Cardiovascular Device Update Executive Editor

DENVER — Interventional cardiologists using catheters to treat atrial fibrillation (AF) may be treading on rather shaky ground — and if patients ever become broadly educated to the fact that it's being done primarily in off-label procedures, that shaky ground could turn into legal quicksand.

That is at least one conclusion that can be drawn from the issuance of a report at this year's Scientific Sessions of the Heart Rhythm Society (HRS; Washington) concerning the need for a more disciplined approach to catheter ablation to treat AF. Though not presented as a mandatory guidance, the report was given global clout by being endorsed by cardiac associations on both sides of the Atlantic: besides the HRS, the American College of Cardiology (Washington), the American Heart Association (Dallas), the Society of Thoracic Surgeons (Chicago); and, representing European cardiology, the European Heart Rhythm Association (EHRA; Sophia Antipolis, France) and the European Cardiac Arrhythmia Society (ECAS).

The interventional method of creating lesions in the atrium — vs. the creation of lesions associated with a surgical procedure — besides receiving increasing off-label use, is getting more attention from catheter manufacturers that are developing a growing number of technologies for this treatment. While ablation devices are approved for "soft tissue" treatments, none are FDA-approved for this specific application, and approvals seem far over the regulatory horizon.

No one knows how many of these procedures are being performed. Informal comments by HRS attendees and presenters suggest that as many as 60,000 are being performed worldwide, but since off-label procedures are especially hard to track the number may be much higher.

While the report does not directly stigmatize the off-label procedure, its detailing of the need for more controlled approaches and its emphasis on the need for longer-term studies with large numbers of enrollees pointed to a critical lack of rigor in performing these procedures. The difficulty of the procedure and the absence of broad studies has resulted in a lack of FDA approvals. While the report seems pitched to create a baseline for regulatory approvals and reimbursement, the report's presenters downplayed these possibilities, emphasizing instead the need to develop some procedural agreements.

Thus, the report concentrates on the areas that practitioners most often agreed on, via anonymous surveying, but this did not mean there was always total agreement, the presenters attempted to emphsize. The primary area of consensus was on the practice of "targeting" the pulmonary vein (PV) "and/or PV antrum [as] the cornerstone for most AF ablation procedures." The goal of this is "complete electrical isolation."

Asked concerning practices where there may have been no general agreement, Hugh Calkins, MD, director of electrophysiology at Johns Hopkins University (Baltimore) and chair of the HRS task force that developed the report, said that there were differences of opinion concerning how to treat what is termed "persistent" AF, that is, when the initial treatment fails to reduce the arrhythmia. Additionally, Calkins said opinions varied concerning the use of an initial "aggressive" approach to ablation vs. a "step-wise" approach, adding that he personally favored the step-wise strategy.

Overall, Calkins, along with the two other presenters — Josep Brugada, MD, of Hospital Clinic, University of Barcelona, representing EHRA; and Riccardo Cappato, MD, Arrhythmia and EP Center (Milan, Italy), representing ECAS — agreed on the need for a great deal more evidence concerning a variety of endpoints.

Thus far, according to the report, ablation to treat AF, whether the surgical or catheter approach, has been focused on improving patient quality of life, and that there has been no evidence to demonstrate longer-term endpoints, such as the ability to prolong life or avoid stroke and other co-morbidities. Other than quality of life, these longer-term endpoints, the report says, "have not been systematically evaluated as part of a large randomized clinical trial and are therefore unproven." It notes that catheter ablation for AF should not be considered for primary therapy but is best used in "the presence of symptomatic AF refractory or intolerant to at least one Class 1 or 3 antiarrhythmic medication."

Overall, the 34-page report (43, given the list of research references) offers a rather daunting group of challenges for pushing forward with research in this area. These include a list of 14 "unresolved questions" concerning clinical trial considerations and a 21 standards for better understanding the safety and efficacy of AF ablation.

These standards are needed, the report says, because of "substantial differences in treatment modalities, endpoints of acute and long-term success, post-ablation blanking periods, follow-up, redo and cross-over treatments, as well as variability in accounting for asymptomatic AF, and incomplete accounting for adverse events occurring beyond the first week of therapy."