Heart attacks are strange things. They either hit you like a ton of bricks or sneak up over a time span. Thinking back after my first and second ones those were slow in coming up on me. The first one I thuoght about it later and had a smaller one a week or so before. The second was what appeared at first as by back being out of whack but both were warning signs that you'd normally put off as something else.
I'm just guessing here but Bob might have thought of his as a backache as it will be between the shoulder blades in the center of your back but almost directly behind the heart.
If any of the symptoms start, try to stay calm. In the ambulance you could feel uncomftable laying flat on the gurney, I felt better laying at a 45 degree angle. Take at least one 375mg aspirin as aspirin is a blood thinner