Long-Term Outcomes of Patients With Acute Coronary Syndrome and Nonobstructive Coronary Artery Disease

Patients with acute coronary syndrome (ACS) and nonobstructive coronary artery disease (CAD) have a substantial risk of subsequent coronary events within 1 year. The aim of the present study was to evaluate the prevalence, long-term outcomes, and adherence to oral antiplatelet therapy in patients with ACS and nonobstructive CAD compared with patients with ACS and obstructive CAD who had undergone percutaneous coronary intervention. Nonobstructive CAD was defined as an angiographic finding of <50% diameter stenosis in any major epicardial artery. These patients were further stratified into 2 groups: those with normal coronary arteries (0% angiographic stenosis) and those with mild CAD (0% to 50% angiographic stenosis). Major adverse cardiac events, defined as death, myocardial infarction, ACS leading to hospitalization, and nonfatal stroke, were recorded and compared with a historical control group of patients with ACS and obstructive CAD who had undergone percutaneous coronary intervention. Of 2,438 consecutive patients with ACS undergoing coronary angiography, 318 (13%) had nonobstructive CAD. Of the 318 with nonobstructive CAD, 160 had normal coronary arteries and 158 had mild CAD. Patients with obstructive CAD had experienced greater rates of major adverse cardiac events at 26 ± 16 months (16.6% vs 9.1%, p = 0.001), driven by a greater rate of myocardial infarction compared with those without (5.3% vs 0%, p <0.001). However, the rate of death, ACS leading to hospitalization, and stroke was similar. After adjusting for baseline characteristics, no difference was found in the risk of major adverse cardiac events across the groups. Only 50% of patients with nonobstructive CAD were prescribed dual antiplatelet therapy. In conclusion, patients with ACS and nonobstructive CAD remain at high risk of long-term recurrent ischemic events.