The Food and Drug Administration's (FDA) Circulatory System Device Panel met on Oct. 8, 2014, for the third time to discuss Boston Scientific's application for approval of the WATCHMAN device, a left atrial appendage closure device. The panel voted six to five with one abstention that the benefits outweighed the risks of the device for the specified patient population, a far closer vote than those of previous panels. The close nature of the vote reflected the panel's concerns regarding the proposed label indication. Discussion throughout the day conveyed panel members' concerns that this be an option only as a second-line therapy for a select group of patients and the need to include this as part of the label indication. Other concerns included the need for sufficient patient education regarding the benefits and risks of the WATCHMAN device, as well as the sufficiency of the proposed post approval study should the device be approved.

The major debate of the day was whether the new data from the PREVAIL trial was robust enough to stand alone versus the pre-specified agreed-upon Bayesian analysis that merged the PREVAIL data with data from the PROTECT AF trial. The new data showed increased ischemic events compared to the control group, raising concerns among panel members regarding the device's effectiveness.

The panel voted unanimously that the device was safe and tied on effectiveness. The Chair broke the tie with a "no" vote.

Keywords: Atrial Appendage, Bayes Theorem, Risk Assessment, United States Food and Drug Administration

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