I went googling and found this: A study at Johns Hopkins University School of Medicine has demonstrated that sudden emotional stress can result in reversible heart failure[1]. It goes on "a traumatic event such as a breakup, the death of a loved one, or even the shock of a surprise party can provoke a heart attack in people who don't have heart disease and are otherwise healthy, researchers say". and

"Dr. Wittstein and his research team found that some people may respond to sudden, overwhelming emotional stress by releasing large amounts of adrenalin and other chemicals into the blood stream. These chemicals can be temporarily toxic to the heart, effectively stunning the muscle and producing symptoms similar to those of a typical heart attack: chest pain, fluid in the lungs, shortness of breath and heart failure. However, there are no further similarities between "broken heart" syndrome and cardiac arrest. Closer inspection using blood tests and magnetic resonance imaging scans failed to show the typical heart attack signs, such as irreversible muscle damage and elevated levels of certain enzymes."

If that happened, it would have been avoidable; it doesn't necessarily mean he was sickly and this was the straw that broke the camel's back.

(Aside: I wonder if anyone here would think comparable things of the organizers of a surprise party, 16 years after it's published in a medical journal that they can be fatal? What if the birthay person was known to hate surprise parties? Anyone calling for a death penalty or years in prison?)

[1] https://www.jhunewsletter.com/article/2005/03/sudden-shock-c...