Figure 1.

Simplified clinical algorithm for acute chest pain. ^aST segment elevation myocardial infarction (STEMI) electrocardiogram (ECG) criteria: new-onset ST segment elevation in ≥2 contiguous leads (with J-point elevation ≥2.5 mm in men aged <40 years, ≥2 mm in men aged ≥40 years and ≥1.5 mm in women for leads V2–3, and J-point elevation ≥1 mm in all other leads). ^bNew-onset left bundle brunch block (LBBB) used to be considered STEMI equivalent; however, it is now recognised that a presumed new LBBB should not be interpreted in isolation, but rather in the context of clinical findings and cardiac enzymes to determine its significance. ^cSTEMI equivalent ECG patterns: left main coronary artery occlusion, Wellen’s syndrome, de Winter’s T waves. ^dElevated troponins in the context of myocardial ischaemia is defined as ≥20% rise and/or fall in serially trended troponins with at least one value >99th percentile of the upper reference limit. ^eCardiovascular risk factors: smoking, obesity, diabetes mellitus, hypertension, hyperlipidaemia, family history of premature coronary artery disease (first-degree relative; for men aged <55 years, for women aged <65 years) ACS: acute coronary syndrome, GTN: glyceryl trinitrate, MI: myocardial infarction, NSTEMI: non-ST segment elevation myocardial infarction