Anticoagulation in patients with device-detected atrial fibrillation with and without a prior stroke or transient ischemic attack: The NOAH-AFNET 6 trial

Background
Short and rare episodes of atrial fibrillation (AF) are commonly detected using implanted devices (device‐detected AF) in patients with prior stroke or transient ischemic attack (TIA). The effectiveness and safety of oral anticoagulation in patients with prior stroke or TIA and device‐detected AF but with no ECG‐documented AF is unclear.
Methods and Results
This prespecified analysis of the NOAH‐AFNET 6 (Non‐Vitamin K Antagonist Oral Anticoagulants in Patients With Atrial High Rate Episodes) trial with post hoc elements assessed the effect of oral anticoagulation in patients with device‐detected AF with and without a prior stroke or TIA in the randomized, double‐blind, double‐dummy NOAH‐AFNET 6 trial. Outcomes were stroke, systemic embolism, and cardiovascular death (primary outcome) and major bleeding and death (safety outcome). A prior stroke or TIA was found in 253 patients with device‐detected AF randomized in the NOAH‐AFNET 6 (mean age, 78 years; 36.4% women). There was no treatment interaction with prior stroke or TIA for any of the primary and secondary time‐to‐event outcomes. In patients with a prior stroke or TIA, 14 out of 122 patients experienced a primary outcome event with anticoagulation (5.7% per patient‐year). Without anticoagulation, there were 16 out of 131 patients with an event (6.3% per patient‐year). The rate of stroke was lower than expected (anticoagulation: 4 out of 122 [1.6% per patient‐year]; no anticoagulation: 6 out of 131 [2.3% per patient‐year]). Numerically, there were more major bleeding events with anticoagulation in patients with prior stroke or TIA (8 out of 122 patients) than without anticoagulation (2 out of 131 patients).
Conclusions
Anticoagulation appears to have ambiguous effects in patients with device‐detected AF and a prior stroke or TIA in this hypothesis‐generating analysis of the NOAH‐AFNET 6 in the absence of ECG‐documented AF, partially due to a low rate of stroke without anticoagulation.