Key result
T-wave alternans exhibited heart rate-dependent hysteresis and differed significantly during recovery between patients who developed arrhythmic events and those who did not (e.g., 38 μV vs 21 μV at 90 bpm; P<0.05).
Why the study?
Does T-wave alternans analysis during the recovery phase of exercise testing help identify primary prevention ICD patients at increased risk of arrhythmic events?
Cohort (n=266)
Does T-wave alternans analysis during the recovery phase of exercise testing help identify primary prevention ICD patients at increased risk of arrhythmic events?
T-wave alternans exhibits heart rate-dependent hysteresis, and analyzing TWA during the recovery phase of exercise testing may help identify ICD patients at increased risk for ventricular arrhythmias.
Answers are grounded in this paper and cite their sources.
Recovery TWA may aid arrhythmic risk stratification in primary-prevention ICD patients; hypothesis-generating and requires prospective validation.
BACKGROUND: T-wave alternans (TWA) is usually performed at accelerated heart rates (HR) during exercise, while recovery TWA is typically not analyzed. Consequently, it is still unknown if TWA shows a HR-dependent hysteresis or not. Thus, the aim of the present study was to investigate TWA dependency on HR during both the exercise and recovery phases of an ergometer test, and to evaluate if recovery TWA may contribute to identify subjects at increased risk of arrhythmic events. METHODS: Our HR adaptive match filter was used to identify TWA from electrocardiographic recordings acquired during a bicycle ergometer test in 266 patients with implanted cardio-defibrillator. During the 4-year follow-up, 76 patients developed tachycardia or ventricular fibrillation (ICD_Cases) and 190 did not (ICD_Controls). RESULTS: TWA was statistically lower during exercise than recovery for HRs between 75 and 110 bpm (16-21 μV vs 20-27 μV; P < 0.05), and reverse for HRs between 120 and 130 bpm (41-51 μV vs 28 μV; P < 0.05). ICD_Cases and ICD_Controls showed significantly different TWA at 80 bpm (20 μV vs 15 μV; P < 0.05) and 140 bpm (15 μV vs 22 μV; P < 0.05) during exercise, and at 90 bpm (38 μV vs 21 μV; P < 0.05) and 95 bpm (33-24 μV vs 28 μV; P < 0.05) during recovery. CONCLUSIONS: TWA shows a HR-dependent hysteresis and there is a different behavior of TWA in ICD_Cases and ICD_Controls groups. Consequently, beside exercise TWA also recovery TWA may contribute to identify subjects at increased risk of arrhythmic events.
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Burattini et al. (2015) conducted a cohort in Primary prevention ICD patients (n=266). T-wave alternans (TWA) during exercise and recovery vs. ICD_Controls (no arrhythmic events) was evaluated on T-wave alternans (TWA) amplitude differences between patients with and without arrhythmic events (p=<0.05). T-wave alternans exhibited heart rate-dependent hysteresis and differed significantly during recovery between patients who developed arrhythmic events and those who did not (e.g., 38 μV vs 21 μV at 90 bpm; P<0.05).
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