Background: Clinical outcomes and treatment selection after completing the randomized phase of modern trials, investigating antiplatelet therapy (APT) after percutaneous coronary intervention (PCI), are unknown.

Objectives: The authors sought to investigate cumulative 15-month and 12-to-15-month outcomes after PCI during routine care in the MASTER DAPT trial.

Methods: The MASTER DAPT trial randomized 4,579 high bleeding risk patients to abbreviated (n = 2,295) or standard (n = 2,284) APT regimens. Coprimary outcomes were net adverse clinical outcomes (NACE) (all-cause death, myocardial infarction, stroke, and BARC 3 or 5 bleeding); major adverse cardiac and cerebral events (MACCE) (all-cause death, myocardial infarction, and stroke); and BARC type 2, 3, or 5 bleeding.

Results: At 15 months, prior allocation to a standard APT regimen was associated with greater use of intensified APT; NACE and MACCE did not differ between abbreviated vs standard APT (HR: 0.92 [95% CI: 0.76-1.12]; P=0.399 and HR: 0.94 [95% CI: 0.76-1.17]; P= 0.579; respectively), as during the routine care period (HR: 0.81 [95% CI: 0.50-1.30]; P= 0.387 and HR: 0.74 [95% CI: 0.43-1.26]; P= 0.268; respectively). BARC 2, 3, or 5 was lower with abbreviated APT at 15 months (HR: 0.68 [95% CI: 0.56-0.83]; P= 0.0001) and did not differ during the routine care period. The treatment effects during routine care were consistent with those observed within 12 months after PCI.