Which President died of congestive heart failure while in office?

Warren G. Harding died from a sudden heart attack due to congestive arteries in his hotel suite while visiting San Francisco at around 7:35 p.m. on August 2, 1923. His death quickly led to theories that he had been poisoned or committed suicide. Suicide appears unlikely, since Harding was planning for a second term election. Rumors of poisoning were fueled, in part, by a book called The Strange Death of President Harding, in which the author suggested that Mrs. Harding had poisoned her husband after learning of his infidelity. Mrs. Harding's refusal to allow an autopsy on President Harding only added to the speculation. According to the physicians attending Harding, however, the symptoms in the days prior to his death all pointed to congestive heart failure. Harding's biographer, Samuel H. Adams, concluded that "Warren G. Harding died a natural death which, in any case, could not have been long postponed".