[1] Baylor Coll Med, Div Cardiol, Houston, TX 77030 USA
[2] Oregon Hlth Sci Univ, Div Cardiol, Portland, OR 97201 USA
[3] Dalhousie Univ, Div Cardiol, Halifax, NS, Canada
[4] Univ Florida, Coll Med, Div Cardiol, Gainesville, FL USA
[5] Rutgers State Univ, Robert Wood Johnson Med Sch, Div Cardiol, Piscataway, NJ 08854 USA
[6] Univ N Carolina, Dept Biostat, Collaborat Studies Coordinating Ctr, Chapel Hill, NC USA