Outcomes of non-valvular atrial fibrillation elderly patients maintained on VKAs' treatment compared to patients switched to DOACs: results from the START2-AF registry.

Direct oral anticoagulants (DOAC) have similar efficacy for stroke prevention in patients with non-valvular atrial fibrillation (AF) with improved safety. Recently, a higher bleeding risk was reported when elderly AF patients were switched from VKAs to DOACs. AF patients aged ≥ 75 years who were maintained on VKA treatment or who were switched from VKAs to DOACs at the time of enrollment in the START-AF Register were followed. Bleedings, thrombotic events, and deaths that occurred during follow-up were collected. We included 4230 AF patients, 2930 (69.3%) on VKAs and 1300 patients (30.7%) shifted to DOACs. Low-dose DOACs were prescribed to 732 (56.3%) patients, 257 (35.1%) of whom received off-label low-dose. Thrombotic events were more frequent among patients switched to DOACs compared to patients continuing VKAs (1.0 and 0.6 × 100pt-yrs p = 0.05). The rate of bleeding events was similar between the two groups (3.0 and 2.5 × 100pt-yrs; p = 0.2), and was higher in the subgroup treated with on-label low-dose DOACs (3.4 × 100pt/yrs) compared to patients on VKAs (2.5 × 100pt-yrs)(RR1.4, 95%CI 0.9-2.0; p = 0.1). Conversely, patients on off-label low-dose DOACs showed higher rates of thrombotic events compared to patients on VKAs (1.4 vs 0.6 × 100pt/yrs, p = 0.05). Mortality was significantly higher in VKA patients than in DOACs patients independently from the dosage (6.7 and 2.9 × 100pt-years; p = 0.05). Elderly AF patients switched from VKAs to DOACs are at increased risk of thrombotic events than patients who remain on VKAs but with a lower risk of mortality. Switching to low-dose DOACs may expose patients to a higher risk of adverse outcomes.