Abstract
IntroductionThe prognostic significance of beat-to-beat variability of spatial heterogeneity of repolarization measured from standard 12-lead ECG is not well-understood.MethodsWe measured the short-term variability of repolarization parameters, such as T-wave heterogeneity in leads V4–V6 (TWH) and QT interval (QT), from five consecutive beats of previously recorded standard 12-lead ECG in 200 victims of unexpected sudden cardiac death (SCD) confirmed to be due to complicated atherosclerotic coronary artery disease (CAD) in medico-legal autopsy and 200 age- and sex-matched controls with angiographically confirmed CAD. The short-term variability of repolarization heterogeneity was defined as the standard deviation (SD) of the measured repolarization parameters. All ECGs were in sinus rhythm, and no premature ventricular contractions were included in the measured segment.ResultsTWH-SD and QT-SD were significantly higher in SCD victims than in subjects with CAD (6.9 ± 5.6 μV vs. 3.8 ± 2.6 μV, p = 1.8E-11; 8.3 ± 13.1 ms vs. 3.8 ± 7.1 ms, p = 0.00003, respectively). After adjusting in the multivariate clinical model with factors, such as diabetes, RR interval, and beta blocker medication, TWH-SD and QT-SD retained their significant power in discriminating between the victims of SCD and the patients with CAD (p = 0.00003, p = 0.006, respectively). TWH-SD outperformed QT-SD in identifying the SCD victims among the study subjects (area under the curve in the receiver operating characteristics curve 0.730 vs. 0.679, respectively).ConclusionIncreased short-term variability of repolarization heterogeneity measured from standard 12-lead ECG is associated with SCD.
Highlights
The prognostic significance of beat-to-beat variability of spatial heterogeneity of repolarization measured from standard 12-lead ECG is not wellunderstood
In the present case–control study, we tested the hypothesis that beat-to-beat variability of parameters describing spatial heterogeneity of repolarization determined from standard 12-lead ECG discriminate the victims of unexpected sudden cardiac death (SCD) verified to be due to atherosclerotic coronary artery disease (CAD) by autopsy from the CAD patients who remained alive during the follow-up
Temporal variability of repolarization analyzed from five consecutive beats of the standard 12-lead ECG represented by QT-standard deviation (SD), T-window-H-SD, TCRT-SD, TMD-SD, TMDpre-SD, TMDpost-SD, and T-wave heterogeneity (TWH)-SD was significantly higher in the victims of SCD than in the subjects with CAD
Summary
The prognostic significance of beat-to-beat variability of spatial heterogeneity of repolarization measured from standard 12-lead ECG is not wellunderstood. Earlier studies have used several different approaches, such as the evaluation of QT/RR relationship, circadian pattern of heart rate corrected QT interval (QTc), various methods describing temporal variability of QT interval, and T-wave alternans (TWA). Increased spatial heterogeneity of repolarization measured from standard 12-lead ECG has been associated with the risk of SCD (Porthan et al, 2013). In the present case–control study, we tested the hypothesis that beat-to-beat variability of parameters describing spatial heterogeneity of repolarization determined from standard 12-lead ECG discriminate the victims of unexpected SCD verified to be due to atherosclerotic coronary artery disease (CAD) by autopsy from the CAD patients who remained alive during the follow-up
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