Further studies needed to determine cause , cause of death . Smith , 81 , was undergoing a surgery at clinic ; she suffered cardiac and respiratory arrest . An autopsy on comedian Joan Rivers has been completed , but more studies will be needed to determine the cause and manner of her death , New York City medical examiner 's office spokeswoman Julie Bolcer She had been on life support at Manhattan 's Mount Sinai hospital .
Further studies needed to determine cause , cause of death . Smith , 81 , was undergoing a surgery at clinic ; she suffered cardiac and respiratory arrest . She had been on life support at Manhattan 's Mount Sinai hospital .