Diabetic cardiomyopathy is abnormal cardiac function leading to congestive heart failure symptoms in individuals without coronary artery disease, valvular disease, rheumatic fever, or other known cardiac disease. Hence, individuals with diabetic cardiomyopathy have classic symptoms of congestive heart failure (i.e., paroxysmal nocturnal dyspnea, orthopnea, edema, dyspnea on exertion) in the absence of any obvious cause for their cardiomyopathy besides diabetes mellitus. Pathologically, these individuals have a dilated cardiomegaly and interstitial fibrosis. Some reports have described an interstitial deposition of a periodic acid-Schiff-positive material. Approximately, 15% of the individuals with diabetes and congestive heart failure in the Framingham study were believed to have diabetic cardiomyopathy. As such, this is a common clinical entity.
Is angina a reliable marker of ischemic disease in diabetics?
No. Classically, many individuals with diabetes have been thought to have silent ischemia. Individuals with diabetic autonomic neuropathy clearly have an increased incidence of silent myocardial infarction secondary to abnormal enervation of the heart. However, despite a plethora of studies, it has not been shown conclusively whether silent ischemia is more common in diabetics without autonomic neuropathy.
Because there is a significant incidence of autonomic neuropathy that could impair angina or anginal equivalents in individuals with diabetes, it is important to do an aggressive workup of nonspecific symptoms or those of early congestive heart failure, especially in individuals with long-standing diabetes.
In acute myocardial infarction, what are the implications of concurrent diabetes?
Overall, individuals with diabetes do significantly worse than nondiabetics in the setting of acute myocardial infarction. They suffer from an increased frequency of events during their initial hospitalization as well as long-term.
In the acute setting, individuals with diabetes are more prone to develop shock, congestive heart failure, myocardial rupture, and reinfarction, all of which are associated with increased mortality. Because of the increased catecholamine surge associated with acute myocardial infarction a transient increase in glucose concentration frequently develops.
Delayed complications of acute myocardial infarction are also more common among diabetics. The survival following myocardial infarction at 1, 2, and 5 years is 82%, 78%, and 58% in diabetics compared with 94%, 92%, and 82% in nondiabetics. Although (3-blockers are relatively contraindicated in diabetes, they are of benefit after myocardial infarction and should be given. An associated asymptomatic hypoglycemia may be present and requires frequent monitoring in patients on insulin and oral agents.