Doc, how to know if I already have ‘silent’ blockages in my coronary arteries?

This is a reasonable and commonly asked question, because some of us may have 'silent' coronary disease without any symptoms and if we know it, we can take steps to prevent future catastrophe.

Recently a 62-year-old gentleman died in his sleep without any symptoms. Could he have had silent coronary disease? If yes, how could it have been diagnosed while he was alive?

A recent research found that some degree of coronary artery disease is prevalent in almost 50% of people over the age of 45.

At present the commonest way to diagnose coronary artery disease accurately is with catheter angiography performed in the hospital. But performing angiography on every human without symptoms of heart disease is expensive, not harmless and inappropriate.

Another type of angiography which does not need hospitalization is CT angiography, which can be used to diagnose coronary artery disease. But it has the disadvantage of exposure to radiation and the possible adverse reaction to the intravenous liquid (contrast) injected. Hence, the test is currently only advised in people with symptoms of heart disease and is not recommended in people without any symptoms. However, in the near future when machines that emit less radiation become available, this test may become more widely used, especially since, as noted above, about 50% of people may have small or large blockages in the arteries of the heart.

One of the disadvantages of these tests in an asymptomatic person is that if an abnormality is detected, then it may lead to a procedure which may (with exceptions) be unnecessary. So that has to be guarded against.

A third way to detect heart disease is finding the coronary calcium score- a simple CT scan that measures how much calcium is in the arteries of the heart. This is useful for people over the age of 40 and those with high cholesterol, or those with risk factors, especially when it comes to decision making about taking drugs like statins. Calcium gets deposited in the arteries only when they are diseased. So arterial calcium is a sign of its disease.

A fourth way to detect heart disease is the treadmill stress test. In people without symptoms it has the disadvantage of being falsely positive (abnormal test result without disease) or falsely negative (normal test result despite underlying disease) in some people.

So, for people without symptoms the test is recommended in only for some, such as those over 40 or those with risk factors such as diabetes who have been sedentary until now and who now want to start regular and intensive exercise, or whose occupation involves responsibility of many people, such as airplane pilots, air traffic controllers, etc. People who are at intermediate risk due to presence of risk factors and those who have to undergo any surgery can also have this test done. One advantage of this test is that it can measure your work capacity (cardiovascular fitness) which is related to future heart attacks.

The fifth method is an electrocardiogram (ECG) and echocardiogram. These tests determine whether a person has had an attack in the past or not. Coronary blockages are not detected by these tests if there  are no active symptoms or thyere has been no heart attack (or damage to the heart) in the past.

The sixth method is to measure the blood pressure of the arms and legs. If the leg pressure is equal to or less than the arm pressure, it is a sign of leg artery disease which may be accompanied by coronary artery disease. If there is a difference of more than 20 in the left and right arm pressure, it is a sign of arterial disease in the arm and the possibility of coronary artery disease increases in such people.

The seventh method is to measure all the risk factors and determine the chance of having a heart attack in the next 10 years through some formulae called risk scores. Obviously this can only give an estimate, not absolute prediction. Risk scores such as ASCVD risk score or JBS3 risk score can be found on the net.

The eighth way is to do doppler test of one’s carotid (neck) and femoral (thigh) arteries to check for fatty deposits. People with fatty deposits in these arteries are more likely to have the same in coronary arteries too.  

So, to tell whether you have a blockage or an obstruction in the coronary artery or not, one has to select a test (or combination of tests) most appropriate to your condition and decide.

But your lifestyle is more important than knowing whether you have undiagnosed arterial disease or not. This is because despite having the disease, if the lifestyle is good, the future is good, and conversely,  if there is no disease, but the lifestyle is bad, the disease may still occur. Of course, if any abnormality is found in these tests, there is an opportunity and motivation to improve lifestyle and start preventive medication like statins and aspirin under medical guidance.

-          Dr Akshay Mehta