Heart Attacks can Kill

by Kee Tuan Chye, New Straits Times

HEART attacks can kill, we all know that. And most heart attacks trace their origins to the build-up of plaque in our arteries, a process called  atherosclerosis. The conventional wisdom is that when an artery gets  severely blocked, it can lead to a heart attack.

But recent findings have revealed that even a  less than 50 per cent blockage can be equally lethal. Studies show that more than two-thirds of heart attacks occur with less than 50 per cent lesions. It all depends on the nature of the plaque – stable or unstable.

The young lipid rich plaque that has not been around long enough to be stabilized by the body’s repair mechanisms is more prone to be unstable.  It typically has a thin fibrous cap that can tear, ulcerate or rupture. When this happens, thrombosis occurs, leading to a heart attack.

This revelation is not all that cheering. It means that people who have never had any indication of heart disease -- because a lesion of 50 per cent or less may not produce symptoms -- are as much targets of heart attacks as those who have been diagnosed to be suffering from severe atherosclerosis. In fact, the cases of ostensibly healthy people dropping dead after a game of badminton or squash are manifestations of this seeming paradox.

So, what can we do to avoid being among those suddenly surprised by the silent killer? We could have a screening test done to determine if we already carry in our arteries the beginnings of heart disease. 

One of the tests available now that is quick and painless is Coronary Artery Scanning (CAS) via Electron Beam Computed Tomography (EBCT). It sounds a mouthful but the process itself is quite simple. You lie on a bed and hold your breath a couple of times to allow the radiologist to take pictures of your heart using the Ultrafast CT scanner. The process is over in less than 10 minutes. After the information has been processed, the doctor interprets for you the results as he shows you the data on the computer. 

What the CAS essentially does is measure your "calcium score". This will indicate the extent of plaque build-up in your arteries and help predict the level of risk you’re at of experiencing a heart attack. The higher your calcium score, the greater your risk. It may be that you will register a score of zero, which would be very good news indeed, but if the scan shows a positive score, it indicates that you already have at least some coronary artery disease. This would alert you to the fact and prompt you to take the necessary measures to counter it.  These measures could include modifying your lifestyle, reducing your cholesterol level, embarking on regular exercise, controlling your blood pressure, throwing away the pack of cigarettes you last bought. It is now believed that with treatment, there is a good chance of reversing the process of plaque build-up. If you don’t treat it, the amount of plaque will double every 2.5 years. 

The CAS is however only 95 per cent accurate. And the presence of calcium doesn’t automatically mean your arteries are blocked. If you require a more comprehensive profile of your heart and arteries, the next-step test is the Electron Beam Angiography (EBA). This takes about half an hour to perform, and a dye is injected through a vein in your arm to help the scanner accomplish a 3-D imaging of your heart while you hold your breath for 60 seconds. From this, the doctor can pinpoint exactly where any artery blockage or narrowing has occurred. 

In Kuala Lumpur, the place to go for CAS and EBA is Mahameru International Medical Center Sdn Bhd, housed in one of the converted bungalows along Jalan Maarof in Bangsar. Its the only place that is equipped with the Ultrafast CT scanner and specialises in EBCT procedures.In fact, HeartScan has been conducting EBCT scans for three-and-a-half years but, according to its cardiologist, the  technique is still "the country’s best-kept secret".  Bound by professional ethics, the centre is not able to promote its services through the mass media, which explains why EBCT remains relatively unknown. In the United States, clinical use of CAS was approved by the Food and Drug Administration (FDA) in 1987 and the EBA only in November last year. And although the American Heart Association cited EBCT as one of the top 10 research advances in heart disease and stroke for 1999, it is still awaiting further data before recommending widespread EBCT scanning.

 "The EBA is a new and very advanced technique, so there hasn’t been enough comparative literature on it yet," admits Jack Marquess, Vice-President of Sales at Imatron, the manufacturer of Electron Beam Tomography (EBCT) scanners. "But its a hotly-debated and thought-about topic, and its changing the way a cardiologist treats heart disease because its a very useful tool for early detection and prevention. "

People who come for scans are usually not sick people but those who want to know the condition of their heart or monitor its progress. "If you’ve undergone angioplasty or bypass surgery, you’d also find this a good way to check how you are doing a few years after. Its safe and non-invasive, and its cheaper than doing an angiogram, which requires the insertion of a catheter into your arteries, a procedure that comes with a very small but measurable risk." 

Jack Marquess reckons that if everyone underwent an EBCT at around the age of 45, "we would be able to prevent premature  death due to heart disease", which is now the number one killer.  "I' m interested in promoting the concept of prevention," he says. "We have to change people's thinking and give them the new information. Some people think, for instance, that  heart disease is irreversible and always fatal, but this is not true.  When you find out you are beginning to have heart disease, you can actually do something to counter it."  Jack cites the existence of a wide diagnostic gap for the identification of patients who are at high risk of dying from  heart disease.  

Despite all the tests at our disposal today --treadmill test, stress thalium, stress echocardiogram -- we are not able to diagnose more than half the number of people who eventually get a heart attack. Statistics in the U.S. show that 58 per cent of people in the age group of 45-64 who die from various  causes were discovered at autopsy to have heart disease. Only 10 per cent were identified to have had it before they died. The reason for this diagnostic gap is that the tests we have been using depend on the presence of severe artery blockage to detect heart disease, but the new wisdom tells us that less than 50 per cent of narrowing in arteries has been causing heart attacks.

 "We’ve been looking for and treating the severe lesions when in fact, the greater than 90 per cent lesions have been responsible for a lesser number of heart attacks compared to the so-called insignificant lesions. This is because the severe lesions  are usually heavily calcified and stable  and less likely to rupture," says Jack Marquess.   

"A treadmill test is only 70 per cent accurate. It can miss those who are going to get a heart attack because their disease is not advanced enough to be detected. Its accuracy is even lower in women."

What we need now is a paradigm shift – from interventional cardiology, that is, waiting for something to happen, like chest pains and heart attacks, to preventive cardiology, that is, detecting and treating before severity sets in. "And that is where ECBT has a role to play."