I thought your article was good overall. Thanks for taking the time to write it.
One thing I did take issue with was your concluding paragraph:
"Your responsibility lies in knowing what your risk factors are and being aware of symptoms that must be checked out. Know your blood pressure, cholesterol levels, and family history of heart disease, and take measures to keep these under control. Be aware of lightheadedness, dizziness, nausea, fainting episodes, sudden fatigue, and, of course, chest pain during any exertion, especially swimming. Get into your physician to get these symptoms and risk factors evaluated."
As far as blood pressure and cholesterol, these, as you pointed out, help you know if you are at risk for heart attack. They are not risk factors, necessarily, for sudden cardiac arrest (SCA).
Family history is considered to be a risk factor for both SCA and heart attack. An obvious risk factor for SCA is having an episode of SCA previously...which, thanks, but it would be helpful to know before the fact. Additionally, a person who has experienced SCA may not have detectable rhythmic or morphological abnormalities of the heart.
Regarding symptoms of heart attack during exercise, I think most people are aware that men's symptoms of heart attacks may differ from women's. Obviously not everyone will experience the same symptoms.
With SCA, there may not be warning signs before arrest occurs. If the heart stops (or goes into an arrhythmia) during exercise, blood pressure rapidly drops and the person passes out. The heart continues to beat erratically unless a corrective shock is delivered from a portable device.