Impact of prior use or recent withdrawal of oral antiplatelet agents on acute coronary syndromes

Background - Oral antiplatelet agents (OAAs) can prevent further vascular events in cardiovascular disease. How prior use or recent discontinuation of OAA affects clinical presentation of acute coronary syndromes (ACS) and clinical outcomes ( death, myocardial infarction [MI]) is unclear. Methods and Results - We studied and followed up for up to 30 days a cohort of 1358 consecutive patients admitted for a suspected ACS; of these, 930 were nonusers, 355 were prior users of OAA, and 73 had recently withdrawn OAA. Nonusers were at lower risk, more frequently presented with ST-elevation MI on admission, and more frequently had Q-wave MI at discharge than prior users (36.6% versus 17.5%, P < 0.001; and 47.8% versus 28.2%, P < 0.001, respectively). However, there was no difference regarding the incidence of death or MI at 30 days between nonusers and prior users (10.3% versus 12.4%, P = NS). In addition, prior users experienced more major bleeds within 30 days compared with nonusers (3.4% versus 1.4%, respectively; P = 0.04). Recent withdrawers were admitted on average 11.9 +/- 0.8 days after OAA withdrawal. Interruption was primarily a physician decision for scheduled surgery ( n = 47 of 73). Despite a similar cardiovascular risk profile, recent withdrawers had higher 30-day rates of death or MI (21.9% versus 12.4%, P = 0.04) and bleedings (13.7% versus 5.9%, P = 0.03) than prior users. After multivariate analysis, OAA withdrawal was found to be an independent predictor of both mortality and bleedings at 30 days. Conclusions - Among ACS patients, prior users represent a higher-risk population and present more frequently with non - ST-elevation ACS than nonusers. Although patients with a recent interruption of OAA resemble those chronically treated by OAA, they display worse clinical outcomes.