Sassi R, Rivolta M W, Mainardi L T, Reis R C, Rocha M O C, Ribeiro A L P, Lombardi F
Roberto Sassi, Dipartimento di Informatica, Università degli Studi di Milano, Via Bramante 65, 26013 Crema (CR), Italy, E-mail:
Methods Inf Med. 2014;53(6):464-8. doi: 10.3414/ME14-01-0002. Epub 2014 Jun 27.
We investigated if cardiac spatial repolarization heterogeneity might be associated with an increased risk of death in patients with chronic Chagas disease.
Repolarization heterogeneity was assessed using the V-index, a recently introduced metric founded on a biophysical model of the ECG. This metric provides an estimate of the standard deviation of the repolarization times across the heart. We analyzed 113 patients (aged 21- 67 years) enrolled between 1998 and 1999 who had a known serological status showing positive reactions to Trypanosoma cruzi. Fourteen subjects died during a 10-year follow-up period.
The V-index was significantly lower in survivor (S) than in non-survivor (NS) subjects (S: 31.2 ± 13.3 ms vs NS: 41.2 ± 18.6 ms, single-tail t-test: p = 0.009, single-tail Wilcoxon rank sum test: p = 0.029). A V-index larger than 36.3 ms was related to a significantly higher risk of death in a univariate Cox proportional-hazards analysis (hazard ratio, HR = 5.34, p = 0.0046). In addition, V-index > 36.3 ms retained its prognostic value in a multivariate Cox proportional-hazards analysis after adjustment for other three clinical variables (left ventricular ejection factor < 0.50, QRS duration > 133 ms, ventricular tachycardia during stress testing or 24 hours Holter) and for T-wave amplitude variability > 30 μV, even using shrinkage, a statistical procedure that protects against over-fitting due to small sample size.
The study showed that an increased dispersion of repolarization times in patients with Chagas disease, as measured by the V-index, is significantly correlated with the risk of death in a univariate survival analysis. The V-index captures prognostic information not immediately available from the analysis of other established risk factors.
我们研究了慢性恰加斯病患者心脏空间复极异质性是否可能与死亡风险增加相关。
使用V指数评估复极异质性，V指数是一种基于心电图生物物理模型的最新指标。该指标可估计心脏复极时间的标准差。我们分析了1998年至1999年间纳入的113例患者（年龄21 - 67岁），这些患者已知血清学状态显示对克氏锥虫呈阳性反应。14名受试者在10年随访期内死亡。
幸存者（S）的V指数显著低于非幸存者（NS）（S：31.2±13.3毫秒 vs NS：41.2±18.6毫秒，单尾t检验：p = 0.009，单尾威尔科克森秩和检验：p = 0.029）。在单变量Cox比例风险分析中，V指数大于36.3毫秒与显著更高的死亡风险相关（风险比，HR = 5.34，p = 0.0046）。此外，在对其他三个临床变量（左心室射血分数<0.50、QRS波时限>133毫秒、应激试验或24小时动态心电图监测期间的室性心动过速）以及T波振幅变异性>30μV进行调整后，即使使用收缩法（一种防止因样本量小而过度拟合的统计程序），V指数>36.3毫秒在多变量Cox比例风险分析中仍保留其预后价值。
该研究表明，以V指数衡量，恰加斯病患者复极时间离散度增加与单变量生存分析中的死亡风险显著相关。V指数捕捉到了其他既定风险因素分析中无法立即获得的预后信息。
