(P026) EVALUATING THE IMPACT OF DAPT PRESCRIPTION PATTERNS ON CARDIOVASCULAR OUTCOMES IN NON-REVASCULARIZED, MEDICALLY TREATED, MYOCARDIAL INFARCTION PATIENTS

Background: Current clinical guidelines barely address the antiplatelet management of patients with acute coronary syndrome (ACS) treated medically alone, without revascularization. Consequently, antiplatelet therapy approaches may be variable in routine clinical practice in this population that represents a substantial proportion (~10-30%) of hospitalized patients with a myocardial infarction (MI) according to Canadian registries. Hence, this study seeks to explore the real-world antiplatelet strategy patterns used in patients with ACS treated medically, and to characterize this population.

METHODS AND RESULTS: A retrospective cohort study was conducted at the Montreal Heart Institute, spanning July 31, 2020, to April 30, 2023. Patients hospitalized for an MI and discharged without revascularization were included. Data collection included discharge medication (dual antiplatelet therapy [DAPT], single antiplatelet [SAPT], none), treatment duration, and clinical outcomes. Female representation was 40% (n=56), with an average age of 72.7 years. Reasons for not undergoing revascularization included: MI with non-obstructive coronary arteries (MINOCA) (n=47, 33.6%), no angiography performed (n=45, 32.1%), severe disease not amenable to PCI or CABG (n=38, 27.1%), spontaneous coronary artery dissection (SCAD) (n=6, 4.3%), and small branch disease (n=4, 2.9%). DAPT, single antiplatelet therapy, and no antiplatelet strategies at discharge were used in 45% (n=63), 35.7% (n=50), and 19.3% (n=27), respectively. The most common antiplatelet regimens prescribed at discharge were clopidogrel/aspirin (n=51, 36.4%), aspirin monotherapy (n=24, 24.3%), clopidogrel monotherapy (n=16, 11.4%), ticagrelor/aspirin (n=12, 8.6%) and prasugrel/aspirin (n=1,0.7%). Discharge antiplatelet therapy was prescribed for 12 months in 81.4% of patients. One year following discharge, the incidence of major adverse cardiovascular events (MACE: all-cause death, repeat MI, coronary or severe heart failure) was 25.7%. Occurrence of MACE events was higher in patients treated with clopidogrel/aspirin (n=15, 29.4%), and in patients not treated with any medication (n=8, 29.6%), compared to those prescribed Single Antiplatelet Therapy (SAPT) (n=4, 8.0%) (p < 0.02).

Conclusion: Substantial variability exists in the antiplatelet strategies used for the treatment of patients with non-revascularized MI. Hence, further investigation should evaluate the optimal antiplatelet strategies to optimize outcomes and potentially influence future guidelines in this vulnerable yet understudied population.