Cardiac Imaging for Risk Stratification in Diabetes

Abstract

Worldwide, 200 million individuals currently have diabetes, and projections by the World Health Organization and others suggest that its prevalence will exceed 300 million by 2025 and 360 million by 2030 (1,2). More than 90% of these individuals will have type 2 diabetes. Management guidelines in Europe (3) and the U.S. (4) consider type 2 diabetes to be a cardiovascular disease equivalent. These patients have a two- to fourfold higher risk of a cardiovascular event than nondiabetic patients. Importantly, cardiovascular death is the most common cause of mortality in the type 2 diabetic population (5). It has been estimated that after a myocardial infarction, 79% of diabetic patients die of cardiac complications (6). Accordingly, accurate cardiovascular risk stratification of patients with type 2 diabetes is needed. This can be problematic in that the clinical presentation and progression of coronary artery disease (CAD) differs between diabetic and nondiabetic patients. In addition to a higher prevalence of CAD (7), patients with diabetes experience more diffuse, calcified, and extensive CAD, more often have left ventricular dysfunction, often have more advanced coronary disease at the time of diagnosis, and more often experience silent ischemia. In addition, diabetic patients generally have a less favorable response to revascularization (with frequent need for repeat percutaneous coronary intervention or coronary artery bypass grafting) and a reduced long-term survival. Accordingly, early accurate diagnosis of CAD in patients with diabetes is needed, and reliable prognostication is mandatory. The American Diabetes Association has recommended an algorithm whereby symptomatic diabetic patients would be referred for either stress perfusion imaging or stress echo or evaluation by a cardiologist. The exception would be individuals with atypical chest pain and a normal electrocardiogram who might undergo a simple exercise stress test unless they have multiple other cardiovascular risk factors, in which case imaging …