Practice Variation in Anticoagulation Prescription and Outcomes after Device-Detected Atrial Fibrillation: Insights from the Veterans Health Administration.
Practice Variation in Anticoagulation Prescription and Outcomes after Device-Detected Atrial Fibrillation: Insights from the Veterans Health Administration. Circulation 2019Abstract
BACKGROUND: Device-detected atrial fibrillation (AF) is associated with increased risk of stroke. However, there are no clearly-defined thresholds of AF burden for which to initiate oral anticoagulation (OAC). We sought to describe OAC prescription practice variation in response to new device-detected AF and the association to outcomes.METHODS: We performed a retrospective cohort study using data from the Veterans Health Administration linked to remote monitoring data that included day-level AF burden. We included patients with cardiac implantable electronic devices (CIED) and remote monitoring from 2011-2014, CHA2DS2-VASc =2, and no prior stroke or OAC receipt in the preceding 2 years. We determined the proportion of patients prescribed OAC within 90-days following new device-detected AF across a range of AF thresholds (=6 minutes to >24 hours), and examined site variation in OAC prescription. We used multivariable Cox proportional hazards regressions to determine the association of OAC prescription with stroke by device-detected AF burden.RESULTS: Among 10,212 patients with CIEDs, 4,570 patients (45%), 3,969 patients (39%), 3,263 patients (32%), and 2,469 patients (24%) had device-detected AF >6 minutes, >1 hour, >6 hours, and >24 hours, respectively. For device-detected AF >1 hour, 1,712 patients met inclusion criteria (72±10 years; 1.5% female; CHA2DS2-VASc 4.0±1.4; HAS-BLED 2.6±1.1). The proportion receiving OAC varied based on device-detected AF burden (=6 minutes: 272/2,101 (13%); >1 hour: 273/1,712 (16%); >6 hours: 263/1,279 (21%); >24 hours: 224/818 (27%)). Across 52 sites (N=1,329 patients), there was substantial site-level variation in OAC prescription after device-detected AF >1 hour (median: 16%; range: 3%-67%; median odds ratio: 1.56 [95% credible interval 1.49-1.71]). In adjusted models, OAC prescription after device-detected AF >24 hours was associated with reduced stroke risk (HR 0.28, 95% CI 0.10-0.81, p=0.02), although the propensity-adjusted model was significant when AF lasted at least 6 minutes.CONCLUSIONS: Among Veterans with CIEDs, device-detected AF is common. There is large practice variation in 90-day OAC initiation after new device-detected AF with low rates of treatment overall, even for episodes >24 hours. The strongest association of OAC with reduction in stroke was observed after device-detected AF >24 hours. Randomized trials are needed to confirm these observational findings.
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