My sincere and heart felt condolences for the sad event in your family of sudden death. I appreciate your predicament and all the questions which you have raised very intelligently and logically.
Unfortunately sudden death is the commonest presentation of heart attack and blocked arteries of heart. One of the most advanced heart facility in the world is called the Seattle Heart Watch. One of the important findings of Seattle Heart Watch, which came as an eye opener to most of us as doctors also, was the first presentation of blocked arteries of the heart was sudden death in almost 40-50% of patients.
Sudden death was defined as death occurring within 2 hours of the onset of first symptom or death occurring before any medical attention could be sought. Therefore currently the research world over is directed at how to identify these patients who are prone to sudden death and lot of advances have been made in this field, yet we are far from finding a final answer. Blocked arteries may be missed on clinical symptoms in a very large percentage of cases and even on ECG. As high as 50-70% of patients with blocked arteries have a normal ECG. Even stress testing like stress bicycle TMT has a sensitivity and specificity of only 85%. Stress Dobutamine Echo of 92%, Stress Thallium of 95-96% but the only gold standard which can pick up blocked arteries definitively is coronary angiography.
Unfortunately coronary angiography is an invasive test and can not be done for all patients and therefore cannot be used as screening test. Recently CT based angiography has been launched but the technology is still under development and the learning curve is going to be there but I suspect over the next year or two, this modality of investigation may turn out to be more useful than the other ones. However, cost is an important factor, and is roughly Rs. 10,000/- for carrying out CT angiography.
Currently what we suggest is that every patient beyond the age of 35 years must have an executive health check performed once in 5 years. Beyond the age of 45, once in two years and beyond the age of 60 years - once every year. This executive health check up should include 2D Echocardiography, Treadmill testing, blood sugar testing and clinical examination by cardiologist besides routine testing like ECG & Chest X-ray. I am not saying that executive health check up will pick 100% of patients but certainly a large number of patients who have blockages and are prone to sudden death can be picked up by these tests. Here, I would also like to clarify that sudden death is not always due to blocked arteries, it may be due to irregular rhythm of the heart and due to certain other disease processes like prolapse mitral valve and hypertrophic obstructive cardiomyopathy. Also sudden death can be because of any event related to the brain (stroke) or any irregular rhythms of the heart because of electrical disturbances. Comments to your specific questions:
1) An apparently totally fit and fine person can also suffer from a heart attack and roughly 10% of patients undergoing bypass surgery at Sir Ganga Ram Hospital are in this age group of <40 years which is a very young age and fitness and age is no bar to heart attacks. This is most true for patients of Indian descent because we are genetically prone to develop diabetes, obesity and blocked arteries.
2) Well if the patient dies suddenly during his sleep, obviously he won't be able to call any one and seek any medical attention.
3) Most patients do not come to know of these problems and it comes absolutely as a bolt from the blue and that's the reason that I have stressed on the need for executive health checks
4) If the patient dies in sleep because of massive heart attack or because of sudden onset of electrical disturbances of the heart called VF cardiac arrest then it will be a sudden death and patient wouldn't even know about it nor will he have any feelings. However, if the patient lives for an hour or two after the first development of the symptom, he may get feeling of impending doom and all the attendant emotional consequences would be present. Let me tell you, maybe non-scientifically, that lots of patients are able to communicate to us that they are going and that they do get a premonition of death but I can't say that scientifically. This is my gut feeling which I have noticed from few of those patients who have forecast their death an hour or two before they actually die.