受心脏再同步治疗除颤器的患者中测量了RA、RV、LV和BV起搏期间的TWA。BV起搏时TWA幅度（V(alt)）低于RV（P<0.01）、RA（P<0.01）或LV起搏。因此，BV-TWA比RV-TWA（P<0.01）、LV-TWA和RA-TWA更常为阴性，尤其是在起搏模式不一致时（P<0.01）。总体而言，83%的TWA记录异常（25%不确定），17%为阴性。与RV起搏和LV起搏相比，BV起搏降低了T波振幅（P<0.05）和TpTe（P<0.005）（分别为P<0.05；P<0.005）。值得注意的是，所有起搏模式下TWA幅度均与T波振幅呈线性变化（P<0.001）。在410±252天的随访中，RV-TWA对死亡和ICD治疗的联合终点具有86%的阴性预测价值（P<0.05）。BV-TWA、RA-TWA和其他复极指标无预测价值。
BV起搏可减轻TWA并伴有T波幅度降低。在这些基线QRS增宽的患者中，RV-TWA比BV-TWA和RA-TWA更有效地预测事件。需要进一步研究以了解心室激动改变如何影响复极动力学和心律失常倾向。
