Change of heart

Early disease detection followed by aggressive management of risk factors - that is the basis of a new approach to managing coronary artery disease. TAN SU YEN reports

MOST of us have some inkling of the statistics. It really doesn't surprise us that coronary artery disease is the second biggest killer in Singapore after cancer or that in 2001, heart disease accounted for 26 per cent of deaths and stroke for 9 per cent.

What remains fuzzy is just how we can avoid that slippery slide towards heart disease or stroke. Is it enough to limit the pan-fried foie gras to the occasional three-hour lunch with your top clients?

Does your Sunday morning stroll in the Botanical Gardens count as exercise? But pondering the whys and wherefores of prevention begs the question of how to tell if we are at risk of coronary artery disease in the first place. The answer lies in early disease detection.

Says Dr Lim Tai Tian, consultant cardiologist & physician, MD Specialist Healthcare, a member of Pacific Healthcare: 'One of the new technologies that is in place that makes early detection of coronary artery disease feasible is the Multislice CT scan - a relatively good screening tool that allows us to pick up disease early and to pick up more diseases.'

So how does this wonder machine work? The Multislice CT is a high speed, new generation scanner that allows multiple images or 'slices' of a patient's body to be captured simultaneously. Useful as a screening tool for various cancers, it also measures calcifications in coronary arteries, an indicator of the imminent onset of coronary artery disease.

More importantly for those at risk of heart disease, the Multislice goes where the treadmill fears, or rather fails, to tread. Says Dr Lim: 'In the past when the traditional treadmill test came back with negative results and the patient had no complaints, even if he had risk factors, doctors were very likely to give the patient a clean bill of health. With the Multislice scan, we can actually pick up significant disease such as those requiring cardiac catheterisation, a stent or even bypass surgery. This is particularly helpful in patients who display no symptoms of the disease but who are at high risk nonetheless.'

Dr Lim adds: 'We also pick up mild disease through the Multislice scan and this allows us to move in at an early stage to manage the risk factors aggressively without resorting to surgery.'

All the same, Dr Lim is quick to point out that the Multislice is not for everyone. 'Do I send every patient for such a scan? The answer is no; it would be a waste of money and expose them unnecessarily to radiation. But if you are talking about a 50-year-old man with multiple cardiac risk factors, the answer is yes because you do pick up disease much earlier than with the traditional treadmill test.'

One important caveat to bear in mind is that the Multislice is not accurate all of the time. Says Dr Lim: 'It picks up disease with about 90 per cent accuracy and if disease is picked up, it achieves an accuracy rate of about 60-70 per cent. In other words if the scan shows that a patient has a blockage in his arteries, the scan is only accurate about the extent of the blockage 60-70 per cent of the time. The rest of the time the blockage may in fact be less or more than indicated.'

Notwithstanding the limitations, the Multislice scan is a useful diagnostic tool for patients with multiple risk factors for heart disease. And it is the usual list of suspects that puts people at risk of heart disease - high cholesterol, high blood pressure, diabetes, inactivity, obesity, smoking and a family history of coronary artery disease.

The most hopeful aspect of recent advances in the management of heart disease is that in many instances heart disease can be managed without resorting to surgery. Says Dr Lim: 'What people don't realise is that with mild coronary artery disease, that is, blockage of 50 per cent or less, by treating the risk factors like high blood pressure and high cholesterol aggressively we can reduce the risk of a heart attack, a stroke or the occurrence of a blockage by 50 to 60 per cent.'

Dr Lim also points out that clinical studies conducted in Europe indicate 80 per cent of patients with high blood pressure, high cholesterol and diabetes are treated sub-optimally. In other words, they don't reach the target levels of blood pressure control or of cholesterol control that would lower their risk of coronary artery disease. The new thinking in heart disease prevention is to set far more aggressive target levels for risk factor control. Says Dr Lim: 'We aim for a blood pressure level of less than 120/80. As for cholesterol levels, with patients that have known coronary artery disease, we aim for LDL or bad cholesterol level of less than 70ml/dl.'

The same no-nonsense approach applies to the patients who have diabetes. 'With diabetic patients, we aim for strict cholesterol control where we aim for a LDL of less than 100 mg/dl, strict blood pressure control where we aim for a blood pressure of less than 120/80mm Hg and strict blood sugar control, and we do this by checking a value called HbA1c, which measures the average blood sugar over the last three months. Strictly speaking, if through medication and diet we can achieve a HbA1c of less than 6.5 per cent, we are happy.' But how receptive are patients to this clean living regime of medication and lifestyle changes? 'If patients know they are at risk, most will be motivated to take their pills, lose weight and exercise three times a week especially if you explain the benefits of aggressive risk factor control to them. The one thing older people are most afraid of is stroke and if you can reduce the risk of heart disease and stroke by 50 to 60 per cent, then why not?'

HEALTH

Forewarned, forearmed

Reversing the damage from a stroke or an arterial blockage is an uphill battle. That's why it pays to look out for early warning signs, reports TAN SU YEN

STROKES don't just happen without warning. A numbness or weakness on one side of the body, slurred speech, vomiting or a headache - all these are possible warning signs of an imminent stroke. And even if these symptoms come and go, they could still indicate the onset of a stroke. Says Dr Adrian Tan, consultant neurologist & physician, MD Specialist Healthcare, a member of Pacific Healthcare: 'One of the early warning signs of a stroke is a transient weakness in the limbs. Your arm or leg may go numb for half an hour. Most people ignore this but it is a forewarning; several episodes of transient numbness may occur one to five days before the actual stroke.'

Similarly, Dr Tan points out that a headache in a patient with elevated levels of high blood pressure could indicate a bleed in the brain or a haemorrhagic stroke. A haemorrhagic stroke happens where a blood vessel in the brain ruptures. Thirty per cent of all strokes are haemorrhagic. The other more common type of stroke is an ischaemic stroke. Ischaemic strokes account for 70 per cent of all strokes and occur when a blood vessel in the brain is blocked.

Haemorrhagic strokes are usually more serious than ischaemic strokes, although both types of stroke can be fatal. As with other types of trauma, early intervention is paramount. Says Dr Tan: 'If a patient with an ischaemic stroke comes to us within three hours of the onset of symptoms, we can immediately administer tPA or tissue plasminogen activator intravenously and this can sometimes reverse the effects of a stroke dramatically.'

tPA is essentially a clot buster but it is not without its risks as it could cause a bleed in the brain in the process of breaking up the blood clot. If a patient is attended to more than three hours after a stroke, Dr Tan explains that the emphasis is on supportive care. 'We administer a blood thinner such as aspirin or clopidogrel, make sure oxygenation is adequate and control the blood pressure.'

With haemorrhagic strokes, surgical intervention may be necessary. Says Dr Tan: 'If the bleed is very large, sometimes surgeons may go in and evacuate the clot to take the pressure off the brain.' A misperception exists among stroke patients and their families that problems with the brain, like the heart, can be corrected through surgery. This is hardly the case, says Dr Tan: 'People think the brain is like the heart where you can put a stent in and open up the blood vessel. But it is not, not yet at least. The heart is a very tolerant organ but the brain is not. You fiddle around with the brain and you could get a worse stroke.'

What heart disease and stroke have in common are the risk factors like high cholesterol, high blood pressure and diabetes. These same risk factors also apply to peripheral arterial disease or PAD, explains Dr John Tan, consultant general and vascular surgeon, MD Specialist Healthcare. 'Peripheral arterial disease refers to blood vessel disease outside the heart or the brain; in particular those that occur in the legs, hands and abdomen.'

PAD can take the form of an arterial blockage, in which an artery is blocked by a blood clot or it could take the form of an aneurysm of the artery where a blood vessel is dilated and in danger of rupture. Says Dr (John) Tan: 'The most common manifestation of PAD is an arterial blockage and this blockage could be functional or critical. In its critical form, a severe blockage in the leg could lead to tissue loss as a result of insufficient blood supply. This is serious because when the tissue dies, the site becomes infected, ultimately leading to an amputation.'

A case in point, says Dr Tan, would be an old lady with diabetes whose toes turn black when the blood supply to the toes ceases and gangrene sets in. 'Commonly, patients who have insufficient blood supply will injure their toes or get blisters on their legs that don't heal. 'But even before these symptoms, patients with insufficient blood supply will have smooth, shiny skin that is very thin and hairless - the blood supply is insufficient to support hair growth,' he says.

On their part, PAD patients with a milder form of the disease suffer from symptoms only when they are active and not when they are at rest. Says Dr Tan: 'With this group of patients, the symptoms are less severe and only come on with exertion. For example, every time a patient walks a certain distance, say 300 metres, they feel a pain in their calf. They rest for two or three minutes and the pain goes away. This is a sure sign that a blockage is causing insufficient blood supply to the limbs.'

These easily recognised symptoms make a strong case for greater awareness of arterial disease among the public and early detection by GPs and family doctors. Says Dr Tan: 'It is important for doctors to pick up PAD as early as possible because arterial diseases don't happen in isolation. Very often, a patient with a blocked artery in his leg may have heart disease or be at high risk of stroke and heart disease. We need to identify these patients and start treating them for their general condition with blood thinning medication like Aspirin or Plavix.'

Early detection of PAD can be easily done in any outpatient setting. Dr Tan explains: 'The ankle brachial test compares the pressure in the arm with the pressure in the legs to detect a blockage. It is a simple, inexpensive test that will help us identify and treat arterial diseases and their related conditions early and effectively.'

Copyright © 2005 Singapore Press Holdings Ltd. All rights reserved.

Source: Business Times 15 September 2006