Effect of Pioglitazone on Left Ventricular Diastolic Function in Type 2 Diabetes Mellitus

Cross sectional and population-based studies indicate that at least one third of all patients with congestive heart failure (CHF) have a normal or near normal ejection fraction, which is thought to be secondary to diastolic dysfunction or failure. The mortality rates among the patients with diastolic failure ranges from 5-8% annually, as compared with 10-15% among patients with systolic heart failure. The morbidity associated with diastolic heart failure is similar to that of systolic heart failure. Several studies have shown that even simple Doppler evidence of diastolic dysfunction is an independent risk factor for the development of CHF and cardiac death and increased all cause mortality. Several studies indicate that left ventricular diastolic dysfunction (LVDD) represent the earliest preclinical manifestation of diabetic cardiomyopathy that can progress to symptomatic heart failure. Recent studies have demonstrated up to 60% of asymptomatic, normotensive patients with type 2 diabetes have LVDD when assessed by conventional echocardiography including the response to the Valsalva maneuver. A recent study using conventional Doppler, valsalva maneuver, color M-mode echocardiography and tissue doppler imaging assessed the diastolic dysfunction in asymptomatic normotensive patients with diabetes mellitus and found diastolic dysfunction in about 75% of these patients. Cardiovascular disease is the leading cause of death in patients with type 2 diabetes mellitus. Although diabetic patients have a large number of cardiovascular risk factors, like hyperlipidemia and hypertension, the diabetic cardiomyopathy occurs independent of these risk factors. Recently animal models have shown that LVDD may be prevented by chronic treatment with peroxisome-proliferator-activated receptors gamma (PPAR) agonists, like thiazolidinediones, in type 2 diabetic rats. Thiazolidinediones act through PPAR, but the exact mechanism by which they improve LVDD is not known. With this background knowledge, we wanted to study the effect of Pioglitazone, which is PPAR agonist and partial PPAR agonist, on the left ventricular diastolic dysfunction in type 2 diabetic human subjects, which has not been studied so far. If this therapy proves to have beneficial effect on the LVDD it will help in preventing the deleterious consequences of diastolic dysfunction in diabetic patients.