1. From the Departments of Cardiology (R.Y., J.B., Y.B., R.S., C.P.d.V., J.E., A.G.-M., A.B., F.F.-A.) and Gastroenterology and CIBERehd (C.R., R.B.), Hospital General Universitario Gregorio Marañón, Madrid, Spain; Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain (R.Y., J.B., Y.B., R.S., C.P.d.V., J.E., A.G.-M., A.B., F.F.-A., C.R., R.B.); and Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla (P.M.L.).