Prevention of ischaemic heart disease and atherosclerosis

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Patients at risk for cardiovascular diseases (such as stroke or myocardial infarction) may benefit from lifestyle modification and lipid-lowering medicine therapy. Patients should be managed according to their level of risk, and lipid lowering medicines should be given to those with a high risk of CVD even if cholesterol is within the desirable range.

Indications for lipid lowering medicine therapy

Patients with any of the following factors are at a relatively high risk for a cardiovascular event and should receive lipid lowering therapy:

  • Established atherosclerotic disease:
    • ischaemic heart disease
    • peripheral vascular disease
    • atherothrombotic stroke
  • Type 2 diabetes with age > 40 years.
  • Diabetes for > 10 years.
  • Diabetes with chronic kidney disease (eGFR < 60 mL/min).

Patients with any of the following factors are also potentially at risk for cardiovascular disease (other than the categories above)

  • diabetes mellitus
  • hypertension
  • central obesity: waist circumference ≥ 94 cm (men) and ≥ 80 cm (women)
  • smoking
  • age: men > 55 years of age, women > 65 years of age

These patients should be managed according to their 10-year risk of a cardiovascular event as calculated using either:

A. BMI-based risk assessment, or

B. Framingham risk score (cholesterol-based assessment).

Management is based on the patient’s 10-year risk of a cardiovascular event as follows:

  • < 10% risk: lifestyle modification and risk assess patient every 5 years
  • 10–20% risk: lifestyle modification and risk assess patient annually
  • ≥ 20% risk: lifestyle modification and start statin treatment

Cardiovascular disease risk assessment

A: BMI-based risk assessment:

  1. Measure body mass index (BMI): BMI=weight (kg)/[height (m) x height (m)]
    LoEIII [1]
  2. Measure blood pressure.
  3. Calculate 10-year risk of a cardiovascular event using the BMI-based CVD risk tool.
    (BMI and BMI-based CVD risk tools are available on the EML Clinical Guide mobile application or at: https://www.framinghamheartstudy.org/fhs-risk-functions/cardiovascular-disease-10-year-risk/).

B: Framingham risk score (cholesterol-based):

Calculation of risk of developing cardiovascular events over 10 years (in the absence of cardiovascular disease or genetic disorders such as familial hypercholesterolaemia)

To derive the absolute risk as a percentage of patients who will have a cardiovascular event (i.e. death, myocardial infarction or stroke) over 10 years, add the points for each risk category (Section A). The risk associated with the total points is then derived from Section B.

SECTION A
Age
(years) 		MEN WOMEN
30–34 0 0
35–39 2 2
40–44 5 4
45–49 6 5
50–54 8 7
55–59 10 8
60–64 11 9
65–69 12 10
70–74 14 11
75–79 15 12
Total cholesterol
(mmol/L) 		MEN WOMEN
<4.1 0 0
4.1–5.19 1 1
5.2 – 6.19 2 3
6.2–7.2 3 4
>7.2 4 5
HDL cholesterol
(mmol/L) 		MEN WOMEN
>1.5 –2 –2
1.3–1.49 –1 –1
1.2–1.29 0 0
0.9–1.119 1 1
<0.9 2 2
MEN WOMEN
Smoker 4 3
Diabetic* 3 4

*Type 2 diabetics > 40 years of age qualify for statin therapy irrespective of risk score.

MEN MEN WOMEN WOMEN
Systolic BP (mmHg) Untreated Treated Untreated Treated
<120 –2 0 –3 –1
120–129 0 2 0 2
130–139 1 3 1 3
140–149 2 4 2 5
150–159 2 4 4 6
≥160 3 5 5 7

SECTION B

Total points

Total points
MEN 10-year risk % WOMEN 10-year risk %
≤–3 <1 ≤–2 <1
–2 1.1 –1 1.0
–1 1.4 0 1.2
0 1.6 1 1.5
1 1.9 2 1.7
2 2.3 3 2.0
3 2.8 4 2.4
4 3.3 5 2.8
5 3.9 6 3.3
6 4.7 7 3.9
7 5.6 8 4.5
8 6.7 9 5.3
9 7.9 10 6.3
10 9.4 11 7.3
11 11.2 12 8.6
12 13.2 13 10.0
13 15.6 14 11.7
14 18.4 15 13.7
15 21.6 16 15.9
16 25.3 17 18.5
17 29.4 18 21.5
≥18 >30 19 24.8

Calculation of CVS risk using the table:

A risk of MI > 20% in 10 years equates to ≥ 15 points for men, and ≥ 18 points for women. It is important to score each patient individually, as there are many combinations of risk factors that can add up to those total points.

For example:

  • A male patient > 60 years old with systolic BP > 140 mmHg on treatment would score:
    • 11 points for his sex and age
    • 4 points for his on-treatment BP
    • Total: 15 points
  • A male patient > 50 years old with systolic BP > 130 mmHg on treatment who is a smoker would score:
    • 8 points for his sex and age
    • 3 points for his on-treatment BP
    • 4 points for his smoking status
    • Total: 15 points
  • A female patient > 70 years old with systolic BP > 160 mmHg on treatment would score:
    • 11 points for her sex and age
    • 7 points for her on-treatment BP
    • Total: 18 points

Screening for familial hypercholestareamia:

In addition to the above cardiovascular risk assessment, measure random total cholesterol in patients with the following features (suggestive of familial hypercholesterolaemia or other heritable dyslipidaemias), regardless of their cardiovascular risk:

  • cardiovascular event < 55 years in men or < 65 years in women
  • family history of early onset cardiovascular disease in male relatives < 55 years of age and in female relatives < 65 years of age
  • skin or tendon xanthomata in patient or first degree relative
  • family history of familial hyperlipidaemia

Refer patients with random total cholesterol > 7.5 mmol/L for further investigation.

GENERAL MEASURES

All people with any risk factors for cardiovascular disease should be encouraged to make the following lifestyle changes as appropriate.

  • maintain ideal weight, i.e. BMI < 25 kg/m2
  • weight reduction in the overweight patient, i.e. BMI > 25 kg/m2
  • reduce alcohol intake to ≤ 2 standard drinks/day for men and ≤ 1 for women on no more than 5 out of 7 days per week (1 standard drink is equivalent to 25 mL of spirits, 125 mL of wine, 340 mL of beer or sorghum beer, or 60 mL of sherry)
  • follow a prudent eating plan i.e. low fat, high fibre and unrefined carbohydrates, with fresh fruit and vegetables
  • regular moderate aerobic exercise, e.g. 30 minutes brisk walking 3–5 times/week (150 minutes/week)
  • stop smoking

MEDICINE TREATMENT

Note:

  • Lipid lowering medicines should be given to those with a high risk of CVD even if cholesterol is within the desirable range.
  • When lipid-lowering medicines are used, this is ALWAYS in conjunction with ongoing lifestyle modification.
  • HMGCoA reductase inhibitors (statins), according to table below:
INDICATION HMGCOA REDUCTASE INHIBITOR (STATIN) DOSE
A: Primary prevention  - no existing CVD
  • Type 2 diabetes with age > 40 years.

  • Diabetes for > 10 years.

  • Diabetes with chronic kidney disease.

  • ≥ 20% 10-year risk of cardiovascular event.
    		•
  • HMGCoA reductase inhibitors (statins), e.g.:
    • Simvastatin, oral, 10 mg at night.
    		•
  • Patients on protease inhibitors.
    (Risks as above, after switching to atazanavir – see section below).
    		•
  • Atorvastatin, oral, 10 mg at night.
    		•
    B: Secondary prevention – existing CVD
  • Ischaemic heart disease.

  • Atherothrombotic stroke.

  • Peripheral vascular disease.
    		•
  • HMGCoA reductase inhibitors (statins), e.g.:
    • Simvastatin, oral, 40 mg at night.

    LoEI [2]
  • Patients on protease inhibitors.
    		•
  • Atorvastatin, oral, 10 mg at night.

    • LoEI [3]
  • Patients on amlodipine (and not on protease inhibitor).
    		•
  • Simvastatin, oral, 10-20 mg at night.

    • LoEIII [4]
  • If patient complains of muscle pain.
    		•  Reduce dose
  • HMGCoA reductase inhibitors (statins), e.g.:
    • Simvastatin, oral, 20 mg at night.
    o If 20 mg not tolerated, reduce to 10 mg.
    OR
        Consult specialist for further management.
    LoEIII [5]

    • Note: Lipid-lowering medicines must always be used in conjunction with ongoing lifestyle modification.

    LoEI [2]

    LoEI [3]

    LoEIII [4]

    LoEIII [5]

    Protease inhibitor-induced dyslipidaemia:

    • Certain antiretroviral medication, particularly protease inhibitors, can cause dyslipidaemia. Fasting lipid levels should be done 3 months after starting lopinavir/ritonavir. Lopinavir/ritonavir is associated with a higher risk of dyslipidaemia (specifically hypertriglyceraemia) than atazanavir/ritonavir.
    • Patients at high risk (> 20% risk of developing a CVS event in 10 years) should switch to atazanavir/ritonavir and repeat the fasting lipid profile in 3 months.
    • Patients with persistent dyslipidaemia despite switching, qualify for lipid lowering therapy. Criteria for initiating lipid lowering therapy are the same as for HIV-uninfected patients. Many statins (including simvastatin) cannot be used with protease inhibitors, as protease inhibitors inhibit the metabolism of the statin resulting in extremely high blood levels.
    • Patients who fail to respond to lifestyle modification and have dyslipidaemia treat with:
      • Atorvastatin, oral, 10 mg at night.

    REFERRAL

    • Random cholesterol > 7.5 mmol/L (to be evaluated for genetic disorders), after excluding secondary causes such as uncontrolled diabetes, hypothyroidism, or protease inhibitor use.
    • Tendon or skin xanthomata (except xanthelasma around the eyes).
    • Statins not tolerated by patients, despite lower dose (for consideration of alternative treatment).