Electromechanical interplay in diabetic cardiomyopathy: relationship between diastolic dysfunction and T-wave alternans

Abstract

Background: Diabetes mellitus (DM) may alter cardiac structure and function in the absence of hypertension and coronary artery disease, a condition called diabetic cardiomyopathy. While patients with this entity may develop lethal arrhythmia, the underlying mechanism is uncertain. The present study sought the potential electromechanical association in patients with diabetic cardiomyopathy by (A) detailed echocardiography for cardiac mechanical assessment and (B) T-wave alternans (TWA) for evaluation of repolarization abnormalities. Methods: A total of 77 patients with type 2 DM without cardiovascular disease were recruited. Transthoracic echocardiography was performed and analyzed in detail with the following parameters: (i) LV systolic function was assessed by Simpson's method derived ejection fraction and speckle tracking derived longitudinal strain (LS), (ii) myocardial structural alteration by calibrated integrated backscatter (cIBS) and (iii) diastolic function by tissue Doppler derived E/e' ratio. Further, TWA (performed noninvasively during submaximal exercise and analyzed by the Modified Moving Average method) were evaluated in all subjects. A positive TWA was defined as ≥60 mV. Results: The mean age of the population was 64±8 years and 50% were male. The mean LV ejection fraction was 62±12% and none of them were less than 45%. A total of 6 (8%) patients had positive TWA. Patients with positive TWA and with negative TWA (as a categorical variable) had a similar LV ejection fraction, cIBS, LS and E/e' ratio. However, TWA (as a continuous variable) was significant correlated with E/e' (R=0.28, P=0.01) but not LS and cIBS (all P>0.05). Linear regression demonstrated that E/e' (β=0.22, P=0.04) was the only variables associated with TWA after adjustment with potential confounding factors. Conclusion: The present study demonstrated that TWA significantly correlates with E/e' ratio. Importantly, the association remains after multivariate adjustment, suggestive of an independent relation between TWA and diastolic dysfunction. The link between these 2 parameters highlighted the potential mechanism for the electromechanical interplay in patients with diabetic cardiomyopathy.