Diabetic cardiomyopathy: predictors of progression and outcome after 10 years of follow up.

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Type 2 diabetes mellitus (T2DM) is the fastest growing chronic disease in Australia today with an estimated 275 new cases every day. Currently 1.7 million Australians have diabetes and it is thought that up to half of these individuals are as yet undiagnosed. The annual cost of diabetes to the Australian healthcare system is estimated at least $3 billion. Diabetes was the underlying cause for 3.0% deaths registered in Australia in 2009 and additionally contributed to 10.1% deaths as either an underlying or associated cause of death. Worldwide it is anticipated that by the year 2025 there will be 300 million people with the disease especially given the epidemic of obesity and impact of sedentary lifestyles. It is known that individuals with diabetes have a significantly increased risk of cardiovascular disease. Recent data showed that this condition is underappreciated with 48% of all diabetic individuals, who had no previous history of structural heart disease, having evidence of Diabetic Cardiomyopathy echocardiographically. In diabetics, a complex series of metabolic disturbances results in heart fibrosis and enlargement. which ultimately leads to clinical heart failure. Despite 4 decades of research there are currently no specific treatments for diabetic cardiomyopathy. Prevention of this condition requires its early identification and treatment. Early treatment with medications known to improve heart failure outcome such as angiotensin-converting enzyme inhibitors (ACEI) and beta-blockers has been suggested from meta-analysis data specifically looking at diabetic subjects in the major heart failure trials to be beneficial . There is yet to be a long term follow-up study to definitively confirm this. Much of the previous work focusing on the early identification of this condition has been carried out by the Cardiovascular Imaging Research group through involvement in an NHMRC Centre of Clinical Research Excellence Award (455832). Work initiated in 2003 studied a large cohort of T2DM patients in a randomized controlled trial of lifestyle intervention. The results of this research were groundbreaking, proving that diabetic cardiomyopathy was able to be identified using novel echocardiographic imaging techniques. The proposed project aims to provide long term (10 year) follow up data on these original participants. To our knowledge this will be unique data within the literature allowing identification of markers of long term adverse prognosis and information about the factors affecting the progression of diabetic cardiomyopathy over time. Hypotheses The following hypotheses will be tested: 1. Diabetic cardiomyopathy is prevalent and progressive over time. Clinical and widely available testing including echocardiography and cardiopulmonary exercise testing is able to identify long term risk markers for diabetic cardiomyopathy which result in adverse cardiovascular morbidity and mortality. 2. Novel echocardiographic techniques, are superior to current echocardiographic techniques for the detection of diabetic cardiomyopathy and are better able to assess cardiac risk as evidenced by subclinical left ventricular dysfunction. 3. ACE inhibitor/Angiotensin Receptor Blocker (ARB) therapy and/or beta-blocker therapy will prevent the progression of DCM over long term follow-up.