Rosemarie Pasmantier, MD, is assistant professor of medicine, Division of Endocrinology, State University of New York Health Sciences Center, Stony Brook, New York.

Coronary artery disease (CAD) accounts for approximately 75% of deaths in patients with diabetes.¹ Since risk for cardiovascular complications may be modified by interventions, early detection of CAD is important. Several studies highlight the means of noninvasive early detection.¹

In the Detection of Ischemia in Asymptomatic Diabetics study, 1123 patients with type 2 diabetes without known CAD, aged 50 to 75 years, were randomly assigned to stress testing or follow-up only over 5 years.² At baseline, 113 of 522 (22%) had silent ischemia as assessed by adenosine technetium-99 sestamibi single-photon emission-computed tomography myocardial perfusion imaging. Moderate or large perfusion defects were present in 33 patients. Cardiac autonomic dysfunction was a strong predictor of ischemia, although other risk factors were not.

A population-based autopsy study of 293 individuals with and 1736 without diabetes examined the association between diabetes and coronary atherosclerosis.³ Among decedents with diabetes without clinical CAD, nearly three quarters had high-grade coronary atherosclerosis and more than half had multi-vessel disease, a disease burden similar to persons without diabetes but with clinical CAD.

In another report, 4755 patients with symptoms of CAD who were undergoing stress myocardial perfusion imaging were prospectively followed for 2.5 years for occurrence of cardiac events.⁴ Among 929 patients with diabetes, 80 cardiac events (8.6%) occurred (39 deaths and 41 myocardial infarctions [MIs]) compared with 172 (4.5%; 69 deaths and 103 MIs) among those without diabetes. The presence and the extent of abnormal stress myocardial perfusion imaging independently predicted subsequent cardiac events.

In this journal, Scognamiglio and Fraccaro report their experience with 1899 asymptomatic patients with type 2 diabetes aged 60 years or younger, screened with dipyridamole stress myocardial contrast echocardiography. They divided the patients into 2 groups—group A had 2 or more additional risk factors for CAD and comprised 62% of the sample, while group B had 1 or less. Patients with perfusion defects underwent coronary angiography. Although the 2 groups had similar prevalence of an abnormal stress-myocardial contrast echocardiography (59.4% vs 60%) and significant CAD (64.6% vs 65.5%), the patients with more risk factors had a higher prevalence of advanced disease. They concluded that myocardial perfusion defects in patients with type 2 diabetes might result not only from epicardial coronary stenosis but also from microvascular disease and endothelial dysfunction.

Current American Diabetes Association guidelines for screening of asymptomatic patients with diabetes for silent myocardial ischemia fail to pick up significant numbers of patients with CAD. Although evidence suggests noninvasive tests can improve assessment of future risk, conclusive evidence that such testing will improve outcomes is lacking. For now, clinicians may want to perform noninvasive tests in asymptomatic patients with diabetes with 2 or more cardiac risk factors, those with cardiac autonomic neuropathy, and before patients start an exercise program. Ongoing trials will attempt to answer the question of whether screening with stress myocardial perfusion imaging for all asymptomatic patients with diabetes decreases the morbidity and mortality associated with CAD.

References

1. Wackers FJ. Diabetes and coronary artery disease: the role of stress myocardial perfusion imaging. Cleve Clin J Med. 2005; 72(1):21-33.
2. Wackers FJ, Young LH, Inzucchi SE, et al. Detection of silent myocardial ischemia in asymptomatic diabetic subjects: the DIAD study. Diabetes Care. 2004;27(8):1954-1961.
3. Goraya TY, Leibson CL, Palumbo PJ, et al. Coronary atherosclerosis in diabetes mellitus: a population-based autopsy study. J Am Coll Cardiol. 2002;40(5):946-953.
4. Giri S, Shaw LJ, Murthy DR, et al. Impact of diabetes on the risk stratification using stress single-photon emission computed tomography myocardial perfusion imaging in patients with symptoms suggestive of coronary artery disease. Circulation. 2002;105(1):32-40.