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PREVAIL: Watchman device promising for stroke prevention in nonvalvular AF
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SAN FRANCISCO — Results from the highly anticipated PREVAIL trial show that left atrial appendage closure with the Watchman device provides a safe alternative to warfarin in patients with nonvalvular AF.
For the PREVAIL trial, 407 patients with nonvalvular AF at risk for stroke were randomly assigned 2:1 to receive either the Watchman left atrial appendage closure device (Atritech/Boston Scientific; n=269) or warfarin (n=138). The CHADS2 score was used to determine patients’ risk for stroke. Compared with the PROTECT AF trial, which also tested the device and was conducted in 2009, patients had higher CHADS2 scores, and a higher likelihood of having diabetes and history of prior stroke or transient ischemic attack.
PREVAIL had a design similar to PROTECT AF, but was expanded to include new centers and implanting physicians to demonstrate whether training programs have been effective in improving rates of complications and procedure-related stroke.
According to results, the pre-specified criteria for the study’s first primary endpoint of acute occurrence of death, ischemic stroke, systemic embolism and procedure- or device-related complications requiring major CV or endovascular intervention was met (95% upper CI limit <2.67%). Similarly, the rate of ischemic stroke or systemic embolism occurring greater than 7 days post-randomization, the study’s third primary endpoint, was also met (95% CI upper limit <0.0275%).
However, despite similar rates of the study’s second co-primary endpoint — the rates of stroke, systemic embolism, and CV or unexplained death — between both groups at 18 months of follow-up, the pre-specified non-interiority criteria was not met, as it exceeded the upper 95% CI bound.
Safety data from PREVAIL also revealed that serious vascular complications were markedly reduced when compared with PROTECT AF (8.7% vs. 4.6%; P=.004) in the 7 days post-randomization, as were the rates of procedure-related stroke (P=.019) and need for surgical repairs (P=.027). The success rates for implanting the device were also higher in PREVAIL (95.1% vs. 90.9%; P=.04).
The results of the PREVAIL trial were initially planned to be presented as a late-breaking session at the American College of Cardiology Scientific Sessions, but the presentation was pulled after the manufacturer of the device broke the embargo.
Perspective
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Peter R. Kowey, MD
The PREVAIL trial provides more data regarding the safety of the Watchman device. The challenge will be how it will and can be incorporated into clinical practice. Clearly, it will not be for everyone, and we envision having it available for patients with a very high stroke risk but for whom systemic anticoagulation is not feasible. More problematic will be its use in more mainstream practice. Those issues will need to be addressed in the context of its overall safety and efficacy in comparison to oral anticoagulation, especially with the novel drugs that are superior to warfarin, the comparator agent in PREVAIL.
Perspective
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Samin K. Sharma, MD
In scientific rigor, the ACC takes a very tough stance. I remember when the COURAGE trial was released, the embargo was also broken, and the ACC took a very tough stance then and here with the PREVAIL trial is another example. However, the news is left atrial appendage closure with the Watchman device is safe. Now we need to know whether it is also effective. That is the big issue and we probably won’t know it for the next few days.
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