1. Hypertrophic Cardiomyopathy Center, Heart and Vascular Institute, Cleveland Clinic, OH (A.T.-R., M.Y.D.).
2. Department of Cardiology, University of Virginia, Charlottesville (C.M.K.).
3. Department of Cardiology, University of Oxford, United Kingdom (S.N.).
4. Department of Cardiology, Houston Methodist Hospital, TX (S.F.N.).