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Clinical guidelines

National guide to a preventive health assessment for Aboriginal and Torres Strait Islander people Second edition

Cardiovascular disease prevention

Author Dr David Peiris
Expert reviewers Dr Alex Brown, Professor Andrew Tonkin

Overview

In this chapter cardiovascular disease (CVD) is used as a collective term to include coronary heart disease (CHD), stroke and transient ischaemic attacks (TIAs) and peripheral vascular disease (PVD).

Despite improving trends, CVD remains Australia’s biggest killer, accounting for 16% of the total disease burden and 11% of national health system expenditure.1 Aboriginal and Torres Strait Islander people experience around a five times greater vascular disease burden than other Australians.2 This vascular disease burden rises sharply from early adulthood. Mortality rates from CVD for Aboriginal and Torres Strait Islander people aged 25–64 years are up to eight times higher than for the general population,3 and CVD is the single biggest contributor to the disease burden gap for those aged 35 years and older.2 Reductions in the prevalence of seven risk factors (tobacco smoking, high body mass, physical inactivity, high blood cholesterol, excessive alcohol intake, high blood pressure, and low fruit and vegetable intake) represent the most effective prevention strategies in closing the vascular disease burden gap for Aboriginal and Torres Strait Islander people.2 Based on the National Health Survey and the National Aboriginal and Torres Strait Islander Health Survey, nearly all Aboriginal and Torres Strait Islander people have at least one CVD risk factor from the age of 18 years and 53% have three or four of these risk factors.4

Absolute risk approach to CVD prevention 

Estimating the risk of CVD events requires simultaneous assessment of several risk factors. Based on large scale epidemiological studies, there has been a fundamental shift away from screening and managing single risk factor abnormalities (eg. hypertension or hypercholesterolaemia, in which arbitrary cut-points are used for defining presence or absence of a condition) towards a global assessment of multiple risk factors to determine a person’s overall or ‘absolute’ risk of experiencing a cardiovascular event. This approach provides greater ability to predict who is at greatest risk of a CVD event than the traditional single risk factor approach.5 

The contribution of various risk factors to a person’s overall risk is derived from large cohort studies and several absolute CVD risk prediction equations are now available based on these data. Importantly, however, there are currently no Aboriginal and Torres Strait Islander population specific risk prediction equations. The 1991 Anderson Framingham Risk Equation (FRE),6 derived from the USA Framingham study, is the currently recommended equation for risk estimation in Australia.7 This equation should only be applied for people without established CVD.

There are several limitations to applying the FRE to Aboriginal and Torres Strait Islander populations:

  • it is validated for the age range 30–74 years only
  • it may underestimate risk, especially for younger age groups and when local risk factor prevalence rates and CVD incidence exceed that of non-Indigenous populations8
  • in areas where there is a high prevalence of additional risk factors that are not part of the FRE but are known to be independently associated with CVD, risk may be underestimated.

Non-FRE risk factors of known high prevalence in Aboriginal and Torres Strait Islander communities include family history of premature CVD, elevated body mass index, markers of chronic kidney disease, socioeconomic hardship, depression and psychosocial stress, and impaired fasting glucose.4 Further, literature reviews conducted by the National Vascular Disease Prevention Alliance have identified several clinical conditions which, if present, confer a high degree of risk regardless of the risk estimate using the FRE.7 Table 12.1 lists the FRE risk factors, additional risk factors for CVD that do not feature in the FRE and a list of clinically high risk conditions in whom absolute risk calculation can be assumed to be high. It is recommended that a comprehensive vascular risk assessment requires assessment of all these factors.

Table 12.1. Framingham and non-Framingham CVD risk factors
Framingham risk equation factors*†Non-Framingham risk equation factors‡Clinically high risk conditions
  • Age
  • Gender
  • Smoking status
  • Systolic blood pressure
  • Total cholesterol§
  • HDL cholesterol§
  • Diabetes status
  • Left ventricular hypertrophy (LVH)†
  • Obesity (BMI >30 kg/m2 and/or waist circumference >102 cm in men, >88 cm in women)
  • Family history of CVD before age 55 years in a mother, father or sibling
  • Presence of albuminuria#
  • Atrial fibrillation
  • Impaired fasting glucose ≥6.1 mmol and <7.0 mmol or glucose intolerance (2 hour glucose ≥7.8 mmol and ≤11.0 mmol)
  • Socioeconomic hardship
  • Depression or other psychosocial stress
  • Excessive alcohol intake
  • Extreme risk factor elevations (SBP ≥180 or DBP ≥110, total cholesterol >7.5 mmol/L)
  • Type 2 diabetes and age >60 years
  • Type 2 diabetes and albuminuria#
  • Moderate to severe chronic kidney disease (eGFR <45 mL/min/1.73 m2 or persistent proteinuria)
  • Familial hypercholesterolaemia
* The 1991 Framingham risk equation is intended for people without CVD. The most recently recorded pre-treatment measures for blood pressure or lipids should be used to estimate CVD risk in people already receiving treatment. Where this is not possible, clinicians should make decisions on use of pharmacotherapy based on discussions with the patient and consideration of the individual context
† It is preferable to assess for LVH on the basis of echocardiography criteria rather than via an electrocardiogram
‡ There are many additional risk factors that are independently associated with increased CVD risk such as C-reactive protein, coronary calcium scores, and plasma homocysteine levels. Measurement of such factors can be costly and invasive and there is limited evidence to suggest that assessment of these risk factors substantially improves risk prediction over those listed in Table 12.1
§ Fasting lipid specimens are recommended, but a reasonable estimation of risk will be obtained from a non-fasting sample in most circumstances
# Albuminuria is defined as an albumin excretion rate >20 mcg/min or urinary albumin to creatinine Ratio >2.5 mg/mmol in males
and >3.5 mg/mmol in females
Sources: Framingham risk equation factors from Anderson K, Odell P, Wilson P, Kannel W 19916; non-Framingham risk equation factors from National Vascular Disease Prevention Alliance 2009 and Colagiuri S, Davies D, Girgis S, Colagiuri R 20097,31 and clinically high risk conditions from National Vascular Disease Prevention Alliance 20097

Interventions

Although there is substantial work needed to improve the evidence base for absolute risk based screening and management for Aboriginal and Torres Strait Islander people, the following recommendations have been made. The following tables outline the recommendations for people without CVD and for those with established CVD.

Recommendations: For people without an established diagnosis of CVD
Preventive intervention typeWho is at risk?What should be done?How often?Level/strength of evidence
Screening Age 12–17 years Assess smoking status, physical activity, nutrition, BMI and waist circumference (see Chapter 1: Lifestyle)
Advise lifestyle risk reduction accordingly (see Chapter 1: Lifestyle)
Opportunistic and as part of an annual health assessment GPP4
Age 18–34 years without any vascular risk factors Assess smoking status, physical activity, nutrition, BMI and waist circumference
Also assess BP, family history of premature CVD, diabetes risk (see Chapter 14: Diabetes prevention), psychosocial risk factors (see Chapter 10: Mental health) and socioeconomic risk factors
Advise lifestyle risk reduction accordingly (see Chapter 1: Lifestyle)
Opportunistic and as part of an annual health assessment GPP9
Age 18–34 years and one or more of the following is present: family history of premature CVD or chronic kidney disease (CKD), overweight/obesity, smoking, diabetes, elevated BP Assess risk factors as above*
Also assess serum lipids and screen for CKD (see Chapter 13: Chronic kidney disease prevention and management)
Advise lifestyle risk reduction accordingly (see Chapter 1: Lifestyle)
Opportunistic and as part of an annual health assessment GPP9–11
Age 35–74 years Assess for the presence of any Framingham, non-Framingham risk factors and clinically high risk conditions (see Table 12.1)
If no clinically high risk conditions are present then calculate absolute 5 year CVD risk using the Australian cardiovascular risk charts (Appendix 1) or the Framingham risk equation (FRE) calculator (see Resources)
As part of an annual health assessment and review according to level of risk (see below) IIB7,12–15
Age over 74 years Assess for presence of any Framingham, non-Framingham risk factors and clinically high risk conditions (see Table 12.1) but assume CVD risk is high Review according to clinical context GPP14,15
Behavioural People with low absolute 5 year CVD risk (<10%) Advise lifestyle risk reduction as needed for the following (see Chapter 1: Lifestyle):
  • physical activity
  • weight loss
  • smoking cessation
  • salt reduction to less than 4 g salt/day (1600 mg sodium/day)
  • diet rich in fruit and vegetables, wholegrain cereals, nuts and seeds, legumes, fish, lean meat, poultry, low fat dairy products and limiting saturated and trans fat intake
  • limit alcohol intake to ≤2 standard drinks/day
Review risk every 2 years IA9,14,16–19
People with the following:
  • absolute 5 year CVD risk moderate or high (≥10%)
  • presence of any clinically high risk conditions (see Table 12.1)
Advise lifestyle risk reduction as above
Provide intensive intervention support (see Chapter 1: Lifestyle)
Review according to clinical context IB9,11,14,15,20–22
Chemoprophylaxis People at low absolute risk:
  • <10% 5 year CVD risk and with BP persistently ≥160/100 mmHg
Consider commencing a BP lowering medication unless contraindicated Review according to clinical context GPP14
People at moderate absolute risk:
  • 10–15% 5 year CVD risk
Review individual risk factor profile and recommend commencing a BP lowering medication and/or lipid lowering medication unless contraindicated** Review according to clinical context IB9,11,14,15,20–22
  • People at high absolute risk:

    >15% 5 year CVD risk or presence of any clinically high risk conditions (see Table 12.1)
Recommend commencing both a BP lowering medication and lipid lowering medication regardless of risk factor levels unless contraindicated** Review according to clinical context IB9,11,14,15,20–22
Aspirin is not routinely recommended IC14
Patients with atrial fibrillation (AF) without prior CVD Determine the cause of AF and manage rate and rhythm control. Assess and manage CVD risk as above. Consider oral anticoagulant treatment if valvular heart disease is present or two or more of the following risk factors are present (based on the CHADS2 score23):
  • Congestive heart failure
  • Hypertension
  • Age >75 years
  • Diabetes
  • prior Stroke or TIA
Review according to clinical context IA12,24–26
* Although absolute CVD risk assessment is currently not recommended in Aboriginal and Torres Strait Islander people aged less than 35 years, a multifactorial assessment of CVD risk factors is still recommended to guide management decisions. Treatment on the basis of elevated single risk factors may still be appropriate depending on the clinical context
** Specific choice of BP and lipid lowering agents and guidelines on treatment targets is beyond the scope of this guideline. See Resources for links to specific management guidelines. If BP or lipid levels are extreme or non-responsive to treatment then further investigation for underlying causes is recommended
Recommendations: For people with an established diagnosis of CVD
Preventive intervention typeWho is at risk?What should be done?How often?Level/strength of evidence
Screening People with CVD Calculation of the absolute CVD risk using the FRE calculator is not recommended. Five year risk of a subsequent CVD event is assumed to be high14 N/A  
Behavioural People with CVD Intensive lifestyle risk factor management as for patients without an established diagnosis of CVD (see Table 12.1) Review at every visit 1A9,13,14,16–19
A tailored cardiac rehabilitation program should be offered to all people post myocardial infarction (MI) and other acute coronary syndromes, and to those who have undergone revascularisation procedures Post CVD event 1A
Chemoprophylaxis People with CVD Commence BP lowering treatment at any BP level unless there is symptomatic hypotension* Lifelong IA9,13,27
Commence lipid lowering treatment with a statin at any cholesterol level unless contraindicated* Lifelong IA11,13,27
Commence low dose aspirin treatment (75–150 mg) unless contraindicated
Consider alternative antiplatelet agents such as clopidogrel (75 mg) if aspirin hypersensitivity is present
For people with ischaemic stroke combination aspirin/dipyridamole may also be considered
Lifelong IA13,27–29
People with CHD with stent insertion or recent acute coronary heart disease Consider clopidogrel (75 mg) in combination with aspirin For 12 months post stent insertion depending on stent type and circumstances of implantation IIB27,29
People with stroke/TIA Oral anticoagulant treatment is recommended if AF or cardio-embolic stroke is present unless contraindicated. Consultation of specific management guidelines is recommended (see Resources) Lifelong IA13,26,30
* Specific choice of BP and lipid lowering agents and guidelines on treatment targets is beyond the scope of this guideline. See Resources for links to specific management guidelines. If BP or lipid levels are extreme or non-responsive to treatment then further investigation for underlying causes is recommended

Resources

For absolute risk calculation consult:
The Australian cardiovascular risk charts (see Appendix 1) and
www.heartfoundation.org.au/ SiteCollectionDocuments/aust-cardiovascular-risk-charts.pdf

Calculators embedded in clinical software programs
Framingham Risk Equation calculator
www.cvdcheck.org.au

For blood pressure and lipid management guidelines consult:
Guidelines for the management of absolute cardiovascular disease risk:
www.heartfoundation.org.au/ SiteCollectionDocuments/Guidelines-management-absolute-cardiovascular-disease-risk.pdf

For oral anticoagulant management recommendations consult:
Therapeutic Guidelines: Cardiovascular.

References

  1. Australian Institute of Health and Welfare. Australia’s health 2010. Australia’s health series no. 12. Cat. no. AUS 122. Canberra: AIHW, 2010. Cited October 2011. Available at www.aihw.gov.au/ publications/index.cfm/title/11374.
  2. Vos T, Barker B, Stanley L, Lopez AD. The burden of disease and injury in Aboriginal and Torres Strait Islander peoples 2003. Brisbane: School of Population Health, The University of Queensland, 2007.
  3. Couzos S, Murray R. Aboriginal Primary healthcare: an evidence-based approach, 3rd edn. Melbourne: Oxford University Press, 2008.
  4. Australian Institute of Health and Welfare. Cardiovascular disease and its associated risk factors in Aboriginal and Torres Strait Islander peoples 2004–05. Cardiovascular disease series no. 29. Cat. no. CVD 41. Canberra: AIHW, 2008.
  5. Jackson R, Lawes C, Bennet D, Milne R, Rodgers A. Treatment with drugs to lower blood pressure and blood cholesterol based on an individual’s absolute cardiovascular risk. Lancet 2005;365:434–41.
  6. Anderson K, Odell P, Wilson P, Kannel W. Cardiovascular disease risk profiles. Am Heart J 1991;121(1):293–8.
  7. National Vascular Disease Prevention Alliance. Guidelines for the assessment of absolute cardiovascular risk. National Vascular Disease Prevention Alliance, 2009.
  8. Wang Z, Hoy W. Is the Framingham coronary heart disease absolute risk function applicable to Aboriginal people? Med J Aust 2005;182(2):66–9.
  9. National Heart Foundation of Australia. Guide to management of hypertension 2008. Sydney: National Heart Foundation of Australia, updated December 2010. Cited January 2012. Available at www.heartfoundation.org.au/ SiteCollectionDocuments/Hypertension Guidelines2008to2010Update.pdf.
  10. Caring for Australasians with Renal Impairment. Screening for chronic kidney disease – draft guideline. Sydney: CARI, 2011.
  11. National Heart Foundation of Australia, Cardiac Society of Australia and New Zealand. Position Statement on Lipid Management. Heart Lung Circ 2005;14:275–91.
  12. Goldstein LB, Adams R, Alberts MJ, et al. Primary prevention of ischemic stroke: a guideline from the American Heart Association/American Stroke Association Stroke Council. Stroke 2006;37(6):1583.
  13. National Stroke Foundation. Clinical guidelines for stroke management. Melbourne: National Stroke Foundation, 2010.
  14. National Vascular Disease Prevention Alliance. Guidelines for the management of absolute cardiovascular disease risk. National Vascular Disease Prevention Alliance, 2012.
  15. New Zealand Guidelines Group. New Zealand cardiovascular guidelines handbook: a summary resource for primary care practitioners. Wellington: New Zealand Guidelines Group, 2009. Cited October 2011. Available at www.nzgg.org.nz/ search?resource_type=Guideline+summary.
  16. Wolff T, Miller T. Evidence for the reaffirmation of the US Preventive Services Task Force recommendation on screening for high blood pressure. Ann Intern Med 2007;147(11):787.
  17. Dickinson HO, Mason JM, Nicolson DJ, et al. Lifestyle interventions to reduce raised blood pressure: a systematic review of randomized controlled trials. J Hypertens 2006;24:215–33.
  18. McFadden CB, Brensinger CM, Berlin JA, Townsend RR. Systematic review of the effect of daily alcohol intake on blood pressure. Am J Hypertens 2005;18(2):276–86.
  19. Xin X, He J, Frontini MG, Ogden LG, Motsamai OI, Whelton PK. Effects of alcohol reduction on blood pressure: a meta-analysis of randomized controlled trials. Hypertension 2001;38(5):1112.
  20. Mancia G, De Backer G, Dominiczak A, et al. 2007 Guidelines for the management of arterial hypertension: The Task Force for the Management of Arterial Hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC). J Hypertens 2007;25(6):1105.
  21. National Institute for Health and Clinical Excellence. Management of hypertension in adults in primary care. London: National Institute for Health and Clinical Excellence, 2006. Cited October 2011. Available at www.nice.org.uk/ nicemedia/pdf/CG034NICE guideline.pdf.
  22. National Institute for Health and Clinical Excellence. Lipid modification: cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease. London: National Institute for Clinical Excellence, 2008. Cited October 2011. Available at www.nice.org.uk/ nicemedia/pdf/CG67NICE Guideline.pdf.
  23. Gage BF, van Walraven C, Pearce L, et al. Selecting patients with atrial fibrillation for anticoagulation. Circulation 2004 October 19,2004;110(16):2287–92.
  24. Aguilar MI, Hart R. Oral anticoagulants for preventing stroke in patients with non-valvular atrial fibrillation and no previous history of stroke or transient ischemic attacks. Cochrane Database Syst Rev 2005;July 20;(3):CD001927.
  25. Singer DE, Albers GW, Dalen JE, et al. Antithrombotic therapy in atrial fibrillation. Chest 2008;133(Suppl 6):546S.
  26. National Institute for Health and Clinical Excellence. The management of atrial fibrillation. London: National Institute for Health and Clinical Excellence, 2006. Cited October 2011. Available at http://guidance.nice.org.uk/ CG36/Guidance/pdf/English.
  27. National Heart Foundation of Australia, Cardiac Society of Australia and New Zealand. Reducing risk in heart disease (updated 2008). Melbourne: National Heart Foundation, 2007. Cited January 2012. Available at www.heartfoundation.org.au/ SiteCollectionDocuments/Reduce-risk-in-heart-disease-guideline.pdf.
  28. Graham I, Atar D, Borch-Johnsen K, et al. European guidelines on cardiovascular disease prevention in clinical practice. Fourth Joint Task Force of the European Society of Cardiology and other societies on cardiovascular disease prevention in clinical practice. Eur J Cardiovasc Prev Rehabil 2007;14:S1.
  29. Acute Coronary Syndrome Guidelines Working Group. Guidelines for the management of acute coronary syndromes. Med J Aust 2006;184(8 Suppl):S9–29.
  30. Furie KL, Kasner SE, Adams RJ, et al. Guidelines for the prevention of stroke in patients with stroke or transient ischemic attack: a guideline for healthcare professionals from the american heart association/american stroke association. Stroke 2011 Jan;42(1):227–76.
  31. Colagiuri S, Davies D, Girgis S, Colagiuri R. National evidence based guideline for case detection and diagnosis of type 2 diabetes. Canberra: NHMRC and Diabetes Australia, 2009. Cited October 2011. Available at www.nhmrc.gov.au/ _files_nhmrc/publications/attachments/di17-diabetes-detection-diagnosis.pdf
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