First, we have to be clear about what we are discussing. There are many different forms of heart disease including valve abnormalities, high blood pressure, abnormalities of the heart muscle (so called cardiomyopathy) and electrical abnormalities of the heart.

For the most part, we are concerned with coronary artery disease and its prevention. Today, we are faced with a vast array of tests that can be undertaken including so called “low dose” CT coronary imaging that is discussed in another section.

Every patient is different so there is no simple formula!! In general, we need to know whether you are high risk, low risk or in between for what is called a coronary event (such as heart attack, sudden death, chest pain). This would depend on many factors including your genes, sex, whether you are a smoker, have diabetes, high blood pressure, your blood lipids and of course your life-style etc. Here, it is important to point out that simply having a relatively high cholesterol level does not mean that you are at high risk for a coronary event. There are many individuals, often women, who have high cholesterol levels and in fact live to a ripe old age! On the other hand, you could be young, smoke with diabetes and despite having a “normal” cholesterol level, your risk of having a cardiac event including a heart attack may be high.

The treadmill stress test is commonly used as a screening test for coronary artery disease and is often incorporated into many screening “packages”. It is important to understand what this test does and more importantly its limitations. It is designed to detect significantly blocked coronary arteries but the sensitivity is only about 68%. What this means is that if we have 100 individuals with significant blockages in their coronary arteries, we can detect at best only about 2/3. The other 1/3, the test may be normal (a false negative test). Furthermore, the treadmill stress test is not able to detect disease in small vessels, or branches and more importantly, it is unable to detect early coronary disease where the diameter of the narrowed artery has not been compromised. CT coronary imaging is now being used to address this important issue of early detection but as I will address in another section, it has its own set of limitations and problems including the small but not insignificant amount of radiation that one would receive.

In general, a “normal” stress test indicates a lowish probabily of severe blocked arteries and a favourable outlook. Here, I would then raise the issue of what I call… “ how much uncertainty can you live with?”….. and whether one should proceed to CT imaging. If someone has no risk factors and say both parents lived to their eighties and nineties, I would in all likelihood suggest that we should stop after the treadmill stress test. Most patients I think would probably come to the same conclusion. On the other hand, if someone has a strong family history of coronary disease or have several risk factors, I think it is not unreasonable to consider CT coronary imaging despite a normal treadmill stress test. In between these extremes, the “wisdom” and implications of CT coronary imaging including the real risk of opening up Pandora’s box leading to a coronary arteriogram should be discussed.

I should also add that if you are a smoker and your treadmill stress test is normal, it does not mean that you are immune to a heart attack from a blood clot in your coronary arteries and that you can continue to smoke. Rather than having repeated treadmill stress tests or CT scans to allay your anxieties, its smarter to quit smoking altogether !!

Again, this cannot be answered with a simple yes or no!! I am assuming that the patient has no symptoms and simply wants a "check-up". If someone has symptoms suggestive of coronary disease like angina or heart failure or has an unequivocally abnormal treadmill stress test, then it may be more appropriate to proceed to a definitive "road map" of the coronary arteries with invasive coronary arteriography rather than CT imaging.

CT coronary imaging is now being incorporated into many "platinum" screening programs which in my view may not be entirely appropriate. Patients are often not informed about the small absolute or relative amount of radiation that they would receive and the real possibility of precipitating a cascade of further testing including invasive coronary arteriography and even the implantation of a coronary stent.

Certainly, with current “low dose” coronary imaging, we can now visualize the coronary arteries well including the enticing prospect (as yet unproven) of so called “plaque vulnerability” ie whether certain plaques can rupture and cause a heart attack. The average amount of radiation for one of these scans is estimated at approximately 1-2 millisievert (mSv) which is equivalent to approximately 50-100 single view chest xrays. (The radiation dose for a standard single view chest x-ray is approximately 0.02 mSv. 1-2 divided by 0.02 comes to approximately 50-100 single view chest rays). It is hoped that with the newer generation of machines, the amount of radiation exposure may even be lower. This is a marked improvement compared to machines several years ago when the radiation exposure was almost 6-8 times greater.

The information obtained by CT coronary imaging is extremely valuable but it has to be interpreted with great caution. In many instances, it is invaluable to discuss the images with an experienced radiologist because artifacts can occur.

What are some of the possible scenarios after a CT coronary scan? One is that we pick up a very dangerous and life-threatening blockage affecting the proximal coronary arteries necessitating open heart bypass surgery and we save a person's life. In my experience, this is quite rare in someone who has no symptoms and whose screening treadmill stress test is absolutely normal. At the other extreme, we have a scan which shows no calcification of the coronary arteries and pristine arteries. This of course would be the happiest outcome. This is not uncommon even in older postmenopausal women.

The more likely scenario particularly if we screen older individuals is that there will be, not unexpectedly, some calcification or hardening of the arteries and various narrowings. Some reports would even include visual estimates like 50%, 65%, 75% or even up to 90%. These numbers should be viewed with considerable skepticism because the images on CT imaging are not precise (unlike coronary arteriography) and such eye-ball or visual estimates are inaccurate. Patients are invariably terrified when they see such numbers thinking that with a 90% narrowing, they would perish if it becomes 100%. In some patients often diabetics, there is heavy calcification and here it is almost impossible to estimate how narrowed the artery is. Often the report will say that there is heavy calcification and that the narrowing cannot be quantified and invasive angiography is recommended! So one test leads to another test…. this is a scenario that has to be discussed with certain older patients if CT coronary imaging is undertaken…. the opening of Pandora's box!!

MRI Imaging of the coronary arteries is currently being promoted in several private imaging centres. MRI does not involve radiation and this is its major selling point. MRI of the entire body is now being incorporated in some screening programs. MRI imaging for relatively immobile structures like the brain, spinal cord and the arteries of the head and neck is well established. With moving structures like the coronary arteries, the images were relatively poor in the past. With improved technology, we can now certainly see the coronary arteries. The problem is that artifacts are not uncommon and at this time, the images are not as precise as that with CT imaging. Hopefully in the future, we can visualize the coronary arteries with greater accuracy.

Here I am assuming that there is a good reason for you to undergo an invasive coronary angiogram. If a patient is experiencing what is called an acute coronary syndrome or an acute heart attack, an urgent or semi-urgent invasive coronary angiogram with the possibility of immediate stent implantation is quite appropriate today. However, if you have chronic stable coronary disease with mild symptoms or even no symptoms, this approach may be questionable.

Let us be clear at the outset why a coronary angiogram either obtained invasively via a needle puncture or CT coronary imaging is undertaken. This is a question that I myself would pose if I were to undergo the procedure. The primary reason is to ensure that we are not dealing with what I call severe proximal coronary disease involving the major trunks that would be “life-threatening”. In most instances, when we deal with such serious disease, a coronary bypass operation is usually recommended.

With the widespread use of CT coronary imaging today, many well patients with no symptoms (and even normal treadmill stress tests) are diagnosed with incidental coronary disease. In some instances, coronary stenting is conducted immediately after the diagnostic angiogram. This sounds very enticing, cost-effective since the patient feels that he has a “two for one” deal and that he has a problem “fixed” at one sitting obviating the need for another procedure later.

There are instances where such an approach is reasonable and I myself have on many occasions undertaken such an “ad hoc” approach. In general, these are patients who have symptoms or some objective evidence of shortage of blood flow in the heart that clinically necessitates an intervention.

So the question of coronary stenting immediately after the diagnostic angiogram in stable coronary disease is in my view of secondary importance and should ideally be discussed in a balanced incentive-neutral environment. To ask a patient whether he wants his artery stented while he is lying flat on a table with a tube in either his groin or wrist cannot be considered “balanced”. Coronary stenting is not a cure and certainly it does not “clear” anything. In fact, when applied prematurely, it may harm you. There are many patients with complex anatomies where a discussion on informed choices and alternative therapies including elective surgery or just taking medications and changing your life-style should ideally be provided.

I am assuming that a road map of the coronary arteries has already been performed either by CT imaging or by invasive coronary arteriography (cardiac catheterization) and that various "blockages" have been uncovered.

The first question that I suggest one should ask is whether there is a need to undergo either of these revascularization procedures at all!! Just because there is a narrowing in a coronary artery does not mean that we have to "fix" it with either a coronary stent or a bypass operation.

In general, a coronary bypass operation is more suited for older sicker patients with severe blockages affecting several arteries, some of which may be totally occluded and therefore not amenable for angioplasty or stenting. On the other end of the spectrum, coronary stenting is the treatment of choice in patients who have more focal or discrete disease. With improvements in stent technology, more complex disease that would in the past have been treated with surgery can now be stented. In general, the trials comparing surgery versus stenting in patients where both approaches are feasible, have yielded quite consistent results. Surgery offers more long lasting benefits but of course the initial trauma is greater. In diabetics with multiple blockages, bypass surgery has now been shown in many trials to be more effective compared to multiple stenting in preventing heart attacks and living a little longer but there is a slightly higher risk of strokes during the first month after the surgery.

Stenting also benefits patients with comparable survival rates but the downside is that, due to scarring in the stent and recurrence of disease, patients may have to undergo more procedures as the years go by including the possibility of surgery. With certain drug-eluting stents, two blood thinning medications have to be taken for at least a year or in some cases indefinitely. Once a stent is inserted into a coronary artery, it cannot be removed. So, the danger of chronic anxiety after stenting is a real possibility and many patients undergo repeated testing with either CT angiogram or invasive angiogram because every year when they see the doctor, they will invariably ask " How is my stent doing ?".

So there are no quick fixes or easy answers to this question. Each patient's anatomy, medical conditions and I should add his/her wishes and expectations are different. Of course there are diverse opinions and rightly so. Surgeons not unexpectedly would want to operate and those of us that do these interventional procedures would present the bright side of the picture. A period of deliberation and reflection on these matters might be in your best interest.

The statins (Simvastatin, Atorvastatin and Rosuvatstatin) have revolutionalized the treatment of coronary artery disease over the last 30 years. In general, if you are at a higher risk, the benefits of long term treatment outweigh the potential side effects. Thus, if you have proven coronary artery disease (e.g. previous heart attack, bypass operation or stenting), lowering your "bad" or LDL-cholesterol level with a statin is quite appropriate. Even if you have no symptoms and your so called "absolute" risk is high e.g. family history, multiple risk factors including diabetes or you have been shown to have occult coronary disease with e.g. CT imaging, then you should also probably be taking these medications.

What is more controversial is whether so called "well" patients should be taking these drugs for the rest of their lives. This is now rampant because of widespread "screening" programs. There are diverse opinions on this issue and I am in sympathy with patients who are befuddled on this subject. As a doctor, I must confess that it is much easier for me not to agonize and to start treatment. Since we are allowed to dispense in our part of the world, there are economic benefits to us doctors. Patients also feel a sense of relief to see their cholesterol levels drop!! But if I was a patient and am faced with taking a medication for the rest of my life, I would certainly agonize.

We deal with probabilities and not certainties. While taking a statin may reduce your statistical risk for say getting a heart attack, you need to know that even with a lower cholesterol number, you can still have a heart attack i.e. there is no total or 100% protection in modern medicine!! Furthermore, you may be one of the many patients who is being treated unnecessarily. There are many patients who have high cholesterol levels who live to a ripe old age. Today, we have a number of specific tests that may help us decide whether to treat or not. CT imaging has been discussed but do you really want to be irradiated to decide whether you should change your life-style? In certain situations, I have used carotid ultrasonography to see if there is thickening and plaquing of the carotid arteries. If there is, one can probably assume that there is also plaquing in the coronary arteries and drug treatment is probably indicated.

Unfortunately, there are no free lunches!! Long term statin treatment can lead to a variety of side effects some of which are often quite subtle and often dismissed as "ageing" or "old age" like memory loss or intellectual impairement. So one must be constantly vigilant if one is to take these pills for the rest of one's life.

Here I should add a somewhat philosophic note about the limits of medicine and the mismatch with patients' expectations. A recent study from the Cleveland Clinic using coronary ultrasonography demonstrated that even with very low levels of cholesterol, approximately 1/3 of patients demonstrate continued progression of their disease. So, the search is on for new molecules to see if we can halt the disease process and there are a number of exciting new compounds being tested. Unfortunately, in medicine, we often find a new molecule that reduces some marker of disease but when we test it out in trials, there is often no benefit and in some cases, more harm is done e.g. Hormone Replacement Therapy (HRT) in post-menopausal women. So, I think we should be circumspect in our expectations.

I take this opportunity to mention an important issue regarding regular testing and health in general. We are all anxious to lead a long and healthy life. In our anxieties, many believe that frequent doctor visits with the inevitable testing and numerous procedures can bring health. This is now a big business with almost daily promotion in the newspapers. Unfortunately, you should be aware that tests are simply tests and they do not necessarily indicate current or future health. Indeed, I often see patients who in their anxieties undergo many tests including CT coronary angiograms around the region. In many cases, incidental disease is found, Pandora's box is opened and sad to say, these patients become even more anxious.

There is no test in medicine that is perfect. You may have no disease, and yet a test may be abnormal (false positive test). For example, the stress test is being used for screening for heart disease and many patients have a very borderline tracing (a false positive) and they are told that its "abnormal" and this often leads to more testing including CT angiography, various imaging tests and even invasive arteriography.

You can have advanced disease e.g. cancer and yet all the tumour markers are absolutely normal (false negative test). And as I mentioned previously, the treadmill stress test may be normal and yet there are blocked arteries.

Life is full of uncertainties and unfortunately, whether we like it or not, it is not possible to purchase the assurance of future health. We can certainly purchase tests and many expensive procedures and scans. I occasionally see patients who smoke and do not take care of themselves who subconsciously believe that by repeated testing (often with radiation exposure), they can continue with their current life-style. I think most of you would also agree that this is somewhat foolish.

In my view, the most important aspect of health promotion and prevention is the patient needs to be informed, motivated and to take an active interest in his/her own risk factors and to participate in the more complex issues and decisions of which tests or procedures would be appropriate at any one time. Ultimately, one also has to accept the reality that there are no guarantees for future health and that uncertainty is part and parcel of life.