Non-invasive diagnostic imaging techniques as a window into the diabetic heart: A review of experimental and clinical data

Epidemiological and clinical studies show a clear association of diabetes mellitus with congestive heart failure and cardiovascular events independent of blood pressure and ischemic heart disease. The definition of 'diabetic cardiomyopathy' as a clinical entity, however, relies on distinct myocellular and interstitial alterations found in the myocardium of patients with diabetes. The histological findings comprise myocellular hypertrophy, thickening of capillary basement membranes, interstitial fibrosis and ratification of mitochondria on the ultrastructural level. For clinical routine, early detection of diabetic cardiomyopathy seems crucial for identification of patients at cardiovascular risk since the prevalence of heart failure in individuals with diabetes is markedly increased. Recent technical developments in cardiac magnetic resonance imaging (MRI), echocardiography as well as nuclear scintigraphy have advanced the diagnostic applications for the detection of diabetic heart disease. This review aims to present distinct aspects of diabetic cardiomyopathy that were identified using non-invasive imaging techniques. Due to the wide availability and the low costs of echocardiography, it is the most frequently used imaging technique to detect left ventricular dysfunction in patients with diabetes. MRI on the other hand can provide assessment of myocardial structure with higher spatial resolution and allows objective assessment of left ventricular function. This makes MRI an attractive alternative for the detection of discrete alterations, particularly in patients with poor echogenic windows. Finally, nuclear scintigraphy can provide information on cardiac autonomic integrity and accurately detect defects in autonomic control, which are considered a major cardiovascular risk factor in patients with diabetes.