Staff Writer

Boston Scientific Corp. reported five-year positive outcomes data from its PREVAIL study of the company's Watchman left atrial appendage closure (LAAC) device. Data from the study and the most recent five-year data from the PROTECT-AF trial suggest the device is a safe and effective option in reducing stroke compared to long-term warfarin usage among patients with non-valvular atrial fibrillation (AF). Results were presented at the Transcatheter Cardiovascular Therapeutics meeting in Denver and published Nov. 2 in the Journal of the American College of Cardiology.

AF, the most common form of arrhythmia, is associated with increased risk of stroke and is typically treated with anticoagulant therapy, such as warfarin or available alternatives, referred to as non-warfarin oral anticoagulants.

"The problem with anticoagulants is that while they work, there are some patients who don't tolerate them well," Vivek Reddy, principal investigator and director, cardiac arrhythmia services, Mount Sinai Hospital and Mount Sinai Health System told BioWorld MedTech.

Warfarin and anticoagulant alternative

Increased bleeding and other side effects may impact a patient's ability to take the medication long-term, leading a desire for an alternative to blood thinners.

"There is a fair amount of data suggesting that when a clot is seen in a patient with AF, it's typically in the left atrial appendage (LAA)," said Reddy. "So, the question was: if you occlude the LAA" with a local mechanical device, would that present the same benefit as warfarin, or another systemic anticoagulation medication? Warfarin was used in Boston Scientific's trials as that was the market-available anticoagulant at the time the studies began.

Marlborough, Mass.-based Boston Scientific's study, "Long-term results with left atrial appendage closure: watching the watchman," along with PROTECT suggested the device was able to reduce stroke risk among patients considered high risk due to non-valvular AF. The reported results are based on a meta-analysis of five-year data from both trials, which included a total of 1,114 randomized patients and 4,343 patient years. Data suggested patients saw a reduced risk of stroke similar to warfarin regimen, reduced incidence of fatal stroke or stroke with catastrophic effects, as well as reduced major bleeding not related to a procedure. The two studies evaluated the Watchman device and included participants with similar profiles.

A tale of two trials

Combined analyses of the two trials demonstrated a 55 percent drop in disabling or fatal stroke, including an 80 percent statistically significant decreased risk in experiencing a hemorrhagic stroke. Non-procedure bleeding was reduced by 52 percent. Compared to long-term warfarin usage, the Watchman also reduced all-cause mortality incidence.

"With complete five-year follow up in two randomized clinical trials, LAAC with the Watchman device continues to demonstrate statistically significant reductions in death," said Reddy. "Importantly, the data further prove the Watchman device is a safe and effective therapeutic alternative for stroke prevention in appropriate patients, enabling them to stop taking warfarin."

Watchman's mechanical action provides benefit to patients seeking to reduce stroke risk while it is limited to affecting only the LAA, said Reddy. However, for patients unable to tolerate a warfarin regimen, Watchman offers "a reasonable alternative" treatment. "Overall what we believe is that these data show that Watchman is as good as warfarin at preventing stroke," said Reddy. Watchman is delivered to the LAA percutaneously via leg puncture and routing of the sheathed device to the heart. Patients are placed under general anesthesia in a hospital for the hour-long procedure, stay overnight and typically go home the following day.

Cost benefit and additional study

Reddy also presented a poster at TCT on the budget impact for Medicare and its beneficiaries on LAAC versus warfarin or NOAC. According to the poster, at five years LAAC Medicare costs were $21,577, while NOAC were $23,269 and warfarin $10,034. However, total costs at nine years placed LAAC lower than either. "At 10 years, LAAC was least costly to Medicare and patients ($34,097), with combined costs being 15 percent lower than warfarin and 48 percent lower than NOACs," according to the poster.

Additional postmarket studies will gather data on the Watchman, such as the American College of Cardiology's LAAO registry designed to study LAA occlusion procedures as part of CMS' LAAC national coverage determination. A prospective randomized trial also is underway to evaluate patients who cannot tolerate the initial six-week warfarin therapy that usually occurs after surgery.

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