[1] Boston Univ, Sch Med, Whitaker Cardiovasc Inst, Boston, MA 02118 USA
[2] Boston Univ, Sch Med, Evans Dept Med, Cardiol Sect, Boston, MA 02118 USA
[3] Case Western Reserve Univ, Dept Epidemiol & Biostat, Cleveland, OH 44106 USA
[4] Case Western Reserve Univ, Dept Genet, Cleveland, OH 44106 USA