Like most Gladwell related information, there's an anecdotal relationship between a town that doesn't have much heart disease and a subjective observation about its inhabitants' lifestyle.

However, I would suspect that self promotion is correlated with heart disease in general because people who have to self promote are under stressful conditions. They're trying to change things which they really have little control over: other people's minds.

I try to avoid that stress by looking for ways to succeed that don't require much self promotion. Part of that involves finding areas where you have enough edge that the benefit of other parties working with you is obvious. Admittedly not a very generalizable route, but I believe I'd be happy just trying as long as I don't have to bend to others' whims.