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

Abstract

IntroductionSystemic 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. MethodsWe performed a prospective multicentre study on 242 low-risk AF patients (CHADS2 score 0–1) that started on warfarin for elective cardioversion to evaluate their bleeding risk. Results178 were males (73.6%), mean age 63.9±9.8years, 60 patients (25%) were aged ≤59years. Patients with CHADS2 score=0 were 73 (30%), those with CHADS2 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 159days (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. ConclusionOur 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.