Editor's Note: Commentary based on Bunch TJ, May HT, Bair TL, et al. Atrial fibrillation ablation patients have long-term stroke rates similar to patients without atrial fibrillation regardless of CHADS2 score. Heart Rhythm 2013;10:1272-7.

Background:

Atrial fibrillation (AF) is associated with a significant increase in overall mortality and thromboembolic events (TEs).^1,2 Radiofrequency catheter ablation of AF (RFA) has evolved as an effective treatment modality to eliminate AF over the last decade. Several observational studies have suggested that RFA may help reduce the risk of stroke in patients with AF.^3,4 However benefits of RFA on stroke risk remains poorly understood.

Methods:

A total of 4212 consecutive patients who underwent RFA were compared with 16,848 age and sex-matched controls with AF (no ablation) and to 16,848 age and sex-matched controls without AF. Patients were enrolled from the large ongoing prospective Intermountain Atrial Fibrillation Study and were followed with a mean length of follow up 2.9 + 2.9 years. The baseline risk factors and outcomes of interest (stroke) were determined using ICD-9 diagnosis codes.

Results:

Patients with no history of AF were younger and had lower rates of hypertension, heart failure, renal failure, and valve disease compared to the other two groups. The AF group who did not undergo ablation was slightly older and had a higher rate of diabetes and a prior stroke. The AF ablation group had higher rates of hypertension, transient ischemic attack, and valvular heart disease. The CHADS2 risk profiles were similar among groups; however, more patients with no history of AF had scores from 0 to 1. A total of 1296 (3.4%) patients had a stroke over the follow-up period. At one year, 893 (2.4%) patients had a stroke. There was a significantly higher rate in those patients with AF who did not undergo ablation (3.5%, n=590) compared to those with AF who underwent ablation (1.4%, n=61) and those with no history of AF (1.4%, n=242) Across all CHADS2 profiles and ages, AF patients with ablation had a lower long-term risk of stroke compared to patients without ablation. Furthermore, AF ablation patients had similar long-term risks of stroke across all CHADS2 profiles and ages compared to patients with no history of AF.

Conclusion:

Patients with AF after RFA have a significantly lower risk of stroke compared to selected AF patients who do not undergo RFA independent of baseline stroke risk score.

Commentary:

Rhythm control strategies utilizing drugs have not been effective in reducing the risk of stroke in patients with AF.⁵ This has been partly due to the ineffective nature of antiarrhythmic drugs in maintaining SR (and perhaps suboptimal anticoagulation). The current study suggests that patients who undergo RFA may have a lower risk stroke than patients with AF who do not undergo RFA. There are several important limitations when considering the results of this study. The patients were only matched according to gender and age. The authors did not employ more advanced statistical techniques such as propensity matching or adjusted survival curves with inverse probability weights to account for other differences in patient characteristics, which may influence long-term risk of stroke. Therefore, patients with AF who undergo RFA may represent a much healthier population as evidenced by the very small risk of mortality and stroke over a long follow up period. Furthermore, it is possible that subsequent care after ablation may affect outcomes associated with AF. It is unclear whether the reduction in stroke observed in this and other observational studies is related to maintenance of SR, anticoagulation or other procedural and patient related characteristics. Therefore, management of thromboembolic risk after RFA should continue to be based on clinical risk factors⁶ regardless of whether RFA was performed.

References

1. Benjamin EJ, Wolf PA, D'Agostino RB, et al. Impact of atrial fibrillation on the risk of death: The framingham heart study. Circulation 1998;98:946-952.
2. Piccini JP, Hammill BG, Sinner MF, et al. Incidence and prevalence of atrial fibrillation and associated mortality among medicare beneficiaries, 1993-2007. Circ Cardiovasc Qual Outcomes 2012;5:85-93.
3. Oral H, Chugh A, Ozaydin M, et al. Risk of thromboembolic events after percutaneous left atrial radiofrequency ablation of atrial fibrillation. Circulation 2006;114:759-765.
4. Bunch TJ, Crandall BG, Weiss JP, et al. Patients treated with catheter ablation for atrial fibrillation have long-term rates of death, stroke, and dementia similar to patients without atrial fibrillation. J Cardiovasc Electrophysiol 2011;22:839-845.
5. Wyse DG, Waldo AL, DiMarco JP, et al. A comparison of rate control and rhythm control in patients with atrial fibrillation. N Engl J Med 2002;347:1825-1833.
6. 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: a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation. Heart Rhythm 2012;9:632-696.

Keywords: Atrial Fibrillation, Catheter Ablation, Heart Failure, Hypertension, Stroke

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