Primary Prevention of Cardiovascular Disease

• Primary prevention involves prevention in patient groups without existing CVD (as opposed to secondary prevention for patients with known CVD who should be all considered for risk reduction therapy).
• However the recently revised Joint British Societies' guidelines (JBS2) on prevention of cardiovascular disease (CVD) in clinical practice recommend that cardiovascular disease prevention should focus equally on people with established cardiovascular disease, people with diabetes mellitus and those with CVD risk of 20% or greater over 10 years.¹

The guidelines recommend that more intensive lifestyle intervention and the appropriate use of antihypertensive, lipid lowering, glucose lowering and other cardiovascular protective therapies should also be used to reduce overall cardiovascular risk in those with:

• Elevated blood pressure: equal to or above 160 mmHg systolic or 100 mmHg diastolic, or lesser degrees of blood pressure elevation with target organ damage
• Elevated total cholesterol to HDL cholesterol ratio equal to or above 6.0
• Familial dyslipidaemia, e.g. familial hypercholesterolaemia or familial combined hyperlipidaemia

There are separate articles that discuss Secondary Prevention of Cardiovascular Disease and How to use the Coronary Risk Prediction Charts for Primary Prevention.

• NICE recommends that the Framingham 1991 10-year risk equations (as used in the JBS2 risk calculator) should be used to assess CVD risk.²
  • CVD risk should be calculated as 10-year risk of fatal and non-fatal stroke, including transient ischaemic attack, + 10-year risk of coronary heart disease (CHD).² CHD risk includes the risks of death from CHD, and non-fatal CHD, including silent myocardial infarction, angina and coronary insufficiency (acute coronary syndrome).²
  • The JBS2 risk calculator (which is based on the Framingham equations) is not the only risk calculator in use and tends to be less accurate for certain population groups, e.g. women, ethnic minority groups, social deprivation.
• The JBS2 Guidelines recommend that all adults from 40 years onwards who have no history of CVD or diabetes, and who are not already on treatment for blood pressure or lipids, should be considered for an opportunistic comprehensive CVD risk assessment in primary care.¹
• Adults under 40 years with a family history of premature atherosclerotic disease should also have their cardiovascular risk factors measured.¹
• The American Heart Association guidelines also recommend recording the pulse rate and rhythm to screen for atrial fibrillation.³
• Risk assessment should include ethnicity, smoking habit history, family history of CVD, and measurements of weight, waist circumference, blood pressure, non-fasting lipids (total cholesterol and HDL cholesterol) and non-fasting glucose.
• The JBS2 cardiovascular risk chart or calculator should be used to estimate total risk of developing CVD over 10 years based on five risk factors: age, sex, smoking habit, systolic blood pressure and the ratio of total cholesterol to HDL cholesterol.
• It is becoming recognised that the pulse pressure (PP) is a better independent risk factor in the elderly, and represents an age-related shift in the risk component of blood pressure from diastolic to systolic to pulse pressure. It is possible that future risk prediction tables and calculators might reflect this change.⁴
• Total CVD risk should be estimated for the person's current age. A total CVD risk of over 20% over 10 years is defined as high risk.
• Other risk factors not included in the CVD risk prediction charts should be taken account of in assessing and managing a person's overall CVD risk:
  • In some ethnic groups the risk charts can underestimate, or sometimes overestimate, CVD risk because they have not been derived from these populations. For people originating from the Indian subcontinent it is reasonable to assume that CVD risk is about 1.4 times higher than predicted from the charts.
  • Abdominal obesity (waist circumference: men > 102 cm, women > 88 cm, and in Asians > 90 cm in men and > 80 cm in women) increases the risk of diabetes and CVD.
  • Impaired fasting glucose and impaired glucose tolerance are both associated with an increased risk of developing diabetes and CVD.
  • Raised fasting triglyceride (> 1.7 mmol/l) increases the risk of CVD.
  • A family history of premature CVD (men <55 years and women <65 years) in a first degree relative increases the risk of developing CVD by about 1.3.
  • Women with a premature menopause will also have an increased risk.
• Risk factors should be monitored at least annually in people on antihypertensive or lipid lowering therapy.⁵
• Cardiovascular risk should be estimated at least every 5 years in adults over 40 with no history CVD, hyperlipidaemia, diabetes or hypertension.⁵
• Over the age of 70 years CVD risk is usually greater than 20% over 10 years, especially for men, but total CVD risk should still be formally estimated using the charts. However, this will underestimate the true total CVD risk of a person older than 70 years.
• Formal risk assessment is not necessary for people with established atherosclerotic CVD, hypertension with target organ damage, familial dyslipidaemias such as familial hypercholesterolaemia, or diabetes. All these groups are at high total CVD risk and should be managed as for secondary prevention.

Reduction of risk of developing CVD involves lifestyle modifications, drug treatment and effective management of any overt underlying medical condition, e.g. diabetes, hypertension, hyperlipidaemia.

Lifestyle factors²

• Advise people to eat a diet in which:
  • Total fat intake is 30% or less of total energy intake.
  • Saturated fats are 10% or less of total energy intake.
  • Dietary cholesterol is less than 300 mg/day.
  • Saturated fats are replaced by monounsaturated and polyunsaturated fats.
• Advise eating at least:
  • Five portions of fruit and vegetables per day.
  • Two portions of fish per week, including a portion of oily fish.
  • Advise pregnant women to limit their intake of oily fish to two portions a week.
  • Do not routinely recommend omega-3 fatty acid supplements or plant sterols and stanols for primary prevention.
• Physical activity:
  • Advise people to take 30 minutes of at least moderate intensity exercise a day at least 5 days a week.
  • Encourage people who cannot manage this to exercise at their maximum safe capacity.
  • Recommend exercise that can be incorporated into everyday life, such as brisk walking, using stairs and cycling.
  • Tell people that they can exercise in bouts of 10 minutes or more throughout the day.
  • Take into account the person’s needs, preferences and circumstances.
  • Agree goals and provide written information about the benefits of activity and local opportunities to be active.
• Weight management:
  • Offer people who are overweight or obese advice and support to work towards achieving and maintaining a healthy weight.
• Alcohol consumption:
  • Advise men to limit their alcohol intake to 3–4 units a day.
  • Advise women to limit their alcohol intake to 2–3 units a day.
  • Advise everyone to avoid binge drinking.
• Smoking cessation:
  • Advise all people who smoke to stop.
  • If people want to stop:
  • Provide structured advice and support, with use of medication to help smoking cessation when appropriate.

Drug treatment

• Hypertension; screen for hypertension and treat appropriately according to British Hypertension Society guidelines.⁶
• Aspirin; although use of aspirin is widely accepted for secondary prevention, results in primary prevention are inconclusive. Low dose aspirin should be considered for people whose 10-year risk of CVD is calculated as being 20% or greater.⁵
• Lipid lowering drugs:⁷
  • Statin treatment as part of primary prevention for adults with a 10 year risk of 20%.
  • Treatment should be with simvastatin 40 mg.
  • Higher dose statins should not be used as there are no randomised controlled trials comparing high and low intensity statins in relation to cardiovascular outcomes in people without cardiovascular disease.
  • Do not set a target concentration for total cholesterol or LDL cholesterol in primary prevention.
  • Once a patient has started taking a statin, repeat lipid measurement is unnecessary. Clinical judgment and the patient’s preference should guide the review of drug treatment and whether to review the lipid profile.