Oral Anticoagulation Choice and Dosage in Very Elderly Patients with Atrial Fibrillation

Background: Selecting the optimal oral anticoagulation (OAC) therapy for elderly patients with atrial fibrillation (AF) remains challenging. Our real-world study investigates clinical factors guiding OAC prescription patterns and compares outcomes between full- and reduced-dose direct-acting oral anticoagulants (DOACs) and vitamin K antagonists (VKAs) in this demographic. Methods: This post hoc analysis of the MISOAC-AF trial focused on hospitalized AF patients aged >= 75 years prescribed OAC at discharge. Predictors of VKA and reduced DOAC dosing were identified using adjusted odds ratios (aORs). Cox regression models calculated adjusted hazard ratios (aHRs) for primary (all-cause mortality) and secondary outcomes (stroke, bleeding, AF or heart failure hospitalization, cardiovascular death). Results: Among 450 elderly patients, 63.6% received DOACs and 36.4% received VKAs. Higher CHA2DS2-VASc and HAS-BLED scores and antiplatelet use predicted VKA prescription. Hypertension, prior stroke, and bleeding history favored DOAC use. Advanced age and chronic kidney disease correlated with reduced DOAC dosing. Over a 3.7-year follow-up period, there was no significant difference in all-cause mortality between the DOAC and VKA groups (aHR 0.79, 95% CI 0.58-1.06) or between the full-dose and reduced-dose DOAC groups (aHR 0.96, 95% CI 0.60-1.53). Secondary analyses also did not yield statistically significant results in either comparison. Conclusions: Clinical profile parameters in elderly AF patients predict VKA or DOAC use. Clinical outcomes were similar between different OAC therapies.