Which Left Ventricular Function Is Impaired Earlier in the Evolution of Diabetic Cardiomyopathy?: An echocardiographic study of young type I diabetic patients
OBJECTIVE To determine whether diastolic dysfunction preceded systolic dysfunction in the evolution of diabetic cardiopathy. RESEARCH DESIGN AND METHODS A total of 157 young (mean age 26.6 years) cardiac asymptomatic type 1 diabetic patients and 54 age- and sex-matched healthy (nondiabetic) subjects were studied. The severity of diabetic complications (retinopathy, nephropathy, and cardiac autonomic neuropathy) was evaluated by the diabetic complication index (DCl), a sum of individual scores for each complication. Left ventricular (LV) function was studied by M-mode echocardiography. Impaired systolic and diastolic functions were presumed if at least two echocardiographic variables for systolic function (fractional shortening [FS], mean velocity of circumference fiber shortening, and stroke index) and for diastolic function (slope of anterior mitral leaflet in early diastole, isovolumic relaxation time [IRT], and left atrium emptying index) were out of the control range (mean ± 2 SD). RESULTS Diastolic dysfunction was twice as common as systolic dysfunction (27% and 12%, respectively, P < 0.001). Of diabetic patients with systolic dysfunction, 83% had impaired diastolic function, whereas only 30% of diabetic patients with diastolic dysfunction had systolic damage (P < 0.001). On the other hand, only 3 of 157 diabetic patients (1.9%) had systolic dysfunction with preserved diastolic function (P > 0.05). Diastolic dysfunction, represented by the interval from minimal LV dimension to mitral valve opening, was seen in diabetic patients ∼8 years after onset of diabetes and systolic dysfunction represented by FS after ∼18 years. Diastolic dysfunction, represente by 1RT, was found in the presence of mild complications (DCl = 2), and systolic dysfunction, represented by FS, was found in the presence of more severe complications (DCl = 4). CONCLUSIONS Our findings indicate that myocardial damage in patients with diabetes affects diastolic function before systolic function. The intentional assessment of diastolic function is advisable for early detection of LV dysfunction before clinical symptoms appear, with follow-up to detect further deterioration of cardiac status.