There is no way he adjusts his diet at all. He believes the body has a battery with a finite amount of energy and exercise is bad because it depletes that battery faster. There's no way he has the mental capacity to understand he needs to change his eating habits when the doctors advise it.

https://www.theguardian.com/science/the-h-word/2017/may/15/trumps-theory-exercise-victorian-britain-eugenics-sexism

At his age with his potential comorbidities? Surgery of any kind is absolutely a possible killer.

Nearly half of all patients with heart failure have a normal ejection fraction (EF). The prevalence of this syndrome, termed heart failure with preserved ejection fraction (HFpEF), continues to increase in the developed world, likely because of the increasing prevalence of common risk factors, including older age, female sex, hypertension, metabolic syndrome, renal dysfunction and obesity. However, we should be aware that the president's ejection fraction has not been disclosed, nor has his BNP, Creatinine & GFR (or troponins/EKG). When was his last ECHO and Stress Test???