Blood pressure and cardiovascular risk

Systemic Hypertension & Peripheral Vascular Disease

Systemic hypertension is the single greatest modifiable risk factor for cardiovascular disease, stroke, chronic kidney disease, and vascular dementia in Australia. Modern clinical practice shifts the therapeutic focus from isolated blood pressure thresholds to comprehensive absolute cardiovascular disease (CVD) risk assessment, ensuring that lifestyle interventions and pharmacotherapy are targeted according to overall vascular risk.

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Diagnostic Criteria and Blood Pressure Measurement Modalities

Accurate measurement of blood pressure is essential to avoid misclassification:

• In-Clinic Measurement: The patient should be seated quietly in a chair with back supported for at least 5 minutes prior to measurement, feet flat on the floor, and the arm supported at heart level. An appropriately sized cuff must be used (bladder encircling $80\%\text{ to }100\%$ of the arm circumference). A diagnosis of hypertension requires a clinic systolic blood pressure (SBP) $\ge 140\text{ mmHg}$ and/or diastolic blood pressure (DBP) $\ge 90\text{ mmHg}$ confirmed across at least two separate clinical consultations, unless the baseline reading is severely elevated ($\ge 180/110\text{ mmHg}$) or accompanied by acute target organ damage.
• Ambulatory Blood Pressure Monitoring (ABPM): Recognized as the reference standard out-of-office modality. Confirms hypertension if the 24-hour mean is $\ge 130/80\text{ mmHg}$, the daytime (awake) mean is $\ge 135/85\text{ mmHg}$, or the nighttime (asleep) mean is $\ge 120/70\text{ mmHg}$. ABPM also identifies abnormal nocturnal non-dipping patterns (failure of SBP to fall by $> 10\%$ at night), which is a powerful independent predictor of adverse cardiovascular and cerebrovascular outcomes.
• Home Blood Pressure Monitoring (HBPM): Recommended for confirming the diagnosis and long-term surveillance. The patient performs duplicate morning and evening measurements for 7 consecutive days. Day 1 measurements are discarded, and the mean of the remaining readings is calculated. A home average $\ge 135/85\text{ mmHg}$ confirms hypertension.
• Phenotypic Discrepancies:
  • White-Coat Hypertension: Elevated in-clinic blood pressure with normal ABPM/HBPM readings. Carries modest long-term risk; managed with lifestyle modification and annual surveillance.
  • Masked Hypertension: Normal clinic blood pressure with elevated out-of-office ABPM/HBPM readings. Carries a cardiovascular risk equivalent to sustained hypertension and requires formal antihypertensive drug therapy.

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Australian Absolute Cardiovascular Disease Risk Assessment (2023+ Guidelines)

In 2023, the Australian Cardiovascular Health and Prevention Alliance and the National Heart Foundation released the updated Australian Guideline for assessing and managing cardiovascular disease risk. This replaced the older Framingham-based risk charts with a modern Australian algorithm derived from the New Zealand PREDICT cohort, recalibrated for contemporary Australian population incidence:

Target Screening Populations

• All asymptomatic individuals aged 45 to 79 years without pre-existing CVD.
• All First Nations (Aboriginal and Torres Strait Islander) peoples aged 30 to 79 years, reflecting earlier onset of vascular disease and health inequities.
• People with diabetes aged 35 to 79 years.

Stratification Categories (5-Year Risk of a Cardiovascular Event)

• Low Absolute Risk ($< 5\%$): Managed with lifestyle interventions (dietary modification, physical activity, alcohol limitation, smoking cessation) with risk recalculation every 5 years.
• Intermediate Absolute Risk ($5\%\text{ to below }10\%$): Lifestyle modification combined with consideration of blood pressure-lowering and lipid-lowering pharmacotherapy if risk factors persist or reclassifying risk modifiers are present (e.g., elevated coronary artery calcium score, persistent socioeconomic disadvantage, family history of premature CVD).
• High Absolute Risk ($\ge 10\%$): After discussing benefits and harms, prescribe blood-pressure-lowering and lipid-modifying treatment unless contraindicated or clinically inappropriate, alongside lifestyle support. Consider baseline pressure, adverse-effect risk and the patient’s preferences.

Clinically determined high risk

Established cardiovascular disease requires secondary prevention. In primary prevention, confirmed familial hypercholesterolaemia or moderate-to-severe CKD establishes high risk without calculation: sustained eGFR below 45 mL/min/1.73 m2 or persistent ACR above 25 mg/mmol in men or 35 in women. Diabetes alone after 60, BP above 180/110 or total cholesterol above 7.5 are older automatic categories and should not replace the current Australian algorithm. Treat severe hypertension and investigate very high lipids independently on their clinical merits.

For eligible patients, low five-year risk is below 5%, intermediate is 5 to below 10%, and high is at least 10%. Discuss lifestyle, preventive medication, benefits and adverse effects using absolute risk and preferences. Reclassification factors and secondary causes can modify the plan.

First-Line Pharmacotherapy and Antihypertensive Selection

Contemporary Australian guidelines recommend three core drug classes for initial therapy:

1. Angiotensin-Converting Enzyme (ACE) Inhibitors or Angiotensin Receptor Blockers (ARBs):
   • Examples: Perindopril, ramipril, candesartan, telmisartan.
   • First-line for patients with type 2 diabetes, chronic kidney disease with albuminuria, heart failure, or history of myocardial infarction.
   • Adverse Effects: Dry cough occurs in $5\%\text{ to }10\%$ of patients on ACE inhibitors due to bradykinin accumulation (necessitating a switch to an ARB); angioedema; hyperkalaemia.
2. Dihydropyridine Calcium Channel Blockers (CCBs):
   • Examples: Amlodipine, lercanidipine.
   • Potent vasodilators especially efficacious in older individuals and isolated systolic hypertension.
   • Adverse Effects: Dose-dependent peripheral ankle oedema (caused by precapillary arteriolar vasodilation rather than generalized fluid retention; does not respond to loop diuretics; combination with an ACEi/ARB reduces capillary hydrostatic pressure and resolves the oedema).
3. Thiazide-Like Diuretics:
   • Examples: Indapamide ($1.25\text{ to }2.5\text{ mg}$ daily) or chlorthalidone.
   • Clinical Note: Thiazide-like diuretics are clinically superior to hydrochlorothiazide (HCTZ) due to longer half-lives, greater 24-hour ambulatory blood pressure reduction, and robust evidence of cardiovascular event reduction in randomized clinical trials.
   • Adverse Effects: Hypokalaemia, hyponatraemia, hyperuricaemia (may precipitate acute gout), and mild dyslipidaemia.

Treatment Strategies

• Monotherapy: Suitable for mild hypertension (Grade 1) with low absolute cardiovascular risk.
• Dual Combination Therapy: Recommended as first-line therapy for patients with baseline blood pressure $\ge 20/10\text{ mmHg}$ above target, or those at high absolute CVD risk. Preferred combinations include an ACEi (or ARB) + CCB or an ACEi (or ARB) + Thiazide-like diuretic.
• Beta-Blockers: No longer recommended as first-line monotherapy for uncomplicated primary hypertension because clinical trials show inferior protection against stroke compared to other classes. Beta-blockers are reserved for compelling cardiac indications (angina, HFrEF, post-myocardial infarction, rate control in atrial fibrillation).

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Primary references (checked 7 October 2026): Australian CVD risk guideline.