Division of Cardiology, University of Western Ontario, London, Ontario, Canada.
J Cardiovasc Electrophysiol. 2010 Nov;21(11):1242-6. doi: 10.1111/j.1540-8167.2010.01788.x.
Genotype and Exercise in LQTS.
Repolarization dynamics during exercise in patients with long-QT Syndrome (LQTS) may be influenced by various factors such as a patient's genotype. We sought to systematically characterize the repolarization dynamics during exercise in patients with LQTS with a particular focus on the influence of genotype.
Three groups of patients were studied on the basis of clinical status and genotype: LQT1, LQT2, and normal controls. Twenty-five age- and gender-matched patients were selected for each group. The QTc was measured during bicycle exercise testing and its dynamics were compared between the 3 groups.
The degree of QTc prolongation during exercise was greater in LQTS patients (LQT1 80 ± 47 ms, LQT2 64 ± 41 ms, Control 46 ± 20 ms, P = 0.02), with significant differences between LQT1 and LQT2 patients observed at heart rates ≥ 60% of the predicted maximum (P < 0.05). LQT1 patients demonstrated progressive or persistent QTc prolongation at higher heart rates, whereas LQT2 patients demonstrated maximum QTc prolongation at submaximal heart rates (50% of the predicted maximum) with subsequent QTc correction toward baseline values at higher heart rates. Importantly, these observations were consistent regardless of age, gender, or exercise type in subgroup analyses.
Reduced repolarization reserve in LQTS is genotype and heart rate specific.
LQTS 中的基因型和运动。
长 QT 综合征（LQTS）患者在运动期间的复极动力学可能受到各种因素的影响，例如患者的基因型。我们试图系统地描述 LQTS 患者在运动期间的复极动力学，特别关注基因型的影响。
根据临床状况和基因型，将三组患者进行研究：LQT1、LQT2 和正常对照。每组选择 25 名年龄和性别匹配的患者。在自行车运动测试期间测量 QTc，并比较三组之间的动态变化。
LQTS 患者在运动期间的 QTc 延长程度更大（LQT1 80 ± 47 ms，LQT2 64 ± 41 ms，对照组 46 ± 20 ms，P = 0.02），在心率≥预测最大心率的 60%时，LQT1 和 LQT2 患者之间存在显著差异（P < 0.05）。LQT1 患者在较高心率时表现出进行性或持续性 QTc 延长，而 LQT2 患者在次最大心率（预测最大心率的 50%）时表现出最大 QTc 延长，随后在较高心率时 QTc 向基线值校正。重要的是，这些观察结果在亚组分析中无论年龄、性别或运动类型如何都是一致的。
LQTS 中的复极储备减少具有基因型和心率特异性。
