Speckle-Tracking Echocardiography is Preferable Measurement for Detecting the Early and Subtle Alterations of Cardiac Dysfunction in Diabetic Rats

Abstract BackgroundMyocardial damage caused by diabetic cardiomyopathy results in cardiac structural and functional abnormalities. Our previous studies have demonstrated that inhibiting RhoA/ROCK signaling pathway improved the structural abnormalities. The early detection of cardiac functional alterations accompanied by structural changes during therapy may facilitate better understanding on the pathophysiologic progress and guiding diabetic cardiomyopathy treatment. This study aimed to identify the optimal diagnostic measures for the early and subtle alterations of cardiac dysfunction in Type 2 diabetes mellitus rats.MethodsTwenty-four male Wistar rats were randomly divided into four groups and treated for 4 weeks: CON (control rats), DM (diabetic rats), DMF (DM + fasudil 10mg/kg/d) and CONF (CON + fasudil 10mg/kg/d). Left ventricular (LV) structure was quantified by histological staining and transmission electron microscopy. LV function and myocardial deformation were performed by high-frequency echocardiography.ResultsMyocardial hypertrophy and fibrosis were increased in diabetic rats and were remarkably alleviated in the DMF group. The diabetic rats had impaired LV performance evidenced by significant reduction of EF, FS and MV E/A, 26%, 34% and 20% respectively, while ROCK inhibition failed to improve the conventional ultrasonic parameters. However, the cardiac time intervals (CTI) parameters and speckle-tracking echocardiography (STE) parameters were significantly improved in the DMF group compared with the DM group (isovolumic contraction time, IVCT: P = 0.029; myocardial performance index, MPI: P = 0.037; fractional area change, FAC: P < 0.001; global circumferential strain, GCS: P = 0.003; global circumferential strain rate, GCSR: P = 0.021). Combining ROC curves with linear regression analysis, STE parameters were characterized by both the optimal predictions for cardiac damage [AUC (95% CI): FAC, 0.927 (0.744 to 0.993); GCS, 0.819 (0.610 to 0.945); GCSR, 0.899 (0.707 to 0.984)] and the strong correlations with cardiac fibrosis (FAC, r = -0.825; GCS, r = 0.772; GCSR, r = 0.829).ConclusionThe results suggest that STE strain and strain rate are preferable indicators of the early detection of subtle alterations in cardiac dysfunction and the quantitation of therapeutic efficacy in diabetic cardiomyopathy.