Glancing at that I'm guessing it's just that people who pig out on steaks and burgers tend to get more heart attacks and it correlates with iron consumption.
No there's more to it than diet. Similar findings have been found in multiple studies. There is evidence to indicate that this is why pre-menopausal women have a lower risk of heart disease than men and post-menopausal women (after controlling for other differences).
https://www.sciencedaily.com/releases/2014/04/140423170903.h...