HRS 2012: Boston Scientific’s Watchman as effective as Warfarin

A medical device made by Boston Scientific (NYSE:BSX) designed to trap blood clots in the heart could be an important tool for preventing stroke in high-risk atrial fibrillation patients, researchers said today at the annual Heart Rhythm Society meeting in Boston.

A study comparing the Watchman left atrial appendage closure device with the anticoagulant drug Warfarin found the device to be more effective in preventing stroke in patients who can’t tolerate the drug. A previous trial showed that the Watchman device was the drug’s equal in preventing stroke in high-risk AF patients, but patients in that trial were treated with Warfarin for 6 weeks until LAA closure could be demonstrated.

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The most recent trial, using data from the ASA Plavix registry, showed that the device worked just as well even in the absence of Warfarin. The researchers enrolled 150 high-risk AF patients who couldn’t take Warfarin and successfully implanted the Watchman device in 141 (94%). After at least a year of follow-up care, there were 4 strokes, 1 embolism and 6 blood clots related to the device.

The study also showed that the Watchman device reduced the incidence of ischemic stroke by 75% in patients treated with just aspirin and cut the stroke rate by 64% in patients treated with aspirin and lifelong Clopidogrel, another blood clot preventer.

Asked if the Watchman device is a game-changer or just another tool in the electrophysiologist’s armamentarium, co-author Dr. Vivek Reddy of the Mount Sinai School of Medicine in New York told MassDevice.com that more studies are needed comparing the device with newer anticoagulants such as dabigatran.

"If the world only had Warfarin and the Watchman, I would say game-changing. As it is right now, I would say it’s an alternative. Right now we have drugs that are better than Warfarin and devices – I would say, that are better than Warfarin," Reddy told us this afternoon at the HRS conference. "So the question then is which of these do we use, or which in combination? You can’t say it’s game-changing unless you prove that 1 is better than the other. Basically, we don’t know which is better. That kind of a study, comparing the new drugs with appendage closure, those are future studies that need to be done."

Another question still to be answered is whether the 6-month post-implantation regimen of the anti-platelet drug Plavix is really necessary, he said.

"The bleeding rate from aspirin-and-Plavix is act quite high, it’s actually as high as Warfarin alone. So the question is, does this combination of these 2 things really add, from a safety perspective, or does it detract from a safety perspective," Reddy said. "The hypothesis behind Plavix is that it will help in the healing process with the device, but it’s not clear if Plavix does anything in terms of helping the healing process. It may be that all Plavix is doing is increasing our bleeding rates.

"The problem is still the older patients. Even with the new drugs, there’s still a risk for bleeding," he told us. "Fundamentally, the question is going to be, does it make sense to do local therapy with appendage closure as opposed to systemic therapy with a blood thinner you have to take every day. The cost may favor the Watchman device, because it’s a 1-time procedure. These are questions that are being raised, but we dont have answers yet."

"Watchman implantation without a Warfarin transition is safe and effective in AF patients with contraindications to even short-term oral anticoagulation," the researchers wrote. "The first formal results from the largest study of LAA closure in patients contraindicated to Warfarin demonstrate the Watchman may be an important alternative for high risk AF patients with limited options for stroke prevention."

"Watchman is the most studied LAA closure device with more than 2,000 patients enrolled in prospective studies and nearly 4,000 patient-years of follow up," BSX chief medical officer Dr. Keith Dawkins said in prepared remarks. "This novel device has been well received in more than 30 countries where it offers a safe and effective alternative to long-term treatment with oral anticoagulants."

"Findings from the ASAP Study are promising in that closure of the LAA with the Watchman Device produced a significant reduction in the expected ischemic stroke rate for this patient population," added lead investigator Dr. Vivek Reddy. "These results are very impressive and show potential for an effective device-based solution for higher-risk patients with limited pharmacologic options to reduce their risk of stroke."

Boston Scientific acquired the Watchman technology in a $100 million buyout of Plymouth, Minn.-based Atritech last year. The value of the deal could spike to $375 million if Watchman meets certain financial and regulatory milestones. In November 2010, Atritech began enrolling patients in the Prevail clinical study, aiming to win a nod from the Food & Drug Administration for the device. It would be the first LAA closure device to reach what could be a $1 billion U.S. market in the next few years, Leerink Swan analyst Rick Wise wrote at the time.

"Although Atritech is a small deal for BSX, we believe this is an interesting take on a potentially compelling new market. That market’s potential now is essentially being validated by two large cardiology players (BSX and [St. Jude Medical (NYSE:STJ)]). STJ’s recent AGA purchase – whose new product pipeline also includes LAA closure technology – along with BSX’s announcement today could suggest that the the LAA closure opportunity is indeed real," according to Wise.

"In structural heart, we continue to expand the commercial presence of our Watchman Device outside the United States while in the United States, we remain on track to complete enrollment in the Prevail trial and submit our PMA by the end of the year," interim CEO Hank Kucheman told analysts last month. "This would set us up for expected FDA approval and launch in the second half of 2013, which we expect will allow us to be the first to market in the United States with this novel technology for a considerable period of time."

The Atritech deal is part of Boston Scientific’s efforts to broaden its portfolio of less-invasive cardiovascular devices.

"The Atritech acquisition significantly strengthens our product offerings in the fast-growing areas of structural heart therapy and atrial fibrillation, which represent two of our Priority Growth Initiatives," CEO Ray Elliott said when the deal closed last year. "Left atrial appendage closure represents a significant growth opportunity for Boston Scientific, and Atritech’s Watchman device is the first such product for atrial fibrillation patients at high risk for stroke."

In February 2011, Boston Scientific added two products for treating peripheral chronic total occlusions to its portfolio of cardiovascular devices.