ClinicalAtrial fibrillationLong-term effects of catheter ablation for lone atrial fibrillation: Progressive atrial electroanatomic substrate remodeling despite successful ablation
Introduction
Atrial fibrillation (AF) currently has been conceptualized to involve an intricate and dynamic interplay between initiating triggers and perpetuating substrate.1 Catheter ablation has become accepted as an effective mainstream therapy for treatment of drug-refractory symptomatic AF.2 Several clinical studies of atrial substrate have demonstrated electroanatomic remodeling of the right atrium in conditions associated with AF and in lone paroxysmal AF patients.3, 4, 5, 6 Experimental models of AF have demonstrated early reversal of electrical remodeling but long-term persistence of established structural remodeling.7, 8 In humans, whether substrate changes are reversed following cure of AF has not been studied. Importantly, there have been no prior reports on the effect of successful catheter ablation of AF on this atrial substrate. The aims of the current study were (1) to confirm the nature of the electroanatomic remodeling in AF patients with lone AF and (2) to document whether there is reverse remodeling or further progression of the atrial substrate in patients who are able to maintain sinus rhythm for least 6 months after a successful ablation procedure. We hypothesized that the remodeled atrial substrate associated with AF may not be fully reversible upon restoration of sinus rhythm.
Section snippets
Study protocol
Patients undergoing radiofrequency ablation (RFA) for AF were screened for study enrollment. Patients with a history of an AF ablation procedure, structural heart disease (left ventricular ejection fraction <50%, left atrial diameter >5 cm, coronary artery disease, valvular heart disease), hypertension with evidence of ventricular hypertrophy on echocardiography (wall thickness >1.1 cm), or severe obstructive sleep apnea were excluded from study enrollment. Patients who had been prescribed
Patient demographics
Baseline patient demographic information is listed in Table 1. There were no significant differences with regard to age, gender, or left ventricular ejection fraction. In the AF group, mean duration between AF diagnosis and catheter ablation was 5.6 ± 4.8 years.
Left atrial size
There was significant left atrial dilation in the AF compared with control group, as evidenced by a significantly greater left atrial diameter (P = .01), area (P = .01), and volume (P = .03; Table 1).
Voltage
A total of 195 ± 116 electroanatomic
Discussion
The major findings of the study can be summarized as follows.
- 1
At baseline compared with a control group, a group of AF patients without structural heart disease demonstrated
- A
Lower regional and global voltage and higher proportion of low-voltage signals
- B
Regional and global conduction slowing
- C
An increased proportion of complex signals
- D
Prolonged regional refractoriness
- E
Left atrial dilation
- A
- 2
In the AF group compared with baseline, the follow-up study demonstrated:
- A
Lower regional and global voltage with
- A
Conclusion
Patients with AF who do not have indicators of structural heart disease nevertheless demonstrate an abnormal atrial substrate characterized by reduction in voltage, conduction slowing, and increased signal complexity. At long-term follow-up after successful catheter ablation, no evidence of reverse remodeling of this atrial substrate was seen, and indeed some evidence of further substrate progression was noted. These findings may have implications for timing of catheter ablation.
Acknowledgments
We thank all of the cardiac technician staff at the Royal Melbourne and Alfred Hospitals for their patience in facilitating the collection of data for this manuscript.
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