Patterns of antiplatelet use in patients with myocardial infarction and subsequent acute coronary syndrome events

Abstract

Background: Antiplatelet drugs are important for secondary prevention of cardiovascular events after myocardial infarction (MI). Objectives: The objectives of this study were to assess the patterns of antiplatelet drug use in patients who had a MI and to evaluate the impact of subsequent acute coronary syndrome (ACS) events on antiplatelet drug use in the Netherlands. Methods: A descriptive retrospective cohort study was conducted on 4719 patients in Utrecht Cardiovascular Pharmacogenetics studies, who had their first MI during 1986-2009. Medication use was assessed through the Dutch PHARMO Record Linkage System (dispensing database linked to the hospital admission registry). Antiplatelet users were classified as continuous users (gap between consecutive prescriptions ≤90 days), discontinued users (gap of >90days or no refills), and restarters (with a new antiplatelet drug episode after earlier discontinuation) and were followed for a maximum of 10years. Antiplatelet drug use in 90days before and after recurrent consecutive ACS events (MI and unstable angina) following the first MI was also compared. Results: At 1 year of follow-up, 83.7% patients continued using antiplatelets, 76.9% were still on aspirin, and only 36.4% patients were continuing clopidogrel. Most of the discontinuers restarted antiplatelet drugs later, leading to 74.7% antiplatelet users, 62.1% aspirin users and 35.2% clopidogrel users in 10 years after the index MI. For a subgroup of MI patients who started dual antiplatelet therapy with aspirin and clopidogrel (DAPT) after hospital discharge in 2002-2009, a total of 28.9% remained continuous users in 1 year, whereas 24% of the subjects switched to aspirin or clopidogrel monotherapy. When a recurrent ACS event occurred, antiplatelet use increased by 3.6% (p