Acute Coronary Syndrome: Overview

❤️ Myocardial Infarction (MI) is necrosis of cardiac muscle due to prolonged ischaemia, usually from coronary artery thrombosis. Rapid recognition and early reperfusion therapy reduce mortality. ACS also includes unstable angina and NSTEMI.

🔬 Pathophysiology

• 📉 Atherosclerotic plaque rupture → platelet aggregation → thrombus → coronary occlusion.
• ⚡ Oxygen supply-demand mismatch → ischaemia → myocardial necrosis (~20–40 min for irreversible injury).
• 🧩 STEMI: complete occlusion → transmural infarction; NSTEMI: partial occlusion → subendocardial infarction.
• 🧪 Cellular changes: coagulative necrosis → neutrophilic infiltration → granulation tissue → fibrosis.
• 🫀 Complications relate to infarct size, location, and residual LV function.

⚠️ Risk Factors

• 🚬 Smoking
• 💉 Hypertension, diabetes mellitus, dyslipidaemia
• 👴 Age, male sex, family history of premature CAD
• ⚖️ Obesity, sedentary lifestyle, poor diet
• 💊 Cocaine use or vasospastic disorders (Prinzmetal angina)

🧩 Clinical Features

• 💔 Central chest pain: crushing, radiates to arm, neck, jaw; >20 min, not relieved by rest or GTN
• 😰 Associated: sweating, nausea, vomiting, palpitations, dyspnoea, syncope
• 🩺 Exam: tachy/bradycardia, hypotension, raised JVP, S3 gallop, pulmonary oedema
• 👵 Elderly, diabetic, women: may present atypically (syncope, confusion, epigastric pain, silent MI)

🔎 Differential Diagnosis

• Unstable angina
• Aortic dissection
• Massive pulmonary embolism
• Pericarditis
• GORD or musculoskeletal chest pain

🧪 Investigations

• 📊 ECG: STEMI → ST elevation ≥1 mm in ≥2 limb leads or ≥2 mm in chest leads ± new LBBB; NSTEMI → ST depression/T inversion or non-specific changes
• 🧬 Cardiac biomarkers: troponin I/T rises 4–6h, peaks 12–24h, normalises 7–14 days
• 🧪 Bloods: FBC, U&E, glucose, lipids, coagulation screen
• 🩻 CXR: pulmonary oedema, alternative causes
• 🩺 Echocardiography: regional wall motion abnormalities, LV function, complications (VSD, MR, pericardial effusion)
• Optional: Coronary angiography for diagnosis & PCI planning

🚑 Immediate & Ongoing Management of Acute MI (MONA-BASH + Long-Term Care)

All recommendations are aligned with NICE NG185: Myocardial infarction: secondary prevention and NICE QS68: Acute coronary syndromes.

• 💊 Morphine + Metoclopramide – for severe pain and nausea; titrate carefully, monitor BP & respiration (NICE QS68, 2020)
• 💨 Oxygen – only if SpO₂ <94%; routine oxygen is not recommended in normoxaemic patients (NICE QS68, NG185)
• 💉 Nitrates – GTN spray or infusion if BP adequate; relieve ischaemic pain, reduce preload (NG185 recommendation 1.4.7)
• 🩸 Aspirin 300 mg PO stat → lifelong low-dose (75–100 mg) unless contraindicated (NG185 1.5.1)
• 💙 Beta-blocker – if no contraindication, start early to reduce mortality, arrhythmia risk, and infarct size (NG185 1.5.2)
• 🩺 ACE inhibitor / ARB – initiate within 24h (low dose, titrate); especially beneficial in anterior MI, LV dysfunction, diabetes, hypertension (NG185 1.5.3)
• 🟠 High-intensity statin – e.g., atorvastatin 80 mg; reduce recurrent MI, stabilise plaques (NG185 1.5.4)
• 💉 Anticoagulation – unfractionated heparin or fondaparinux per protocol; adjust for renal function and bleeding risk (QS68 1.3.2)
• 🧬 Reperfusion therapy – primary PCI if STEMI within 120 min; thrombolysis if delayed or unavailable (NG185 1.4.1–1.4.3)
• 📈 Continuous monitoring – ECG telemetry for arrhythmias, vitals, urine output, fluid balance (QS68 1.2.1)
• 🏥 Early mobilisation – within 24h if stable, to prevent DVT, optimise recovery (NG185 1.6.1)
• 🫀 Cardiac rehabilitation referral – exercise, education, psychosocial support (NG185 1.6.2, QS68 1.6)
• 💊 Dual antiplatelet therapy (DAPT) – aspirin + P2Y₁₂ inhibitor (clopidogrel/ticagrelor/prasugrel) for 12 months unless high bleeding risk (NG185 1.5.1–1.5.2)
• ⚖️ Risk factor optimisation – blood pressure, glycaemic management, weight loss, smoking cessation (NG185 1.7.1–1.7.4)
• 🩺 Follow-up & monitoring – outpatient cardiology review, echocardiography for LV function, ECG, lipid profile (NG185 1.6.3)
• 🧠 Patient education – recognise angina, adherence to medications, lifestyle, emergency plan (NG185 1.6.2)
• 💔 Psychosocial support – address anxiety/depression post-MI; refer to counselling or rehab psychologist if needed (NG185 1.6.2)

📊 ACS Comparison – STEMI vs NSTEMI vs Unstable Angina

📌 Post-ACS Complications – Diagnosis & Management

🫀 Revascularisation Strategies Post-ACS – PCI vs Stenting vs CABG

💡 Teaching Pearls

🔑 ECG within 10 min of chest pain.
⏱️ “Time is muscle” – early reperfusion saves myocardium.
⚠️ Elderly and diabetic patients may present atypically; maintain high suspicion.
🏥 Discharge on secondary prevention: DAPT, beta-blocker, ACEi, statin, cardiac rehab.
🧪 Monitor for arrhythmias, heart failure, mechanical complications, pericarditis, and bleeding during hospital stay.