Prevention of Coronary Heart Disease (CHD) — Park's Framework

Risk Factors for CHD

Non-Modifiable

Modifiable (Major)

Modifiable (Minor/Emerging)

• Hypertriglyceridaemia, Low HDL, Homocysteinaemia, CRP elevation, Fibrinogen, Lipoprotein(a), Oral contraceptive use

The Four Levels of Prevention

🔵 Primordial Prevention

Targets the pre-risk stage — preventing the emergence of risk factors themselves in the population

• National/Community level policies: food labelling, salt reduction in processed foods, tobacco control legislation (FCTC), trans-fat bans
• Health education: promotion of healthy diet, physical activity, non-smoking habits from childhood
• School-based programmes: nutrition education, physical fitness curricula
• Urban planning: creating environments conducive to walking, cycling
• Social/economic development to reduce poverty and improve living standards

Concept: Prevention is directed at social, environmental, and economic conditions that allow risk factors to arise — not at the individual risk factors themselves.

🟢 Primary Prevention

Targets individuals at risk (risk factors present, no disease yet) — preventing CHD from ever occurring

• Health education about CHD risk factors
• Promote balanced diet low in saturated fats, trans fats, salt, and refined sugars
• Encourage regular aerobic exercise (brisk walking, cycling, swimming)
• Weight management & avoidance of central obesity
• Stress management; work–life balance

• Anti-tobacco programmes; smoking cessation support (NRT, counselling)
• Control of hypertension (lifestyle + pharmacotherapy where indicated)
• Control of hyperlipidaemia (statins in high-risk individuals, diet)
• Glycaemic control in diabetes
• Aspirin in selected high-risk individuals (as per guidelines)
• Screening and referral programmes for risk factor detection

Key principle: Even a modest reduction in population-wide risk factor levels produces large absolute reductions in CHD incidence (Rose's strategy).

🟡 Secondary Prevention

Targets those with established CHD — halting progression, preventing recurrence and complications

• ECG, stress testing, coronary angiography
• Screening of high-risk asymptomatic individuals

• Thrombolysis/primary PTCA/CABG for acute MI
• Antiplatelet therapy (aspirin + clopidogrel)
• Beta-blockers (post-MI cardioprotection)
• ACE inhibitors/ARBs (post-MI, HF with reduced EF)
• High-intensity statins (LDL-C ≥ 50% reduction)
• Nitrates for angina
• Rehabilitation post-MI

• Prevent heart failure progression
• Prevent arrhythmias (ICD implantation where indicated)
• Prevent re-infarction through strict risk factor control

🔴 Tertiary Prevention

Targets those with severe/complicated CHD — restoring maximal function and preventing further disability

• Cardiac rehabilitation programme (Phase I–III):
  • Phase I: In-hospital mobilisation
  • Phase II: Supervised outpatient exercise
  • Phase III: Long-term community maintenance
• Psychosocial rehabilitation; management of depression and anxiety
• Vocational rehabilitation — return to work

• Continued pharmacotherapy adherence (statins, antiplatelets, beta-blockers, ACEi)
• Lifestyle modification reinforcement
• Regular follow-up and monitoring

• Management of end-stage heart failure (diuretics, device therapy, transplant evaluation)
• Palliative care for irreversible cardiac disability

Summary Diagram (Textual)

NATURAL HISTORY OF CHD
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
  No risk       Risk factors     Subclinical     Clinical     Complications
  factors       emerging         CHD             CHD          / Death
     │               │               │               │              │
     ▼               ▼               ▼               ▼              ▼
┌──────────┐  ┌───────────┐  ┌───────────┐  ┌────────────┐  ┌──────────┐
│PRIMORDIAL│  │  PRIMARY  │  │ SECONDARY │  │ SECONDARY  │  │TERTIARY  │
│Prevention│  │Prevention │  │Prevention │  │Prevention  │  │Prevention│
│(pop-level│  │(risk factor│  │(early Dx &│  │(treatment) │  │(rehab &  │
│ policies)│  │ control)  │  │ screening)│  │            │  │ palliate)│
└──────────┘  └───────────┘  └───────────┘  └────────────┘  └──────────┘
     ↑               ↑               ↑               ↑              ↑
 Leavell &     Leavell &        Leavell &       Leavell &      Leavell &
 Clark Level  Clark Level 1    Clark Level 2   Clark Level 3  Clark Level 4/5
   (added      (Health         (Early diag.    (Treatment     (Rehab)
  by WHO)      Promo +          + Rx)            + Disab.
               Specific                          limit.)
               Protection)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Key Park's Concepts in CHD Prevention

Note: Park's Textbook of Preventive and Social Medicine (24th ed.) places CHD prevention within the broader framework of non-communicable disease (NCD) control, emphasising that primordial prevention — absent from earlier Leavell & Clark schemas — is the most impactful level for population-wide CHD burden reduction, as it prevents the very emergence of risk factors.