Detection of Previously Undiagnosed Atrial Fibrillation in Patients With Stroke Risk Factors and Usefulness of Continuous Monitoring in Primary Stroke Prevention

The detection of undiagnosed atrial tachycardia/atrial fibrillation (AT/AF) among patients with stroke risk factors could be useful for primary stroke prevention. We analyzed newly detected AT/AF (NDAF) using continuous monitoring in patients with stroke risk factors but without previous stroke or evidence of AT/AF. NDAF (AT/AF > 5 minutes on any day) was determined in patients with implantable cardiac rhythm devices and >= 1 stroke risk factors (congestive heart failure, hypertension, age >= 75 years, or diabetes). All devices were capable of continuously monitoring the daily cumulative time in AT/AF. Of 1,368 eligible patients, NDAF was identified in 416(30%) during a follow-up of 1.1 +/- 0.7 years and was unrelated to the CHADS(2) score (congestive heart failure, hypertension [blood pressure consistently > 140/90 mm Hg or hypertension treated with medication], age >= 75 years, diabetes mellitus, previous stroke or transient ischemic attack). The presence of AT/AF > 6 hours on >= 1 day increased significantly with increased CHADS(2) scores and was present in 158 (54%) of 294 patients with NDAF and a CHADS(2) score of >= 2. NDAF was sporadic, and 78% of patients with a CHADS(2) score of >= 2 with NDAF experienced AT/AF on < 10% of the follow-up days. The median interval to NDAF detection in these higher risk patients was 72 days (interquartile range 13 to 177). In conclusion, continuous monitoring identified NDAF in 30% of patients with stroke risk factors. In patients with NDAF, AT/AF occurred sporadically, highlighting the difficulty in detecting paroxysmal AT/AF using traditional monitoring methods. However, AT/AF also persisted for > 6 hours on >= 1 days in most patients with NDAF and multiple stroke risk factors. Whether patients with CHADS(2) risk factors but without a history of AF might benefit from implantable monitors for the selection and administration of anticoagulation for primary stroke prevention merits additional investigation. (C) 2012 Elsevier Inc. All rights reserved. (Am J Cardiol 2012;110:1309-1314)