Atrial fibrillation: Surgical and Transcatheter Ablation

MedicalResearch.com Interview with:

Elisa Ebrille, MD
Department of Cardiology, School of Medicine

Fiorenzo Gaita, M.D.
Director Division of Cardiology Department of Medical Sciences
University of Turin, Turin, Italy

MedicalResearch.com What are the main findings of the study?

Answer: We evaluated 33 patients with long-standing atrial fibrillation and valvular heart disease who underwent valve surgery and concomitant cryoablation (pulmonary veins isolation, mitral isthmus and roof line lesions) from 2000 to 2002. The surgically created ablation lesion was validated with electroanatomic mapping. Percutaneous radiofrequency ablation was performed in cases with lesion incompleteness and these patients were followed for over 10 years.

  • A hybrid approach, combining surgical ablation procedure consisting of pulmonary veins isolation and creation of left atrial linear lesions (mitral isthmus and roof lines), along with endocardial ablation, when necessary, led to a significant clinical improvement in patients with long-standing atrial fibrillation and valvular heart disease during a long-term follow-up (> 10 years).
  • With the hybrid approach, pulmonary veins isolation and transmural left atrial linear lesions were obtained in a high percentage of patients (79%). When achieved and electrophysiologically demonstrated, the complete ablation scheme was effective in more than 80% of patients in maintaining sinus rhythm throughout follow-up.

MedicalResearch.com Were any of the findings unexpected?

Answer: As already demonstrated by our previous study (Gaita F et al. Circulation 2005;111:136-142), we expected patients with valvular heart disease and long-standing atrial fibrillation had dilated and remodeled atria. In this subset of patients, ablation results reported in the literature have been dismal. Moreover, we expected that surgical ablation alone did not necessarily mean that the completeness and transmurality of the lesions created was achieved. First, because transmurality is technically difficult to achieve in the left mitral isthmus since it is a thick area. Secondly, because nitrous oxide cryoenergy was utilized for surgical ablation (creating a lesion depth of no more than 4-5 mm). Thirdly, because both surgical and transcatheter ablation used an endocardial approach, making it more difficult to obtain the transmurality. We also expected that the transcatheter evaluation of the transmurality of the surgically created lesions and the detection of conduction gaps together with the capability of adding an endocardial touch-up ablation to eliminate the conduction gaps, would allow a correct and meaningful evaluation of atrial fibrillation recurrences during the follow-up.

It was surprising to see that, at the end of a very long-term follow-up period (more than 10 years), when the electrophysiologic evaluation demonstrated completeness of the lesions created (with surgical cryoablation alone or with transcatheter radiofrequency energy touch-up), the success rate in maintaining sinus rhythm was 81%. Moreover, comparing the clinical results of patients in which a complete linear lesion scheme was obtained to patients in which the conduction gaps still persisted after the hybrid approach, a statistically significant difference in the freedom from permanent atrial fibrillation survival curves was noted. A complete linear lesion scheme, either surgically created or completed by radiofrequency energy, correlated positively with the procedural success at 10-year follow-up.

MedicalResearch.com What should clinicians and patients take away from your report?

Answer: Atrial fibrillation is the most common sustained cardiac arrhythmia in the general population and ablation has become a major therapeutic technique over the past few years. For many years, at least three major schools of thought tried to explain the underlying mechanisms of atrial fibrillation, recognizing the importance of atrial dilation and remodeling in valvular patients. Surgical atrial fibrillation ablation evolved from the original Cox-Maze strategy toward a minimally invasive procedure with good results. Percutaneous transcatheter ablation, trying to mimic the surgical ablation scheme, has also proven to be effective in maintaining sinus rhythm. However, up to now most of the published studies on atrial fibrillation ablation have had limited follow-up.

New hybrid approaches, combining surgical and percutaneous ablation, are now emerging to enhance the success rates of these two procedures. In fact, surgical ablation does not necessarily ensure the completeness and transmurality of the lesions created. The evaluation of the transmurality of the surgically created lesions with an electrophysiologic study and the detection of conduction gaps with the capability of adding an endocardial touch-up ablation when necessary, allowed improving the long-term efficacy of the atrial fibrillation ablation procedure.

Considering the need for very long-term follow-up data, as stressed also by the recently published guidelines, our paper attempted to provide the adequate data. To our knowledge, this represents the longest follow-up reported in the literature of atrial fibrillation ablation.

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Answer: The conclusion of our study was that, in patients with long-standing atrial fibrillation and valvular heart disease, the hybrid approach with surgical cryoablation consisting of pulmonary veins isolation and left atrial linear lesions combined with transcatheter radiofrequency ablation was highly effective in maintaining sinus rhythm or significantly reducing the atrial fibrillation burden in a very long-term follow-up. An electrophysiological evaluation, to validate the transmurality of the surgically created lesions and to complete the lesion scheme applying radiofrequency energy, improved the long-term efficacy of the ablation procedure.

Further validation of our findings in multi-centered studies, investigation in a larger patient population, as well as prospective randomized studies would be needed to ensure the best approach for ablation strategy.

Citation:

Very Long-Term Results of Surgical and Transcatheter Ablation of Long-Standing Persistent Atrial Fibrillation.

Gaita F, Ebrille E, Scaglione M, Caponi D, Garberoglio L, Vivalda L, Barbone A, Gallotti R.

Department of Cardiology, School of Medicine, University of Turin, Turin, Italy.
Ann Thorac Surg. 2013 Jul 31. pii: S0003-4975(13)01141-7. doi: 10.1016/j.athoracsur.2013.05.054. [Epub ahead of print]