The patient declined antiplatelet drugs as she was breast feeding and was consented for emergency coronary angiography. This investigation revealed the left main stem (LMS) to be unobstructed, the left anterior descending artery (LAD) had a dissection in the proximal third, an intermediate coronary artery was occluded in the proximal course and the left circumflex (Cx) artery was co-dominant and demonstrated a dissection in the mid third (figures 1 and ​and2).2). The right coronary artery (RCA) was co-dominant and appeared normal.

At postmortem, the coronary arteries were cut at 2 mm intervals and then further sectioned at 4 μm for the microscopic slides. The sections of the artery on the slide look different to the appearance in life as after death the vessel collapses as there is no blood pressure to keep the vessel ‘open’. Furthermore, in order for the vessel to be processed for histological examination, formalin is added that ‘toughens up’ the tissue allowing sectioning. This has the consequence of causing further distortion to the shape of the cross-section. This artefactual change does not produce dissection. The clefts in the histology slides produced by the coronary artery dissection are accompanied by inflammatory infiltrate (lymphocytes and neutrophils) and fibrin, which would not be present if the appearance was due to artefact.

It is unlikely that the initial dissection was produced by the coronary angiogram procedure since the left coronary system was engaged smoothly and without difficulty, the dissection sites were distal to the catheter, multiple vessels were involved and there was an indication of coronary dissection at the very initial partial opacification of the relevant segment of the blood vessel during the very first contrast injection.

In women, the risk of SCAD appears to be increased during the peripartum period with 25–30% of reports occurring in this setting.^{1 5} Myocardial infarction surrounding pregnancy has been associated with SCAD in 16–54% cases.¹ Most pregnancy related cases occur after delivery of the baby at 13 days postpartum on average,² although the latest reported case occurred at 3 months.^{2 6} Short-term mortality is as high as 38% although up to 82% of survivors were still alive at 3 years.^{1 6}

Women have a higher proportion of LAD artery involvement and LMS involvement whereas men are more likely to have RCA dissection. The Cx artery is infrequently involved in men and women.⁷ Approximately 40% of SCADs are multifocal in nature.⁸

The aetiology is not fully understood. Most patients presenting with SCAD do not have risk factors for coronary artery disease. The haemodynamic stresses of pregnancy and delivery of the baby are thought to play a part.^{2 8 9} Other theories include structural changes in the arterial walls related to the hormones of pregnancy and eosinophilic infiltration resulting in separation of the tunicae intima and media.² Often dissection occurs without an initial tunica intimal damage suggesting the mechanism lies in degeneration of the tunicae media and adventitia.¹

Histologically, an inflammatory reaction in the adventitia has been described suggestive of periarteritis. The inflammatory infiltrate in this case's histology contained lymphocytes and neutrophils. However, this inflammatory response may be reactive rather than causative.⁹

SCAD should be suspected in all young patients without risk factors for coronary artery disease who present with chest pain, acute coronary syndromes or sudden death. This is especially true for women who present in the peripartum period.

Diagnosis is usually made by emergency coronary angiography,^{2 5} although trans-oesophageal ultrasound, intravascular ultrasound, optical coherence tomography and CT coronary angiography have also been used where there is diagnostic difficulty or to guide management.^{1 2 5 6} Non-invasive methods such as CT angiography to diagnose and monitor may also decrease the risk of complications.^{2 6}

The high mortality is falling thanks to early diagnosis and aggressive management.⁵ The rarity of SCAD means that there is uncertainty and a lack of consensus in its management.^{1 2 5}

Medical management may be successful in half of women initially thought suitable for this approach. The remainder may still require intervention later.^{2 5} Medical management involves treatment with heparin, antiplatelets, nitrates and β-blockers.^{1 2 5} Antiplatelets and heparin are thought to help decrease thrombus formation in the false lumen; thus, allowing a more normal flow through the true lumen.^{5 8 10} The use of glycoprotein IIb/IIIa inhibitors is contraindicated.⁵ The use of thrombolysis remains controversial as some cases have reported benefit while others have shown no difference or even extension of the dissection.^{3 5 11–13} Immunosuppressive treatment with prednisone and cyclophosphamide, along with standard treatment, has also been used beneficially in one case lending potential support to the argument that SCAD is an inflammatory process.¹⁴

Where medical treatment is inappropriate (eg, due to haemodynamic compromise or the type of lesion) percutaneous coronary intervention, sometimes assisted by intravascular ultrasound, and coronary artery bypass grafting can be considered.⁵ A LV assist device implant followed by heart transplantation has also been successful.¹⁵

Peripartum SCAD is not an absolute contraindication to future pregnancies. Data on the risk of recurrence are limited and so it may be best to avoid further pregnancies.¹⁶ As such, pre-pregnancy counselling should be considered.