How can it happen that a reasonably fit man can have a full executive medical test, pass with flying colours and a few weeks later drop dead from a heart attack?
The reason is simple. The blockages in the arteries that cause heart attacks in seven out of 10 people are so slight that they are not picked up by the test.
It is not the test’s fault; it is just that there is no technology sophisticated enough to detect when an artery is less than 50 per cent blocked. The smaller the blockage is, the fewer symptoms it produces and the harder it is to find. But there is no comfort to be drawn from having only a slightly blocked artery, because regardless of size, it is just as likely as a major blockage to rupture and cause a heart attack.
During a rupture, the inner lining of an artery opens and exposes plaque to the passing blood. This exposure stimulates a chemical cascade that leads to clot formation, which may then lead to a heart attack.
A coronary artery that is 80 or 90 per cent blocked is relatively easy to pick up. It is more difficult to detect blockages of 70 per cent: an executive medical test will pick up just over half of these. Symptoms are rare if the artery is less than 70 per cent blocked, while if the artery is less than 50 per cent blocked, not even a coronary angiogram will be reliable.
Nevertheless, new research has thrown up an unexpected benefit of lowering cholesterol. It used to be thought that the chief advantage in lowering cholesterol was that it reduced the build-up of fat in the artery walls. Now it has been shown that it also helps to stabilise plaque on artery walls and stop it rupturing, which in turn reduces the likelihood of heart attacks.
Many people who go through executive medicals do not understand that cardiovascular fitness and an ability to perform strenuous exercise are not enough in themselves to prevent a heart attack. Mere fitness does not exclude all the other risk factors for heart disease. A man may be fit but still have minor disease in his arteries sufficient to cause a rupture.
Exercise can be a difficult issue. Being sedentary is a risk factor, so we are encouraged to exercise. But at the time of exercising, a person with disease in their arteries is at increased risk of heart problems. During an executive medical, information is gained about how the heart functions under stress. In some asymptomatic cases, it will usefully detect significant disease; in some, it will miss it.
However, it is recommended that anyone over the age of 35 who is about to undertake a new exercise program should have this medical first. Even if they pass their medicals with flying colours, men should remain vigilant about risk factors (smoking, diet, exercise). Any chest-related pain should be taken directly to hospital.
The problem with heart disease is that it has a long preclinical phase and can take years to declare itself. In 50 per cent of cases, the first manifestation of coronary disease is a significant heart attack. In 25 per cent it is angina. In the final 25 per cent it is sudden death.
Even more worrying is that it is possible to have a heart attack and not know about it. It is estimated that a quarter of all heart attacks that occur are silent and slip by unnoticed. During investigations, it is not uncommon to find medical evidence of old heart attacks in men who have no known history of them.
When questioned they sometimes recall a period of serious indigestion or other pain that wouldn’t go away. Because they didn’t recognise the pain as originating from the heart, they didn’t take any action.
Heart pain is often referred and can be felt down the arm, in the shoulder, in the neck and particularly often in the jaw. There are reports of people who have had total dental clearances for assumed dental disease before the source of their agony was identified as referred heart pain.
The danger of failing to recognise a heart attack is that nothing will be done to limit damage. During an attack, the flow of blood to a section of heart muscle suddenly stops. Without blood, that section of the heart begins to die. Half the section concerned will die in the first 2 hours and the remaining half in the next 4 to 6 hours.
If obtained quickly, medical intervention can save muscle and, in some cases, reverse damage. After a heart attack, prognosis is directly related to the size of the damage. At present, available technology for measuring this muscle damage is not precise. But a test developed in the USA promises to be more accurate. It uses high-resolution imagery to measure the concentrations of a molecule, creatine, in the heart muscle. Drops in this molecule indicate damage.
This test is potentially a significant advance. It can make a difference to the kind of treatment that follows.
*113\105\2*
