Radionuclide imaging in risk assessment after acute coronary syndromes.

T he National Service Framework for coronary artery disease acknowledged a role for myocardial perfusion imaging (MPI) in diagnosis and risk assessment of angina and quoted the cost-effectiveness data from the EMPIRE study. One of its most important effects, however, was to imply increased cardiological management for patients with acute coronary syndromes (ACS). The joint British Cardiac Society and Royal College of Physicians’ guidelines for the management of patients with ACS without persistent ECG ST segment elevation have recommended evaluation of chest pain assessment units based on evidence both from the USA and UK for patients at low cardiac risk. High risk patients, including those with raised troponin, recurrent ischaemic symptoms and/or ST segment changes or adverse stress test results, should have urgent coronary angiography with intention of revascularisation to improve outcomes. In patients with confirmed ACS without recurrent spontaneous symptoms, stress testing provides valuable risk stratification, with pharmacological stress enabling assessment of those who cannot exercise. This article will review the role of radionuclide techniques across the spectrum of patients with ACS, from those presenting with suspected ACS but without diagnostic initial ECG changes, to the now well defined syndromes of unstable angina (UA)/non-ST segment elevation myocardial infarction (NSTEMI) and ST segment elevation myocardial infarction (STEMI). In these settings, radionuclide imaging techniques have a unique role, strongly supported by an evidence base, as contemporary imaging techniques supply simultaneous information on stress and rest perfusion as well as left ventricular (LV) function. Risk assessment together with appropriate aggressive secondary prevention is particularly helpful in the UK situation of uneven access to revascularisation, allowing for appropriate prioritisation of patients.