Peter Munk Cardiac Center, Division of Cardiology, University Health Network, Toronto, ON, Canada.
PLoS One. 2018 Jun 28;13(6):e0199637. doi: 10.1371/journal.pone.0199637. eCollection 2018.
T-wave alternans (TWA), a marker of electrical instability, can be modulated by cardiac resynchronization therapy (CRT). The relationship between TWA and heart failure response to CRT has not been clearly defined.
In 40-patients (age 65±11 years, left ventricular ejection-fraction [LVEF] 23±7%), TWA was evaluated prospectively at median of 2 months (baseline) and 8 months (follow-up) post-CRT implant. TWA-magnitude (Valt >0μV, k≥3), its duration (d), and burden (Valt ·d) were quantified in moving 128-beat segments during incremental atrial (AAI, native-TWA) and atrio-biventricular (DDD-CRT) pacing. The immediate and long-term effect of CRT on TWA was examined. Clinical response to CRT was defined as an increase in LVEF of ≥5%. Native-TWA was clinically significant (Valt ≥1.9μV, k≥3) in 68% of subjects at baseline. Compared to native-TWA at baseline, DDD-CRT pacing at baseline and follow-up reduced the number of positive TWA segments, peak-magnitude, longest-duration and peak-burden of TWA (44±5 to 33±5 to 28±4%, p = 0.02 and 0.002; 5.9±0.8 to 4.1±0.7 to 3.8±0.7μV, p = 0.01 and 0.01; 97±9 to 76±8 to 67±8sec, p = 0.004 and <0.001; and 334±65 to 178±58 to 146±54μV.sec, p = 0.01 and 0.004). In addition, the number of positive segments and longest-duration of native-TWA diminished during follow-up (44±5 to 35±6%, p = 0.044; and 97±9 to 81±9sec, p = 0.02). Clinical response to CRT was observed in 71% of patients; the reduction in DDD-CRT paced TWA both at baseline and follow-up was present only in responders (interaction p-values <0.1).
Long-term CRT reduces the prevalence and magnitude of TWA. This CRT induced beneficial electrical remodeling is a marker of clinical response after CRT.
T 波电交替（TWA）是电不稳定性的标志物，可以被心脏再同步治疗（CRT）调节。TWA 与心力衰竭对 CRT 反应之间的关系尚未明确界定。
在 40 名患者（年龄 65±11 岁，左心室射血分数 [LVEF] 23±7%）中，前瞻性地在 CRT 植入后中位数 2 个月（基线）和 8 个月（随访）评估 TWA。在递增性心房（AAI，原生-TWA）和房室双心室（DDD-CRT）起搏期间，量化移动的 128 个心动周期片段中的 TWA 幅度（Valt >0μV，k≥3）、持续时间（d）和负荷（Valt ·d）。检查 CRT 对 TWA 的即刻和长期影响。CRT 的临床反应定义为 LVEF 增加≥5%。基线时，68%的患者具有临床意义的原生-TWA（Valt ≥1.9μV，k≥3）。与基线时的原生-TWA 相比，DDD-CRT 起搏在基线和随访时减少了 TWA 的阳性节段数、峰值幅度、最长持续时间和峰值负荷（44±5 至 33±5 至 28±4%，p=0.02 和 0.002；5.9±0.8 至 4.1±0.7 至 3.8±0.7μV，p=0.01 和 0.01；97±9 至 76±8 至 67±8sec，p=0.004 和 <0.001；334±65 至 178±58 至 146±54μV.sec，p=0.01 和 0.004）。此外，在随访期间，原生-TWA 的阳性节段数和最长持续时间减少（44±5 至 35±6%，p=0.044；97±9 至 81±9sec，p=0.02）。71%的患者观察到 CRT 的临床反应；仅在应答者中观察到基线和随访时 DDD-CRT 起搏 TWA 的减少（交互 p 值<0.1）。
长期 CRT 降低了 TWA 的发生率和幅度。这种 CRT 诱导的有益的电重构是 CRT 后临床反应的标志物。
