What is acute coronary syndrome (ACS), and what are the two main categories of ACS?

Updated: May 07, 2019
  • Author: A Maziar Zafari, MD, PhD, FACC, FAHA; Chief Editor: Eric H Yang, MD  more...
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The term "acute coronary syndrome" (ACS) refers to a spectrum of conditions that occur due to acute myocardial ischemia and/or infarction as a result of an abrupt reduction in blood flow through the coronary artery circulation.

ACS is divided into two main categories, non–ST elevation (NSTE) ACS and ST-elevation MI (STEMI)


NSTE ACS is further divided into unstable angina (UA) and non–ST-elevation myocardial infraction (NSTEMI). These two conditions resemble each other very closely. UA is distinguished from NSTEMI by the absence of an elevation of cardiac biomarker levels. [1]


The major discriminating feature of STEMI is the presence of symptoms of myocardial ischemia/injury along with persistent ECG ST-segment elevation in addition to the presence of cardiac biomarkers. [2]

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