ECG Diagnosis: ST-Elevation Myocardial Infarction
Perm J 2014 Spring; 18(2):e133 [Full Citation]
ST-elevation myocardial infarction (STEMI) is a clinical syndrome defined by characteristic symptoms of myocardial ischemia in association with persistent electrocardiographic ST elevation (STE) and subsequent release of biomarkers of myocardial necrosis.1 STE is the single best immediately available surrogate marker for detecting acute complete coronary artery occlusion without collateral circulation, signifying a significant region of injured myocardium at imminent risk of irreversible infarction, requiring immediate reperfusion therapy.2 Diagnostic STE is defined as new STE at the J point in at least 2 contiguous leads > 2 mm (0.2 mV) in men or > 1.5 mm (0.15 mV) in women in leads V2-V3 and/or of > 1 mm (0.1 mV) in other contiguous chest or limb leads.3 The presence of reciprocal changes (manifested as ST depression in a region that approximates the vector 180 degrees opposite the major vessel of injury) increases the specificity of STE caused by STEMI.4 New or presumably new left bundle branch block has been considered a STEMI equivalent. Reperfusion therapy should be administered to all eligible patients with STEMI who have experienced symptom onset within the previous 12 hours.1 Primary percutaneous coronary intervention is the recommended method of reperfusion when it can be performed in a timely fashion by experienced operators, with a goal of first medical contact-to-balloon time of 90 minutes or less.5,6
1. O'Gara PT, Kushner FG, Ascheim DD, et al; American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation 2013 Jan 29;127(4):e362-425. DOI: https://doi.org/10.1161/CIR.0b013e3182742c84.
2. Stellpflug SJ, Holger JS, Smith SW. What is the role of the ECG in ACS? In: Brady WJ, Truwit JD, editors. Critical decisions in emergency and acute care electrocardiography. West Sussex, UK: Wiley-Blackwell; 2009. p 85-91. DOI: https://doi.org/10.1002/9781444303551.ch13.
3. Thygesen K, Alpert JS, Jaffe AS, et al; Joint ESC/ACCF/AHA/WHF Task Force for the Universal Definition of Myocardial Infarction. Third universal definition of myocardial infarction. Circulation 2012 Oct 16;126(16):2020-35. DOI: https://doi.org/10.1161/CIR.0b013e31826e1058.
4. Harrigan RA, Chan TC. What is the ECG differential diagnosis of ST segment elevation? In: Brady WJ, Truwit JD, editors. Critical decisions in emergency and acute care electrocardiography. West Sussex, UK: Wiley-Blackwell; 2009:419-27. DOI: https://doi.org/10.1002/9781444303551.ch49.
5. Bates ER, Jacobs AK. Time to treatment in patients with STEMI. N Engl J Med 2013 Sep 5;369(10):889-92. DOI: https://doi.org/10.1056/NEJMp1308772.
6. Levis JT, Mercer MP, Thanassi M, et al. Factors contributing to door-to-balloon times of < 90 minutes in 97% of patients with ST-elevation myocardial infarction: our one-year experience with a Heart Alert protocol. Perm J 2010 Fall;14(3):4-11. DOI: https://doi.org/10.7812/TPP/10-027.