Cardiovascular Risk Classification

Conducting a comprehensive risk assessment

• In adults without known CVD, a comprehensive assessment of cardiovascular risk includes
• consideration of the following:
  • Modifiable risk factors
    • Smoking status
    • Blood pressure
    • Serum lipids
    • Waist circumference and Body Mass Index (BMI)
    • Nutrition
    • Physical activity level
    • Alcohol intake.
  • Non-modifiable risk factors
    • Age and sex
    • Family history of premature CVD
    • Social history including cultural identity, ethnicity and socioeconomic status.
  • Related conditions
    • Diabetes
    • Chronic Kidney Disease (albuminuria ± urine protein, eGFR)
    • Familial hypercholesterolaemia
    • Evidence of atrial fibrillation (history, examination, electrocardiogram).

Absolute cardiovascular disease (CVD) risk assessment 

• The Australian Cardiovascular Disease (CVD) Risk Calculator is based on the New Zealand PREDICT equation but has been recalibrated and adapted for use within the Australian population and healthcare context.
• Optional Risk Factors:
  • The calculator allows for additional risk considerations, including:
    • Geographical Area: Determined by residential postcodes, indicating area-level socioeconomic deprivation.
    • Atrial Fibrillation: Inclusion as an independent risk factor.
    • Type 2 Diabetes: With additional considerations for:
      • HbA1c levels
      • Duration since diabetes diagnosis (in years)
      • Urinary albumin-to-creatinine ratio (uACR)
      • Estimated glomerular filtration rate (eGFR)
      • Body Mass Index (BMI)
      • Use of insulin within the previous 6 months
    • Current Medications:
      • Blood pressure-lowering medications
      • Lipid-modifying medications
      • Antithrombotic medications
• Risk Estimation:
  • The calculator provides a 5-year risk estimate for cardiovascular events, categorized as follows:
    • High Risk: ≥10% risk over 5 years
    • Intermediate Risk: 5% to <10% risk over 5 years
    • Low Risk: <5% risk over 5 years
• These categories differ from the 2012 Guidelines for managing absolute CVD risk, as recalibration has resulted in distinct percentile ranges for high, intermediate, and low classifications.
• Limitations:
  • The Aus CVD Risk Calculator is not validated for use in individuals with type 1 diabetes, as it may yield inaccurate estimates in this population.
• Definition of Cardiovascular Disease (CVD):
  • For this guideline, ‘cardiovascular disease’ encompasses the following conditions:
    • Myocardial infarction (MI)
    • Angina
    • Other coronary heart disease (CHD)
    • Stroke
    • Transient ischaemic attack (TIA)
    • Peripheral vascular disease
    • Congestive heart failure
    • Other ischemic CVD-related conditions

Target population

• not known to have CVD or to be at
• clinically determined high risk
• All people aged 45-79 years
• People with diabetes aged 35-79 years
• First Nations people aged 30-79 years
  • (First Nations people aged 18-29 years should have their individual risk factors assessed)

First Nations people aged 18-29 years  : The following CVD risk factors should be screened, as part of an annual health check (or opportunistically) or at least every 2 years :

• smoking status
• blood pressure (BP)
• blood glucose level or glycated haemoglobin (HbA1c)
• estimated glomerular filtration rate (eGFR)
• serum lipids
• urine albumin-to-creatinine ratio (uACR)
• history of familial hypercholesterolaemia (FH).13

Clinically determined high risk:

• Adults with any of the following conditions do not require absolute cardiovascular risk assessment using Equation because they are already known to be at clinically determined high risk of CVD:
  • Moderate or severe CKD
    • persistent proteinuria
    • eGFR <45 mL/min/1.73 m2
  • Familial hypercholesterolaemia
    • most common inherited cause of premature CHD, with a prevalence of 1 in 250
    • People with diagnosed FH are at clinically determined high risk and should be automatically managed as high CVD risk.
    • FH-specific calculators may be useful

The Variables (1st step):

Mandatory
Variable	Application
Age	validated for adults aged 30 to 79 years.
Sex	sex at birth – (there is currently insufficient data to stratify risk for people who are intersex or non-binary sex)
Smoking status	Choose from three categories: never smoked previously smoked currently smokes
Blood pressure (BP)	Systolic blood pressure (SBP) in mmHg. –        Use the average of the last two seated, in-clinic BP measurements. –        Convert home and ambulatory BP readings to in-clinic equivalents before entering into the calculator.
Cholesterol	Enter ratio of total cholesterol (TC) to high-density lipoprotein cholesterol (HDL-C). Use most recent measurements (fasting or non-fasting).
Diabetesa (type 2 only)	status: YES or NO
CVD medicines	CVD medicines used during the 6 months prior to risk assessment (lipid-modifying, BP-lowering, and/or antithrombotic medicines) Lipid-modifying medicines – atorvastatin, fluvastatin, pravastatin, simvastatin, acipimox, bezafibrate, cholestyramine, clofibrate, colestipol, ezetimibe, ezetimibe with simvastatin, gemfibrozil and nicotinic acid. BP-lowering medicines – angiotensin converting enzyme inhibitors, betablockers, thiazide, angiotensin II receptor blockers and calcium channel blockers. Antithrombotic medicines – aspirin, clopidogrel, dipyridamole, prasugrel, ticagrelor, ticlopidine, warfarin, dabigatran, phenindione and rivaroxaban.

Additional diabetes type 2-specific variables (not compulsory, but gives more accurate assessment of risk)
Time since diagnosis of diabetes	Enter time in years.
Glycated haemoglobin (HbA1c)	Enter HbA1c in mmol/mol or % (single non-fasting).
uACRb	Enter urine albumin-creatinine ratio (uACR) (measured in mg/mmol).
eGFRb	Enter eGFR in mL/min/1.73m2
Body mass index(BMI)	Measure weight in kilograms and height in metres.  Calculate BMI: kg/m2.
Insulin	Record use of insulin in the 6 months before risk assessment.

Non- Mandatory
Postcode	Postcode is used to calculate Socio-Economic Indexes for Areas (SEIFA) quintile, and under the discretion of the clinician, may be manually adjusted to better reflect the socioeconomic status of individual patients.
Medical history of atrial fibrillation	Known history of electrocardiogram (ECG) confirmed atrial fibrillation: YES or NO. Both paroxysmal and persistent AF are included in the definition of AF.

 Consider reclassification factors (step 2)

Factor	Potential to reclassify upward or downward
Ethnicity	↑ or ↓
Family history of premature CVD	↑
Chronic kidney disease	↑
Severe mental illness	↑
Coronary artery calcium score	↑ or ↓

reclassify downward

• Coronary artery calcium score of 0
• East Asian ethnicity (Chinese, Japanese, Korean, Taiwanese, or Mongolian ethnicities)

reclassify upward

• Coronary artery calcium score > 99 units, or ≥ 75th percentile for age and sex
• Ethinicity
  • First Nations people
  • Māori
  • Pacific Islander
  • South Asian ethnicity (Indian, Pakistani, Bangladeshi, Sri Lankan, Nepali, Bhutanese or Maldivian ethnicities)
• Family history of premature coronary heart disease (CHD) or stroke in a first-degree
  • female relative aged <65 years or
  • male relative aged <55 years
• Chronic kidney disease
  • eGFR 45–59mL/min/1.73m2 and/or
  • persistent uACR
    • 2.5–25mg/mmol (men) or
  • 3.5–35mg/mmol (women)
• Severe mental illness (current or recent mental health condition requiring specialist treatment, whether received or not, in the 5 years prior to the CVD risk assessment.)

Risk category	Estimated  5‑year CVD riska	Management	Reassessment interval
High	≥10%	Encourage, support and advise a healthy lifestyle.b Prescribe ·        blood pressure-lowering ·        lipid-modifying pharmacotherapy.c	Formal reassessment of CVD risk is not generally required. High-risk status requires clinical management and follow up supported by ongoing communication.
Intermediate	5% to <10%	Encourage, support and advise a healthy lifestyle.b   Consider blood pressure-lowering and lipid-modifying pharmacotherapy, depending on clinical context.	Reassess risk every 2 years if not currently receiving pharmacotherapy to reduce CVD risk. Assess sooner if close to the threshold for high risk, if CVD risk factors worsen, or new CVD risk factors are identified. For First Nations people, reassess every year as part of an annual health check (or opportunistically) or at least every 2 years.
Low	<5%	Encourage, support and advise a healthy lifestyle.b   Pharmacotherapy is not routinely recommended.	Reassess risk every 5 years. Assess sooner if close to the threshold for intermediate risk, if CVD risk factors worsen, or new CVD risk factors are identified.   For First Nations people, reassess every year as part of an annual health check (or opportunistically) or at least every 2 years.

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Practice Points – Communicating Cardiovascular Risk

1. Presenting CVD Risk in Patient-Friendly Formats

• Use percentage-based language:
  • e.g., “You have a 15% chance of having a heart attack or stroke in the next 5 years.”
• Translate to frequency-based format:
  • e.g., “15 out of 100 people like you will experience a heart event in 5 years.”
• Incorporate visual aids:
  • Use 100-person diagrams or icon arrays to show the proportion at risk.

2. Considering Health Literacy and Receptivity

• Assess patient understanding:
  • e.g., “How comfortable are you with understanding medical risks?”
• Adapt to learning style:
  • Visual learners: charts, infographics
  • Auditory learners: verbal repetition and open discussion
• Offer decision aids:
  • Booklets, smartphone apps, printed visuals
  • Use tools like the Australian Absolute CVD Risk Calculator

3. Linking Risk to Personal Experiences

• Make it personally relevant:
  • e.g., “Your brother’s recent high BP diagnosis increases your genetic risk.”
• Consider life stage:
  • e.g., “Optimising heart health now is important for a healthy pregnancy.”

4. Discussing and Contextualising CVD Risk Factors

• Identify modifiable risks:
  • e.g., smoking, obesity, alcohol, sedentary lifestyle
• Explain impact:
  • e.g., “Quitting smoking can halve your CVD risk within a year.”
• Promote achievable changes:
  • e.g., “Losing 5% of your body weight can improve BP and reduce risk.”

5. Reinforcing Risk Information Over Time

Use repeated conversations:

• Reassess risk at follow-up visits; reinforce key messages.

• Track and re-evaluate risk:
  • Update assessments with lifestyle changes or treatment.
  • Maintain engagement through encouragement and review.

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Coronary Artery Calcium (CAC) Score

Purpose and Function

• Measures the burden and density of coronary artery calcification, reflecting atherosclerotic plaque load.
• Reported in:
  • Agatston units (AU) – absolute score.
  • Percentiles – relative to age- and sex-matched population.

Limitations

• Does not assess degree of luminal stenosis.
• Not appropriate as a standalone test in symptomatic individuals (e.g. chest pain, suspected angina).

Clinical Utility

• Enhances individualised CVD risk stratification, especially in low-to-intermediate risk individuals.
• May guide decisions on initiation or intensification of pharmacological therapies.
• High negative predictive value – a score of zero is associated with low near-term cardiovascular risk.

Age Considerations

• CAC increases with age, including in healthy individuals.
• Limited discriminative value in patients >75 years, where high CAC scores are common and less specific.

Normal CAC Score (Zero)

Re-testing may be considered in 2–5 years to monitor risk progression.

• Approximately 25% of patients with an initial score of zero will develop CAC within 5 years.

When Not to Use CAC Scoring

• Known coronary heart disease, including:
  • Previous MI
  • Prior revascularisation (PCI or CABG)
  • Established high CVD risk (e.g. ≥15% 5-year risk per Australian guidelines)
• Population screening of asymptomatic individuals without risk factors.

Indications for CAC Testing – Clinical Scenarios

Clinical Situation	CAC Testing	Rationale / Implications
Population screening for CVD	Not recommended	Low yield in asymptomatic general population.
High CVD risk (≥15% 5-year risk)	Not recommended	Would not alter management – treatment already indicated.
Known CVD (e.g. MI, stents, CABG)	Not recommended	Does not guide further risk stratification or management.
Low or intermediate CVD risk + additional risk factors	May be considered if available	Can assist reclassification: – CAC = 0 → lower risk – CAC >99 AU / >75th percentile → higher risk
Considering changes to preventive therapy	May be considered	Can support shared decision-making and treatment adjustments.
Previous CAC score of zero	Re-test in 2–5 years	Allows risk reassessment; ~25% develop CAC over 5 years.

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Non-Calcified Atherosclerosis (Soft Plaque)

Composition:

• Lipid-rich core
• Inflammatory cell infiltrate

Imaging:

• Poorly visualised on CT
• Better detected with cardiac MRI

Rupture Risk:

• Higher risk of rupture than calcified plaque
• Rupture can lead to thrombosis and acute coronary syndromes (ACS)

Prevalence and Age:

• More common in middle-aged and older adults
• Can occur in younger patients with risk factors

Associated Events:

• Strongly linked with myocardial infarction and stroke
• Well-established correlation in literature

Risk Factors:

• Poor lifestyle (diet, inactivity, smoking)
• Hyperlipidaemia (↑ LDL or triglycerides)
• Hypertension
• Diabetes (especially uncontrolled)
• Family history of CVD
• Obesity (central adiposity)
• Older age
• Male sex (higher risk at younger age)
• Chronic inflammation

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Statin Therapy in the Elderly (>79 years)

Initiation Considerations:

• Clinical judgment incorporating:
  • Potential benefit vs. risk
  • Life expectancy and co-morbidities
  • Patient’s values and preferences

Indications to Continue Statin in >79 years:

• Established coronary artery disease
• High coronary calcium score
• ABPI < 0.9
• hsCRP > 2 mg/L
• Consider even without above if NNT justifies (NNT = 83 over 3–4 years to prevent 1 MI; Savarese 2013, JACC)

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Ankle Brachial Pressure Index (ABPI)

Definition:

• Ratio of ankle systolic BP to brachial systolic BP

Interpretation:

• <0.9: Suggests peripheral artery disease (PAD)
• >1.4: Likely calcified, non-compressible arteries (still often PAD)

Clinical Use:

• Associated with coronary and cerebrovascular disease
• Not recommended for routine population screening
• Abnormal results warrant CVD risk factor optimisation

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High-Sensitivity C-Reactive Protein (hsCRP)

Definition:

• Liver-produced inflammatory marker
• Detected down to 0.3 mg/L

Normal/Abnormal Values:

• <3 mg/L: Normal
• >2 mg/L: May indicate increased CVD risk

Clinical Relevance:

• Modestly predictive of CV events
• Limited utility as a standalone screening test

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24-Hour Ambulatory Blood Pressure Monitoring (ABPM)

Utility:

• Measures BP throughout daily activity and sleep

Diagnostic Use:

• Identifies:
  • White coat hypertension
  • Masked hypertension
• Assists in BP treatment evaluation

Limitations in CVD Risk Assessment:

• Adds little beyond standard office BP
• Typically 5 mmHg lower than office readings