[1] Univ Colorado, Hlth Sci Ctr, Div Cardiol, Denver, CO 80262 USA
[2] Denver Hlth Med Ctr, Div Cardiol, Denver, CO USA
[3] Antwerp Cardiovasc Inst Middelheim, Antwerp, Belgium
[4] Denver VA Med Ctr, Div Cardiol, Denver, CO USA
[5] Philips Med Syst, Clin Res, Best, Netherlands
[6] Univ Calif San Francisco, Div Cardiol, San Francisco, CA 94143 USA
[7] Univ Utah, Div Cardiol, Salt Lake City, UT 84112 USA