The death of Rick Slayman, the first man to receive a kidney transplant from a genetically engineered pig, was caused by an 'unexpected cardiac event,' and there was no sign his body was rejecting the organ, his transplant surgeon said Wednesday. The disclosure, six months after the 62-year-old Weymouth resident died, was the first public explanation of Slayman's cause of death and the most detailed confirmation that Slayman's new kidney was still viable and doing its job two months after he underwent the historic procedure. In a May press release announcing his death, hospital officials said they had 'no indication' the death was caused by his transplant but provided no additional details.