Heart disease almost always seems to come unannounced and mass media projections tend to reiterate this. Despite the fact that medical technology has evolved considerably, the onset of heart disease continues to be unexpected and dramatic.

With the prevention and detection approach gaining ground, new diagnostic techniques make it possible to discover even the minor plaques setting base in your blood vessels. One of the key tests for this is called the Cardiac CT calcium score (CAC score). This is a noninvasive CT scan that measures the amount of calcium deposited in the calcified plaques in the coronary arteries and calculates a score. Higher the score, the higher the risk of future cardiac events and stroke. A coronary calcium scan is an extremely useful assessment tool for those who are uncertain about their heart disease risk.

Here's how to interpret it

1. CAC Score 0: No detectable calcified plaque in the coronary arteries. However, it does not rule out the presence of soft (non-calcified) plaques or the risk of future cardiac events, especially in younger individuals

2. CAC Score 1-100: Mild calcification and a low to moderate risk of coronary artery disease. Such a person must make lifestyle modifications.

3. CAC Score 101-300: Moderate calcification and a moderate to high risk of coronary artery disease. The doctor will recommend preventive medications.

4. CAC Score above 300: Extensive calcification and a high risk of coronary artery disease, equal to those with prior cardiac events. Intensive medical therapy, lifestyle modifications, and close monitoring are essential for individuals in this range.

The real advantage is that a CAC score can detect blockages even as low as 20-30% which is not detectable via ECG or stress tests. It is when the 30% blockages get missed that the threat of rupture during a marathon is elevated. However, the CAC scores must be interpreted in combination with other risk factors, such as family history, diabetes, hypertension, smoking, alcoholism, hypercholesterolemia etc.

Dr Santosh Kumar Dora, Sr. Cardiologist, Asian Heart Institute and Medical Director to the Tata Mumbai Marathon weighs in on medical fitness for marathoners