Actually I did have risk factors, but the cardiologist was surprised to find that I had blockage at age 41 and being female with the risk factors that I had. I did have a family history with my father being 59 when he had a heart attack. Also my cholesterol was normal but my trigs were slightly elevated and my HDL was low. I didn't have some of the more common risk factors such as smoking, diabetes, or high blood pressure. I have a theory of my own that eating too many carbs and not enough protein contributed in some way.
Although doctors would probably disagree I think I was having symptoms for years but they were so subtle that I ignored them. I would have occasional shortness of breath for about 2 years before the blockage was found. I also had alot of upper back and shoulder discomfort. Twice I had a quick cutting pain in the upper left side of my chest. I remember joking that I hope that's not my heart. Finally one day while cleaning my beauty salon I had pain between the shoulder blades which moved to the center of my chest and down my left arm and I felt like I could hardly breathe. I just knew it was my heart and I called 911 for myself after calling my husband to tell him that I thought I was having a heart attack. The night before all of this I had taken ibuprofen for pain in my left shoulder and about a week before I would get short of breath walking across the parking lot to go to work. I thought it was probably allergy related.
The advice I give comes from personal experience and what I've learned from others since being diagnosed with heart disease.