[1] Med Coll Wisconsin, Div Cardiothorac Surg, FEC, Clement J Zablocki Vet Affairs Med Ctr, Milwaukee, WI 53226 USA
[2] Vet Affairs Med Ctr, Cooperat Studies Program Coordinating Ctr, Perry Point, MD USA
[3] Northport Vet Affairs Med Ctr, Northport, NY USA
[4] Eastern Colorado Hlth Care Syst, Dept Vet Affairs, Denver, CO USA
[5] Vet Affairs Boston, Boston, MA USA
[6] Harvard Univ, Sch Med, Boston, MA USA