Hashimoto Kenichi, Kasamaki Yuji, Soma Masayoshi, Takase Bonpei
Department of Intensive Care Medicine, National Defense Medical College, Saitama, Japan.
Department of General Medicine, Kanazawa Medical University Himi Municipal Hospital, Kanazawa, Japan.
Ann Noninvasive Electrocardiol. 2019 May;24(3):e12620. doi: 10.1111/anec.12620. Epub 2018 Nov 7.
T-wave alternans (TWA) is a risk stratification predictor for sudden cardiac death. However, little is known about the diurnal variation of TWA. Whether TWA are affected by heart rate (HR) or cardiac autonomic nervous activity in the subjects without significant structural heart disease in daily life is not fully understood. Thus, this study was aimed to clarify these issues.
Frequency domain (FD)-TWA analysis was conducted in 47 subjects without significant structural heart disease using 24-hr ambulatory electrocardiogram (AECG). Measurement of heart rate variability (HRV) was performed in order to evaluate the autonomic activity of the heart. The maximum FD-TWA value in each period was measured four times per day (A, 00:00-6:00 hr; B, 06:00-12:00 hr; C, 12:00-18:00 hr; D, 18:00-24:00 hr). Correlations between FD-TWA and either HR or HRV parameters (LF/HF, LFnu, HFnu, SDNN, CVNN, pNN50) were analyzed in each period (A-D).
There was diurnal variation of FD-TWA (median, inter-quartile range [IQR]: A, 8.2 [6.5, 10.6] μV; B, 10.1 [8.4, 15.0] μV; C, 17.6 [12.3, 25.0] μV: D, 11.9 [9.1, 19.9] μV; p < 0.0001). Maximum FD-TWA had positive correlations with HR and LF/HF (HR, r = 0.496, p < 0.0001; LF/HF, r = 0.414, p = 0.004), while FD-TWA had a negative correlation with HFnu (r = -0.291, p = 0.048). On multiple linear regression analysis, HR had an independent effect on log FD-TWA amplitude (β = 0.461, p = 0.001).
FD-TWA has marked diurnal variation in the daily life of the subjects without significant structural heart disease. This variation could be more strongly affected by HR than the HRV indices.
T波交替（TWA）是心脏性猝死的风险分层预测指标。然而，关于TWA的昼夜变化知之甚少。在日常生活中，无明显结构性心脏病的受试者中，TWA是否受心率（HR）或心脏自主神经活动的影响尚不完全清楚。因此，本研究旨在阐明这些问题。
对47例无明显结构性心脏病的受试者进行24小时动态心电图（AECG）检查，采用频域（FD）-TWA分析。为评估心脏自主神经活动，进行心率变异性（HRV）测量。每天在四个时间段（A，00:00 - 6:00时；B，06:00 - 12:00时；C，12:00 - 18:00时；D，18:00 - 24:00时）各测量一次每个时间段的最大FD-TWA值。分析每个时间段（A - D）中FD-TWA与HR或HRV参数（低频/高频比值、低频标准化值、高频标准化值、标准差、变异系数、相邻RR间期差值大于50ms的心搏数占总心搏数的百分比）之间的相关性。
FD-TWA存在昼夜变化（中位数，四分位数间距[IQR]：A，8.2[6.5, 10.6]μV；B，10.1[8.4, 15.0]μV；C，17.6[12.3, 25.0]μV；D，11.9[9.1, 19.9]μV；p < 0.0001）。最大FD-TWA与HR和低频/高频比值呈正相关（HR，r = 0.496，p < 0.0001；低频/高频比值，r = 0.414，p = 0.004），而FD-TWA与高频标准化值呈负相关（r = -0.291，p = 0.048）。多元线性回归分析显示，HR对log FD-TWA振幅有独立影响（β = 0.461，p = 0.001）。
在无明显结构性心脏病的受试者日常生活中，FD-TWA有明显的昼夜变化。这种变化受HR的影响可能比HRV指标更强。
