Timing of intervention in non-ST segment elevation myocardial infarction

In contrast to St-segment elevation myocardial infarction (STEMI), where immediate coronary revascularization by percutaneous coronary intervention (PCI) for completely-occluded infarct-related artery is a guideline-mandated treatment, in non-ST-segment elevation myocardial infarction (NSTEMI) the optimal timing of coronary intervention is less clear. Within NSTEMI there is non-occlusive plaque rupture, resulting in myocardial infarction evidenced by raised biomarkers, specifically troponin, with ischaemic chest pain and electrocardiographic changes. This can result in a heterogenous presentation, with some patients demonstrating higher risk features than others and thus potentially benefitting from earlier intervention. In contrast, the presence of fresh thrombus overlying acute plaque rupture may potentially result in worse outcomes following very early intervention compared to initial pharmacological therapy with antiplatelet agents and anticoagulant therapy followed by interval PCI. This article will review the current evidence base and guideline recommendations for timing of coronary intervention in patients presenting with NSTEMI. We will place this current evidence base in the context of evolving therapies including high-sensitivity troponins and other biomarkers, allowing for earlier diagnosis of NSTEMI and also more potent antiplatelet agents.