Coronary artery disease is caused by a hardening or narrowing of the arteries to your heart.The medical term is atheromaoratherosclerosis. Patches of the inner lining of the arteries become furred up from a mixture of fat, cholesterol and cells deposited in the wall. Veins, unlike arteries, do not ‘fur up’ unless they are asked to do the work of arteries, for example after a bypass operation (see Bypass surgeryin Chapter 3). If you think of an artery as a three-lane motorway, the narrowed part of the artery is like a lane of the motorway being coned off; the flow of blood is restricted a bit like the traffic is slowed down as it tries to filter into the lanes that are open. The patches of narrowing are calledplaque(pronounced‘plack’), so you may hear doctors refer to atheromatous plaque or plaque disease. Plaque may cause a progressive narrowing of your arteries, restricting blood flow and causing angina (see Chapter 3), or it may rupture or tear causing clots to form, which totally block the artery, and this can lead to a heart attack.

The major causes of atheroma developing are:
•    raised cholesterol level;
•    cigarette smoking;and
•    high blood pressure.

Usually symptoms develop leading to a diagnosis of angina, heart attack or heart failure. Occasionally, the first evidence may be when someone dies suddenly from a heart attack, but there is usually a warning and it is important to understand what the warning signs are.
There are some factors in a person’s life called risk factors. People with risk factors have an increased chance of developing a particular condition. For example, working with asbestos or down a coalmine increases the chance (or risk) of developing lung disease,and is thus considered a risk factor. Risk factors for coronary artery disease can be divided into those that can be avoided and those that cannot (see Table 2.1). Avoidable risk factors, including diabetes, account for 90% of coronary disease. Risk factors for coronary disease are like penalty points on a driving licence, only they multiply rather than add up: smoking may give you 3 penalty points and high blood pressure 3penalty points, but both risk factors at the same time may give you 9 penalty points; if you also have 3 penalty points for a high cholesterol level, then your penalty points may multiply to 27 in total.
Are there any risk factors that I can’t change?
Your parents, your age and your sex may increase your risks. Your race may also bring risk: people from the Indian subcontinent have more coronary disease, African-Caribbeans less.Having a family history of heart disease, being a male and getting older means that you need to take more care. A high risk family is one in which a close female relative aged 65 years or less, or a male relative aged 55 years or less, or both, developed coronary disease. But remember that you can lessen many of your risk factors and improve your chances of not developing heart problems. Prevention is always the best medicine so the first part of this chapter looks at what puts you at risk of developing coronary artery disease, and then how it can be prevented or treated.

RISKS OF SMOKING
I have smoked since my teens just as my father and grand father did. My father is still alive and my grandfather lived until he was 65. What are my risks of heart disease?
There is overwhelming evidence that smoking causes hardening of the coronary arteries as well as hardening of your arteries to the brain and legs; this hardening leads to narrowed arteries and thus poor blood flow to your heart. It also leads to chronic lung diseases as well as lung cancer, and increases your chances of developing a stomach ulcer. Whilst some people escape the consequences of cigarette smoking, the majority do not.
There is a lot of talk about the harmful effects of passive smoking. Can other people’s smoke really harm me?
Smoking harms any non-smokers who are breathing in the same air as a smoker, increasing their chance of heart and lung disease. It may also cause sore red eyes, headaches and make asthma worse. This has become known as passive smoking. Children brought up in a household of smokers suffer more infections and disease, compared to those who live in non-smoking households.
The government gives us dire warnings about smoking but I know many people who smoke who are in their seventies or eighties. Are the statistics regarding the harmful effects of smoking really as bad as the press makes out?
Yes. Smoking causes one in five deaths in our population and at least a third of these are due to heart disease. This means that, in the UK, smoking kills over 100 000 people a year. It kills 90% of the 40000 who die from lung cancer, 75% of the 20000 who die from chronic lung disease such as emphysema, and 25% of the 117 000 who die each year from coronary artery disease. Smoking respects no one – it is an equal opportunity killer attacking both sexes and all races. Out of the total number of people who smoke, a quarter will die early as a result, losing an average 10–15 years of life. Worldwide, smoking kills three million people a year. This is predicted to increase to 10 million by 2025, which means that 200 million of today’s children and teenagers will be killed by tobacco. Add these to today’s adults and we get a staggering half a billion of the world’s population being killed by tobacco – 250 million dying young (aged 35–69 years) and each person losing 20 years of expected life. Many people die only after a long disabling disease.
I have changed to a low-tar brand of cigarettes, with a filter. Why will smoking be so harmful to me now?
Components of tobacco, such as tars, are harmful to your health but the main cause is the nicotine in cigarettes as this is an addictive drug. Nicotine increases your heart rate and blood pressure making your heart work harder, whilst at the same time narrowing the arteries. Oxygen is removed from the blood and replaced with carbon monoxide. Carbon monoxide reduces the ability of the blood to carry oxygen and, in heavy smokers, may reduce it by as much as 50%. We have all read of tragedies caused by faulty gas heaters – carbon monoxide build-up is the cause. This means that there is less energy circulating to your heart to cope with the demands that nicotine places on it. The carbon monoxide level in the blood after smoking one cigarette exceeds the legal limit for pollution allowed in industry by eight times. Low tar cigarettes are nice in theory, because it is the tar in cigarettes that causes lung cancer, but actually they make matters worse in that most low tar smokers inhale deeper and increase their carbon monoxide and nicotine blood levels.
Smoking can cause roughening of the smooth lining of your arteries (the endothelium) and this may lead to the development of narrowed areas in the arteries caused by fat being deposited there. Smoking lowers the good cholesterol known as the high density lipoprotein (HDL) (see the section Risks of high cholesterol levels) and increases the blood ingredient (fibrinogen) that promotes clotting. Smoking therefore not only causes hardening of your arteries but increases the chance of clots forming on the narrowed areas and thus a heart attack.