Risk Factors for Silent Myocardial Ischemia in Type II Diabetic Patients

Background- Silent myocardial ischemia is more common in diabetic patients than others. Early detection plays an important role in the prevention of acute myocardial infarction and sudden cardiac death. Routine screening of all diabetics is costly. The aim of this study was to estimate the prevalence of silent myocardial ischemia in type 2 diabetes and define these highrisk patients by routine screening tests. Methods- Between May 2004 and May 2006, this cross-sectional study was performed on 500 type 2 diabetic patients referred to Kerman internal medicine and cardiovascular clinics. Inclusion criteria were age between 35 and 70 years, absence of symptoms and resting electrocardiographic signs of ischemia, evidence of retinopathy or peripheral vascular disease, or at least one major atherogenic risk factor (except diabetes). All the patients underwent treadmill exercise test or thallium scintigraphy with exercise or dipyridamole injection. Data were analyzed with chi-square, t-test, and Mann-Whitney U tests. Results- Five hundred patients, comprised of 232 men and 268 women, were evaluated. Screening tests were positive in 86 (17.2%) patients. There was a significant statistical relation between the duration of diabetes, low density lipoprotein cholesterol, family history of coronary artery disease (CAD), retinopathy, and peripheral vascular disease with silent myocardial ischemia (P<0.05). The prevalence of silent ischemia was not significantly different between the males and females (P>0.05). Among the patients with silent ischemia, body mass index was higher in the females and cigarette smoking was more common in the males (P<0.05). Conclusion- With regard to the high frequency of silent myocardial ischemia in type 2 diabetes mellitus, routine silent ischemia screening by exercise stress test should be recommended in type 2 diabetes if any of these conditions are present: duration of diabetes more than ten years, family history of CAD, LDL cholesterol higher than 160 mg/dL, retinopathy, or peripheral vascular disease (Iranian Heart Journal 2008; 9 (2):37-42).