Acute Coronary Syndrome (ACS): Complications

Related Subjects: |Acute Coronary Syndrome (ACS): Complications |Atherosclerosis |Ischaemic heart disease |Assessing Chest Pain |ACS - General |ACS - STEMI |ACS - NSTEMI |ACS - GRACE Score |ACS - ECG Changes |ACS -Cardiac Troponins |ACS - Post MI arrhythmias |Right Ventricular ST Elevation MI (RVMI) |ACS: LBBB and AMI

⚡ Arrhythmias

• ❤️‍🔥 Ventricular tachycardia: Often seen acutely during ischaemia or infarction. Treat persistent VT with IV amiodarone or lidocaine according to local/ALS guidance. Correct potassium and magnesium. Use synchronised DC cardioversion if haemodynamically compromised.
• 💓 Accelerated idioventricular rhythm: Wide-complex regular rhythm, usually rate <120/min. Often stable and may be a sign of reperfusion. Correct potassium and magnesium. Usually settles without treatment.
• 🚨 Ventricular fibrillation: Usually occurs early after MI and requires immediate defibrillation. Early VF does not always imply long-term ICD need, but VF after the first 24–48 hours is more concerning. Start beta-blockade if not contraindicated and seek cardiology advice for late or recurrent arrhythmias.
• 🫀 Atrial fibrillation: Not uncommon after ACS. Treat rate/rhythm depending on haemodynamic status, LV function and symptoms. Options include beta-blocker, digoxin or amiodarone depending on context. Consider anticoagulation according to stroke and bleeding risk.
• 🐢 Sinus bradycardia: Common with inferior MI. Withhold beta-blockers if significant bradycardia or hypotension. Give atropine if symptomatic. Consider temporary pacing if persistent compromise.
• ⛔ Third-degree AV block: Consider atropine, external pacing and urgent cardiology review. Temporary pacing may be needed, especially if haemodynamic compromise persists. A permanent pacemaker may be required if block does not resolve.
• ⚠️ Second-degree AV block: Mobitz II or 2:1 / 3:1 block is more concerning than Wenckebach and may progress to complete heart block. Seek cardiology advice; temporary pacing may be required.
• 🟡 First-degree AV block: Often needs no treatment. If associated with new bundle branch block or anterior MI, it may suggest more extensive conduction-system disease and requires close monitoring.

🩸 Thromboembolic Complications

• 🧠 Systemic embolism: LV thrombus or atrial fibrillation may lead to embolic stroke or peripheral embolism. Risk is higher after large anterior MI and severe LV impairment. Consider echocardiography and anticoagulation where indicated.
• 🫁 DVT and pulmonary embolism: Immobility, inflammation and acute illness increase venous thromboembolism risk. Use VTE assessment and thromboprophylaxis according to local policy, balancing bleeding risk and antiplatelet/anticoagulant therapy.

🏗 Structural Complications

• 💥 Free wall rupture: Rupture into the pericardium can cause tamponade, pulseless electrical activity and sudden death. Classically occurs several days after a large transmural MI as necrotic myocardium softens.
• 🌊 Severe LV dysfunction / pump failure: Loss of viable myocardium may cause pulmonary oedema and cardiogenic shock. Treat pulmonary oedema with oxygen, nitrates if blood pressure allows, IV diuretics and urgent senior/cardiology input.
• 🫀 Papillary muscle rupture: Presents with acute breathlessness, pulmonary oedema and a new loud pansystolic murmur from acute severe mitral regurgitation. Confirm with urgent echocardiography. Needs urgent cardiac surgical assessment.
• 🧱 Ventricular septal rupture: Presents with acute heart failure, shock and a new harsh pansystolic murmur. Confirm with urgent echocardiography. Requires urgent cardiology/cardiac surgery input.
• 🔁 Ventricular remodelling: Harmful thinning and dilatation after a large transmural MI. ACE inhibitors/ARBs, beta-blockers and mineralocorticoid receptor antagonists where indicated reduce adverse remodelling.
• ➡️ Right ventricular MI: Suspect with inferior STEMI, hypotension, raised JVP and clear lung fields. Check right-sided ECG leads, especially V4R. Avoid excessive nitrates/diuretics; cautious fluid loading may improve RV filling.

🔁 Recurrent Ischaemia and Reinfarction

• 🚨 Reinfarction: Suspect if recurrent chest pain, new ECG changes, haemodynamic deterioration or recurrent troponin rise. Discuss urgently with cardiology for repeat angiography/PCI or reperfusion strategy.
• ➡️ Right ventricular infarction: Presents with hypotension, raised JVP and clear lung fields, usually with inferior MI. ECG may show ST elevation in V4R. Echo is useful. Treat hypotension with cautious fluids and avoid preload-reducing drugs if unstable.

🔥 Inflammatory Complications

• 🫀 Early post-MI pericarditis: Usually occurs within the first few days. Chest pain may be sharp, pleuritic or positional. Avoid routine NSAIDs early after MI unless specialist advice supports use; analgesia and cardiology guidance may be needed.
• 🛡 Dressler’s syndrome: Immune-mediated pericarditis occurring weeks to months after MI. Features include fever, pleuritic chest pain and pericardial effusion. Treat with anti-inflammatory therapy under specialist guidance.

🧠 Psychological Complications

• 😟 Anxiety and depression: Common after ACS and may reduce quality of life, medication adherence and cardiac rehabilitation engagement.
• 💬 Ask about mood, sleep, fear of exertion, return to work, sexual activity and confidence after discharge.
• 🏃 Cardiac rehabilitation improves physical recovery, education, confidence and psychological adjustment.

📝 Exam Pearls

• 🚨 Early VF after MI needs defibrillation; late VF is more concerning for ongoing scar/ischaemia risk.
• 🐢 Inferior MI commonly causes bradycardia and AV block.
• 💥 New murmur plus pulmonary oedema after MI = think papillary muscle rupture or VSD.
• ➡️ Inferior MI + hypotension + raised JVP + clear lungs = right ventricular infarction.
• 🫀 Chest pain days after MI may be pericarditis; weeks later may be Dressler’s syndrome.