Silent Ischemia in People With Diabetes: A Condition That Must Be Heard

Abstract

Angina pectoris has long been considered the cardinal symptom of myocardial ischemia. However, it is now known that angina pectoris may be a poor indicator for myocardial ischemia, particularly in patients with diabetes. Despite the recent advances in our understanding of the complex pathophysiology of coronary artery disease (CAD), the recognition of diabetic patients with asymptomatic and yet significant CAD remains difficult. CAD in diabetic patients poses diagnostic and therapeutic challenges for clinicians, especially when patients are asymptomatic during episodes of myocardial ischemia. In diabetic patients, cardiovascular disease remains the leading cause of death, and myocardial infarctions tend to be more extensive and have a poorer survival rate than in age-, weight-, and sex-matched individuals without diabetes. The medical cost associated with diabetes is staggering, amounting to about $100 billion annually, with vascular complications accounting for the majority of this expenditure. “Silent ischemia” refers to the presence of objective findings suggestive of myocardial ischemia that is not associated with angina or anginal equivalent symptoms. Such objective evidence includes exercise testing or ambulatory monitoring demonstrating electrocardiographic changes, nuclear imaging studies demonstrating myocardial perfusion defects, or regional wall motion abnormalities illustrated by echocardiography. Episodes of silent ischemia can occur with minimal or no physical activity and have been demonstrated in some individuals with stressors as mild as engaging in mental arithmetic. Diabetes, hypertension, previous myocardial infarction, surgical revascularization, and advanced age are all putative risk factors for silent ischemia, although many affected individuals do not have any apparent contributor. In the Framingham Study,1 which was based on 34 years of follow-up of more than 5,000 subjects, about one-fourth of the patients who experienced a heart attack had unrecognized events. Unrecognized infarctions consisted of silent myocardial infarctions and atypical myocardial infarctions. The latter are myocardial infarctions that are accompanied by some symptoms …