title: Risk of bleeding in low-risk atrial fibrillation patients on warfarin waiting for elective cardioversion.
abstract: BACKGROUND
  Systemic embolism is the most serious complication of cardioversion of atrial fibrillation (AF) and the immediate post-cardioversion period is associated with increased risk for thrombus formation. For this reason, treatment with vitamin K antagonist (VKA) is recommended for patients with AF. No information is available about bleeding risk related to this practice.
  
  
  METHODS
  We performed a prospective multicentre study on 242 low-risk AF patients (CHADS(2) score 0-1) that started on warfarin for elective cardioversion to evaluate their bleeding risk.
  
  
  RESULTS
  178 were males (73.6%), mean age 63.9 ± 9.8 years, 60 patients (25%) were aged ≤ 59 years. Patients with CHADS(2) score = 0 were 73 (30%), those with CHADS(2) score = 1 were 169 (70%). Patients were on VKA treatment, maintained at INR intended therapeutic range 2.0-3.0, for a median time of 159 days (range 30-631)total follow-up period 127 patient-years (pt-yrs). Quality of anticoagulation and occurrence of bleeding events were recorded. Patients spent 23%, 64% and 8% of time below, within and above the intended therapeutic range, respectively. When we observed the INR levels, we found that 62 patients (25.6%) had INR>4.5 at least in one occasion, and 23 (9.5%) in ≥ 2. During follow-up, 2 patients had major bleeds (rate 1.6% pt-yrs), one fatal. No embolic complications were recorded.
  
  
  CONCLUSIONS
  Our results show that low-risk AF patients, treated with VKA for elective cardioversion, carry a not irrelevant risk of bleeding. Efforts are required to properly select patients who could benefit from this procedure, reducing the time of warfarin exposure.
authors.affiliation: Dept of Heart and Vessels, Thrombosis Centre, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy. polida@aou-careggi.toscana.it
authors.forename: Daniela
authors.initials: D
authors.lastname: Poli
authors.forename: Emilia
authors.initials: E
authors.lastname: Antonucci
authors.forename: Elisa
authors.initials: E
authors.lastname: Grifoni
authors.forename: Oriana
authors.initials: O
authors.lastname: Paoletti
authors.forename: Elena
authors.initials: E
authors.lastname: Rancan
authors.forename: Francesco
authors.initials: F
authors.lastname: Dentali
authors.forename: Sophie
authors.initials: S
authors.lastname: Testa
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects*; D001281:Atrial Fibrillation / Q000097:blood*; D004554:Electric Countershock / Q000379:methods*; D005260:Female; D006470:Hemorrhage / Q000097:blood / Q000139:chemically induced / Q000209:etiology*; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D014859:Warfarin / Q000008:administration & dosage* / Q000009:adverse effects*
chemical_list: D000925:Anticoagulants; D014859:Warfarin