Patient history, physical examination, 12-lead electrocardiogram (ECG) and cardiac biomarkers are key components of an effective chest pain assessment. The first priority is excluding serious chest pain syndromes, namely acute coronary syndromes (ACSs), aortic dissection, pulmonary embolism, cardiac tamponade and tension pneumothorax. On history, the mnemonic SOCRATES (Site Onset Character Radiation Association Time Exacerbating/relieving factor and Severity) helps differentiate cardiac from non-cardiac pain. On examination, evaluation of vital signs, evidence of murmurs, rubs, heart failure, tension pneumothoraces and chest infections are important. A 12-lead ECG should be interpreted within 10 minutes of first medical contact, specifically to identify ST elevation myocardial infarction (STEMI). High-sensitivity troponins improve the rapid rule-out of myocardial infarction (MI) and confirmation of non-ST elevation MI (NSTEMI). ACS (STEMI and NSTEMI/unstable anginapectoris (UAP)) result from acute destabilisation of coronary atheroma with resultant complete (STEMI) or subtotal (NSTEMI/UAP) thrombotic coronary occlusion. The management of STEMI patients includes providing urgent reperfusion: primary percutaneous coronary intervention(PPCI) if available, deliverable within 60 - 120 minutes, and fibrinolysis if PPCI is not available. Essential adjunctive therapies include antiplatelet therapy (aspirin, P2Y12 inhibitors), anticoagulation (heparin or low-molecular-weight heparin) and cardiac monitoring.

The mode of treatment selected for a patient with CTO is individualised on the basis of the severity of symptoms and ischemia and on the severity of concomitant coronary artery disease (CAD). Patients who remain symptomatic or have a large burden of ischemia despite maximal medical therapy can be considered for revascularisation. Choosing the better revascularisation mode, PCI or coronary artery bypass grafting (CABG) is not always simple. For patients with CTO and significant concomitant left main and /or multivessel CAD, CABG is often considered, given the complexities involved with PCI in this setting and greater likelihood of achieving complete revascularisation compared with PCI. There are, however many settings in which CABG is not an ideal option: single or double vessel disease, especially with a normal LAD, or post CABG with vein graft failure when symptoms demand recanalization of the native vessel CTO.