Spontaneous Coronary Artery Dissection

Separation of the layers of a coronary artery wall that is not caused by atherosclerosis, trauma or an instrument, with an intramural haematoma (with or without an intimal tear) that compresses the true lumen and causes myocardial ischaemia and infarction.

• It causes about 1 to 4% of acute coronary syndromes overall, but 20 to 35% of infarctions in women under 50 and about a quarter of pregnancy associated infarctions. About 80 to 90% of patients are women, mean age 45 to 53 years.
• Predisposing conditions: fibromuscular dysplasia (about half or more of patients when imaged), pregnancy and the postpartum period (up to 12 months), connective tissue disease (vascular Ehlers-Danlos, Marfan and Loeys-Dietz syndromes), systemic inflammatory disease (lupus), severe hypertension, multiparity and exogenous hormones. Triggers: intense emotional stress (about half), extreme exertion with isometric strain, Valsalva, retching, cocaine and other sympathomimetics.
• Sites: mid to distal left anterior descending artery in about 40 to 45%, multivessel in 10 to 20%, left main rarely.
• Angiographic types: type 1 (contrast staining of the wall with multiple luminal lines), type 2 (diffuse smooth narrowing, long), type 3 (focal narrowing mimicking atheroma), type 4 (total occlusion).
• In hospital major events occur in about 5 to 10% and mortality is low (about 1 to 3%). Most untreated dissections heal in 1 to 3 months (about 70 to 90%). Recurrent dissection occurs in about 10 to 30% over 3 to 10 years.

• Chest pain (about 95%), arm or jaw pain, dyspnoea, nausea, diaphoresis. Ventricular tachycardia or fibrillation in about 5 to 10%, and cardiogenic shock in less than 5%. Examination is usually normal.
• Differential diagnosis: atherosclerotic acute coronary syndrome, Takotsubo syndrome, myocarditis, coronary vasospasm, coronary embolism, aortic dissection extending into a coronary artery, and peripartum cardiomyopathy.
• Complications: extension of the haematoma, recurrent dissection, recurrent infarction, heart failure, ventricular arrhythmia, cardiogenic shock, and persistent chest pain after discharge (about half of patients).

• ECG: ST elevation (about 25 to 40%) or ST depression and T wave change (about 60%). High sensitivity troponin raised. Echocardiography: regional wall motion abnormality.
• Coronary angiography is the diagnostic test, performed with minimal contrast and gentle catheter handling (guide catheters can themselves cause dissection). Give intracoronary glyceryl trinitrate 100 to 200 micrograms to exclude spasm before deciding.
• Intracoronary optical coherence tomography or intravascular ultrasound when angiography is equivocal (types 2 and 3); the guidewire and imaging catheter can propagate the haematoma, so use only when it will change management.
• CT coronary angiography is less reliable for distal branches in the acute phase.
• Once stable: CT or MR angiography from the head to the pelvis once to look for fibromuscular dysplasia and aneurysms (intracranial aneurysm in about 10%); examine for connective tissue features and refer for genetic testing when suggestive; blood pressure assessment; antinuclear antibody and inflammatory markers.

• Conservative therapy is preferred for stable patients with normal flow and no ongoing ischaemia, because percutaneous intervention often fails (about half) and risks extending the dissection.
• Medical therapy:
  • Aspirin 75 to 100 mg daily for at least 12 months (many continue long term).
  • Clopidogrel 75 mg daily for 1 to 12 months if a stent was placed; evidence for prolonged dual antiplatelet therapy without a stent is limited.
  • Avoid fibrinolytic drugs and glycoprotein IIb/IIIa inhibitors, which can propagate the haematoma. Stop heparin once the diagnosis is made unless needed during a procedure.
  • Bisoprolol 2.5 to 10 mg daily or metoprolol succinate 50 to 200 mg daily for at least 1 year, probably longer (observational data suggest fewer recurrences).
  • Blood pressure target less than 130/80 mmHg; add ramipril 2.5 to 10 mg daily if ejection fraction is 40% or less or hypertension persists.
  • Statins only for dyslipidaemia or proven atherosclerosis.
  • Amlodipine 5 to 10 mg daily if vasospasm contributes; nitrates for symptoms.
• Revascularisation indications: ongoing ischaemia, haemodynamic instability, ventricular arrhythmia, left main or proximal dissection with a large territory at risk, or absent or very poor flow.
  • Percutaneous intervention: wire the true lumen carefully (confirm with imaging), use long stents covering the whole haematoma, avoid aggressive balloon inflation, and consider cutting balloon fenestration for decompression.
  • Bypass grafting for left main or multivessel disease and failed intervention; native arteries often heal, so grafts may later occlude.
• Cardiogenic shock: urgent angiography, mechanical support (intra aortic balloon pump, venoarterial ECMO, percutaneous ventricular assist device), and revascularisation. Ventricular arrhythmia: give amiodarone or lidocaine and defibrillate for sustained instability; an implantable defibrillator only if arrhythmia occurs later in the course after healing.
• Rehabilitation: cardiac rehabilitation with moderate exercise; avoid heavy isometric lifting (keep loads under about 10 kg), extreme exertion and Valsalva until fully recovered and cleared. Offer psychological assessment (anxiety and depression in about a third to half).
• Pregnancy and hormones: advise against further pregnancy (recurrence risk about 10% and substantial maternal risk); if pregnancy occurs, refer to a high risk obstetric cardiology service. Avoid combined oral contraceptives and menopausal hormone therapy; use barrier methods or a levonorgestrel intrauterine system.
• Special groups:
  • Pregnancy and postpartum: aspirin 75 to 100 mg and metoprolol; revascularisation for ongoing ischaemia.
  • Fibromuscular dysplasia: aspirin, blood pressure control, and surveillance imaging of affected vascular beds.
  • Connective tissue disease: genetic referral, strict blood pressure control, and cautious interventions.
• Red flags: recurrent chest pain with troponin rise, ventricular arrhythmia, hypotension, new neurological symptoms.
• Follow up: review at 2 to 6 weeks, echocardiography at 3 months, annual review; avoid routine repeat angiography, reserving it for recurrent ischaemia; repeat vascular imaging every 3 to 5 years if fibromuscular dysplasia was found.