title: Atrial Fibrillation Burden and Short-Term Risk of Stroke: Case-Crossover Analysis of Continuously Recorded Heart Rhythm From Cardiac Electronic Implanted Devices.
abstract: BACKGROUND
  The temporal relationship of atrial fibrillation (AF) and stroke risk is controversial. We evaluated this relationship via a case-crossover analysis of ischemic strokes in a large cohort of patients with cardiac implantable electronic devices.
  
  
  RESULTS
  We identified 9850 patients with cardiac implantable electronic devices remotely monitored in the Veterans Administration Health Care System between 2002 and 2012. There were 187 patients with acute ischemic stroke and continuous heart rhythm monitoring for 120 days before the stroke (age, 69±8.4 years; 98% with an implantable defibrillator). We compared each patient's daily AF burden in the 30 days before stroke (case period) with their AF burden during days 91 to 120 pre stroke (control period). Defining positive AF burden as ≥5.5 hours of AF on any given day, 156 patients (83%) had no positive AF burden in both periods and, in fact, had little to no AF; 15 (8%) patients had positive AF burden in both periods. Among the discordant (informative) patients, 13 exceeded 5.5 hours of AF in the case period but not in the control period, whereas 3 had positive AF burden in the control but not in the case period (warfarin-adjusted odds ratio for stroke, 4.2; 95% confidence interval, 1.5-13.4). Odds ratio for stroke was highest (17.4; 95% confidence interval, 5.39-73.1) in the 5 days immediately after a qualifying occurrence of AF and decreased toward 1.0 as the period after the AF occurrence increased beyond 30 days.
  
  
  CONCLUSIONS
  In this population with continuous heart rhythm recording, multiple hours of AF had a strong but transient effect raising stroke risk.
authors.affiliation: From the Veterans Affairs Palo Alto Health Care System, CA (M.P.T., S.K.S., J.F., C.T.T.); Department of Medicine, Stanford University School of Medicine, CA (M.P.T.); Medtronic Cardiac Rhythm Disease Management, Mounds View, MN (P.D.Z.); San Francisco Veterans Affairs Medical Center, CA (E.K.K.); and Division of General Internal Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston (Y.C., D.E.S.). mintu@stanford.edu.
authors.forename: Mintu P
authors.initials: MP
authors.lastname: Turakhia
authors.affiliation: From the Veterans Affairs Palo Alto Health Care System, CA (M.P.T., S.K.S., J.F., C.T.T.); Department of Medicine, Stanford University School of Medicine, CA (M.P.T.); Medtronic Cardiac Rhythm Disease Management, Mounds View, MN (P.D.Z.); San Francisco Veterans Affairs Medical Center, CA (E.K.K.); and Division of General Internal Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston (Y.C., D.E.S.).
authors.forename: Paul D
authors.initials: PD
authors.lastname: Ziegler
authors.affiliation: From the Veterans Affairs Palo Alto Health Care System, CA (M.P.T., S.K.S., J.F., C.T.T.); Department of Medicine, Stanford University School of Medicine, CA (M.P.T.); Medtronic Cardiac Rhythm Disease Management, Mounds View, MN (P.D.Z.); San Francisco Veterans Affairs Medical Center, CA (E.K.K.); and Division of General Internal Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston (Y.C., D.E.S.).
authors.forename: Susan K
authors.initials: SK
authors.lastname: Schmitt
authors.affiliation: From the Veterans Affairs Palo Alto Health Care System, CA (M.P.T., S.K.S., J.F., C.T.T.); Department of Medicine, Stanford University School of Medicine, CA (M.P.T.); Medtronic Cardiac Rhythm Disease Management, Mounds View, MN (P.D.Z.); San Francisco Veterans Affairs Medical Center, CA (E.K.K.); and Division of General Internal Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston (Y.C., D.E.S.).
authors.forename: Yuchiao
authors.initials: Y
authors.lastname: Chang
authors.affiliation: From the Veterans Affairs Palo Alto Health Care System, CA (M.P.T., S.K.S., J.F., C.T.T.); Department of Medicine, Stanford University School of Medicine, CA (M.P.T.); Medtronic Cardiac Rhythm Disease Management, Mounds View, MN (P.D.Z.); San Francisco Veterans Affairs Medical Center, CA (E.K.K.); and Division of General Internal Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston (Y.C., D.E.S.).
authors.forename: Jun
authors.initials: J
authors.lastname: Fan
authors.affiliation: From the Veterans Affairs Palo Alto Health Care System, CA (M.P.T., S.K.S., J.F., C.T.T.); Department of Medicine, Stanford University School of Medicine, CA (M.P.T.); Medtronic Cardiac Rhythm Disease Management, Mounds View, MN (P.D.Z.); San Francisco Veterans Affairs Medical Center, CA (E.K.K.); and Division of General Internal Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston (Y.C., D.E.S.).
authors.forename: Claire T
authors.initials: CT
authors.lastname: Than
authors.affiliation: From the Veterans Affairs Palo Alto Health Care System, CA (M.P.T., S.K.S., J.F., C.T.T.); Department of Medicine, Stanford University School of Medicine, CA (M.P.T.); Medtronic Cardiac Rhythm Disease Management, Mounds View, MN (P.D.Z.); San Francisco Veterans Affairs Medical Center, CA (E.K.K.); and Division of General Internal Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston (Y.C., D.E.S.).
authors.forename: Edmund K
authors.initials: EK
authors.lastname: Keung
authors.affiliation: From the Veterans Affairs Palo Alto Health Care System, CA (M.P.T., S.K.S., J.F., C.T.T.); Department of Medicine, Stanford University School of Medicine, CA (M.P.T.); Medtronic Cardiac Rhythm Disease Management, Mounds View, MN (P.D.Z.); San Francisco Veterans Affairs Medical Center, CA (E.K.K.); and Division of General Internal Medicine, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston (Y.C., D.E.S.).
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Singer
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000150:complications* / Q000503:physiopathology*; D002545:Brain Ischemia / Q000209:etiology*; D018592:Cross-Over Studies; D017147:Defibrillators, Implantable; D005260:Female; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D012307:Risk Factors; D020521:Stroke / Q000209:etiology*; D013997:Time Factors
keywords: United States Department of Veterans Affairs; atrial fibrillation; cross-over studies; defibrillators, implantable; stroke