In 1944 FDR had acute congestive heart failure, along with what they called "reduced lung capacity", due they said to acute bronchitis. His systolic blood pressure was in the 180s, when they bothered to check it, which apparently wasn't often. In May his cardiologist Dr. Bruenn put him on digitalis, changed his diet and made him stop smoking, but sometimes he did not get out of bed for days at a time. When he did, his doctors only let him work for four hours a day.
This was, of course, all concealed from the press and the public.
He was flown to Yalta in this condition in January of 1945, and was unable handle negotiating with Stalin, to Churchill's horror.
Three months later he was dead.
Ah, ratts. Y’all have blown my great image of FDR. You’re right...FJB is a muuuuch better president. /S!