[294] After Eisenhower's death in 1969 (see below), an autopsy revealed an undiagnosed adrenal pheochromocytoma,[296] a benign adrenalin-secreting tumor that may have made him more vulnerable to heart disease during his presidency. Eisenhower suffered seven heart attacks from 1955 until his death.[294]

End of presidency
The 22nd Amendment to the U.S. Constitution, which set a two-term limit on the presidency, was ratified in 1951. Eisenhower was the first president constitutionally prevented from serving a third term.
Eisenhower was also the first outgoing president to come under the protection of the Former Presidents Act; two living former presidents, Herbert Hoover and Harry S. Truman, had left office before the act was passed. Under the act, Eisenhower was entitled to a lifetime pension, state-provided staff and a Secret Service security detail.[297]
In the 1960 election to choose his successor, Eisenhower endorsed Nixon over Democrat John F. Kennedy. He told friends, "I will do almost anything to avoid turning my chair and country over to Kennedy."[140] He actively campaigned for Nixon in the final days, although he may have done Nixon some harm. 