Temporal relationship between subclinical atrial fibrillation and embolic events

Circulation. 2014 May 27;129(21):2094-9. doi: 10.1161/CIRCULATIONAHA.113.007825. Epub 2014 Mar 14.


Background: Among patients with implantable pacemakers and defibrillators, subclinical atrial fibrillation (SCAF) is associated with an increased risk of stroke; however, there is limited understanding of their temporal relationship.

Methods and results: The Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial (ASSERT) enrolled 2580 pacemaker and defibrillator patients aged ≥65 years with a history of hypertension but without a history of atrial fibrillation. Pacemakers and implantable cardioverter-defibrillators precisely logged the time and duration of all episodes of SCAF and recorded electrograms that were adjudicated by experts. We examined the temporal relationship between SCAF >6 minutes in duration and stroke or systemic embolism. Of 51 patients who experienced stroke or systemic embolism during follow-up, 26 (51%) had SCAF. In 18 patients (35%), SCAF was detected before stroke or systemic embolism. However, only 4 patients (8%) had SCAF detected within 30 days before stroke or systemic embolism, and only 1 of these 4 patients was experiencing SCAF at the time of the stroke. In the 14 patients with SCAF detected >30 days before stroke or systemic embolism, the most recent episode occurred at a median interval of 339 days (25th to 75th percentile, 211-619) earlier. Eight patients (16%) had SCAF detected only after their stroke, despite continuous monitoring for a median duration of 228 days (25th to 75th percentile, 202-719) before their event.

Conclusions: Although SCAF is associated with an increased risk of stroke and embolism, very few patients had SCAF in the month before their event.

Clinical trial registration url: http://www.clinicaltrials.gov. Unique identifier: NCT00256152.

Keywords: arrhythmia; pacemaker; stroke.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Atrial Fibrillation / diagnosis
  • Atrial Fibrillation / epidemiology*
  • Atrial Fibrillation / surgery
  • Embolism / diagnosis
  • Embolism / epidemiology*
  • Embolism / surgery
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Pacemaker, Artificial* / trends
  • Prospective Studies
  • Risk Factors
  • Stroke / diagnosis
  • Stroke / epidemiology*
  • Stroke / surgery
  • Time Factors

Associated data

  • ClinicalTrials.gov/NCT00256152