Cardiothoracic surgeons learn of latest surgical innovations

By Larry Haimovitch

Medical Device Daily Contributing Writer

February 1, 2011

SAN DIEGO — The 47th annual meeting of the Society of Thoracic Surgeons (STS; Chicago) which is taking place here, was well-attended as cardiothoracic (CT) surgeons gathered to meet and gain up-to-date information on their subspecialty.

With the economy in a tailspin in the past couple of years, procedures like coronary artery bypass grafts (CABG) and valve repair and replacement, which in the past were viewed as virtually immune to economic pressures, have been negatively impacted. With declining volume in their most important procedures, CT surgeons are definitely more open than ever to find new procedures that can serve their patients and generate incremental volume.

This attitude was best exemplified by two sessions, one titled "Transcatheter Aortic Valve Implantation (TAVI): Preparing for a Disruptive Technology," where virtually every speaker noted that a "tsunami" would soon be arriving and that CT surgeons had better get on board or their practices could be significantly impacted. The second session, titled "Less Invasive Valve Surgery" discussed surgical techniques designed to reduce patient morbidity and accelerate the healing from valve surgery.

A typical comment in the first session came from Eric Roselli, MD, a CT surgeon from the Cleveland Clinic (Cleveland), who said that "we must get trained early and actively participate now by becoming a heart valve specialist, not just a CT surgeon."

Roselli discussed several different options to prepare for the "coming revolution in heart valve interventions," noting that the STS held one Transcatheter Heart Valve Therapies Symposium in December 2010 and has two more planned for 2011. These courses will educate CT surgeons for minimally invasive aortic valve replacement.

He also discussed two other options for CT surgeons, a three to six month "mini-fellowship" program to further prepare them to participate for TAVI and a formal one-year fellowship program to prepare surgeons for independent practice in transcatheter valve cases.

While there is no doubt that TAVI has fostered tremendous benefits for frail patients unable to withstand conventional open chest valve surgery, there are potentially serious and life threatening complications that can arise in this patient cohort. Importantly, Roselli pointed out that these complications are best managed by surgeons, not interventionalists, creating a clearcut role for CT surgeons.

Another hot topic at STS is closure of the left atrial appendage (LAA). Over the past few months, LAA closure has been in the limelight with the St. Jude Medical (STJ; St. Paul, Minnesota) acquisition of crosstown medical device company AGA Medical (AGA; Golden Valley, Minnesota) for about $1.3 billion in STJ common stock in December 2010. Several industry sources felt that one of the principal attractions of AGA is the huge market potential for LAA occlusion. Indeed, in a report in January 2010, one analyst noted that "LAA occlusion represents a significant market opportunity . . . representing potential annual revenues of around $2 billion". AGA has already gained CE mark approval for its Amplatzer Cardiac Plug, though it has registered minimal sales to date.

More recently, Boston Scientific (Natick, Massachusetts) reported the purchase of Atritech (Plymouth, Minnesota) for $100 million in cash upfront with potential earnout payments of an additional $275 million. The latter is viewed as the leader in this embryonic market, although the FDA denied marketing clearance of its Watchman device despite: (1) A successful pivotal trial (PROTECT-AF), that met its primary endpoint of being non-inferior to warfarin and (2) A positive recommendation from an FDA advisory panel. The FDA's major concern was a higher risk of procedure-related complications and Atritech recently began a second pivotal trial dubbed PREVAIL to address this concern and provide more supporting data.

Both the AGA/STJ and Atritech devices are delivered percutaneously.

So, why is the LAA occlusion device market deemed to be so attractive? Simply put, in patients who suffer from atrial fibrillation (AF), their blood is not pumped completely out of the atria, potentially causing the blood to pool, forming thrombus and causing AF patients to have a five-fold higher risk of suffering an ischemic stroke. AF strokes are typically far more severe than other types of ischemic strokes.

The gold standard to treat AF is anti-coagulation medications, namely warfarin, but patient compliance with this drug is well-recognized to be abysmally low. Thus, there is significant interest in device-based approaches to occlude the LAA, where it is thought that as much as 90% of thrombus accumulation originates.

In June 2010, Atricure (West Chester, Ohio) became the first company to receive FDA approval for any LAA occluder, its device is implanted in an open chest procedure. The company's device, tradenamed the AtriClip Gillinov-Cosgrove Left Atrial Appendage Exclusion, has quickly established itself as an important new product in the CT surgery world, with about $1 million of revenue in its first full quarter of commercialization.

Atricure sponsored an evening symposium here titled "The Left Atrial Appendage: A New Surgical Frontier," which drew a standing room only crowd. Three luminaries in the field of atrial fibrillation discussed the tremendous need for this exciting new product.

Andrea Natale, MD, executive medical director at St. David's Medical Center (Austin, Texas) and widely-regarded as one of the world leaders in electrophysiology and AF provided a comprehensive overview of the anatomy and physiology of the LAA , discussed the PROTECT-AF trial in detail and described other percutaneuolsly implanted devices in development.

His main conclusion was that the PROTECT-AF trial "clearly established the rationale for LAA exclusion" and that this market will flourish in the coming years.

Patrick McCarthy, MD, chief of the division of cardiothoracic surgery at Northwestern Memorial Hospital (Chicago) and one of the most highly-respected CT surgeons in the U.S., made a strong case for LAA occlusion in all patients undergoing a surgical AF ablation procedure.

McCarthy discussed the traditional techniques of occluding the LAA, namely suturing or stapling and bluntly stated that "we do a lousy job with these approaches." He went on to say that stapling is often inadequate because of the difficulty in getting to the base of the appendage and thus achieving only partial removal of the LAA, while flow across the staple line can result in a potentially disastrous complication. Suturing can also be risky and very often does not achieve complete occlusion.

Another AF luminary, Marc Gillinov, MD, surgical director of the Center for Atrial Fibrillation – Cleveland Clinic Heart Center, fully supported McCarthy's views, stating that "treating the appendage without complete closure is worse than not doing anything." Gillonov, one of the inventors of the device, emphasized not only the efficacy of the device, but also that it is safe to use and quite easy to deploy.

Gillinov noted that the question of whether LAA occlusion actually reduces embolic stroke risk remains unanswered but said that "we think that left atrial appendage closure reduces stroke risk."

Strong support for LAA occlusion occurred in mid-2010, when the UK's National Institute for Health and Clinical Excellence (NICE; London) issued a new guidance related to closure of the left atrial appendage. NICE, which is an independent organization responsible for providing national guidance on promoting good health and preventing and treating ill health, is known for its rigorous analysis. It concluded that "current evidence suggests that . . . occlusion of the left atrial appendage (LAA) is efficacious in reducing the risk of thromboembolic complications associated with non-valvular atrial fibrillation (AF)."

2011 Society of Thoracic Surgeons Annual Meeting

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