TCT 2017: PREVAIL's Watchman is effective, but not '1st-line therapy' for AFib

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A meta-analysis of the PREVAIL and PROTECT trials, two studies aimed at evaluating the efficacy of left atrial appendage closure (LAAC) with the Watchman device in atrial fibrillation (AFib) patients, ultimately found that LAAC with Watchman provides stroke prevention for nonvalvular AFib patients comparable to warfarin, with additional decreases in major bleeding events and mortality. The 5-year findings were presented at the 29th annual Transcatheter Cardiovascular Therapeutics convention in Denver.

AFib patients have mainly achieved stroke prophylaxis through oral anticoagulants (OAC), including warfarin and nonwarfarin OACs, for decades, Vivek Y. Reddy, MD, and colleagues wrote in their research, which was published today in the Journal of the American College of Cardiology.

Despite its benefits of lowering ischemic stroke risk, the bleeding risks associated with an OAC regimen often prevent AFib patients from taking the medication.

Boston Scientific’s Watchman device, a permanent heart implant that boasts simple upkeep and risk reduction after a one-time procedure, was initially studied in the PROTECT trial, which effectively demonstrated that LAAC with the device was equivalent to warfarin for preventing stroke. The study yielded mixed results, though—patients who underwent the procedure also saw high rates of complications.

The second major randomized trial, PREVAIL, was more focused on assessing safety, Reddy and co-authors said, maintaining a design similar to and primary outcomes identical to PROTECT but with slight modifications to inclusion criteria. In both clinical trials, a total 1,114 patients were randomized 2:1 to LAAC or warfarin treatment.

The complication rate was low in the PREVAIL trial, Reddy et al. reported, with the warfarin cohort experiencing an unexpectedly low rate of ischemic stroke. In the study, the first composite coprimary endpoint of stroke, systemic embolism or cardiovascular/unexplained death did not achieve noninferiority, but the second coprimary endpoint of post-procedure ischemic stroke/systemic embolism did achieve noninferiority.

While endpoints were similar between the groups, the researchers wrote, differences in hemorrhagic stroke, disabling or fatal stroke, cardiovascular or unexplained death, all-cause death and post-procedure bleeding favored the LAAC cohort.

Reddy said at a press conference Thursday the results are hopeful, but he thinks it’s unrealistic to expect a device like the Watchman to immediately decrease stroke rates like systemic treatment proven to decrease those risks.

“We do agree that this is not a first-line therapy,” he said. “But there are a large number of patients who can’t tolerate long-term anticoagulation. At least we know that for five years, it’s safe.”