The people I know who have died from heart attacks have almost all tended to be thin and slight in build.
As I visit my anti-coag clinic on a regular basis, I must assume that a large majority of the people there are so because of heart problems - indeed the 'greyness' in so many faces offers more than a clue. The people to whom I refer are, by a huge majority, not overweight.
I suspect that 'the extra pounds' may well have an effect where diabetes is concerned but although 'carrying too much weight' might have some measurable effect on cardiac problems this is not of any great significance.