T-wave alternans predicts mortality in a population undergoing a clinically indicated exercise test

Abstract

Aims: As a part of the Finnish Cardiovascular Study, we tested the hypothesis that T-wave alternans (TWA) predicts mortality in a general population of patients referred for a clinical exercise test. Methods and results: A total of 1037 consecutive patients (mean age ± SD of 58 ± 13 years, 673 men and 364 women) with a clinically indicated exercise test and with technically successful electrocardiographic (ECG) data during a bicycle ergometer test were included in the study. Digital ECGs were recorded and TWA was analysed continuously with the time-domain modified moving average method. The maximum TWA value at heart rate (HR) <125 b.p.m. was derived and its capacity to stratify risk for all-cause death, cardiovascular death, and sudden cardiac death (SCD) was tested. During a follow-up of 44 ± 7 months (mean ± SD), 59 patients died; 34 were due to cardiovascular causes and 20 were due to SCD. In multivariate analysis after adjustment for age, sex, use of β-blockers, functional class, maximal HR during exercise, previous myocardial infarction, and other common coronary risk factors, the relative risk of TWA ≥65 μV for SCD was 7.4 (95% CI, 2.8-19.4; P < 0.001), for cardiovascular mortality 6.0 (95% CI, 2.8-12.8; P < 0.001), and for all-cause mortality 3.3 (95% CI, 1.8-6.3; P = 0.001). Conclusion: Time-domain TWA analysis powerfully predicts mortality in a general population undergoing a clinical exercise test. © The European Society of Cardiology 2007. All rights reserved.