[1] Duke Univ, Duke Clin Res Inst, Med Ctr, Durham, NC 27705 USA
[2] Northwestern Univ, Ctr Cardiovasc Innovat, Dept Emergency Med, Feinberg Sch Med, Chicago, IL 60611 USA
[3] Ahmanson UCLA Cardiomyopathy Ctr, David Geffen Sch Med, Los Angeles, CA USA