Early failure of the diabetic heart.

3 T hat diabetes is a risk factor for conges-tive heart failure has been established for decades, but knowledge of the pathophysiology and treatment of heart failure in diabetes is limited. The prevalence of diabetes in different surveys and clinical trials of heart failure ranges from 10 to Ͼ30% (1). In the community setting, data from the Framingham Heart Study have shown an increased incidence of congestive heart failure in diabetic subjects irrespective of coronary heart disease and hypertension (2). The relative impact of diabetes on developing heart failure was found to be greater in women. In the Studies of Left Ventricular Dysfunction (SOLVD) Trials and Registry, diabetes was found to be an independent risk factor for mortality and morbidity in both symptomatic and asymptomatic heart failure (3). A common finding in diabetic patients enrolled in clinical trials of myocar-dial infarction is a discrepancy between left ventricular systolic function and heart failure symptoms (4,5). Despite similar left ventricular systolic function, patients with diabetes have more pronounced heart failure symptoms, use more diuretics, and have an adverse prognosis compared with those without diabetes. One putative explanation for this discrepancy is diastolic dysfunction of the left ventricle. In overt heart failure, diastolic dys-function often coexists with systolic dys-function as a consequence of ischemic heart disease. However, as described in the article by Poirier et al. (6) in this issue of Diabetes Care, diastolic dysfunction is a frequent finding in many studies of cardiac function in type 2 diabetic subjects without symptoms and signs of heart disease. Most of these studies did not angiograph-ically exclude coronary artery disease, which implies that preclinical atheroscle-rosis as a contributory cause of diastolic dysfunction is a potential source of bias. Diastolic dysfunction independent of ischemic heart disease is presumably due to diabetic cardiomyopathy (7). Previous studies estimating the prevalence of diastolic filling abnormalities in diabetic subjects have used measurements of transmitral Doppler flow velocity and have categorized the patients into groups of impaired relaxation or restrictive impairment. The intermediary stage between the two groups has not been thoroughly investigated. This stage is characterized by a normal ventricular relaxation at the expense of an increased left atrial filling pressure, resulting in a pseudonormalized pattern of diastolic filling. This stage cannot be distinguished from the normal pattern by standard transmitral flow measures. The pseudonormal ventricular filling pattern is always a pathological phenomenon, whereas impaired relaxation is also a feature …