Boston Sci suspends EU sales of next-gen Watchman, but CMO says current-gen device is safe and effective

The second-generation Watchman FLX implant--Courtesy of Boston Scientific

Boston Scientific ($BSX) has suspended European sales of the CE-marked Watchman FLX to prevent stroke due to a high embolization rate.

The device embolization rate of 2.9% (or 6 cases out of 207 implantations of the device) compares to a 30-day embolization rates of 0.2% for the first-generation Watchman, tctmd reports, citing a data registry. One of the 6 patients died from a postoperative infection following implant retrieval.

During an investor meeting at the Chicago gathering of the American College of Cardiology, Boston Scientific told Wall Street that it will study whether physician training and implantation technique is leading to the high adverse event rate.

According to Reuters the suspension does affect the company's projection of $175 to $200 million in structural heart sales this year, for commercialization of the latest-generation of the Watchman was only just underway in Europe, following its CE-marking in November. The Watchman FLX is not available in the U.S., where only the first generation of the device is FDA-approved.

Doctors interviewed by MedPage Today weren't overly distressed by the incident, and stressed that it doesn't impact the U.S. market, where about 100 centers currently offer the Watchman (but not the Watchman FLX).

"These types of things do happen with device iterations," Dr. Roxana Mehran of the Icahn School of Medicine told the publication, "so I don't have any concerns."

Meanwhile, Dr. Gordon Tomaselli of Johns Hopkins University commented, "Of course, anyone will be a little nervous, but I think this is a different technology, and I frankly don't think it will affect the uptake here significantly. … One of the reasons I say the standard Watchman uptake is not going to be hurt all that much, at least initially, is there is a lot of pent-up demand for this technology."

Boston Scientific spokeswoman Trish Backes has said left atrial appendage closure procedures in European can continue with the first-generation Watchman, which is still widely available on the continent.

Boston Scientific CMO bullish on the Watchman's U.S. experience

In an interview conducted just prior to the disclosure, during the just-concluded meeting of the American College of Cardiology, Boston Scientific chief medical officer of cardiac rhythm management devices Dr. Ken Stein said the first-generation Watchman, which is used in the U.S., is safe and effective. 

Stein pointed to data presented at the meeting on the first 1,600 Watchman U.S. patients, who fared similarly to those in the clinical trial, and posted a 95% implantation success rate. 

The main safety concern about the device has been acute post-procedural bleeding from a laceration to the left atrial appendage, not embolism formation. The risk (which was once around 5%) contributed to the FDA's rejection of the device in 2010. 

According to Stein the risk is now in the 1% range and can be managed by physicians. "What's clear from the clinical trial is that warfarin significantly reduces cardiovascular mortality compared to blood thinning medicines like warfarin, and from a safety standpoint we don't think that's an issue at all," he said. 

Stein stressed that the company has mandated a rigorous training program for docs who wish to implant the Watchman. It includes ensuring that all institutions that offer the device meet certain prerequisities, an in-person training event conducted by independent physicians, use of simulators and models, observation, optional proctoring and Boston Scientific support during procedures. 

In addition to those warfarin patients with a history or high risk of severe bleeding, the device can be implanted in patients who are having a hard time with medication management, Stein said. "Today it can be very difficult at times to maintain people within a therapeutic range. The problem with warfarin is it's got very variable physiologic affects. You have to do routine blood tests to measure the level of blood thinning. Some patients you can get to a stable dose, but there are some patients who just bounce all over the place all the time."

- here's more from Reuters
- here's MedPage Today's take (reg. req.) | tctmd's take