Editor's Note: Commentary based on Karasoy D, Hilmar G, Hansen J, et al. Oral anticoagulation therapy after radiofrequency ablation of atrial fibrillation and the risk of thromboembolism and serious bleeding: long-term follow-up of nationwide cohort in Denmark. Eur Heart J 2015;36:307-15.

Background

Radiofrequency ablation (RFA) is a treatment option recommended for certain patients with symptomatic atrial fibrillation (AF).¹ RFA is associated with the reduction of AF-related symptoms,² yet it remains uncertain whether it is associated with a reduction in thromboembolic complications related to AF. Current European Society of Cardiology guidelines for the management of AF recommend sustaining oral anticoagulation (OAC) for at least two months after RFA, with further continuation based on the patient's thromboembolic and bleeding risk. Yet, data on the efficacy and safety of long-term OAC treatment after RFA are lacking.

Methods

This study was a retrospective analysis based on the Danish National Patient Registry of patients undergoing first-time RFA between the years 2000-2011.³ OAC use after discharge was identified by data from prescription claims. The primary outcome measure was thromboembolism defined as hospitalization for ischemic stroke, transient ischemic attack (TIA), or peripheral artery embolism. The secondary outcome measure was serious bleeding, defined as hospitalization for intracranial bleeding, or bleeding from respiratory, gastrointestinal, or urinary tract. The risk of thromboembolism and serious bleeding according to OAC treatment was analyzed using Coxproportional-hazard models. The RFA cohort was further compared with a non-ablated AF population in a propensity score-matched analysis.

Results

A total of 4,050 patients (median age 59.5 years, 73.5% men) underwent first-time RFA for AF. Approximately half of the patients, and 70% of high-risk patients (CHA₂DS₂-VASc ≥2) remained on OAC beyond the first year after RFA. During a median follow-up of 3.4 years (IQR: 2.0-5.6), 103 thromboembolic events were recorded (2.5%), a third of which occurred during the first three months post-RFA. Overall, after three months following RFA, OAC discontinuation was not associated with increased thromboembolic risk (adjusted hazard ratio [HR] 1.42; 95% confidence interval [CI], 0.86-2.35). However, OAC therapy was associated with higher incidence rates of serious bleeding compared with OAC discontinuation (adjusted HR 2.05; 95% CI, 1.25-3.35). Recurrent AF and prior stroke/TIA were associated with thromboembolic risk, but other CHA₂DS₂-VASc score variables were not. Previous history of bleeding, OAC therapy, aspirin use, and kidney dysfunction were significantly associated with increased serious bleeding. The thromboembolic risk was relatively low in patients undergoing RFA as compared with a non-ablated matched cohort of AF patients (adjusted incidence rate ratio 0.53; 95% CI, 0.43-0.65 in favor of the RFA cohort).

Conclusion

Thromboembolic risk beyond three months post-RFA was low as compared with matched non-ablated AF cohort. In this retrospective, non-randomized analysis, the risk of serious bleeding associated with OAC may outweigh the benefits of thromboembolic risk reduction. Further studies are warranted to examine these results.

Commentary/Perspective

Regardless of the patient's baseline thromboembolic risk, OAC therapy is indicated to prevent thromboembolism during, and shortly after, catheter ablation procedure for AF due to the increased periprocedural risk of stroke or TIA.¹ The long-term continuation of OAC following the procedure is less evidence-based, and is currently tailored according to the patient's thromboembolic and bleeding risks.^1,4 Other factors might be weighed in this decision making: on the one hand, the long-term risk of stroke after AF ablation, as shown by this trial and others,⁵ is low; on the other hand, AF recurrence after ablation is more likely to be asymptomatic and can recur late after the procedure.⁶

The key finding of this study is that the continuation of OAC therapy beyond three months post-RFA did not significantly reduce thromboembolic risk, even in patients with higher CHA₂DS₂-VASc scores. However, OAC treatment was associated with an increased risk of serious bleeding, suggesting that in these patients, the risk of serious bleeding associated with OAC may outweigh the benefits of thromboembolic risk reduction.

This study provides some useful information for clinicians who are weighing the risks and benefits of long-term OAC in patients following AF ablation, However, it should also be interpreted with caution due to its significant limitations, namely the observational retrospective design, the low number of endpoints, and substantial missing data of international normalized ratio (INR) values and recurrent AF events. Ongoing clinical trials, such as the Catheter Ablation Versus Antiarrhythmic Drug Therapy for Atrial Fibrillation (CABANA) study and Early Therapy of Atrial Fibrillation for Stroke Prevention Trial (EAST), might provide new information for assessing whether AF catheter ablation is superior to standard therapy for reducing thromboembolic events, and thus, could perhaps assist in guiding the administration of OAC therapy after RAF.

References

1. January CT, Wann LS, Alpert JS, et al. American College of Cardiology/American Heart Association Task Force on Practice Guidelines. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol 2014;64:e1-76.
2. Wokhlu A, Monahan KH, Hodge DO, et al. Long-term quality of life after ablation of atrial fibrillation: the impact of recurrence, symptom relief, and placebo effect. J Am Coll Cardiol 2010;55:2308-16.
3. Karasoy D, Hilmar G, Hansen J, et al. Oral anticoagulation therapy after radiofrequency ablation of atrial fibrillation and the risk of thromboembolism and serious bleeding: long-term follow-up in nationwide cohort of Denmark. Eur Heart J 2015;36:307-15.
4. Calkins H, Kuck KH, Cappato R, et al. 2012 HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design. Europace 2012;14:528-606.
5. Verma A, Champagne J, Sapp J, et al. Discerning the incidence of symptomatic and asymptomatic episodes of atrial fibrillation before and after catheter ablation (DISCERN AF): a prospective, multicenter study. JAMA Intern Med 2013;173:149-56.
6. Themistoclakis S, Corrado A, Marchlinski FE, et al. The risk of thromboembolism and need for oral anticoagulation after successful atrial fibrillation abaltion. J Am Coll Cardiol 2010;55:735-43.

Keywords: Anti-Arrhythmia Agents, Arteries, Aspirin, Atrial Fibrillation, Catheter Ablation, Confidence Intervals, Decision Making, Embolism, Follow-Up Studies, Hospitalization, Incidence, International Normalized Ratio, Intracranial Hemorrhages, Ischemic Attack, Transient, Outcome Assessment, Health Care, Propensity Score, Proportional Hazards Models, Registries, Retrospective Studies, Risk, Risk Assessment, Risk Reduction Behavior, Secondary Prevention, Stroke, Thromboembolism, Urinary Tract, Anticoagulants

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