Acute Coronary Syndrome (ACS)
Definition:
ACS refers to a spectrum of clinical conditions caused by acute
myocardial ischemia and/or infarction, resulting from a sudden
reduction in coronary blood flow due to plaque rupture and
thrombosis.
Spectrum of Ischemic Heart Disease (Flowchart)
1. Chronic Ischemic Heart Disease:
-Stable angina
-Silent myocardial ischemia
2. Acute Coronary Syndrome:
-Unstable angina
-Non-ST-elevation myocardial infarction (NSTEMI)
-ST-elevation myocardial infarction (STEMI)
Clinical Features
Symptoms:
Chest pain: Retrosternal, crushing, radiating to the left arm, jaw, or
back.
Associated symptoms: Dyspnea, diaphoresis, nausea, vomiting,
fatigue, syncope.
Physical Signs:
Tachycardia or bradycardia, hypotension or hypertension.
Signs of heart failure: Pulmonary crackles, jugular venous distension.
Third or fourth heart sound, new murmur (mitral regurgitation or
ventricular septal defect).
Complications
1. Arrhythmias:
Ventricular tachycardia, ventricular fibrillation, atrial fibrillation,
bradyarrhythmias.
2. Cardiogenic Shock:
Severe LV dysfunction causing systemic hypoperfusion.
3. Ventricular Failure:
Acute heart failure or chronic ventricular remodeling.
4. Mechanical Complications:
Ventricular septal rupture, papillary muscle rupture (causing mitral
regurgitation), free wall rupture.
5. Embolism:
Thromboembolism leading to stroke or peripheral ischemia.
6. Ventricular Aneurysm:
Thinning and dilation of the ventricular wall, causing heart failure or
thrombus formation.
7. Pericarditis:
Acute pericarditis or Dressler’s syndrome (post-MI pericarditis).
Investigations of Myocardial Infarction
1. Electrocardiogram (ECG):
STEMI: ST-segment elevation, new Q waves.
NSTEMI: ST-segment depression, T-wave inversion.
2. Plasma Cardiac Biomarkers:
Troponins (cTnI, cTnT): Highly specific, remain elevated for 7–10
days.
Creatine kinase-MB (CK-MB): Peaks at 12–24 hours, returns to
baseline in 3 days.
Myoglobin: Early marker but non-specific.
Lactate dehydrogenase (LDH): Elevated in later stages.
Aspartate aminotransferase (AST): Non-specific, elevated in
myocardial injury.
3. Other Blood Tests:
Complete blood count, lipid profile, renal function tests, coagulation
profile.
4. Imaging:
Chest X-ray: To rule out other causes of chest pain (e.g., aortic
dissection, pulmonary edema).
Echocardiography: Wall motion abnormalities, ventricular function,
complications like aneurysms.
Radionuclide Scanning: Assess perfusion and viability of myocardium.
Management of Acute Coronary Syndrome (ACS)
1. General Measures:
Oxygen: If SpO₂ < 90% or respiratory distress.
Monitoring: Continuous ECG, vital signs, and hemodynamics.
2. Control of Pain:
Nitroglycerin: Sublingual or IV for chest pain.
Morphine: IV for severe pain and anxiety relief.
3. Specific Therapy:
Antiplatelet Therapy:
-Aspirin (loading 300 mg, then 75–100 mg daily).
-P2Y12 inhibitors (Clopidogrel, Ticagrelor) to prevent thrombus
formation.
Anticoagulants:
-Enoxaparin, unfractionated heparin, or bivalirudin to prevent clot
propagation.
Beta-Blockers: Reduce myocardial oxygen demand (e.g., Metoprolol).
ACE Inhibitors/ARBs: For anterior MI, heart failure, or reduced EF
(<40%).
High-dose Statins: Atorvastatin 80 mg daily to stabilize plaques and
reduce LDL.
4. Revascularization:
Percutaneous Coronary Intervention (PCI):
Preferred in STEMI or high-risk NSTEMI patients.
Involves balloon angioplasty and stent placement to restore blood
flow.
Ideal within 90–120 minutes (door-to-balloon time).
Coronary Artery Bypass Grafting (CABG):
Indicated in multi-vessel disease, significant left main coronary
artery stenosis, or when PCI fails.
A surgical procedure that creates new pathways around blocked
coronary arteries using grafts (e.g., saphenous vein or internal
mammary artery).
5. Aftercare and Rehabilitation:
Medications for long-term prevention: Aspirin, statins,
beta-blockers, ACE inhibitors.
Lifestyle modifications: Healthy diet, exercise, smoking cessation,
stress management.
