There are many contributing factors to heart disease, many of which you will be aware of: age, gender, smoking, cholesterol and blood pressure. However, these do not take into account all aspects of risk as evidenced by the fact that most heart attacks occur in the middle risk group as currently defined.
Your coronary calcification score is a far better way of assessing your risk of heart disease. Coronary calcification is a dynamic process which results from the rupture of coronary arteries following the build-up of a fatty gooey plaque. These small ruptures can happen several times without a heart attack occurring and result in calcification of the arteries.
Based on a paper published in the British Medical Journal which reviewed 840,000 heart attacks in the UK, 70% of all heart attacks were sudden with no previous knowledge of heart disease. Unfortunately, a similar study has not been done in Ireland but if you apply this study to the Irish population it would mean that over 3,500 heart attacks per year are caused by plaque rupture.