Screening for silent myocardial ischaemia in type 2 diabetic patients with additional atherogenic risk factors: applicability and accuracy of the exercise stress test

Abstract

OBJECTIVE: Coronary artery disease (CAD), a major cause of mortality in patients with type 2 diabetes (T2D), is often diagnosed late because of silent myocardial ischaemia (SMI). Exercise electrocardiogram testing (ECG) stress is the most utilized screening test for SMI. Its applicability and accuracy, which have never been reported in asymptomatic high-risk T2D patients, have been investigated in this study. DESIGN: A cross-sectional study with coronary angiography as the gold standard for detecting CAD was used. METHODS: Two hundred and six consecutive T2D patients, without symptoms and resting ECG signs of ischaemia but with peripheral vascular disease (PVD) and/or > or = two atherogenic factors, were studied. Ischaemia at ECG stress was indicated by horizontal or downsloping ST segment depression > or =1 mm at 0.08 s after the J point. CAD was defined by stenosis > or =70%. RESULTS: Only 141/206 (68%) patients had a diagnostic test: 27 (19%) tested positive and 114 (81%) tested negative. Coronary angiography in 71 patients (the 27 who tested positive and 44 randomly selected patients who tested negative) indicated a CAD prevalence of 29% and the ECG stress accuracy was 79%. 'False negative' patients (18%) had a higher prevalence (P<0.01) of long duration of diabetes and PVD. CONCLUSIONS: This is the first study which provides insights into the applicability and accuracy of ECG stress in screening SMI in high-risk patients with T2D. Due to the high prevalence of CAD, alternative screening tests in patients unable to perform the test and in those with a high chance of being 'false negative' should be looked for and validated.