Approach to chest pain and acute myocardial infarction
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 angina pectoris (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.