Funding Support and Author Disclosures Dr Mehra has received travel support and consulting fees, paid to Brigham and Women’s Hospital, from Abbott; has received fees for serving on a steering committee from Medtronic and Janssen (Johnson and Johnson), for serving on a data and safety monitoring board from Mesoblast, and for serving as a scientific board member from NuPulseCV, Leviticus, Transmedics and FineHeart; and has received consulting fees from Natera, Paragonix, Moderna, the Baim Institute of Clinical Research, and Broadview Ventures. Dr Desai has received institutional grant support from Abbott, Alnylam, AstraZeneca, Bayer, and Novartis; and has received consulting fees from Abbott, Alnylam, AstraZeneca, Avidity, Axon Therapeutics, Bayer, Biofourmis, Boston Scientific, Cytokinetics, GlaxoSmithKline, Merck, Novartis, Parel, Regeneron, Roche, and Verily. Dr Nayak has reported that she has no relationships relevant to the contents of this paper to disclose.