title: Asymptomatic atrial fibrillation burden and thromboembolic events: piecing evidence together.
abstract: BACKGROUND
  Contributory evidence on a direct association between asymptomatic atrial fibrillation (AF) burden and thromboembolic events is conflicting and contradictory. The aim of the article is to gather evidence available for a direct correlation between burden and stroke.
  
  
  METHODS
  A literature search was performed to capture studies reporting data on the impact of asymptomatic AF burden on the risk of stroke. Data was then extracted from each included study including burden of AF, hazard ratio (HR) for stroke, and CHADS2 score. A random effects meta-analysis was carried out on the log-transformed HRs for different subgroups of AF burden. A meta-regression was performed on the two variables: burden of asymptomatic AF and CHADS2 score.
  
  
  RESULTS
  The random-effect pooled analysis performed on a single subgroup of the six studies reporting data on HR, showed a HR of 2.150 (95% CI 1.523-3.003) for stroke during asymptomatic AF compared to sinus rhythm. At univariate meta-regression, no correlation was detected between burden of asymptomatic AF and HR for stroke (p-value 0,874). When CHADS2 score was included in the regression model as a covariate, no significant association was detected (p-value 0,939).
  
  
  CONCLUSIONS
  A direct correlation between burden of asymptomatic AF and HR for stroke cannot be detected in our pooled analysis. However, due to the limitations acknowledged in the analysis, our findings need to be confirmed in large cohort studies.
authors.affiliation: a Cardiology Department , Luigi Sacco Hospital , Milan , Italy.
authors.forename: R
authors.initials: R
authors.lastname: Proietti
authors.affiliation: b McGill University Health Centre , Montreal , Quebec , Canada.
authors.forename: C
authors.initials: C
authors.lastname: Labos
authors.affiliation: b McGill University Health Centre , Montreal , Quebec , Canada.
authors.forename: A
authors.initials: A
authors.lastname: AlTurki
authors.affiliation: b McGill University Health Centre , Montreal , Quebec , Canada.
authors.forename: V
authors.initials: V
authors.lastname: Essebag
authors.affiliation: c Hackensack University Medical Center , Hackensack , NJ , USA.
authors.forename: T V
authors.initials: TV
authors.lastname: Glotzer
authors.affiliation: d Heart Rhythm Program , Southlake Regional Health Centre , Newmarket , Canada.
authors.forename: A
authors.initials: A
authors.lastname: Verma
mesh_terms: D058070:Asymptomatic Diseases; D001281:Atrial Fibrillation / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D017281:Cost of Illness; D006801:Humans; D012107:Research Design; D018570:Risk Assessment / Q000379:methods / Q000706:statistics & numerical data; D013223:Statistics as Topic; D020521:Stroke / Q000209:etiology / Q000517:prevention & control; D013923:Thromboembolism / Q000209:etiology / Q000517:prevention & control
keywords: Atrial fibrillation; CHADS score; burden; stroke; thromboembolic events