Managing the asymptomatic diabetic patient with silent myocardial ischaemia
Coronary artery disease is common in diabetic patients and remains the major cause of death in these patients. However myocardial ischaemia resulting from coronary lesions does not always give rise to symptoms. The managing physician must therefore consider the benefit of screening for silent myocardial ischaemia in diabetic patients. Screening all diabetic patients is not recommended. The challenge to the physician is to select the patient subgroups likely to benefit from screening. Patients with more than one cardiac risk factor (dyslipidaemia, hypertension, smoking, family history, microalbuminuria) in addition to diabetes, as well as patients with established macrovascular disease, e.g. peripheral vascular disease, will benefit most from screening. A standard treadmill stress ECG is the recommended screening test. A number of additional tests have been proposed to select high-risk patients for screening. Of these, testing for microalbuminuria and elevated CRP levels are most likely to influence decision-making. Once silent ischaemia has been detected in a diabetic patient, the mainstay of treatment remains the aggressive control of risk factors, improvement of glycaemic control and aspirin therapy. The use of beta-blockers and ACE-inhibitors often need consideration. The attending physician must then consider referring the patient to a cardiologist for angiography and possible intervention. This decision is based on the presence of poor prognostic signs during the stress ECG and the number of risk factors present. Microalbuminuria and elevated CRP levels are helpful in assisting with the risk stratification process.