The absence of chest pain doesn’t mean there’s no underlying heart problem. About one-third of heart attacks are silent

BOTH men had silent heart artery disease but only one escaped the clutches of death. Mr A , head of a public-listed company, was in his 60s, was careful with his diet and exercised regularly. His doctors had not mentioned the presence of heart artery disease and hence, he never had a scan of his heart arteries.

On that fateful day, he had just finished his daily routine but somehow felt more tired than usual. He went to bed and never woke up. The autopsy confirmed significant heart artery disease as the cause of his sudden death.

A different fate

Mr B was in his late 40s and had undergone a treadmill test the previous year which was reported as normal. He had no chest pain but his bad cholesterol level was highly elevated. His doctor had advised him to do vigorous exercise in the mistaken notion that exercise will burn off the bad cholesterol. The reality is that research studies have shown that vigorous exercise not only does not lower bad cholesterol but can also increase the likelihood of sudden death in those at risk.

His family advised him to seek further evaluation as he was in the high risk category. An outpatient scan of the heart arteries, which was completed in a few seconds, confirmed the presence of extensive and severe narrowing of his major heart arteries.

This week, Mr B underwent opening of his heart arteries through a small 2mm access site in his leg artery under local anaesthesia. New generation absorbable cylindrical polymer meshes were expanded by tubings with balloons and placed in the narrowed segments of the heart arteries to fully open the arterial lumen. By the next day, Mr B was given a new lease of life and was ready to go back to his usual routine without fear of sudden death from heart disease. In three years’ time, the polymer meshes in his heart arteries will be absorbed by the body and his heart arteries will have been restored to their natural state.

No chest pain

Most people make the assumption that if they do not have chest pain, even while exercising, they do not have any underlying heart problems. However, the National Heart Lung and Blood Institute, USA, states that about one-third of heart attacks are silent.

These silent heart attacks tend to affect the old, elderly and the diabetic.

As in the case of Mr A and Mr B, men can have severe underlying heart disease without the presence of any symptoms. While left-sided chest discomfort is the most typical symptom, it can also present as upper body discomfort involving one or both arms, the back, shoulders, neck, jaw, or upper part of the abdomen.

Sometimes, the only symptom is shortness of breath. Other less common symptoms of a heart attack include cold sweats, a sensation of being unusually fatigued without any obvious reason, nausea and vomiting or sudden dizzy spells.

Therefore, while chest discomfort is the most commonly recognised symptom, the presence of these other less common symptoms in high-risk individuals should alert one to the possibility of an impending heart attack or underlying heart disease.

False confidence

Treadmill stress testing has been used for decades to assess the presence of underlying blockage of the heart arteries. One should be aware that a normal treadmill stress test result does not mean that there is no severe narrowing of a major heart artery.

The worst thing that can happen is when an individual with severely diseased heart arteries who has had a normal treadmill test result, believes that he has no underlying heart disease and embarks on vigorous physical exercise.

In a publication in Circulation journal in 1980 by Silverberg, treadmill testing in patients with significant heart artery disease showed a sensitivity of 59 per cent and a specificity of 69 per cent. What this means is that if a hundred individuals with severe heart artery disease were to undergo treadmill stress testing, 41 per cent will have a normal treadmill stress test result.

It also means that in that published study, among those without underlying heart artery disease, 69 per cent were correctly identified as having no underlying heart disease and 31 per cent had an abnormal treadmill stress test result despite being healthy.

Choice between life and death

If you have symptoms suggestive of heart disease or you have multiple risk factors for heart disease, even if the treadmill stress test result is normal, advice should be sought from your doctor as to whether you will benefit from more accurate assessment. Non-invasive tests for heart artery disease can be divided into two broad categories.

The first category of tests assesses the adequacy of blood flow to the heart muscle when the heart is put under stress.

The underlying rationale is that if there is severe narrowing of the heart artery, the blood flow may not be sufficient to meet the increased demand when the heart is stressed and this will be manifested as reduced heart muscle function on ultrasound (stress echocardiography) or decreased distribution of radioactive isotopes in the areas of heart muscle with decreased blood flow (myocardial nuclear perfusion scan or PET scan).

The main drawback of these tests is that by attempting to assess the blood flow, they are an indirect means of assessing heart artery disease and do not provide any direct images on the status of the heart arteries. Hence, the tests can be normal even if there is complete occlusion of a major heart artery as long as there is adequate cross supply from other arteries in the heart.

The second category of tests allows direct visualisation of the heart arteries and the tests available currently include Computed Tomography (CT) scan of the heart arteries or Magnetic Resonance Imaging (MRI) of the heart arteries.

CT scan of the heart arteries can be completed in seconds and involves the use of special X-ray machines and the injection of iodine-based contrast media. The radiation dose and the accuracy varies from centre to centre.

In a USA study on 50 hospitals using similar 64-slice CT scanners to scan the heart arteries, the radiation dose in the hospital with the highest radiation dose was six times higher than the hospital with the lowest radiation dose.

In a highly experienced centre, CT scan of the heart arteries can be both accurate and safe. MRI scan of the heart arteries is a relatively newer modality and can be performed without any X-ray radiation or any contrast injection. The major limitations of this technique are that it is not widely available and may not be suitable for some patients who have metal implants.

Understanding the options available may help patients make an informed choice. For patients who are at high risk of heart disease, knowing whether their heart arteries are severely blocked or not can make a big difference between life or death.