What is acute coronary syndrome?

Acute coronary syndrome (ACS) refers to a spectrum of conditions defined by a sudden reduction in blood flow to the heart. Most often, the underlying cause is a gradual buildup of fatty deposits called plaque inside the arteries supplying the heart. ACS includes two distinct types of heart attacks, known as STEMI and NSTEMI, and a serious condition called unstable angina that’s often a prelude to a heart attack. All warrant immediate medical attention.