A heart attack occurs when the walls of the coronary arteries become narrowed by a build up of fatty material, called atheroma. The atheroma can eventually block an artery or trigger formation of a blood clot, which can reduce blood supply to the heart, resulting in a heart attack.
Nearly all deaths from CHD are the result of a heart attack. More than 250,000 people in the UK suffer a heart attack every year and 40 per cent of these are fatal.
Although death rates from heart disease are falling, the incidence of CHD is not. It kills one in four men and one in five women. However, CHD is largely preventable. It's never too late to take action to reduce the risk significantly.
Smoking doubles the risk of developing CHD, yet 27 per cent of the population still smokes. It is a major factor in the build up of atheroma in the arteries and stopping smoking is the single most important thing a smoker can do to avoid a heart attack.
Forty-five per cent of men and 34 per cent of women in the UK are overweight. Being overweight or obese leads to an increase in blood pressure and cholesterol levels and increases the risk of developing diabetes. If these obesity trends persist, by 2010, one in four people will not fit into an office chair. However, it is not just an adult concern; 17 per cent of 15-year-olds are now obese. More than half the UK population has a cholesterol level above the recommended limit of 5.0mmoll. To reduce your levels of harmful cholesterol (LDL) try to cut the saturated fat from your diet.
Physical activity lowers the risk of developing CHD by increasing the level of HDL ("good" cholesterol) and reducing obesity. Adults should aim for 30 minutes of moderate activity (brisk walk) five days a week and children should do at least one hour of exercise seven days a week.
Raised blood pressure increases the risk of having a heart attack. About 40 per cent of people in the UK have a raised blood pressure, but four in five of them are either not being treated for or are unaware they have it. Steps to reduce blood pressure include increasing physical activity, maintaining a healthy weight, reducing salt intake and limiting alcohol consumption.
Understanding how the risk factors may affect you and taking very simple steps to reduce these risks may mean that "it really won't happen to you".
Professor Sir Charles George is the medical director of the British Heart Foundation. www.bhf.org.uk