I had a heart attack just after my 39th birthday, then another 15 months later (most likely due to the fact that the stent was bare metal and there was scarring). I've been a slender, non-smoking, non drinking, vegetarian with low blood pressure and cholesterol.
The culprit my doctors and I found was inflammation- due to stress and eating sugar, breads & pastas and processed foods. Basically eliminating those foods, taking fish oil and magnesium daily and increasing meditation and exercise have been my answers to being happy and healthier than ever 4 years later. (Also, I've gotten off all my meds and now take Hawthorne on the rare occasion I feel an arrhythmia. Don't try this on your own.)
Also, if you're taking statin drugs, be sure to take Co-Q10 as the statins deplete it!