Nonatherosclerotic causes of acute coronary syndrome: recognition and management.

Acute coronary syndromes (ACS) frequently result from the rupture or erosion of a vulnerable coronary plaque, with associated intracoronary thrombosis. ACS also may occur in patients with angiographically normal coronary arteries. Some of these patients, however, still have angiographically silent underlying coronary artery disease. In this setting, subtle atherosclerotic changes frequently associated with unstable morphologic features or residual intracoronary thrombus may be detected with intracoronary imaging techniques. Nevertheless, other patients develop ACS as a result of nonatherosclerotic coronary artery disease (NA-CAD). ACS in patients with NA-CAD may be the consequence of coronary spasm or transient coronary embolic phenomena. In these patients, after the initial ischemic insult, late coronary angiography usually reveals normal epicardial coronary vessels. Kounis syndrome is a type of ACS generated by allergic reactions. Takotsubo cardiomyopathy is characterized by normal coronary arteries with a distinct pattern of transient left ventricular wall motion abnormalities. ACS also may occur in young patients following illicit drug use. Finally, spontaneous coronary artery dissection and intramural hematoma represent other etiologies of NA-CAD. In this review, we discuss current evidence regarding diagnostic and treatment strategies in patients presenting with ACS as a result of NA-CAD.