Was the Carvel Ice Cream Guy Murdered?

When Tom Carvel died 17 years, it was determined to be a heart attack.

But now, his niece thinks he was murdered.

I'm not saying he wasn't murdered, I obviously have not been privy to the evidence one way or the other, but is it really a stretch to think an 84 year old man who was associated with ice cream his whole life might have heart problems?