Steven Nissen is a heart specialist and chairman of cardiovascular medicine at the Cleveland Clinic.
He first gained prominence when he developed techniques in 1987 to thread miniaturized ultrasound imaging devices into a patient’s heart to reveal the exact composition of plaques causing the early stages of artery damage. This allowed much easier evaluation of anticholesterol medications.
His efforts in 2004 linked COX-2 inhibitors such as Celebrex and Merck’s Vioxx with heart attacks, and prevented Merck’s similar product, Arcoxia, from being approved. In 2005, he attacked the experimental diabetes drug Pargluva, from Bristol-Myers Squibb, for its serious heart risks. A Food and Drug Administration advisory panel had strongly recommended approval, but Pargluva was withdrawn.
Source - http://en.wikipedia.org/wiki/Steven_Nissen