Coronary heart disease: treatments and prevention

What you'll learn

Coronary heart disease (CHD) is a major health concern in the UK and globally, caused by the narrowing of coronary arteries that supply the heart muscle with oxygenated blood. This revision guide covers the medical treatments used to manage CHD, including surgical interventions and medications, as well as the lifestyle modifications that can prevent or reduce the risk of developing this condition. You'll learn how to evaluate different treatment options and understand the biological principles behind prevention strategies.

Key terms and definitions

Coronary heart disease (CHD) — a condition where the coronary arteries become narrowed or blocked by the build-up of fatty deposits called plaques, restricting blood flow to the heart muscle

Stent — a small mesh tube inserted into a narrowed artery to hold it open and maintain blood flow to the heart muscle

Statin — a medication that reduces blood cholesterol levels by blocking the enzyme in the liver responsible for cholesterol production

Atherosclerosis — the build-up of fatty deposits (plaques) on the inner walls of arteries, causing them to narrow and harden

Bypass surgery — a surgical procedure where a healthy blood vessel is taken from another part of the body and used to redirect blood flow around a blocked coronary artery

LDL cholesterol — low-density lipoprotein, often called "bad cholesterol" because high levels contribute to plaque formation in arteries

Platelets — small cell fragments in the blood that help form clots; they can contribute to blockages when they accumulate at sites of arterial damage

Anticoagulant — a medication that reduces blood clotting, helping to prevent blockages in narrowed arteries

Core concepts

Understanding how coronary heart disease develops

The coronary arteries branch off the aorta and supply oxygenated blood directly to the heart muscle tissue. When these arteries become narrowed through atherosclerosis, the heart muscle receives insufficient oxygen, particularly during exercise when oxygen demand increases.

The process of atherosclerosis begins when:

• High levels of LDL cholesterol in the blood lead to fatty deposits accumulating in the artery walls
• These deposits form plaques that gradually grow larger
• The plaques cause the artery lumen to narrow, restricting blood flow
• The artery walls lose elasticity and become hardened

Risk factors that accelerate atherosclerosis include:

• High-fat diet (particularly saturated fats)
• Smoking
• Lack of physical activity
• High blood pressure
• Genetic predisposition
• Type 2 diabetes
• Age (risk increases with age)

If a coronary artery becomes severely narrowed or completely blocked, the section of heart muscle it supplies will be deprived of oxygen. This causes chest pain (angina) or, if severe, a heart attack (myocardial infarction) where heart muscle cells die.

Medical treatments: stents

Stents are the most common mechanical intervention for treating blocked or narrowed coronary arteries. The procedure involves:

1. A thin tube (catheter) is inserted into an artery, usually in the groin or wrist
2. The catheter is guided through the blood vessels to the blocked coronary artery
3. A balloon attached to the catheter is inflated to widen the artery
4. A stent (wire mesh tube) is expanded and left in place to keep the artery open
5. The balloon and catheter are removed, leaving the stent permanently in position

Advantages of stents:

• Minimally invasive procedure with relatively quick recovery time (often performed under local anaesthetic)
• Immediate improvement in blood flow to the heart muscle
• Effective at reducing symptoms of angina
• Lower risk compared to open-heart surgery
• Can be performed as emergency treatment during a heart attack

Disadvantages of stents:

• Risk of blood clots forming on the stent (thrombosis), particularly in the first few months
• Requires patients to take anticoagulant medications long-term
• The artery may narrow again over time (restenosis) as scar tissue forms
• Small risk of artery damage during the procedure
• Does not address the underlying causes of CHD
• Not suitable for all types or locations of blockages

Medical treatments: statins

Statins are prescribed medications that lower blood cholesterol levels. They work by:

• Inhibiting (blocking) the enzyme HMG-CoA reductase in the liver
• This enzyme is essential for cholesterol synthesis
• Reducing cholesterol production forces the liver to remove more LDL cholesterol from the blood
• This decreases the amount of cholesterol available to form new plaques

Advantages of statins:

• Proven to reduce the risk of heart attacks and strokes
• Can slow or even reverse the progression of atherosclerosis
• Easy to take (usually one tablet daily)
• Relatively inexpensive
• Reduce inflammation in blood vessels
• Stabilise existing plaques, making them less likely to rupture

Disadvantages of statins:

• Must be taken long-term (often for life) to maintain benefits
• Possible side effects including muscle pain, digestive problems, headaches
• Rare but serious side effects such as liver damage or muscle breakdown
• Do not work immediately — benefits accumulate over months and years
• Some patients cannot tolerate statins due to side effects
• Does not address lifestyle factors that contribute to CHD

Other medical treatments

Bypass surgery is used for severe CHD when multiple arteries are blocked or stenting is not suitable:

• A surgeon removes a healthy blood vessel (usually from the leg or chest)
• This vessel is grafted to redirect blood flow around the blocked section
• The procedure requires opening the chest and often uses a heart-lung machine
• Recovery time is several weeks to months

Anticoagulant and antiplatelet medications help prevent blood clots:

• Aspirin reduces platelet stickiness, making clots less likely to form
• Other anticoagulants like warfarin or newer drugs prevent clot formation through different mechanisms
• Particularly important after stent insertion
• Must be carefully monitored as they increase bleeding risk

Lifestyle modifications for prevention

Preventing CHD focuses on reducing the risk factors that lead to atherosclerosis. Evidence-based lifestyle changes include:

Dietary modifications:

• Reduce saturated fat intake (found in butter, cream, fatty meats, processed foods)
• Limit salt consumption to reduce blood pressure
• Increase consumption of fruits, vegetables, and whole grains
• Choose unsaturated fats (olive oil, nuts, oily fish) instead of saturated fats
• Reduce sugar intake to help maintain healthy body weight
• Limit alcohol consumption

Regular physical activity:

• At least 150 minutes of moderate exercise per week (UK NHS guidelines)
• Exercise strengthens the heart muscle
• Helps maintain healthy weight and blood pressure
• Improves cholesterol balance (increases HDL "good" cholesterol)
• Examples: brisk walking, cycling, swimming, dancing

Smoking cessation:

• Smoking damages artery walls, making atherosclerosis more likely
• Carbon monoxide reduces oxygen-carrying capacity of blood
• Nicotine increases heart rate and blood pressure
• Chemicals in tobacco make blood more likely to clot
• Stopping smoking is the single most effective lifestyle change for reducing CHD risk

Weight management:

• Obesity increases strain on the heart
• Excess weight is linked to high blood pressure, high cholesterol, and type 2 diabetes
• Body Mass Index (BMI) should be maintained in the healthy range (18.5-24.9)

Stress reduction:

• Chronic stress raises blood pressure and may increase inflammation
• Stress management techniques include meditation, yoga, adequate sleep
• Social connections and support networks reduce stress

Evaluating treatments and prevention strategies

When comparing different approaches to managing CHD, consider:

Cost-effectiveness:

• Prevention through lifestyle changes costs little but requires sustained behaviour change
• Statins are relatively inexpensive for healthcare systems
• Stents and surgery involve significant initial costs but may reduce long-term healthcare expenses

Compliance and adherence:

• Lifestyle changes require high motivation and long-term commitment
• Many people find dietary changes and regular exercise difficult to sustain
• Medication adherence can be problematic if side effects occur

Individual circumstances:

• Some patients have genetic factors that limit effectiveness of lifestyle changes alone
• Severity of CHD determines whether surgery is necessary
• Age, other health conditions, and personal preferences influence treatment choices

Combination approaches:

• Most effective strategy combines prevention and treatment
• Patients with stents or after surgery must also modify lifestyle and take medications
• Prevention should start early, before significant atherosclerosis develops

Worked examples

Example 1: Evaluating stent treatment

Question: A patient has a partially blocked coronary artery causing chest pain during exercise. Doctors recommend inserting a stent. Evaluate the use of stents in treating coronary heart disease. (6 marks)

Model answer:

Stents are wire mesh tubes inserted into narrowed coronary arteries to hold them open and improve blood flow (1 mark). An advantage is that stent insertion is minimally invasive compared to surgery, with faster recovery time and can be done under local anaesthetic (1 mark). Stents provide immediate improvement in blood flow, relieving symptoms like chest pain (angina) (1 mark).

However, there is a risk of blood clots forming on the stent, particularly in the first few months after insertion (1 mark). This means patients must take anticoagulant medications long-term, which carry their own risks such as increased bleeding (1 mark). Additionally, stents do not address the underlying causes of CHD, such as high cholesterol or poor diet, so lifestyle changes and medication are still necessary (1 mark).

Examiner note: This answer provides balanced evaluation with both advantages and disadvantages, using appropriate scientific terminology and explaining consequences of treatment.

Example 2: Prevention strategies

Question: Describe how lifestyle changes can reduce the risk of developing coronary heart disease. (4 marks)

Model answer:

Eating a diet low in saturated fats reduces cholesterol levels in the blood, which decreases the build-up of fatty plaques in coronary arteries (1 mark). Regular exercise strengthens the heart muscle and helps maintain healthy blood pressure and weight (1 mark). Stopping smoking prevents damage to artery walls and reduces the tendency for blood to clot (1 mark). Maintaining a healthy body weight reduces strain on the heart and lowers the risk of high blood pressure and type 2 diabetes, which are risk factors for CHD (1 mark).

Examiner note: Each lifestyle change is linked to a specific biological mechanism that reduces CHD risk.

Example 3: How statins work

Question: Explain how statins help to reduce the risk of coronary heart disease. (3 marks)

Model answer:

Statins are drugs that reduce blood cholesterol levels (1 mark). They work by blocking the enzyme in the liver that produces cholesterol (1 mark). This reduces the amount of LDL cholesterol in the blood available to form fatty plaques in the coronary arteries / slows the progression of atherosclerosis (1 mark).

Examiner note: The answer explains the mechanism of action and links this to reduced CHD risk. Using the term "LDL cholesterol" demonstrates precise knowledge.

Common mistakes and how to avoid them

• Confusing stents with bypass surgery — Remember that stents are inserted into the existing artery to hold it open, while bypass surgery creates a new route around the blockage using a blood vessel from elsewhere in the body. Don't describe stents as "replacing" arteries.

• Stating that treatments "cure" CHD — Treatments manage symptoms and reduce risks, but CHD is a chronic condition. Stents and statins do not cure the underlying disease process. Always use terms like "treat," "manage," or "reduce risk" rather than "cure."

• Failing to explain mechanisms in "Explain" questions — When asked to explain how statins work, don't just say "they lower cholesterol." State that they inhibit/block the enzyme that produces cholesterol in the liver, which then reduces blood cholesterol levels.

• Not providing balanced evaluation — In "Evaluate" questions, you must discuss both advantages and disadvantages of treatments. Listing only positives or only negatives will limit your marks significantly.

• Vague lifestyle advice without biological reasoning — Instead of simply stating "eat healthily," specify reducing saturated fat intake and explain that this reduces cholesterol levels and plaque formation. Link recommendations to biological mechanisms.

• Confusing risk factors with causes — Smoking, poor diet, and lack of exercise are risk factors that increase the likelihood of developing CHD, not direct causes. The cause is atherosclerosis (plaque build-up narrowing arteries).

Exam technique for "Coronary heart disease: treatments and prevention"

• Command word awareness: "Describe" requires you to state features or characteristics; "Explain" needs mechanisms and reasons (use "because," "this causes," "which leads to"); "Evaluate" demands advantages AND disadvantages with a judgment about relative importance or effectiveness.

• Use data when provided: Questions may include graphs showing cholesterol levels or heart disease rates. Extract specific figures and trends, then link them to biological knowledge. For example, "The data shows cholesterol decreased from 6.2 to 4.8 mmol/L after statin treatment, which would reduce plaque formation."

• Structure longer answers logically: For 6-mark questions, write in clear paragraphs. Start with advantages of a treatment (with explanations), then disadvantages (with explanations), then potentially a conclusion balancing both sides or relating to the specific scenario given.

• Mark allocation guides detail: A 3-mark question needs three distinct points. If asked to "explain," each point needs a mechanism or reason, not just a statement. One mark typically = one developed point with explanation.

Quick revision summary

Coronary heart disease results from atherosclerosis narrowing the coronary arteries. Stents mechanically hold arteries open, providing immediate symptom relief but requiring long-term anticoagulants and not addressing underlying causes. Statins reduce cholesterol by inhibiting liver enzymes, slowing disease progression but requiring lifelong use. Bypass surgery reroutes blood around severe blockages. Prevention focuses on lifestyle: reducing saturated fat intake, regular exercise, stopping smoking, and maintaining healthy weight. All approaches work best when combined. Evaluation questions require balanced discussion of advantages, disadvantages, and suitability for different patients.