Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.
Heart Rhythm. 2011 Aug;8(8):1237-42. doi: 10.1016/j.hrthm.2011.03.055. Epub 2011 Mar 30.
Increased temporal variability of repolarization, as reflected by QT interval variability measured over 10-15 minutes, predicted spontaneous ventricular arrhythmias and death in implantable cardioverter-defibrillator patients in mild to moderate heart failure (HF).
The purpose of this study was to test our hypothesis that increased mean QT variability over 24 hours would be associated with increased cardiovascular (CV) mortality in a heterogeneous HF population.
The Gruppo Italiano per lo Studio della Sopravvivenza nell'Insufficienza Cardiaca-Heart Failure trial prospectively enrolled subjects with HF of any cause. Twenty-four-hour Holter recordings from 268 subjects were analyzed using a template-matching, semiautomatic algorithm to measure QT and heart rate time series in sequential 5-minute epochs over 24 hours. The QT variability index (QTVI) was expressed as the log ratio of the normalized QT variance over normalized heart rate variance. Total and CV mortality were assessed as a function of continuous and dichotomous QTVI (>-0.84) in univariate and multivariable Cox proportional hazards models, adjusting for significant clinical predictors.
After a median of 47 months, there were 53 deaths, of which 44 were from CV causes. A significant association with the outcome was found for QTVI both as continuous and dichotomous variables after adjustment for clinical covariates (age >70, New York Heart Association class III-IV, left ventricular ejection fraction, nonsustained ventricular tachycardia, creatinine): QTVI hazard ratio (HR) 4.0 (confidence interval [CI] 1.8-88; P = .008) for total and 4.4 (CI 1.9-10.1; P = .0006) for CV mortality; QTVI >-0.84 HR 2.0 (CI 1.1-3.6; P = .02) for total and 2.1 (CI 1.1-3.8; P = .02) for CV mortality.
Increased repolarization lability, as reflected in QTVI measured over 24 hours, is associated with increased risk for total and CV mortality in a heterogeneous population with chronic HF.
QT 间期变异性（通过 10-15 分钟测量得出）可反映复极的时变，在轻度至中度心力衰竭（HF）的植入式心脏复律除颤器患者中，其预测自发性室性心律失常和死亡。
本研究旨在验证我们的假设，即在异质性 HF 人群中，24 小时 QT 变异性均值增加与心血管（CV）死亡率增加相关。
Gruppo Italiano per lo Studio della Sopravvivenza nell'Insufficienza Cardiaca-Heart Failure 试验前瞻性纳入任何病因 HF 患者。对 268 例患者的 24 小时动态心电图记录进行分析，采用模板匹配半自动算法，在 24 小时内以连续 5 分钟的顺序测量 QT 和心率时间序列。QT 变异性指数（QTVI）表示归一化 QT 方差与归一化心率方差之比的对数。在单变量和多变量 Cox 比例风险模型中，根据连续和二分 QTVI（>-0.84）评估总死亡率和 CV 死亡率，调整显著临床预测因子。
中位随访 47 个月后，共有 53 例死亡，其中 44 例死于 CV 原因。调整临床协变量（年龄>70 岁、纽约心脏协会心功能分级 III-IV 级、左心室射血分数、非持续性室性心动过速、肌酐）后，QTVI 与结局呈显著相关性，无论是连续变量还是二分变量：总死亡率的 QTVI 风险比（HR）为 4.0（95%置信区间[CI] 1.8-88；P=.008），CV 死亡率的 QTVI HR 为 4.4（95%CI 1.9-10.1；P=.0006）；总死亡率的 QTVI >-0.84 HR 为 2.0（95%CI 1.1-3.6；P=.02），CV 死亡率的 QTVI >-0.84 HR 为 2.1（95%CI 1.1-3.8；P=.02）。
24 小时测量的 QTVI 反映复极不稳定性增加与慢性 HF 异质性人群的总死亡率和 CV 死亡率增加相关。
