Non-ST-segment elevation acute coronary syndrome: understanding the full spectrum to guide management

Acute coronary syndromes are caused by obstructive coronary thrombosis complicating myocardial ischaemic disease and are dichotomously classified according to their electrocardiographic presentation as ST-segment elevation myocardial infraction or non-ST-segment elevation acute coronary syndrome, either without or with elevated myocardial necrosis markers. Initial diagnosis and risk stratification are reliably guided by symptoms, electrocardiographic changes, and troponin elevation and require exclusion of alternative conditions, such as Type 2 myocardial infarction and myocardial injury due to systemic conditions. Timely coronary angiography is a key component of the initial diagnosis to assess the presence of occlusive coronary artery disease, rather than an myocardial infarction with non-occluded coronary arteries, and the suitability for revascularization. While clinical trials with randomization prior to angiography have shown reduction in recurrent myocardial infarction and urgent revascularization with a neutral effect on mortality from an early invasive approach, increased revascularization rates have been systematically associated with reduced mortality in registries and administrative databases. Complete revascularization in patients with multivessel disease has been shown to reduce mortality compared with culprit-only revascularization. The safety of this approach has been shown even in fragile, elderly, and multimorbid patients. Post-acute treatment should be focused on patient-tailored antithrombotic therapy and disease-modifying secondary prevention approaches. This review describes the complex spectrum of non-ST-segment elevation acute coronary syndrome and the importance of complete clinical and coronary angiographic assessment for optimal patient-centred treatment.