Reducing CVD risk and treatmentsEdexcel International A Level Biology: Revision notes

Body mass index (BMI) = mass (kg) ÷ height² (m²). For example 98 kg and 1.75 m gives 98 ÷ 1.75² = 32.0 kg m⁻². A BMI of 25–30 is overweight and above 30 is obese.

Waist-to-hip ratio = waist circumference ÷ hip circumference. A high ratio (above about 0.9 in men and 0.85 in women) shows fat stored around the abdomen, which is linked to a higher risk of CHD.

Limitation of BMI: it does not distinguish fat from muscle or show where fat is stored, so waist-to-hip ratio can be a better indicator for some people.

Diet: less saturated fat lowers LDL cholesterol; less salt lowers blood pressure; more fruit and vegetables provide antioxidants; eating fewer calories reduces BMI.

Exercise: regular exercise lowers blood pressure, raises HDL, helps control body mass and strengthens the heart muscle.

Stopping smoking: removes chemicals and carbon monoxide that damage the endothelium and reduce oxygen transport, and platelets become less sticky. Heart rate and blood pressure fall.

These changes act together, so the combined effect on CHD risk is greater.

Antihypertensives lower blood pressure:

• Diuretics increase urine production, reducing blood volume.
• Beta blockers reduce heart rate and force of contraction.
• Vasodilators (for example calcium channel blockers) widen arteries.

Benefit: lower risk of stroke and heart attack. Risks: dizziness or fainting from low blood pressure, fatigue, and for some drugs a slow heart rate.

Statins inhibit an enzyme in the liver that makes cholesterol, so LDL falls and less atheroma forms. Risks: muscle pain, liver problems, digestive upset.

Anticoagulants (for example warfarin) reduce blood clotting, so there is less risk of a thrombus. Used for patients at risk of clots, such as after heart valve surgery or with an irregular heartbeat.

Platelet inhibitors (for example aspirin) make platelets less sticky, so they are less likely to clump and start a clot. Used for patients who have had a heart attack or stroke.

Benefit: lower risk of thrombosis, heart attack and stroke. Risk: excessive bleeding, such as bruising, internal bleeding or stomach bleeding. Doses are monitored.

Every drug has side effects. For high-risk patients the benefits usually outweigh the risks, but doctors consider the individual's risk factors, other medicines and age, and monitor the patient. Drugs are used with lifestyle changes, not instead of them.

In evaluation answers, name a specific benefit, a specific risk, and finish with a judgement.