By Mackenzie Tatananni
Shares in Boston Scientific tumbled to their lowest level in more than two years on Monday after the medical device maker shared what should have been encouraging new data for its Watchman heart implant.
Shares slumped 9.1% to $62.87, heading for their lowest close since Jan. 30, 2024, when they ended the session at $61.42. The slump came after Boston Scientific presented trial results for its Watchman FLX device, a heart implant for patients with non-valvular atrial fibrillation (AfiB), at a conference Monday.
The data showed the device wasn't inferior to modern blood thinners, which are sold under brand names including Eliquis and Xarelto. Watchman users also had a lower level of bleeding compared with the blood thinner group, and saw a statistically significant reduction in non-procedural bleeding risk to meet the study's primary endpoint.
Although the data was released Friday, shares tumbled in the following session after investors focused on certain details. Truist Securities noted Monday that some conference attendees raised discussion around numerically higher ischemic strokes in patients using the device at 3.2% versus 2% for patients on blood thinners.
However, this wasn't a primary outcome of the study, and researchers plan to follow patients for five years to determine whether the device is non-inferior to blood thinners for ischemic stroke. Ischemic stroke occurs when a clot or fatty plaque obstructs blood flow to the brain, and can result in cell death within minutes.
Marty Leon, the study's co-chair, described the data as "a very strong endorsement" for use of the device in a broader patient population. The study showed a 0.33% annualized increase in either ischemic stroke or systemic embolization versus about a 2.6% reduction in bleeding, he noted. "That's going to be a balancing act that's going to allow us to be able to have meaningful conversations with patients," Leon said.
Boston Scientific's chief medical officer, Ken Stein, was similarly upbeat. "Even if you do believe that there is a small difference in the ischemic stroke rate -- and let's see how the five year data play out -- the rates in both arms are incredibly low, and the difference on an annualized basis is very small relative to the potential benefit in terms of reduction of clinically meaningful bleeding," Stein told attendees on Monday.
Despite what the stock reaction might suggest, overall feedback at the conference was positive, Truist pointed out. Other firms were similarly constructive. Leerink Partners noted that in-person feedback gave the firm increasing confidence that the trial results "will indeed support an uptick in Watchman procedure volumes."
Boston Scientific was named a Barron's stock pick in 2025. Since an article recommending the stock was published on Oct. 29, shares have cratered more than 37%.
The stock needs all the good news it can get. Although Boston Scientific posted solid fourth-quarter earnings at the start of February, shares sank as the company's first-quarter outlook underwhelmed investors. Counting Monday's losses, the stock has fallen 34% this year against a 7.1% decline for the benchmark S&P 500.
Write to Mackenzie Tatananni at mackenzie.tatananni@barrons.com
This content was created by Barron's, which is operated by Dow Jones & Co. Barron's is published independently from Dow Jones Newswires and The Wall Street Journal.
(END) Dow Jones Newswires
March 30, 2026 14:31 ET (18:31 GMT)
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