[1] BRIGHAM & WOMENS HOSP, HOWARD HUGHES MED INST, BOSTON, MA 02115 USA
[2] BRIGHAM & WOMENS HOSP, DIV CARDIOVASC, BOSTON, MA 02115 USA
[3] ST GEORGE HOSP, SCH MED, DEPT CARDIOL SCI, LONDON SW17 0RE, ENGLAND
[4] MINNEAPOLIS HEART INST FDN, MINNEAPOLIS, MN USA