Acute coronary syndromes

Coronary syndromes that cause a relatively rapid onset or increase of symptoms or ischemia are termed acute coronary syndromes (ACSs). ACS is a continuum of unstable coronary syndromes that stretches from unstable angina to acute ST-segment myocardial infarction (STEMI). In this chapter, we will discuss the portion of the spectrum that extends from unstable angina to minor non-ST-segment myocardial infarction (NSTEMI). STEMI and related syndromes are discussed in Chap. 18. The hallmark of ACSs is a fairly abrupt onset of angina (or equivalent ischemic symptoms, such as dyspnea and diaphoresis) or rapid worsening of preexisting ischemic cardiac symptoms. For more than a century, this change in clinical symptoms has been associated with a high risk of subsequent myocardial infarction or cardiac death (Lancet 1:860, 1972). The syndrome has also been termed crescendo angina, preinfarction angina, and unstable angina, all connoting its ominous natural history.