Detection of previously undiagnosed atrial fibrillation in patients with stroke risk factors and usefulness of continuous monitoring in primary stroke prevention

Am J Cardiol. 2012 Nov 1;110(9):1309-14. doi: 10.1016/j.amjcard.2012.06.034. Epub 2012 Jul 20.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Distribution
  • Aged
  • Aged, 80 and over
  • Anti-Arrhythmia Agents / therapeutic use
  • Atrial Fibrillation / diagnosis*
  • Atrial Fibrillation / epidemiology*
  • Atrial Fibrillation / therapy
  • Cardiac Resynchronization Therapy / methods
  • Cohort Studies
  • Combined Modality Therapy
  • Defibrillators, Implantable
  • Delayed Diagnosis
  • Female
  • Follow-Up Studies
  • Humans
  • Incidence
  • Kaplan-Meier Estimate
  • Male
  • Middle Aged
  • Monitoring, Physiologic / methods*
  • Pacemaker, Artificial
  • Risk Factors
  • Severity of Illness Index
  • Sex Distribution
  • Stroke / epidemiology*
  • Stroke / physiopathology
  • Stroke / prevention & control*
  • Survival Analysis
  • Treatment Outcome


  • Anti-Arrhythmia Agents