Pattern of crescendo TWA may disclose the underlying cardiac pathology.

We present an exercise test case in which crescendo TWA preceded ventricular tachycardia (VT). The patient was examined due to suspicion of ischemic heart disease. The ST-segment became elevated simultaneously with a distinct alternation in the ST-segment and the first half of the T-wave, and the patient developed polymorphic VT. Coronary angiography disclosed marked stenoses. Earlier reports of TWA in patients with congenital long QT syndrome show a pattern in which the T wave frequently alternates above and below the isoelectric line without concomitant ST-segment changes. In Brugada syndrome patients, the signature ST-T wave pattern is the locus of alternation. Future investigation should elucidate whether specific TWA morphologies may expose underlying heart disease.

Enhanced predictive power of quantitative TWA during routine exercise testing in the Finnish Cardiovascular Study.

INTRODUCTION: We examined whether quantification of T-wave alternans (TWA) enhances this parameter's capacity to evaluate the risk for total and cardiovascular mortality and sudden cardiac death (SCD). METHODS AND RESULTS: The Finnish Cardiovascular Study (FINCAVAS) enrolled consecutive patients (n = 2,119; 1,342 men and 777 women) with a clinically indicated exercise test with bicycle ergometer. TWA (time domain-modified moving average method) was analyzed from precordial leads, and the results were grouped in increments of 10 microV. Hazard ratios (HR) for total and cardiovascular mortality and SCD were estimated for preexercise, routine exercise, and postexercise stages. Cox regression analysis was performed. During follow-up of 47.1 +/- 12.9 months (mean +/- standard deviation [SD]), 126 patients died: 62 were cardiovascular deaths, and 33 of these deaths were sudden. During preexercise, TWA >or= 20 microV predicted the risk for total and cardiovascular mortality (maximum HR >4.4 at 60 microV, P < 0.02 for both). During exercise, HRs of total and cardiovascular mortality were significant when TWA measured >or=50 microV, with 90 microV TWA yielding maximum HRs for total and cardiovascular death of 3.1 (P = 0.03) and 6.4 (P = 0.002), respectively. During postexercise, TWA >or=60 microV indicated risk for total and cardiovascular mortality, with maximum HR of 3.4 at 70 microV (P = 0.01) for cardiovascular mortality. SCD was strongly predicted by TWA levels >or=60 microV during exercise, with maximum HR of 4.6 at 60 microV (P = 0.002), but was not predicted during pre- or postexercise. CONCLUSION: Quantification of TWA enhances its capacity for determination of the risk for total and cardiovascular mortality and SCD in low-risk populations. Its prognostic power is superior during exercise compared to preexercise or postexercise.

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

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 beta-blockers, functional class, maximal HR during exercise, previous myocardial infarction, and other common coronary risk factors, the relative risk of TWA>or=65 microV 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.