Impact of Chronic Antiplatelet Therapy on Infarct Size and Bleeding in Patients With Acute Myocardial Infarction.

BACKGROUND

Patients hospitalized with acute myocardial infarction (AMI) are often on prior single antiplatelet therapy (SAPT) or a dual antiplatelet therapy (DAPT). Whether chronic SAPT or DAPT is beneficial or associated with an increased risk in AMI is still controversial.

METHODS AND

RESULTS

We prospectively enrolled 1718 consecutive patients with AMI (798 ST-segment elevation myocardial infarction and 920 non-ST-segment elevation myocardial infarction) who were divided according to their chronic APT (no APT, SAPT, or DAPT). The study primary end point was the infarct size, as estimated by troponin I peak. Incidence of major bleeding was also evaluated. Five hundred thirty-six (31%) patients were on chronic SAPT and 215 (13%) on DAPT. A graded increase in Global Registry of Acute Coronary Events (GRACE) and Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the ACC/AHA guidelines (CRUSADE) risk scores was found going from patients without APT to those with DAPT, while a progressive smaller troponin I peak was observed with the increasing number of chronic antiplatelet agents (11.2 [interquartile range: 2-45] ng/mL, 6.6 [1-33] ng/mL, and 4.1 [1-24] ng/mL; P < .001 for trend). This result was maintained after adjustment for baseline ischemic risk profile (GRACE score) and other major confounders ( P < .001). The incidence of bleeding was higher in patients on chronic APT than in those without APT (5.2% vs 2.4%; P = .002). However, when the bleeding risk was adjusted for the CRUSADE risk score, chronic SAPT (odds ratio [OR]: 1.40, 95% confidence interval [CI]: 0.77-2.53) and DAPT (OR: 0.70, 95% CI: 0.29-1.70) were not associated with an increased bleeding risk.

CONCLUSION

In patients with AMI, chronic APT is associated with higher baseline ischemic and bleeding risks. Despite this and unexpectedly, they have a smaller infarct size and similar adjusted bleeding risk.