Clinical aspects of silent myocardial ischaemia: with particular reference to diabetes mellitus

Silent ischaemia is a common, under-recognised condition that is associated with an adverse prognosis. It is a marker of significant underlying coronary artery disease and therefore of future cardiovascular events. It is more prevalent in the diabetic population and diagnosis is usually made by a positive exercise tolerance test, positive myocardial perfusion scan or stress echo. The basis of treatment, in diabetic and non-diabetic subjects, is risk factor modification and coronary revascularisation of prognostically important coronary disease. Diabetic patients should receive risk factor modification even in the absence of ischaemia. Detection of silent ischaemia allows patients with prognostically important disease to be offered further treatment. The difficulty lies in deciding who to investigate further for this surreptitious disorder. The following clinical markers are of predictive use in this regard: electrocardiographic changes; erectile dysfunction; peripheral vascular disease and cardiac autonomic neuropathy. Their presence should prompt further investigation for silent ischaemia. Conventional risk factors and breathlessness on exertion may also be helpful. We have proposed an algorithm for the detection, investigation and management of silent myocardial ischaemia in diabetic patients.