Funding Support and Author Disclosures Dr Lakdawala has received support from the O’Hare Family Foundation directed toward research on cardiolaminopathy; has received unrestricted research funding from Bristol Myers Squibb and Pfizer; and has received modest consulting fees from Bristol Myers Squibb, Pfizer, Alexion, Akros, Cytokinetics, Tenaya, Bayer, and Nuevocor. Dr Claggett has consulted for Alnylam, Cardior, Cardurion, Corvia, CVRx, Eli Lilly, Intellia, and Rocket. Dr Connors has received compensation for consulting, scientific advisory boards, and data safety monitoring boards from Alexion, Anthos, Bayer, Bristol Myers Squibb, Janssen, Pfizer, Peropshere Technologies, and Regeneron. Dr Tedrow has received honoraria and consulting fees, as well as compensation for scientific advisory boards and data safety monitoring boards from Biosense Webster (JNJ MedTech), Boston Scientific, Abbott Medical, and Thermedical. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.