Department of Medical Education, Nagoya City University Graduate School of Medical Sciences Nagoya, Japan.
Front Physiol. 2011 Sep 30;2:65. doi: 10.3389/fphys.2011.00065. eCollection 2011.
Non-Gaussianity index (λ) is a new index of heart rate variability (HRV) that characterizes increased probability of the large heart rate deviations from its trend. A previous study has reported that increased λ is an independent mortality predictor among patients with chronic heart failure. The present study examined predictive value of λ in patients after acute myocardial infarction (AMI). Among 670 post-AMI patients, we performed 24-h Holter monitoring to assess λ and other HRV predictors, including SD of normal-to-normal interval, very-low frequency power, scaling exponent α(1) of detrended fluctuation analysis, deceleration capacity, and heart rate turbulence (HRT). At baseline, λ was not correlated substantially with other HRV indices (|r| < 0.4 with either indices) and was decreased in patients taking β-blockers (P = 0.04). During a median follow-up period of 25 months, 45 (6.7%) patients died (32 cardiac and 13 non-cardiac) and 39 recurrent non-fatal AMI occurred among survivors. While all of these HRV indices but λ were significant predictors of both cardiac and non-cardiac deaths, increased λ predicted exclusively cardiac death (RR [95% CI], 1.6 [1.3-2.0] per 1 SD increment, P < 0.0001). The predictive power of increased λ was significant even after adjustments for clinical risk factors, such as age, diabetes, left ventricular function, renal function, prior AMI, heart failure, and stroke, Killip class, and treatment ([95% CI], 1.4 [1.1-2.0] per 1 SD increment, P = 0.01). The prognostic power of increased λfor cardiac death was also independent of all other HRV indices and the combination of increased λ and abnormal HRT provided the best predictive model for cardiac death. Neither λ nor other HRV indices was an independent predictor of AMI recurrence. Among post-AMI patients, increased λ is associated exclusively with increased cardiac mortality risk and its predictive power is independent of clinical risk factors and of other HRV predictors.
非高斯指数（λ）是心率变异性（HRV）的一个新指标，它描述了心率从趋势中较大偏离的可能性增加。先前的研究报告称，λ增加是慢性心力衰竭患者独立的死亡率预测因子。本研究探讨了 λ 在急性心肌梗死（AMI）后患者中的预测价值。在 670 例 AMI 后患者中，我们进行了 24 小时动态心电图监测，以评估 λ 以及其他 HRV 预测因子，包括正常-正常间期的标准差、低频功率、去趋势波动分析的标度指数 α(1)、减速能力和心率震荡（HRT）。在基线时，λ与其他 HRV 指数相关性不大（与任何指数的相关系数均小于 0.4），且服用β受体阻滞剂的患者中 λ 降低（P=0.04）。在中位随访 25 个月期间，45 例（6.7%）患者死亡（32 例为心源性，13 例为非心源性），幸存者中 39 例再次发生非致死性 AMI。虽然这些 HRV 指数均为心源性和非心源性死亡的显著预测因子，但 λ 增加仅预测心源性死亡（RR [95%CI]，每增加 1 个标准差为 1.6 [1.3-2.0]，P<0.0001）。即使在调整了临床危险因素（如年龄、糖尿病、左心室功能、肾功能、既往 AMI、心力衰竭和卒中、Killip 分级和治疗）后， λ 增加的预测能力仍有意义（RR [95%CI]，每增加 1 个标准差为 1.4 [1.1-2.0]，P=0.01）。 λ 增加预测心源性死亡的作用也独立于其他所有 HRV 指数，且 λ 增加和异常 HRT 的组合提供了预测心源性死亡的最佳模型。 λ 或其他 HRV 指数均不是 AMI 复发的独立预测因子。在 AMI 后患者中， λ 增加仅与增加的心脏死亡率风险相关，其预测能力独立于临床危险因素和其他 HRV 预测因子。
