Rapid achievement of therapeutic anticoagulation positively affects outcome in patients undergoing cardioversion for persistent atrial fibrillation

Background: Current guidelines recommend anticoagulation with warfarin with documentation of an International Normalized Ratio (M) of 2-3 for 3 weeks prior to cardioversion of persistent atrial fibrillation (AF). Achievement of adequate anticoagulation often takes longer than 3 weeks, increasing the time to cardioversion. Hypothesis: The goal of the study was to quantify the total time elapsed for adequate anticoagulation and to identify differences in time to cardioversion between patients managed by primary care physicians (PCP) compared with those enrolled in a structured anticoagulation clinic (AC). Finally, we assessed the effect on treatment outcome between groups. Methods: A retrospective chart review identified those patients undergoing elective cardioversion who were started on warfarin at our medical center since 1997. The venue of anticoagulation management, time for adequate maintenance of M, and total time to cardioversion were recorded. A comparison was made between the two groups to identify the effect on treatment outcome. Multivariate analysis was performed to evaluate any effect comorbidities may have played on maintenance of normal sinus rhythm (NSR) within the treatment groups. Results: Of 83 patients, 48 had warfarin therapy monitored at their PCP and 35 were managed at our AC. Average time to therapeutic INR at AC and PCP was 29.1 +/- 9.3 and 50.7 +/- 6.8 days, respectively (p = 0.026). Average time to cardioversion at AC and PCP was 60.6 +/- 11.2 and 88.7 +/- 18.5 days (p = 0.041). At 12 months post cardioversion, 30 of 83 patients maintained NSR. Nineteen of 35 patients (54.3%) managed at AC maintained NSR compared with 11 of 48 patients (22.9%) managed at PCP (RR 0.61, 95% confidence interval 0.45-0.84) (p = 0.015). Conclusion: Therapeutic anticoagulation is more quickly achieved in a specialty anticoagulation clinic than at a PCP and positively affects therapy outcome.