Who knows? Of my 4 senior law partners who had been in WWII, two saw combat. One was the only survivor of his LST which was mined at Ulithi in the Western Pacific. The other was a submariner who while never under direct attack, had to go through a minefield in the Sea of Japan that was just out of the movies in terms of trying (and succeeding) to slowly work through hundreds of mines. He called it his most stressful time.

The first died of a heart attack at age 69. The second turned 88 this month and is in very good shape. Both were lawyers in the high-power category.

Remember, cardiac death for men in the US has fallen something like 75% since 1960. Whatever the exact statistics, they are extraordinary. A combination of a great many factors, including changes in diet, smoking, and exercise, along with far better treatments. But perhaps the biggest factor is routine treatment of high blood pressure, which came effectively in the 60s.

Men died in their 40s and 50s of heart attacks far more often back then than they do these days. I remember 2 of my parents' friends who died thusly in their early 40s in the 1950s. This has become much less common, and frankly I doubt that combat stress was much of a factor for cardiac death years later.