Risk of bleeding in low-risk atrial fibrillation patients on warfarin waiting for elective cardioversion

INTRODUCTION: 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. CONCLUSION: 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.