Impact of Underdosing of Direct Oral Anticoagulants on Clinical Outcomes in Patients With Atrial Fibrillation Undergoing Percutaneous Coronary Intervention.

Background: Underdoses of direct oral anticoagulants (DOAC) are sometimes prescribed due to bleeding risk concerns in patients with atrial fibrillation (AF). We investigated the prevalence of DOAC underdosing and its impact on clinical outcomes in AF patients undergoing percutaneous coronary intervention (PCI).

Methods and results: This multicenter observational cohort study enrolled patients with AF on DOAC undergoing PCI between January 2015 and March 2021 at 15 institutions across Japan. Clinical outcomes within 1 year, including major adverse cardiovascular events (MACE), all-cause mortality, ischemic stroke, and major bleeding events, were evaluated. Of 623 patients enrolled, 167 (26.8%) received underdoses, 224 (36.0%) received appropriate low doses, 210 (33.7%) received appropriate standard doses, and 22 (3.5%) received overdoses. Clinical outcomes were compared between patients with underdoses (n=167) and appropriate doses (n=434). Although the incidence of MACE, all-cause mortality, and major bleeding events did not differ significantly between the 2 groups (log-rank P=0.850, P=0.163, and P=0.711, respectively), ischemic stroke occurred more frequently in the underdose than appropriate-dose group (log-rank P=0.011). After propensity score matching, the same result was observed for the frequency of ischemic stroke (log-rank P=0.026).

Conclusions: Compared with appropriate doses of DOAC, DOAC underdosing was associated with a higher incidence of ischemic stroke, despite no significant difference in MACE, all-cause mortality, and major bleeding events in AF patients undergoing PCI.