The Watchman device, approved for routine use by the Food and Drug Administration in March, gives U.S. atrial fibrillation patients their first alternative to chronic anticoagulant treatment for preventing ischemic stroke.
By closing off the sac-like left-atrial appendage (LAA) with Watchman – a plug-like device placed via percutaneous, transcatheter delivery – blood clots cannot form in the LAA, thereby eliminating the source for most of the thrombi that threaten to cause ischemic strokes in patients with atrial fibrillation (AF).
Peter R. Kowey
But while many cardiologists welcome this new option that, for the first time, gives AF patients a way to avoid years or even decades of daily treatment with an anticoagulant, U.S. rollout of the device out has not been seamless. In many regions, health insurers have been unwilling to cover payment for Watchman and its placement, say physicians. Medicare AF patients in particular have been in a state of limbo for receiving a Watchman device while the Centers for Medicare and Medicaid Services (CMS) makes a national coverage determination, a decision not expected until later this year.
In addition, the AF patients who arguably are the best candidates for receiving this device are technically ineligible based on Watchman’s labeling as well as a very limited evidence base. The FDA approved the device specifically for patients judged “suitable for warfarin,” a decision driven largely by the two Watchman trials that led to approval. Each of these trials randomized warfarin-eligible patients either to receive the device along with a 6-week course of warfarin following placement to ensure against acute thromboembolic complications, or to chronic warfarin treatment with no device.
Although this design allowed head-to-head comparison between Watchman and the traditional standard for anticoagulation in AF patients, it left unaddressed the question of how Watchman performs in the AF patient population with the most obvious indication for a mechanical solution to stroke risk: patients who are completely intolerant of anticoagulation treatment. By strict labeling criteria those patients, desperate for an effective means to reduce their stroke risk, are ineligible to receive Watchman.
“It’s approved for patients who can take warfarin, and that’s wrong,” said Dr. Peter R. Kowey, an AF specialist and professor and director of the Center for Clinical Cardiology at the Lankenau Institute for Medical Research in Wynnewood, Pa. “Most of us in clinical practice believe Watchman has the potential to help patients who would be difficult to anticoagulate long term. This is how it’s used around the world.”
Who should get Watchman right now?
With patients with contraindications for anticoagulants excluded by current labeling, who are the right patients to get this device, especially with long-term experience still relatively limited? Many AF experts say they currently see targeting it to AF patients who are clearly at high risk from both stroke and anticoagulation, as well as possibly also patients who face less of a risk from an anticoagulant treatment but express a strong dissatisfaction with having to remain on such therapy for the rest of their lives.
The Watchman-trial results “were quite compelling, and the device fills a large, unmet need for patients who are inappropriately treated or undertreated” with anticoagulation, said Dr. J. Peter Weiss, an electrophysiologist at the Intermountain Heart Institute in Salt Lake City. “The data show it’s as good as warfarin for preventing ischemic stroke, and the 5-year outcome data [from the PREVENT AF trial] showed a survival advantage largely based on a reduced rate of hemorrhagic stroke” compared with patients on warfarin. “The benefit from Watchman is not just in preventing ischemic strokes,” Dr. Weiss said in an interview.
Researchers presented the 5-year outcomes from PROTECT AF to the FDA in October 2014, and while those results remain unpublished, Dr. Shephal K. Doshi, director of cardiac electrophysiology at Saint Johns Health Center in Santa Monica, Calif., presented them at the Heart Rhythm Society annual meeting in Boston in May. The 5-year outcomes showed that compared with patients treated chronically with warfarin, those who had received a Watchman device had a 39% relative risk reduction for the study’s primary, combined endpoint, a 32% relative risk reduction in the incidence of all strokes, and a 56% statistically significant relative risk reduction in cardiovascular deaths plus unexplained deaths. The 4-year follow-up results from PROTECT AF, with a similar mortality advantage for Watchman over warfarin, were published last year (JAMA. 2014 Nov. 19; 312[19]:1988-98).
Dr. Gordon F. Tomaselli
The patients who could benefit the most from receiving a Watchman device fall into two categories, Dr. Weiss said: AF patients at high risk for both stroke and bleeding, identified by their high scores on both the CHA2DS2-VASc and HAS-BLED formulas, and relatively young AF patients with a high CHA2DS2-VASc score who face the prospect of receiving warfarin or another anticoagulant for a long period of time, possibly several decades. An AF patient who is, for example, 66 years old may have a moderate risk for a serious bleeding event of about 0.5%/year on warfarin or a new oral anticoagulant (NOAC) such as apixaban (Eliquis), dabigatran (Pradaxa), edoxaban (Savaysa), or rivaroxaban (Xarelto), but if that patient were to live for 20 years, the cumulative risk for a major bleeding event could be about 10%, he noted.