Beginning to set the stage for a 1924 re-election bid, in June 1923 President Warren Gamaliel Harding undertook a western tour, a "Voyage of Understanding." Spending part of mid-July in Alaska, on the return leg he stopped in Vancouver on July 26th where he tried to take in a round of golf. But during the outing the first signs of trouble emerged as the President felt so fatigued he was unable to complete the round. Though not realized at the time, Harding had entered into the final stages of heart failure.
Traveling to Seattle the following day presented no issues for President Harding, but on the night of July 27 he would awake to upper abdominal pain. Summoning physicians Charles Sawyer and Joel Boone, they would examine the President and come to different diagnoses: while Sawyer thought Harding was suffering from mere gastric distress, Boone (accurately) identified the problem as cardiac trouble. Continuing on his journey, upon arriving in San Francisco on July 29th, the question would essentially be answered as the President suffered a mild heart attack as he walked from his rail car to a waiting limousine.
Taken to his room at San Francisco's Palace Hotel, President Harding would again be examined by doctors, who diagnosed the heart attack as well as pneumonia. In an age before antibiotics, pneumonia was a very serious matter, and Harding's physicians concluded that the combination of pneumonia with heart failure could be a fatal one. The rest of the President's tour was immediately postponed and Harding would be prescribed the only remedy really available at the time: bed rest. Harding would spend the next four days and nights cloistered in Room 8064 of the Palace Hotel. At 7:30 on the evening of August 2, 1923, Warren Harding would suffer another, this time massive and fatal, heart attack as his wife Florence read to him from his bedside. He was just 57 years old.
What If This Happened Today?
A little personal disclosure before proceeding: I have both first- and second-hand knowledge of heart attacks, angina, and cardiac related issues. Consequently I think I can opine with a fair degree of confidence that Warren Harding was experiencing symptoms of cardiac duress long before 1923. His medical records showed that up to five years prior to that time he was complaining of fatigue and other symptoms which today would be considered classic cardiac indicators. Had Harding a physician who recognized these symptoms for what they were (instead of the homeopath who served as his family physician), it's at least possible that with some lifestyle modifications his lifespan could have been extended, perhaps by years. But fault can't really be laid entirely at Harding's doctors, either. Cardiac failure and heart attack both have classic symptoms, but if you're the one suffering them, you can be quite unclear as to what's happening unless you've gone through it (and obviously, survived) before.
In my own case for example, my cardiac disease began manifesting itself as early as my late 20's, but it would be several years before I recognized the symptoms for what they were. These symptoms (increasing fatigue, numbness in my arms, headaches, presumed gastric distress after meals, a feeling that my face was hot to the touch) were so gradual in their progression that I accepted the increased discomfort I felt as a "new normal." While my family had a history of heart disease (my father suffered at least two heart attacks and underwent a triple bypass at age 51, and would die of another coronary two decades later; my grandfather also suffered lesser but noticeable cardiac symptoms late in his life), I dismissed the notion that I was experiencing similar problems due to my age. With the hindsight of nearly two decades of cardiac issues however, I can readily distinguish between cardiac issues and other types of abdominal discomfort. Harding however likely could not, in part because no one had ever told him "You've a coronary problem, and here are signs you need to be on the lookout for going forward."
If the Harding case were to happen to a President today, both the course of medical action and the ultimate outcome are likely to be far more favorable. Thanks to numerous advances in cardiac medical treatment and care, a likely scenario would be one similar to what Vice President Cheney experienced in 2001 and which I've experienced on seven (and counting) occasions dating back to 2002: undergoing a cardiac catheterization, with any significant blockages discovered being treated via balloon angioplasty and stent implantation. Alternately, if the catheterization results determined that it was necessary, a President could undergo a CABG (coronary arterial bypass graft; a heart bypass) operation. In either case a transfer of power would be warranted under Section 3 of the 25th Amendment, but in the case of a successful angioplastic treatment, a President could resume his constitutional duties probably within eight hours of the procedure.