Like rula said, it is very rare. Any amount of stress and anxiety has a negitive impact on our helth though. The opposite is also true for positive thinking and laughter, it has been found to lower blood pressure and reduce the chance of heart attack and other serious health problems. Even petting a cat/dog has been found to be a benefit to our helth.
The best thing we can do is to try and not worry to much.
Our minds and body are connected and if we lay around all day thinking about health problems we are probably going to end up makeing ourselfs sick. I think this is what dp/dr is all about. I know that when I got dp/dr I was constintly worring about my health at the time. The constint worry and panic along with the drugs I was on made me lose touch with reality.
I think that the way back into reality is through positive thinking, laughter, caring for others and finding something to be a part of that is bigger than yourself. This is what I am currently working on anyway.
I don't think any of us should actually worry about heart attacks.
Worrying about something does not make the problem go away it will just tie up your mind and make you sick.