Resting Left Ventricular Dyssynchrony and Mechanical Reserve in Asymptomatic Normotensive Subjects with Early Type 2 Diabetes Mellitus

Background: Most diabetic patients have silent ischemia and cardiac dysfunction that is usually observed in the late phase of the disease when it becomes clinically obvious. We hypothesized that left ventricular dyssynchrony (LVdys) (or dispersion) is an early marker of myocardial involvement in asymptomatic early type 2 diabetes mellitus (T2DM) patients. Therefore, we aimed to detect early markers of myocardial dysfunction in early T2DM using LVdys and left ventricular mechanical reserve (LVMR). Methods: We examined 91 consecutive subjects with early T2DM with speckle tracking imaging to evaluate LVdys and with dobutamine stress to evaluate LVMR (defined as left ventricular mechanical reserve global longitudinal strain [LVMRGLS] ≥2%). Our patients were divided into two groups according to LVdys: group 1 with LVdys (n = 49), and group 2 without LVdys (n = 42). Results: We found that 49 (54%) subjects in our cohort had resting LVdys (standard deviation of tissue synchronization of the 12 left ventricular segments [Ts-SD-12] ≥34.2 ms). GLS and strain rate were comparable at rest between patients with and without LVdys. On the other hand, LVMR was blunted in those with LVdys (p < 0.001). We found that HbA1c, high-sensitivity C-reactive protein, and left atrial volume index were inversely correlated with LVMR. Multivariate analysis showed that LVdys was the strongest predictor (p < 0.001) of blunted LVMR. Using receiver operating characteristic curve analysis, we found that a Ts-SD-12 ≥36.5 ms was the best cutoff value to predict blunted LVMR (area under the curve = 0.89, p < 0.001). Conclusion: The LVdys (Ts-SD-12) cutoff ≥36.5 ms was the optimal value for prediction of impaired LVMR and might be an early marker of subclinical cardiac dysfunction and risk stratification of subjects with asymptomatic early T2DM with preserved left ventricular ejection fraction.