Clinical Sciences, Cardiology, Lund University, Lund, Sweden.
Pediatric Cardiology and Electrophysiology, University of Minnesota/Masonic Children's Hospital, Minneapolis, Minnesota.
J Cardiovasc Electrophysiol. 2019 Dec;30(12):2907-2913. doi: 10.1111/jce.14210. Epub 2019 Oct 16.
Long QT syndrome (LQTS) mutation carriers have elevated the risk of cardiac events even in the absence of QTc prolongation; however, mutation penetrance in patients with normal QTc may be reflected in abnormal T-wave shape, particularly in KCNH2 mutation carriers. We aimed to assess whether the magnitude of a three-dimensional T-wave vector (TwVM) will identify KCNH2-mutation carriers with normal QTc at risk for cardiac events.
Adult LQT2 patients with QTc < 460 ms in men and <470 ms in women (n = 113, age 42 ± 16 years, 43% male) were compared with genotype-negative family members (n = 1007). The TwVM was calculated using T-wave amplitudes in leads V6, II, and V2 as the square root of (TV6 + TII + (0.5*TV2) ). Cox regression analysis adjusted for gender and time-dependent beta-blocker use was performed to assess cardiac event (CE) risk, defined as syncope, aborted cardiac arrest, implantable cardioverter-defibrillator therapy, or sudden death.
Dichotomized by median of 0.30 mV, lower TwVM was associated with elevated CE risk compared to those with high TwVM (HR = 2.95, 95% CI, 1.25-6.98, P = .014) and also remained significant after including sex and time-dependent beta-blocker usage in the Cox regression analysis (HR = 2.64, 95% CI, 1.64-4.24, P < .001). However, these associations were found only in women but not in men who had low event rates.
T-wave morphology quantified as repolarization vector magnitude using T-wave amplitudes retrieved from standard 12-lead electrocardiogram predicts cardiac events risk in LQT2 women and appears useful for risk stratification of KCNH2-mutation carriers without QTc prolongation.
长 QT 综合征 (LQTS) 突变携带者即使在 QTc 无延长的情况下，也会增加心脏事件的风险；然而，在 QTc 正常的患者中，突变外显率可能反映在异常的 T 波形态上，尤其是在 KCNH2 突变携带者中。我们旨在评估三维 T 波向量 (TwVM) 的幅度是否可以识别出 KCNH2 突变携带者，他们的 QTc 正常但存在心脏事件风险。
将 QTc<男性 460ms 和女性 470ms（n=113，年龄 42±16 岁，43%为男性）的成年 LQT2 患者与基因型阴性家族成员（n=1007）进行比较。TwVM 通过 V6、II 和 V2 导联的 T 波幅度计算得出，计算公式为平方根[TV6+TII+（0.5*TV2）]。采用 Cox 回归分析，调整性别和时间依赖性β受体阻滞剂的使用情况，以评估心脏事件（CE）风险，定义为晕厥、心脏骤停中止、植入式心脏复律除颤器治疗或猝死。
根据中位数 0.30mV 进行二分法，与 TwVM 高的患者相比，TwVM 较低的患者发生 CE 的风险更高（HR=2.95，95%CI，1.25-6.98，P=0.014），且在 Cox 回归分析中包括性别和时间依赖性β受体阻滞剂使用情况后，这一结果仍然具有统计学意义（HR=2.64，95%CI，1.64-4.24，P<0.001）。然而，这些关联仅在女性中发现，而在男性中并未发现，因为男性的事件发生率较低。
使用标准 12 导联心电图从 T 波幅度中提取的复极向量幅度量化的 T 波形态可预测 LQT2 女性的心脏事件风险，并且对于无 QTc 延长的 KCNH2 突变携带者的风险分层似乎有用。
