There’s no evidence that CT angio prevents sudden heart attacks and deaths in those without symptoms

That happens when a person has a heart attack, or their heart stops, or it undergoes a rhythm disturbance. The person could be an athlete exercising or someone with a family history of heart attacks or a heavy smoker. In these cases, the warning signs are already there, so a CT scan is not needed. One needs to be more concerned when there are no warning signs.

What are the known causes of sudden death?

The commonest cause of sudden death is a heart attack. For some patients the first presentation of a heart attack could be death, but for many who survive a heart attack, death could come much later because of a weakened heart. The heart is involved in more than 80 per cent of the causes of sudden death. Other causes could involve major brain strokes or other injuries of the brain or other parts of the body.

There are other familial causes of sudden death like certain familial heart diseases (extreme thickening of the heart muscle called hypertrophic cardiomyopathy), certain familial rhythm disturbances of the heart (called Long QT syndrome) or where the heart muscle becomes weak (dilated cardiomyopathies).

What are the symptoms of a sudden cardiac arrest?

The final manifestation of a cardiac arrest, i.e. when the heart has stopped, will be that the person collapses and there is no pulse, no heartbeat, and the person stops breathing. It is necessary to pick up the warning symptoms which come before this: severe chest pain, sweating, a racing heart, giddiness or palpitations. These symptoms, if detected and treated early, can often prevent a major catastrophe. An example from last week: A senior retired AIIMS doctor, who had undergone a cardiac surgery in the past, called at night to tell us that he was feeling uneasy and experiencing very unusual fluttering in the chest. He had taken a “nitrate pill” under the tongue but did not feel any better. We asked him to come to our ICU. The ECG showed the rhythm was abnormal and beating at 250 beats per minute (the normal is 70 beats per minute). He was given an electric shock and the rhythm returned to normal. The next day, a small device called an “implantable cardioverter defibrillator” was placed into the heart to monitor and treat this abnormal rhythm.

How can we prevent sudden death?

In the case of known diseases like the above, where the risk of death is high, specific medications or implantation of the device mentioned above can prevent death. The commonest cause of sudden death is a heart attack, therefore the focus has to be on preventing it. That requires keeping your BP, LDL, cholesterol and triglyceride levels in check. Keep your weight down and avoid smoking and alcohol. Those with diabetes or a family history of heart attacks are more at risk. If you have the above risk factors, you need to consult your doctor to take preventive measures with lifestyle changes and probably a cholesterol-lowering drug.

Finally, will a CT scan prevent death? What to do if a CT scan is positive? Is a CT calcium score good enough? What is the negative side of a CT scan? When should you use a CT scan?

There are two types of CT scan used. One is a simple CT calcium score: this is a very fast CT, limited radiation and gives an idea of the calcium in the area of the heart. This is currently recommended as an additional test when you want to be very sure that the risk of a heart attack is low. It does not require any contrast. So if you are above the age of 40, after checking your other risk factors and numbers, you can ask your doctor for a CT calcium score. If it is zero, you can be rest assured.

On the other hand, a CT angiogram requires contrast, carries risk of iodine allergy and cannot be done in patients with abnormal kidney function. There is no evidence that it helps prevent death in people who have no symptoms at all. So if you have no symptoms, it would be more useful to control your risk by reducing blood pressure, sugar, cholesterol, weight, and avoid smoking and alcohol rather than going for a CT angio. If you do have symptoms, then there may be a role for a CT angio — but that decision will have to be taken for you by your doctor.