ST-elevation myocardial infarction

ST-elevation myocardial infarction (STEMI) presents with central chest pain that is classically heavy in nature, like a sensation of pressure or squeezing. Examination is variable, and findings range from normal to a critically ill patient in cardiogenic shock.

A clinical working diagnosis of STEMI is made when a patient presents with symptoms suggestive of myocardial ischemia and has persistent ST-segment elevation in two or more anatomically contiguous ECG leads.

Cardiac biomarkers (e.g., cardiac-specific troponins) confirm diagnosis. Treatment should, however, be started immediately in patients with a typical history and ECG changes, without waiting for laboratory results.

Immediate and prompt revascularization can prevent or decrease myocardial damage and decrease morbidity and mortality. Primary percutaneous coronary intervention (PCI) is the best management option for most patients, with fibrinolysis reserved for those without access to timely primary PCI.

Survivors of acute myocardial infarction (MI) should receive cardiac rehabilitation and be closely followed up to ensure adequate modification of risk factors and optimization of (and adherence to) pharmacotherapy for secondary prevention, and to monitor for the development of post MI complications and/or residual angina symptoms.

Myocardial infarction is the irreversible necrosis of heart muscle that occurs because of a prolonged mismatch between perfusion and demand.[1]Anderson HVS, Masri SC, Abdallah MS, et al. 2022 ACC/AHA Key data elements and definitions for chest pain and acute myocardial infarction: a report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Data Standards. Circ Cardiovasc Qual Outcomes. 2022 Oct;15(10):e000112. https://www.doi.org/10.1161/HCQ.0000000000000112 http://www.ncbi.nlm.nih.gov/pubmed/36041014?tool=bestpractice.com This is usually caused by occlusion in the coronary arteries.

In the appropriate clinical context, a STEMI is diagnosed clinically when there is new (or increased) and persistent ST-segment elevation in at least two contiguous leads of ≥1 mm in all leads other than leads V2-V3 where the following cutoff points apply:[2]Thygesen K, Alpert JS, Jaffe AS, et al. Fourth universal definition of myocardial infarction (2018). Eur Heart J. 2019 Jan 14;40(3):237-69. https://academic.oup.com/eurheartj/article/40/3/237/5079081 http://www.ncbi.nlm.nih.gov/pubmed/30165617?tool=bestpractice.com

• ≥2.5 mm in men <40 years old

• ≥2 mm in men >40 years old

• ≥1.5 mm in women regardless of age

1 mm = 1 small square (at a standard ECG calibration of 10 mm/mV).

Contiguous ECG leads lie next to each other anatomically and indicate a specific myocardial territory.