Later in the progression, a prolonged QT interval may be indicative of fibrosis. Given that diabetic cardiomyopathys definition excludes concomitant atherosclerosis or hypertension, there are no changes in perfusion or in atrial natriuretic peptide levels up until the very late stages of the disease, when the hypertrophy and fibrosis become very pronounced. Pathophysiology
Defects in cellular processes such as autophagy and mitophagy are thought to contribute to the development of diabetic cardiomyopathy. Diabetic cardiomyopathy is characterized functionally by ventricular dilation, enlargement of heart cells, prominent interstitial fibrosis and decreased or preserved systolic function in the presence of a diastolic dysfunction.While it has been evident for a long time that the complications seen in diabetes are related to the hyperglycemia associated to it, several factors have been implicated in the pathogenesis of the disease. Etiologically, four main causes are responsible for the development of heart failure in diabetic cardiomyopathy: microangiopathy and related endothelial dysfunction, autonomic neuropathy, metabolic alterations that include abnormal glucose use and increased fatty acid oxidation, generation and accumulation of free radicals, and alterations in ion homeostasis, especially calcium transients. Additional effects include inflammation and upregulation of local angiotensin systems. Diabetic cardiomyopathy may be associated with restrictive (HFPEF) and dilated phenotypes (HFREF). HFPEF results predominantly from hyperinsulinemia, hyperglycemia, lipotoxicity, AGEs and microvascular rarefication. HFREF is associated with autoimmunity, hyperglycemia, lipotoxicity, microvascular rarefication and AGE formation. Microangiopathy
Microangiopathy can be characterized as subendothelial and endothelial fibrosis in the coronary microvasculature of the heart. This endothelial dysfunction leads to impaired myocardial blood flow reserve as evidence by echocardiography.
Just like endothelial cells, nerve cells cannot regulate their glucose uptake and suffer the same type of damages listed above. Therefore, the diabetic heart shows clear denervation as the pathology progresses. This denervation correlates with echocardiographic evidence of diastolic dysfunction and results in a decline of survival in patients with diabetes from 85% to 44%. Other causes of denervation are ischemia from microvascular disease and thus appear following the development of microangiopathy. Inflammation
Diabetes is associated with increased inflammation, which is mediated by generation of abnormal fatty acids, AGEs and other mechanisms. The resulting cytokine profile promotes hypertrophy and apoptosis of cardiomyocytes, abnormal calcium signaling, impaired myocardial contractility and myocardial fibrosis. Additionally, it may lead to microvascular dysfunction, either directly or via endothelial damage, thereby promoting myocardial ischemia. Diagnosis
Diagnostic approaches for diabetic cardiomyopathy include echocardiography, cardiac MRI investigations, Multi‐slice computed tomography (MsCT), and nuclear imaging. Potential risks of the investigation (e.g. exposure to radiation) and diagnostic utility should be weighed for an optimised personalised procedure. Treatment
At present, there is no effective specific treatment available for diabetic cardiomyopathy. Treatment centers around intense glycemic control through diet, oral hypoglycemics and frequently insulin and management of heart failure symptoms. There is a clear correlation between increased glycemia and risk of developing diabetic cardiomyopathy, therefore, keeping glucose concentrations as controlled as possible is paramount. Thiazolidinediones are not recommended in patients with NYHA Class III or IV heart failure secondary to fluid retention.As with most other heart diseases, ACE inhibitors can also be administered.