Quantitative Assessment of Microvolt T‐Wave Alternans in Patients with Congestive Heart Failure

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Abstract
Introduction: T‐wave alternans has been shown to be linked to the genesis of ventricular tachyarrhythmias. Currently, only qualitative assessment of microvolt T‐wave alternans (MTWA) is recommended in clinical practise. Whether quantitave assessment of MTWA yields complementary information is unknown. Methods and Results: Noninvasive MTWA determination was performed in 204 consecutive patients with ischemic or nonischemic cardiomyopathy. Of those, 100 tested MTWA positive. In these recordings, MTWA magnitude was quantitatively assessed (alternans voltage, Valt). Patients were followed for a mean of 17 months. Ventricular tachyarrhythmic events constituted the study endpoint. Patients with nonischemic cardiomyopathy had a higher Valt than patients with ischemic cardiomyopathy (10.3 ± 9.2 [median 7.2] vs 6.2 ± 3.2 [median 4.6]μV; P = 0.007). The number of MTWA‐positive ECG leads was also higher in patients nonischemic cardiomyopathy (7.3 ± 2.4 [median 8] vs 6.0 ± 2.5 [median 6]; P = 0.016). Patients who suffered an arrhythmic event during follow‐up had higher MTWA voltages (10.8 ± 10.0 [median 8.8] vs 7.4 ± 5.7 [median 6.4]μV; P = 0.05) a higher number of MTWA‐positive ECG leads (7.6 ± 2.4 [median 8] vs 6.4 ± 2.5 [median 6]; P = 0.05) compared to patients with an uncomplicated course. Conclusion: Patients with nonischemic cardiomyopathy and patients with tachyarrhythmic complications have more extensive MTWA possibly reflecting more extensive myocardial damage and a higher arrhythmia propensity.