Acute Coronary Syndrome – Complications

Complications Post-AMI

First 2-3 Days:

• Cardiac arrhythmias
• Cardiac failure
• Pericarditis

Later Complications:

• Recurrent infarction
• Angina
• Thromboembolism
• Mitral valve regurgitation
• Ventricular septal or free wall rupture

Other Late Complications:

• Dressler’s syndrome
• Ventricular aneurysms
• Recurrent cardiac arrhythmias

Pain Management

• Ongoing pain requires prompt revascularization.
• Pain may indicate extension of the infarct or a new infarct.
• Treatment is similar to primary AMI.
• Streptokinase (SK) should only be considered within three days of the original administration.

Left Ventricular Failure

• Oxygen: 4-6L/min continuous
• Frusemide: 40-80mg IV as required
• Morphine: 2.5-5.0mg IV as required
• GTN: 600 microgram or Isosorbide Dinitrate 5 microgram S/L (if SBP >95)
• Mild Left Failure: Few basal crackles, extra heart sound, upper lobe diversion on CXR (common in 40%)
  • Rx: Few days of low-dose diuretics + ACEI for prognostic benefits
• Severe Heart Failure and Pulmonary Oedema:
  • Rx: Prolonged and powerful diuretics, vasodilators, loop diuretics, sometimes digoxin
• Hypotension and Raised R-Heart Filling Pressures: Common in RV infarcts
  • Rx: Volume expansion
• Cardiogenic Shock: Extreme form of heart failure or circulatory collapse
  • Rx: Inotropic support (Dobutamine, Dopamine), vasodilators (if SBP >90mmHg), haemodynamic monitoring, ventilation, urgent revascularization, consider ECHO and pericardiocentesis for cardiac tamponade
• Cardiac Rupture: Immediate tamponade, usually fatal within minutes
  • Electromechanical dissociation (no pulse or cardiac output despite normal ECG rhythm)

Cardiogenic Shock

• Mortality: Very high
• Management:
  • Inotropic support (Dobutamine 2.5-15mg/kg/min IV +/- Dopamine 2-3 microgram/kg/min IV)
  • Vasodilators (if SBP >90mmHg)
    • GTN 10 microgram/min IV, increase by 10 microgram/min to keep SBP >90mmHg
    • Sodium Nitroprusside 0.3 microgram/kg/min IV, increase by 0.3 microgram/min every 5-10 min to keep SBP >90mmHg
  • Haemodynamic monitoring
  • Ventilation
  • Urgent revascularization
  • Consider ECHO and pericardiocentesis for cardiac rupture and cardiac tamponade

Right Ventricular Infarction

• Diagnosis: ECG changes confirmed by ECHO
• Rx: Saline fluid challenge (100-200mL/30min)

Pericarditis

• Often occurs post Q wave AMI (transmural), usually 1-4 days post-infarct
• Symptoms: Friction rub, sharp CP aggravated by movement and respiration, pericardial rub
• Common in anterior wall infarcts
• ECG: Generalized ST segment elevation with upright peaked T waves
• Rx: Anti-inflammatory drugs; avoid anticoagulants

Arrhythmias

• VF: Increased HR, AF: Decreased HR
• Ventricular Extrasystoles: May precede development of VF
• Ventricular Tachycardia: May degenerate into VF, Rx: IV lignocaine or synchronized cardioversion
• VF: Rx: Prompt defibrillation (200-360J), recurrences treated with Lignocaine infusions or Amiodarone if poor LV function
• AF: Rx: IV digoxin, amiodarone, treat underlying pathology
• Sinus Tachycardia (Inferior Wall Infarcts): Rx: Elevate foot of bed, IV atropine 600μg
• Conduction Disturbances: Rx: Atropine or temporary pacemaker, permanent pacing if block exceeds 2 weeks

Thromboembolic Disease

• Complications: PE, DVT, CVA
• Long-term Therapy: Considered for patients with large AMI and LVF, akinetic or dyskinetic areas, scar or aneurysm formation
• Mural Thrombus: Confirmed with TOE

Cardiac Rupture

• Typically occurs within 1 week post-AMI
• Cause: Necrotic tissue incompletely replaced by fibrous tissue

Ventricular Aneurysm

• Cause: Stretching of collagen fibers replacing infarcted cardiac muscle
• Presentation: Heart failure, arrhythmias, systemic emboli
• Diagnosis: ECG with persistent ST elevation, echo
• Rx: Anticoagulants, ACEIs, anti-arrhythmics, surgical removal in some cases

Dressler’s Syndrome

• Post-AMI pain not associated with vascular insufficiency
• Symptoms: Pyrexia, pneumonitis, pleurisy, pericarditis (2-10 weeks post-AMI)
• Cause: Autoimmune response to damaged cardiac tissue
• Rx: Anti-inflammatory drugs, steroids may be needed

Valvular Heart Disease

• Cause: Rupture or infarct of papillary muscles or valve leaflets