Onset heart rate of microvolt-level T-wave alternans provides clinical and prognostic value in nonischemic dilated cardiomyopathy

AbstractObjectivesThis study was designed to determine the prognostic value of onset heart rate (OHR) in T-wave alternans (TWA) in patients with nonischemic dilated cardiomyopathy (DCM).BackgroundOne of the current major issues in DCM is to prevent sudden cardiac death (SCD). However, the value of the OHR of TWA as a prognostic indicator in DCM remains to be elucidated.MethodsWe prospectively investigated 104 patients with DCM undergoing TWA testing. The end point of this study was defined as SCD, documented sustained ventricular tachycardia/ventricular fibrillation. Relations between clinical parameters and subsequent outcome were evaluated.ResultsForty-six patients presenting with TWA were assigned to one of the following two subgroups according to OHR for TWA of ≤100 beats/min: group A (n = 24) with OHR ≤100 beats/min and group B (n = 22) with 100 < OHR ≤ 110 beats/min. T-wave alternans was negative in 37 patients (group C) and indeterminate in 21 patients. The follow-up result comprised 83 patients with determined TWA. During a follow-up duration of 21 ± 14 months, there was a total of 12 arrhythmic events, nine of which included three SCDs in group A, two in group B and one in group C. The forward stepwise multivariate Cox hazard analysis revealed that TWA with an OHR ≤100 beats/min and left ventricular ejection fraction were independent predictors of these arrhythmic events (p = 0.0001 and p = 0.0152, respectively).ConclusionsThe OHR of TWA is of additional prognostic value in DCM

Acute Effects of Angiotensin II Receptor Blocker on Ventricular Repolarization Alternans in Chronic Heart Failure

Repolarization alternans, which can be detected clinically as microvolt-level T-wavealternans (TWA), is considered an important mechanism underlying the initiation ofventricular tachycardia/ventricular fibrillation (VT/VF) linked to sudden cardiac death(SCD). Recently, the rennin-angiotensin system (RAS) inhibitors have been suggestedto have potential benefits in reducing SCD as well as heart failure death with chronicheart failure (CHF).In this study, we tested the acute effects of an angiotensin II receptor blocker (ARB),valsartan, on the development of TWA and the heart rate at which TWA appeared(onset heart rate; OHR). Fifty consecutive patients with CHF underwent TWAmeasurement. Patients with positive TWA were administered valsartan (80mg/day)orally for 3 days. Alternans voltage in the vector magnitude lead (Valt) and the OHRwere compared before and after the drug exposure.TWA was positive in 19 patients (38%), negative in 16 (32%), and indeterminate in15 (30%). Nineteen patients with positive TWA received valsartan. However, 3patients were withdrawn due to adverse drug reactions. In all the remaining 16patients, markedly reduced Valt (6.1 ± 3.8 μV to 2.5 ± 1.9 μV; P = 0.002) and increasedOHR (94 ± 9 beats/min to 102 ± 9 beats/min; p = 0.002) were observed. In particular,3 patients became TWA negative.These results suggest that the RAS inhibitors prevent SCD by the improvement ofrepolarization abnormality