1. Section of Cardiology, Rocky Mountain Regional VA Medical Center, Aurora, CO (A.S., P.D.V., P.L.H.).
2. Section of Electrophysiology, Division of Cardiology, University of Colorado Anschutz Medical Campus, Aurora (A.S., P.D.V., R.G.A., A.Z.T., J.J.W., W.S.T.).
3. Section of Cardiovascular Medicine, Yale University School of Medicine‚ Center for Outcomes Research and Evaluation, Yale-New Haven Hospital, CT (C.D., J.P.C., J.V.F.).
4. Section of Electrophysiology, Division of Cardiology, Duke University Hospital, Durham, NC (D.J.F.).
5. Division of Cardiology, University of Colorado Anschutz Medical Campus, Aurora (P.L.H.).