Subendocardial Systolic Dysfunction in Asymptomatic Normotensive Diabetic Patients

Background: It remains uncertain whether diabetes itself causes specific echocardiographic features of myocardial morphology and function in the absence of hypertension or ischemic heart disease. The purpose of the present study was to determine the characteristics of pure diabetic cardiomyopathy-related echocardiographic morphology and function using layer-by-layer evaluation with myocardial strain echocardiography. Methods and Results: We enrolled 104 patients with poorly controlled type 2 diabetes mellitus (mean HbA1c level, 10%) with (n=74) or without (n=40) hypertension and 24 age-and sex-matched healthy volunteers. Patients with coronary artery stenosis or structural heart disease were excluded. Myocardial layer-specific strain was analyzed by speckle tracking echocardiography. Compared with the healthy control group, the normotensive diabetes group showed no significant difference in ejection fraction, left ventricular mass index, diastolic properties, left atrial volume index, or B-type natriuretic protein (BNP) level, but global longitudinal strain and subendocardial radial strain were significantly deteriorated. The deterioration of longitudinal strain correlated with body mass index (R=0.49, P<0.01) and blood pressure (R=0.36, P<0.01) in the normotensive diabetes group. Conclusions: Deterioration of left ventricular longitudinal shortening accompanied by decreased subendocardial wall thickening are the characteristic functional abnormalities of diabetic cardiomyopathy in patients without hypertrophy, diastolic dysfunction, or elevated BNP. Obesity and blood pressure may also play important roles in this strain abnormality in asymptomatic patients with type 2 diabetes.