What is the role of ECG in the initial evaluation of patients with suspected acute coronary syndrome (ACS) or myocardial infarction (MI, heart attack)?

Updated: May 07, 2019
  • Author: A Maziar Zafari, MD, PhD, FACC, FAHA; Chief Editor: Eric H Yang, MD  more...
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Answer

The electrocardiogram (ECG) is the most important tool in the initial evaluation and triage of patients in whom an acute coronary syndrome (ACS) is suspected. Obtaining an ECG by emergency medical services (EMS) personnel at the site of first medical contact in patients with symptoms consistent with ST-elevation myocardial infarction (STEMI) not only confirms the diagnosis in more than 80% of cases, but also helps to detect life-threatening arrhythmias and allows early and prompt defibrillation therapy, if indicated. [2, 4]  

Expert medical societies and organizations including the American College of Cardiology (ACC), the American Heart Association (AHA), and the European Society of Cardiology (ESC) have implemented the importance of obtaining a 12-lead ECG in a timely fashion (≤10 mins of presentation) in their recommendations for management of ACS and STEMI, with interpretation by an experience physician. [1, 3]

Examples of ECGs showing MI are seen in the images below.

Acute anterior myocardial infarction. Acute anterior myocardial infarction.
Acute inferior myocardial infarction. Acute inferior myocardial infarction.
Acute posterolateral myocardial infarction. Acute posterolateral myocardial infarction.
The right-sided leads indicate ST-segment elevatio The right-sided leads indicate ST-segment elevations in RV<inf>3</inf> to RV<inf>5</inf>, which are consistent with a right ventricular infarct.

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