Piccirillo Gianfranco, Magnanti Marzia, Matera Sabrina, Di Carlo Silvia, De Laurentis Tiziana, Torrini Alessia, Marchitto Nicola, Ricci Renato, Magrí Damiano
Dipartimento di Scienze dell'Invecchiamento, Policlinico Umberto I, Universitá La Sapienza, Rome, Italy.
Transl Res. 2006 Aug;148(2):72-8. doi: 10.1016/j.trsl.2006.02.001.
The QT variability index (QTVI) indicates temporal dispersion in myocardial repolarization, and a high QTVI is associated with a propensity for sudden death from malignant ventricular arrhythmias in subjects at high risk. In this study, the authors assessed the effects of free breathing, controlled breathing, and sympathetic stress (tilt) on the QTVI in patients with chronic heart failure (CHF) and healthy control subjects. The authors also examined the influence of age on the same variables. To obtain normative data, they calculated 95% confidence intervals for healthy subjects grouped according to age. Under all experimental conditions, the QTVI was larger in the CHF group overall and in the age subsets than in controls. In patients and controls, the QTVI increased significantly during tilt, although no differences were found between the QTVI measured during free and controlled breathing. In healthy controls, the following variables correlated significantly with the QTVI: age and baseline heart rate (P < 0.001). In patients with CHF, aging had no influence on the QTVI.
Age, sympathetic stress, and CHF all tend to increase the QTVI and could potentially induce sudden death. Further studies should assess the usefulness of the QTVI as a marker predicting sudden cardiac death under the various conditions of risk.
QT变异性指数（QTVI）可反映心肌复极的时间离散度，高QTVI与高危患者发生恶性室性心律失常导致猝死的倾向相关。在本研究中，作者评估了自由呼吸、控制呼吸和交感神经应激（倾斜）对慢性心力衰竭（CHF）患者及健康对照者QTVI的影响。作者还研究了年龄对相同变量的影响。为获得正常数据，他们计算了按年龄分组的健康受试者的95%置信区间。在所有实验条件下，CHF组总体及各年龄亚组的QTVI均大于对照组。在患者和对照组中，倾斜期间QTVI显著增加，尽管自由呼吸和控制呼吸期间测量的QTVI无差异。在健康对照组中，以下变量与QTVI显著相关：年龄和基础心率（P<0.001）。在CHF患者中，年龄对QTVI无影响。
年龄、交感神经应激和CHF均倾向于增加QTVI，并可能诱发猝死。进一步研究应评估QTVI作为在各种风险条件下预测心源性猝死标志物的实用性。
