Measurement of microvolt T‐wave alternans, a new arrhythmic risk stratification test, in Type 2 diabetic patients without clinical cardiovascular disease

Abstract

Patients with a positive microvolt T-wave alternans (TWA) are at increased risk of ventricular arrhythmias and sudden cardiac death. Although Type 2 diabetes is associated with an increased risk of these events, there is a dearth of available data on measurements of TWA in people with Type 2 diabetes. We studied 43 Type 2 diabetic volunteers who were free of diagnosed cardiovascular disease (CVD). Microvolt TWA analysis was performed non-invasively using the CH 2000 system during submaximal exercise with the patients sitting on a bicycle ergometer. TWA analysis was positive in 9 (21%) patients, negative in 32 (74.4%) and indeterminate in 2 (4.6%) subjects. TWA positive patients had significantly higher HbA(1c) levels than those with TWA negativity (8.1 +/- 0.9 vs. 7.2 +/- 0.8%, P < 0.01). Age, sex, BMI, blood pressure, lipids, 24-h heart rate variability, QTc interval duration, smoking history, diabetes duration and treatment, and microvascular complication status did not differ between the groups. In regression logistic analysis, HbA(1c) was the only significant predictor of TWA positivity (odds ratio 5.7, 95% CI 1.3-26, P = 0.023) after controlling for potential confounders. These results suggest that in Type 2 diabetic patients without clinically manifest CVD, TWA positivity is common (approximately 20%) and is closely correlated with glycaemic control.