Acute coronary syndrome: Definition, pathophysiology, diagnosis, and management

Acute coronary syndrome (ACS) represents the most severe form of presentation of ischemic heart disease and imposes a significant burden on morbidity and mortality worldwide, particularly in low- and middle-income countries. Within the clinical spectrum of coronary syndrome are ST-segment elevation myocardial infarction (STEMI), non-ST-segment elevation myocardial infarction (NSTEMI), and unstable angina. Although primarily caused by atherosclerotic plaque thrombosis or non-atherosclerotic causes, its pathophysiological mechanisms are not fully understood. Currently, the main mechanisms include plaque rupture, plaque erosion, calcified nodules, and non-atherosclerotic causes such as coronary vasospasm.

For ACS diagnosis, the electrocardiogram (ECG) is recommended primarily, along with high-sensitivity cardiac troponins (hs-cTn), following recommended algorithms to determine the testing interval. Non-invasive diagnostic tools such as echocardiography, computed tomography (CT), and cardiac magnetic resonance (CMR) are also available. These are mainly indicated in patients with inconclusive ECG and hs-cTn results and for establishing differential diagnoses.

The management of ACS should be multidisciplinary, encompassing pharmacological, invasive techniques, and non-pharmacological approaches. It should be individualized considering each patient's characteristics.