Heart Disease UK

Avijit Lahiri, Eric Lim & Vijay D. Anand
The numbers are ominous: From 191 million diabetics worldwide in 1990, the number of diabetics will shoot up to 376 by 2025, say the World Health Organization projections. The incident will be most sharply felt in the developing world with an estimated with 90 million in India and 120 million in China falling pray to it.
Diabetes is a disease with associated with abnormal glucose metabolism. The reason it has attracted such attention is that diabetes is closely associated with the development of cardiovascular diseases such as heart attack, stock hypertension, kidney failure, peripheral vascular diseases (including gangrene) and blindness.
Through the precise reasons are not clear, diabetes damages the lining of blood vessels (including the coronary arteries, which supply the heart with fresh blood) and alters the body’s handling of cholesterol and fat. The end- result is greatly accelerated development of heart disease and other related conditions are responsible for a very significant number of the life- impairing and life- threatening diseases in modern times.
The problem associated with detection of cardiovascular disease in patients with diabetes is linked to the fact that the disease is often ‘silent’. By the time the patient presents the heart disease to the doctor, the condition is usually advanced. In 35 per cent will suffer a heart attack when it is too late to prevent irreversible damage to the heart. It is surprising but well-documented finding that only about 30 per cent of patients will present to the doctor chest pain or other symptoms that can alert a doctor to the presence of cardiovascular disease. Even in this group, diabetic patients have a much poorer outlook than their non-diabetic counterparts.
Surgical treatment for coronary artery disease (coronary artery by-pass surgery) and angioplasty (opening up of narrowed arteries of the heart) are less often successful, repeat procedures are often necessary and the chance of failure of medical (tablet) treatments is high. For these reasons, Drs Brown and Goldstein (both) holders of Nobel Prizes for their work on cholesterol metabolism said, “if one waits for the one symptoms of heart disease, often the first symptom is sudden death, therefore, strategies for early detection of coronary disease are required”.
Highly prevalent worldwide, with World Health Organization projecting a stunning escalation by 2025, with much of the burden of disease failing on developing rather than developed nations, Diabetes is especially menacing for India as more than 70 per cent of the patients with diabetes are likely to die of a cardiovascular cause (mainly heart attack or stroke) eventually. The mortality from this condition in the developing countries will soon be at par with and probably exceed that due to infection (aids, tuberculosis and so on) or cancer.

Avijit Lahiri, Eric Lim & Vijay D. Anand
Health economics, therefore, has to aim its big guns at prevention of diabetes, particularly in the young. The cascade of diabetes as associated with diabetes, starting from high blood pressure (hypertension) to the development of coronary artery disease, unstable angina (acute coronary syndrome), acute myocardial infarction (heart attack) and ultimate development of heart failure (failure of the pump action of the heart) impose a very significant economic burden in developed countries .This includes, not only the cost of treatment – which is life- long – but also the reduced productivity and loss of working time. In the US alone, the direct and indirect economic costs attributable to diabetes exceed $100 billion.
Potentially, the most effective strategies are to limit the causes of diabetes: over-eating and lack of physical inactivity and consequent obesity. However, in those who already have it, a key challenge is early detection of the complications associated with diabetes in order to improve patient outcomes. Also, an exhaustive search for early cardiovascular disease must be the target. The problem is that the usual methods, which doctors currently use to identity ‘silent’ cardiovascular disease – for example, asking about smoking, checking blood pressure and measuring blood cholesterol – are surprisingly imprecise.

Computed tomography
Avijit Lahiri, Eric Lim & Vijay Anand
The recent introduction of cardiac CT (computed tomography) technology provides an exciting new advance. This technology is able to take accurate pictures of the heart from outside the body and, thereby, identity early heart disease; the test is pain – free and can be completed in minutes. With the latest scanners developed by such large multinational businesses as GE Healthcare, scan times are now being reduced to just a few seconds while the quality of images is nothing short astounding.
How do these test work? They work by taking a picture of the heart and identifying calcium deposits. For reasons that are not clear, as heart disease develops, fat (cholesterol) enters the wall of the coronary artery and provokes inflammation. As part of this process, the body sends specialist cells called macrophages to invade the wall of the artery. At the same time, calcium is dense and does not permit x- rays to pass through; these deposits can be visualized even in very minute amounts using cardiac CT.
Cardiac CT has now been shown to be robust technique. Recent studies by Dr Shaw and colleagues from the USA have shown that the more coronary artery calcium present, the higher the risk of death. This is a seminal trial, which has provided for the development for protocols for early investigation and research.
We ourselves have recently completed a trial in 510 diabetics. Although none of these patients had any signs or symptoms of coronary disease, nevertheless, 43 per cent of them where shown to have coronary artery calcium using electron beam CT scanning technology. Our initial data also appears to confirm that the amount of coronary artery calcium strongly predicts future cardiac events (death, heart attack, stroke and so on). Besides, the data clearly shows that prediction based on the scan result were superior to those based on the measurement of all other standard risk factors and biochemical tests. We went further by performing another test called myocardial perfusion imaging (with a so call radioactive tracer known as technetium sestamibi). This test told us that in patients with high coronary artery calcium scores, blockage of the arteries supplying the heart was very common in those with the symptom of chest pain.
The combination if the two tests were superior to either independently and allowed us to completely define the early management of disease in these patients. This trial adds further proof that “silent” heart disease is predominant in patients with diabetes and it’s early detection may not only improve the quality of the life but also save lives.

Avijit Lahiri, Eric Lim & Vijay D. Anand
What about the economic burden of such an imaging strategy? Since these scans are versatile and many patients can be imaged in the same day, the cost of the test can be relatively low when performed in large volumes ($200 – 300 in the West). Since patients who do not have coronary artery calcification have an excellent outcome (<0.5 percent death rate per year) in a five – year follow up (Shaw and colleagues), using this model, over 50 per cent of the patients with diabetes would then be sent for standard medical treatment, whereas those with higher amounts of coronary artery calcium would undergo further testing (such as myocardial perfusion imaging described earlier). Those with negative tests would then be treated aggressively medically (tablets and the like). However in those with positive tests, opening up the artery physically (so-called coronary angioplasty) or even surgery may be more appropriate. In symptomatic patients, it is possible that using that using these tests can be very coat-effective. For example, patients with chest pain are often investigated using a test called exercise stress testing followed by coronary angiography. In the U.K. (where Dr Lahiri practices), this would cost per patient over ₤1200. If instead CT scanning were used, followed by myocardial perfusion imaging, a back-of-the-envelope calculation shows that it is quite possible to lower the cost by as much as 50 per cent. This translates to over half a million pounds per 1,000 patients.
These developments in the area of early detection of coronary artery disease will be even more exciting once they can be linked to emerging new therapeutic regimes for heart disease. For example, in animal models, early trails by Dr Shaw and colleagues have shown that it may be possible to develop a “vaccine” against heart disease. In the future, this potent combination of technologies, namely, early detection and powerful treatments, may be able to stem the misery of heart disease associated with diabetes.