Frederick “Mike” Humeston, long bothered by knee pain from a Vietnam War wound, had been taking the painkiller Vioxx for barely two months when he had a heart attack four years ago.

Now 60, the postal worker and ex-Marine from Boise, Idaho, has permanent heart muscle damage, is constantly fatigued and worries about increased risk of a second heart attack, said one of Humeston’s attorneys, Chris Seeger of 21-attorney firm Seeger Weiss.