When a study found a tentative link between reduced leaflet mobility in TAVRs and the incidence of stroke in the fall, many turned to the FDA for insight on the mechanical issue, wondering whether they should alter clinical practice. The FDA's advice: "Limited available data do not allow us to fully characterize the causes, incidence, and short- and long-term risks of reduced valve leaflet motion, or to recommend appropriate treatment." Get used to more "I don't knows." The FDA just released a guidance formalizing its practice of notifying the public of "emerging signals," or situations in which the agency is monitoring risks that have not yet been fully validated, and for which the agency does not have specific recommendations. After all, saying "I don't know" can have a calming effect and prevent an overreaction. In the case of the problematic TAVRs, the FDA said to continue to use the devices to enable treatment in patients too frail for open heart surgery. The latest guidance appears to be inspired by that episode, and includes a list of considerations for determining when to notify the public of an "emerging signal," as well as the template for communicating the issue. The issuance of a formal policy suggests the FDA anticipates increased communication of emerging signals as it beefs up its surveillance capabilities through tools like UDI and post-market monitoring. Read the draft guidance | here's the TAVR notification