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Abstract：
BACKGROUND: Few small-sample studies have quantified the T-wave alternans (TWA) value by 24-hour ambulatory recordings or exercise stress tests in patients with long QT syndrome (LQTS). The cutoff point of TWA ≥47 μV was based on patients with myocardial infarction. In our study, we aimed to (1) evaluate the association of TWA with life-threatening arrhythmic events (LAEs); (2) compare the predictive model of LAEs according to the TWA value measured by 24-hour ambulatory recordings and exercise stress tests; and (3) propose a cutoff point for the high risk of LAEs in patients with LQTS.
RESULTS: The study cohort included 110 patients with LQTS referred to our hospital, and the primary outcome was LAEs. Thirty-one patients with LQTS (31/110 [28.2%]) developed LAEs during the following 24 (12-47) months. Peak TWA value quantified from 12 leads by 24-hour ambulatory recordings in patients with LQTS with LAEs (LQTS-LAEs group) was significantly higher than LQTS without LAEs (LQTS-non-LAEs group) (64.0 [42.0-86.0] μV versus 43.0 [36.0-53.0] μV; P<0.01). There was no statistical difference in TWA value measured by exercise stress tests between the 2 groups (69.0 [54.5-127.5] μV versus 68.5 [53.3-99.8] μV; P=0.871). The new cutoff point of the peak TWA value measured by 24-hour ambulatory recordings was 55.5 μV, with a sensitivity of 75.0% and a specificity of 78.6%. A univariate Cox regression analysis revealed that TWA value ≥55.5 μV was a strong predictor of LAEs (hazard ratio [HR], 4.5 [2.1-9.6]; P<0.001]. A multivariate Cox regression analysis indicated that TWA value ≥55.5 μV remained significant (HR, 2.7 [1.1-6.8]; P=0.034).
CONCLUSIONS: Peak TWA measured by 24-hour ambulatory recordings was a more favorable risk stratification marker than exercise stress tests for patients with LQTS.
RESULTS: The study cohort included 110 patients with LQTS referred to our hospital, and the primary outcome was LAEs. Thirty-one patients with LQTS (31/110 [28.2%]) developed LAEs during the following 24 (12-47) months. Peak TWA value quantified from 12 leads by 24-hour ambulatory recordings in patients with LQTS with LAEs (LQTS-LAEs group) was significantly higher than LQTS without LAEs (LQTS-non-LAEs group) (64.0 [42.0-86.0] μV versus 43.0 [36.0-53.0] μV; P<0.01). There was no statistical difference in TWA value measured by exercise stress tests between the 2 groups (69.0 [54.5-127.5] μV versus 68.5 [53.3-99.8] μV; P=0.871). The new cutoff point of the peak TWA value measured by 24-hour ambulatory recordings was 55.5 μV, with a sensitivity of 75.0% and a specificity of 78.6%. A univariate Cox regression analysis revealed that TWA value ≥55.5 μV was a strong predictor of LAEs (hazard ratio [HR], 4.5 [2.1-9.6]; P<0.001]. A multivariate Cox regression analysis indicated that TWA value ≥55.5 μV remained significant (HR, 2.7 [1.1-6.8]; P=0.034).
CONCLUSIONS: Peak TWA measured by 24-hour ambulatory recordings was a more favorable risk stratification marker than exercise stress tests for patients with LQTS.
摘要：
背景：很少有小样本研究通过长QT综合征（LQTS）患者的24小时动态记录或运动压力测试来量化T波交替（TWA）值。TWA≥47μV的截止点基于心肌梗死患者。在我们的研究中,我们的目的是(1)评估TWA与危及生命的心律失常事件(LAE)的相关性;(2)根据通过24小时动态记录和运动压力测试测得的TWA值,比较LAE的预测模型;(3)提出LQTS患者LAE高风险的临界点.
结果：该研究队列包括转诊至我院的110例LQTS患者，主要结局是LAEs.31例LQTS患者(31/110[28.2%])在随后的24(12-47)个月内发生LAE。有LAE的LQTS患者（LQTS-LAE组）通过24小时动态记录从12根导线中量化的TWA峰值显着高于无LAE的LQTS（LQTS-非LAE组）（64.0[42.0-86.0]μV对43.0[36.0-53.0]μV；P<0.01）。两组之间通过运动压力测试测得的TWA值无统计学差异（69.0[54.5-127.5]μV对68.5[53.3-99.8]μV；P=0.871）。通过24小时动态记录测得的TWA峰值的新截止点为55.5μV，敏感性为75.0%，特异性为78.6%。单变量Cox回归分析显示，TWA值≥55.5μV是LAE的强预测因子(风险比[HR]，4.5[2.1-9.6]；P<0.001]。多变量Cox回归分析表明，TWA值≥55.5μV仍然显著(HR，2.7[1.1-6.8];P=0.034)。
结论：对于LQTS患者，通过24小时动态记录测量的TWA峰值是比运动压力测试更有利的风险分层指标。
结果：该研究队列包括转诊至我院的110例LQTS患者，主要结局是LAEs.31例LQTS患者(31/110[28.2%])在随后的24(12-47)个月内发生LAE。有LAE的LQTS患者（LQTS-LAE组）通过24小时动态记录从12根导线中量化的TWA峰值显着高于无LAE的LQTS（LQTS-非LAE组）（64.0[42.0-86.0]μV对43.0[36.0-53.0]μV；P<0.01）。两组之间通过运动压力测试测得的TWA值无统计学差异（69.0[54.5-127.5]μV对68.5[53.3-99.8]μV；P=0.871）。通过24小时动态记录测得的TWA峰值的新截止点为55.5μV，敏感性为75.0%，特异性为78.6%。单变量Cox回归分析显示，TWA值≥55.5μV是LAE的强预测因子(风险比[HR]，4.5[2.1-9.6]；P<0.001]。多变量Cox回归分析表明，TWA值≥55.5μV仍然显著(HR，2.7[1.1-6.8];P=0.034)。
结论：对于LQTS患者，通过24小时动态记录测量的TWA峰值是比运动压力测试更有利的风险分层指标。
