An autopsy performed on the exhumed body of Tammy Wynette showed the country singer died of heart failure caused by damage from repeated blood clots. The role drugs may have played in Wynette’s 1998 death is impossible to determine because the autopsy took place a year after she died, Nashville Medical Examiner Bruce Levy said Thursday. The exhumation and autopsy were prompted by a $50 million wrongful death lawsuit filed by Wynette’s four daughters. They allege their mother could have lived longer were it not for the painkillers she was given prior to her death.