Department of Cardiovascular Medicine, Università Cattolica del Sacro Cuore, Rome, Italy.
Europace. 2012 Feb;14(2):272-7. doi: 10.1093/europace/eur285. Epub 2011 Sep 8.
Microvolt T-wave alternans (TWA) predicts arrhythmic risk in patients with ischaemic heart disease (IHD). While TWA has widely been assessed by the spectral method, it has been poorly characterized in healthy people as well as in IHD patients by the modified moving average (MMA) method.
We enrolled 729 consecutive subjects, referred for exercise stress test (EST). T-wave alternans was assessed by the MMA method, considering all 12 electrocardiogram (ECG) leads (TWA_tot) or the 6 ECG pre-cordial leads only (TWA_prec). Patients were divided into five groups: (i) no history of IHD and normal EST (Group 1); (ii) no history of IHD but positive EST (Group 2); (iii) ischaemic heart disease without any acute myocardial infarction [AMI (Group 3)]; (iv) old AMI (Group 4); (v) recent AMI (Group 5). T-wave alternans values >95th percentile of those measured in Group 1 were considered 'abnormal'. The 95th percentile of TWA values in Group 1 was 75 µV for TWA_tot and 65 µV for TWA_prec. T-wave alternans values and prevalence of abnormal TWA increased from Groups 1-2 to Group 5 (P< 0.00001 for both). Group 4 and Group 5, compared with Group 1, showed a significant higher prevalence of abnormal values of TWA_tot [odds ratio (OR) 1.70 (P= 0.002), and 2.07 (P= 0.01), respectively] and TWA_prec [OR 1.51 (P= 0.02) and 2.37 (P= 0.003), respectively] at multivariable analysis. In IHD patients EST-induced ischaemia did not influence TWA; in AMI patients, impaired left ventricular function was associated with higher TWA values.
In healthy people, TWA_tot and TWA_prec were ≤75 and ≤65 µV, respectively, in 95% of subjects. In IHD patients TWA values were higher compared with healthy individuals; a history of AMI was independently associated with abnormal TWA values.
微伏级 T 波电交替（TWA）可预测缺血性心脏病（IHD）患者的心律失常风险。虽然 TWA 已广泛通过频谱方法进行评估，但通过改良移动平均（MMA）方法，它在健康人群和 IHD 患者中的特征描述较差。
我们纳入了 729 例连续就诊行运动应激试验（EST）的患者。通过 MMA 方法评估 T 波电交替，考虑所有 12 个心电图（ECG）导联（TWA_tot）或仅 6 个胸前导联（TWA_prec）。患者分为五组：（i）无 IHD 病史且 EST 正常（第 1 组）；（ii）无 IHD 病史但 EST 阳性（第 2 组）；（iii）无急性心肌梗死（AMI）的缺血性心脏病（第 3 组）；（iv）陈旧性 AMI（第 4 组）；（v）近期 AMI（第 5 组）。TWA 值大于第 1 组测量值的第 95 百分位数被认为“异常”。第 1 组 TWA 值的第 95 百分位数为 TWA_tot 为 75µV，TWA_prec 为 65µV。T 波电交替值和异常 TWA 的发生率从第 1 组到第 5 组逐渐增加（两者均 P<0.00001）。与第 1 组相比，第 4 组和第 5 组 TWA_tot[比值比（OR）1.70（P=0.002）和 2.07（P=0.01）]和 TWA_prec[OR 1.51（P=0.02）和 2.37（P=0.003）]的异常值发生率显著更高，差异具有统计学意义。在 IHD 患者中，EST 诱发的缺血并不影响 TWA；在 AMI 患者中，左心室功能障碍与较高的 TWA 值相关。
在健康人群中，95%的受试者 TWA_tot 和 TWA_prec 分别≤75µV 和≤65µV。与健康个体相比，IHD 患者的 TWA 值更高；AMI 病史与异常 TWA 值独立相关。
