Burattini Laura, Man Sumche, Burattini Roberto, Swenne Cees A
Department of Information Engineering, Polytechnic University of Marche, Ancona, Italy.
Ann Noninvasive Electrocardiol. 2012 Apr;17(2):130-40. doi: 10.1111/j.1542-474X.2012.00490.x.
T-wave alternans (TWA), an electrophysiologic phenomenon associated with ventricular arrhythmias, is usually detected from selected ECG leads. TWA amplitude measured in the 12-standard and the 3-orthogonal (vectorcardiographic) leads were compared here to identify which lead system yields a more adequate detection of TWA as a noninvasive marker for cardiac vulnerability to ventricular arrhythmias. Our adaptive match filter (AMF) was applied to exercise ECG tracings from 58 patients with an implanted cardiac defibrillator, 29 of which had ventricular tachycardia or fibrillation during follow-up (cases), while the remaining 29 were used as controls. Two kinds of TWA indexes were considered, the single-lead indexes, defined as the mean TWA amplitude over each lead (MTWAA), and lead-system indexes, defined as the mean and the maximum MTWAA values over the standard leads and over the orthogonal leads. Significantly (P < 0.05) higher TWA in the cases versus controls was identified only occasionally by the single-lead indexes (odds ratio: 1.0-9.9, sensitivity: 24-76%, specificity: 76-86%), and consistently by the lead-system indexes (odds ratio: 4.5-8.3, sensitivity: 57-72%, specificity: 76%). The latter indexes also showed a significant correlation (0.65-0.83) between standard and orthogonal leads. Hence, when using the AMF, TWA should be detected in all leads of a system to compute the lead-system indexes, which provide a more reliable TWA identification than single-lead indexes, and a better discrimination of patients at increased risk of cardiac instability. The standard and the orthogonal leads can be considered equivalent for TWA identification, so that TWA analysis can be limited to one-lead system.
T波交替（TWA）是一种与室性心律失常相关的电生理现象，通常从选定的心电图导联中检测出来。在此比较了在12导联标准心电图和3个正交（心电向量图）导联中测量的TWA幅度，以确定哪种导联系统能更充分地检测TWA，将其作为心脏易患室性心律失常的无创标志物。我们的自适应匹配滤波器（AMF）应用于58例植入式心脏除颤器患者的运动心电图记录，其中29例在随访期间发生室性心动过速或颤动（病例组），其余29例用作对照组。考虑了两种TWA指标，单导联指标，定义为每个导联上的平均TWA幅度（MTWAA），以及导联系统指标，定义为标准导联和正交导联上的平均MTWAA值和最大MTWAA值。仅偶尔通过单导联指标发现病例组的TWA显著高于对照组（P<0.05）（优势比：1.0 - 9.9，敏感性：24 - 76%，特异性：76 - 86%），而通过导联系统指标则始终如此（优势比：4.5 - 8.3，敏感性：57 - 72%，特异性：76%）。后一种指标还显示标准导联和正交导联之间存在显著相关性（0.65 - 0.83）。因此，使用AMF时，应在一个系统的所有导联中检测TWA以计算导联系统指标，该指标比单导联指标能提供更可靠的TWA识别，并且能更好地区分心脏不稳定风险增加的患者。标准导联和正交导联在TWA识别方面可视为等效，因此TWA分析可限于一个导联系统。
