Is microvolt T wave alternans associated with the heart failure survival score?

Background: Heart failure survival score (HFSS) is a multivariate risk model widely used to evaluate patients with heart failure and stratify the risk of adverse outcome. However the HFSS does not incorporate an arrhythmic risk factor. Microvolt T wave alternans (TWA) has been associated with poor outcomes in patients with heart failure. We attempted to determine whether non-invasive clinical variables and the composite HFSS are associated with TWA. Methods: 168 patients in sinus rhythm, left ventricular dysfunction (EF≤40%) with NYHA class I, II or III and without a prior history of ventricular tachyarrhythmia were eligible. TWA was measured using a spectral method and analyzed automatically using the D10 version of the CH2000 software (Cambridge Heart, Bedford, MA). TWA results were classified as low risk (negative) and high risk (positive and indeterminate). Seven variables (serum sodium, EF, peak VO2, etiology of heart disease, QRS duration, resting heart rate and mean blood pressure) and the composite HFSS score were compared in patients with high vs. low risk TWA using an unpaired t-test and chi square test. Results: Of the total, 40% had ischemic heart disease and 62.6% had a high risk TWA result. The mean ejection fraction was 23.2±7.6%. Patients with high risk TWA had a slightly lower peak VO2 (17.1 vs. 18.5 ml/kg/min, p<0.05) and a slightly longer QRS duration (118.8 vs. 109.2 ms, p<0.05). None of the other variables differed by TWA status. Based on the HFSS, 64.8% were classified as low risk, 28.5% as medium risk and 11% as high risk. There was no association between TWA status and HFSS classification. Conclusions: TWA appears to provide independent information from the HFSS. Future studies are needed to determine if TWA provides additional prognostic information above and beyond that provided by HFSS in patients with left ventricular dysfunction and heart failure.