By Larry Haimovitch

Medical Device Daily Contributing Writer

January 23, 2008

BOSTON – How often have we heard one of the world’s most renowned and veteran physicians describe the state of knowledge of his subspecialty as “overwhelmingly ignorant” — especially if that physician is the organizer of an outstanding annual conference in his field of expertise?

Yet, that comment was made to Medical Device Daily by Jeremy Ruskin, MD, director of the Cardiac Arrhythmia Service at Massachusetts General Hospital (Boston), a world-famous electrophysiogist and founder of the highly regarded Boston Atrial Fibrillation Symposium (BAFS), held here late last week.

Begun 13 years ago – with just 100 attendees its inaugural year — BAFS has grown dramatically. Nearly 1,300 physicians, EP industry clinicians, aspiring entrepreneurs and the investment community attended this year, sitting through live cases, all-day lectures from the world’s most knowledgeable physicians treating atrial fibrillation (AF) and a pot-pourri of educational programs running late into the evening. Why is BAFS attendance growing so?

The simple answer: atrial fibrillation (AF) — the most common sustained rhythm disturbance and the most perplexing cardiac rhythm facing physicians. Described by several physicians here as a ”progressive chronic atrial cardiomyopathy,” AF’s causes, mechanisms of actions and optimal treatment modalities are still in an embryonic state of understanding. And this depressing fact, despite the millions spent annually by industry and academia, became very obvious during BAFS, greatly frustrating symposium attendees.

It had long been estimated that about 2 million Americans were afflicted with AF. However, an article in the July 11, 2006 issue of Circulation argued that its prevalence has been significantly underestimated, the authors putting its actual prevalence at over 5 million. And with the growing numbers of aging Americans, AF prevalence is expected to skyrocket to nearly 16 million by 2050.

The Atrial Fibrillation Foundation (Reading, Massachusetts) has said that while AF afflicts a modest 2.3% of the population over the age of 40, it occurs in about 6% of those over 65 and nearly 10% of those over 80.

Remarkably, despite the lack of consensus concerning optimal AF treatment, a large number of procedures are performed to treat the condition. MDD estimates about 40,000 percutaneous catheter ablations performed in the U.S. in 2007 — a 40% to 50% increase over 2006 – and being done despite the fact that not one of the companies developing cardiac ablation systems have won FDA approval for this application.

Catheter procedures are also very lengthy, are poorly reimbursed, have mediocre clinical outcomes and may have disastrous results. But because AF is a chronic disease, many patients are seeking a permanent “fix,” not the palliation and onerous adverse effects produced by drugs. About 25,000 AF surgical ablations concomitant to other open heart surgeries were performed in the U.S. in 2007. And a “stand-alone” AF ablations market is now emerging, with about 3,000 performed in 2007.

Basically, with a minor exception, companies selling surgical AF ablation devices are marketing them without the benefit of FDA approval for cardiac tissue. Thus, about 65,000 “off-label” procedures were performed in the U.S. last year, reflecting, in part, the woeful failures of medical (drug) management.

At a symposium titled “Surgical Management of Atrial Fibrillation,” moderator Ralph Damiano, MD, chief of cardiac surgery at Barnes-Jewish Hospital (St. Louis), and one of the world’s most highly-regarded cardiac surgeons, said that “perhaps, in 10 years, we will totally understand [AF].”

The statement, though specifically referring to the current state of cardiac surgery, echoed the sentiments of many physicians at the conference concerning AF in general. Lending further murkiness to the discussions on AF in general and surgical ablation in particular, was a talk titled “Is There a ‘Best’ Energy Source for Surgical Ablation?” from David Kress, MD, a cardiac surgeon from the Midwest Heart Surgery Institute (Milwaukee, Wisconsin).

“All energy systems have their advantages and shortcomings,” he declared, and that “the best” energy source will not be known until all have been subjected to the rigors of a well-designed clinical trial.

Those results, based upon the clinical trials currently underway, appear to be several years away. In yet another example of the lack of clarity for AF therapy, Marc Gillinov, MD, a noted cardiac surgeon at the Cleveland Clinic, spoke on the topic “The Left Atrial Appendage,” asking the question: “Should the left atrial appendage ([LAA] be removed or occluded?” His answer, not surprisingly, was “maybe.” Gillinov’s pros and cons ranged from “it is there for a reason” to “we can certainly live without it.”

The LAA is generally believed to be the outflow location of micro-emboli that can develop in the left atrium. This occurs far most commonly in AF patients, whose atria are not pumping efficiently, thus allowing blood to pool and clots to form. An LAA occlusion device can be viewed as a non-pharmacological stroke-prevention strategy for AF patients.

Discussing two new LAA devices, Gillinov termed them “promising.”  Both the Cardiac Surgery division of Medtronic (Minneapolis) and Atricure (West Chester, Ohio) areconducting human clinical trials for occlusion devices that appear to be simple to use, rapidly deployable and minimally invasive. Atricure, with 11 human cases completed to date in Switzerland, submitted its 510(k) in March 2007, and analysts are predicting FDA approval in the next several months.

Closing out this session, Damiano asked: “Where Will Standalone AF Surgery Be in Five Years?” And he specifically asked the panelists: “Will you be doing more AF surgery or less?”

Cardiac surgeon James Edgerton, MD, from the Texas Hospital of the Southwest (Plano), developer of the largest and most impressive AF surgical ablation data, was ebullient about the future of AF ablation. “We will be doing a ton of patients,” he exclaimed. The other panelists were far more restrained, however, saying that, in the future, surgeons are likely to play a much more modest role in AF treatment. Damiano’s challenged that, saying: “If we get far better data than we have now, the role of AF surgical ablation is bright.”


Controversy, uncertainty cast large shadows over AF ablation

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