PatientPlus articles are written for doctors and so the language can be technical. However, some people find that they add depth to the articles found in the other sections of this website which are written for non-medical people.

Primary Prevention of Cardiovascular Disease (CVD)

Ischaemic heart disease (IHD) causes 30% of male and 22% of female deaths in the England (higher in Scotland). The focus of prevention in recent guidelines has switched from IHD to cardiovascular disease to emphasise the need for stroke prevention.
Primary prevention involves prevention in patient groups without existing CVD (as opposed to secondary prevention as in patients with known CVD who should be all considered for risk reduction therapy - eg statins). However the recently revised Joint British Societies' guidelines on prevention of cardiovascular disease (CVD) in clinical practice¹ 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. 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 mm Hg systolic or 100 mm Hg 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.

Cardiovascular risk estimation Primary care has an important role in identifying those patients at highest risk (eg with multiple risk factors). Such patients should receive informed advice on risk reduction, and offered antihypertensive or lipid lowering therapy based on the assessment of their total cardiovascular risk, aided by the new cardiovascular risk chart or calculator - to help in the decision.¹ It is not the only risk calculator in use. ^10,11

• The recent Joint Society Guidelines recommend 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 care¹.
• Adults under 40 years with a family history of premature atherosclerotic disease should also have their cardiovascular risk factors measured¹.
• Assessment of the family history at nurse-led registration medical will include some of the risk factors, but it is suggested that some may follow the approach recommended by the American Heart Association in formally screening from age 20. ². Note: they also recommend recording the pulse, to screen for atrial fibrillation. Extending the remit of the registration medical and opportunistic screening by GPs might even impact on the continuing toll of premature MIs in those in their 20's and 30's, though these are often the very ones that DNA appointments and follow-ups.
• 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 new cardiovascular risk chart 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. This is the estimated probability (percentage chance) of developing CVD over the next 10 years.
• 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 BP from DBP to SDP to PP. It is possible that future risk prediction tables and calculators might reflect this change. ¹²
• Total CVD risk should be estimated for the person's current age group: 50 years, 50-59 years, or over 60 years. 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 (40 inches), women > 88 cm (35 inches), 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, and especially CHD (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 have an increased risk.
• Those who are not found at this comprehensive cardiovascular risk assessment to be at high total CVD risk based on the Joint British Societies' charts, or started for other reasons on drug therapy to lower blood pressure, lipids, or glucose, should have their risk assessment repeated, ideally within five years.
• 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.

Interventions

1. Lifestyle factors see BPASSOC website. The guidelines are broadly similar to those of the American Heart Association, though they use a CHD risk of >20%. ²
   • Smoking Incontrovertible evidence links cigarette smoking with CVD and the risk increases with the number of cigarettes smoked daily and the length of time smoking. Smoking cessation significantly lowers risk but may be several years before full benefit is seen. Smoking as few as 5 cigarettes a day have an increased risk, and patients should be advised on complete smoking cessation and not reduction. Simultaneous advice on preventing weight gain is needed as this is often associated with stopping smoking. Therefore:
     • Should be actively discouraging patients from continuing to smoke.
     • Should give 'brief and supportive advice' on smoking cessation as often as possible.
     • Should consider routine use of nicotine replacement therapy (gives 1 year cessation rates of approx. 20%).
   • Diet Increase intake of fresh fruit and vegetables (to 5 portions/day), encourage dietary fibre, reducing intake of total and saturated fats, replacing saturated with mono-unsaturated fats (olive or rapeseed oil), increasing consumption of (oily) fish. Reduce salt intake (to <100 mmol/day <6g NaCl or <2.4g sodium/day). Foods rich in plant stanols or sterols (usually margarine), taken at about 2g/day, can achieve a 10% reduction in LDL cholesterol, and an estimated reduction in the risk of heart disease by 25%. ⁶
     Some may need intensive dietary advice from a qualified dietitian or other trained professional.
   • Obesity and overweight Ideal is to maintain normal weight (BMI 20-25 kg/m2). There is a significantly increased risk with BMI =30 and in patients with excess intra-abdominal fat can use waist circumference as a simple indicator of risk: =88cm (35 inches) in women and =102cm (40 inches) in men indicated substantially increased risk. Recommendations are:
     • Set realistic targets of 5-10kg weight loss for overweight and obese patients.
     • Advise on diet and exercise and also help with behavioural changes through support systems to facilitate maintenance of weight loss.
   • Physical activity Sedentary lifestyle is associated with raised risk of CVD. Starting moderate physical activity in middle age may reduce the risk and lower total and LDL cholesterol and increase HDL cholesterol. Also recently been shown that moderate physical exercise leads to a reduction in mortality. Recommendations are that:
     • Patients who are not taking regular exercise should aim to take half an hour's moderate physical activity nearly every day.
     • Patients who are already active, should undertake vigorous intensity aerobic exercise for 30 mins 3x per week.
   • Alcohol consumption Light-moderate alcohol consumption of up to 21 units/week for men and up to 14 units/week for women of alcohol is not a problem and may provide some protection against CVD. US suggested limits are stricter at 2 drinks/day for men, and no more than 1 drink/day for women, but they lack the wine-drinking culture of Europe. ² Even though a standard drink in the US contains 14g of ethanol compared to the UK's 8g, the limits are higher in the UK ⁷ Heavy drinking raises blood pressure and triglycerides, adds to obesity and raises both cardiac and total mortality. Benefits of drinking are not such that non-drinkers should be encouraged to start!
   • Duration of trial for lifestyle measures Patients at high risk may be considered for immediate prescription of lipid lowering drugs, but for most patients should pursue them for 3-6 months. They should then be continued even after starting drugs.
2. Drug treatment
   • Hypertension Screen for hypertension and treat appropriately according to British Hypertension Society guidelines.³
   • Aspirin Although use of aspirin is widely accepted for secondary prevention, results in primary prevention are inconclusive. Low dose aspirin should be considered for patients whose risk of CHD is sufficiently high to also justify the use of lipid lowering drugs. Note: US guidelines suggest the use of aspirin at a CHD risk level >10%. ²
   • Lipid lowering drugs A 10 year CVD risk >20%, is approximately equivalent to the CHD risk of >15% on the old charts and is the recommended level of intervention, although a staged approach targeting higher risk patients first may be required when available resources are limited. Note: different guidelines will produce different numbers of patients recommended for treatment. ⁸ The US National Guideline Clearinghouse has compared different guidelines in use in the USA. ⁹
     • Statins are generally first line - although hepatoxicity occurs in 1% of patients and liver function should be monitored before and once during therapy (but not again if results normal). Rhabdomyolysis is most serious side affect occurring in <0.1% patients.
     • Ezetimibe (inhibits intestinal adsorption of cholesterol) may be added to a statin, and can further reduce LDL-cholesterol by 25%.
     • Fibrates should be considered in patients with a high risk where both total cholesterol and triglycerides are >5.0mmol/l. In combination with a statin, there is an increased risk of rhabdomyolysis, therefore caution and close monitoring is advised.
     • Resins are only indicated when statins or fibrates are not tolerated or contraindicated.
     • Optimal cholesterol lowering should reduce the total cholesterol by 25% or LDL-cholesterol by 30% or achieve a total cholesterol of <4.0 mmol/l or LDL-cholesterol of <2.0 mmol/l, whichever is the greatest reduction.¹
     • Remember to consider and exclude secondary causes of hyperlipidaemia including hypothyroidism, drugs, and nephrotic syndrome.
3. Referral Consider for referral patients who:
   • Are refractory to treatment with first line drug therapy when secondary causes have been excluded and dietary and other lifestyle measures have been attempted.
   • Those where drug therapy is contraindicated or poorly tolerated.
   • Patients with family history.
   • Pregnant women.
4. Patients with heterozygous familial hypercholesterolaemia
   • Diagnosis for this requires:
     • cholesterol >7.5mmol/l in adult
     • or >6.7mmol/l in children under 16
     • or LDL cholesterol >4.9mmol/l in adults plus tendon xanthomas in the patient or a first or secondary relative.
   • It is recommended that these patients should be treated aggressively with dietary advice and lipid lowering drugs with close monitoring and follow-up.
   • They should also be referred to a specialist clinic both for treatment and genetic counselling.
5. Patient screening Screening of all patients for hyperlipidaemia is not advised and a targeted approach should be taken against specific groups likely to be at increased risk, e.g.:
   • Diabetes and impaired glucose tolerance
   • Hypertension
   • Smoking
   • Family history of premature CHD (first degree male relative at <55 years or female relative <65 years).
   • Clinical signs of hyperlipidaemia, e.g. tendon xanthomas and xanthelasmas.

References Used

1. British Cardiac Society, British Hypertension Society, Diabetes UK, HEART UK, Primary Care Cardiovascular Society, The Stroke Association; JBS 2: Joint British Societies' guidelines on prevention of cardiovascular disease in clinical practice. Heart 2005;91;1-52.
2. Primary Prevention in the Adult: American Heart Association.
3. Williams B, Poulter NR, Brown MJ, Davis M, McInnes GT, Potter JF, Sever PS, Thom SM; BHS guidelines working party, for the British Hypertension Society. British Hypertension Society guidelines for hypertension management 2004 (BHS-IV): summary. BMJ. 2004 Mar 13; 328(7440):634-40. [BMJ full text]. - See the British Hypertension Society Guideline (2004) as pdf download
4. SIGN Guidelines
5. Cappuccio FP, Oakeshott P, Strazzullo P, et al; Application of Framingham risk estimates to ethnic minorities in United Kingdom and implications for primary prevention of heart disease in general practice: cross sectional population based study.;BMJ 2002 Nov 30;325(7375):1271.[abstract]
6. Sterols, stanols, and cholesterol.
7. Safe Alcohol Consumption: A comparison of Nutrition and your health: dietary guidelines for Americans and Sensible drinking.
8. Statins: whom should we treat? Bandolier.
9. Lipid screening in the primary prevention of coronary heart disease and atherosclerotic cardiovascular disease in adults; National Guideline Clearinghouse.
10. PROCAM risk calculator: International Task Force for Prevention of Coronary Heart Disease.
11. Calculating global risk: the key to intervention. Assmann G, European Heart Journal.
12. Importance of arterial pulse pressure as a predictor of coronary heart disease risk in PROCAM European Heart Journal.

Internet

• British Hypertension Society Website
• BP Association (Patient Website) and BP Association Lifestyle advice

Acknowledgements EMIS is grateful to Dr Colin Tidy for updating this article and to Dr Huw Thomas for inclusion of the calculator. The final copy has passed peer review of the independent Mentor GP authoring team. ©EMIS 2006.

Last issued 30 Aug 2006