The 1st spontaneous CAD case was published in 1931,3 and a total of 152 such cases had been described in the medical literature through 2002.4 However, the true number of cases is no doubt much higher, due to the frequency with which spontaneous CAD leads to sudden death without diagnosis.4 De Maio and colleagues5 were the 1st to describe 3 different groups of patients with spontaneous CAD: patients with underlying coronary atherosclerosis, women in the 3rd trimester of pregnancy or the early postpartum period, and patients with idiopathic disease.
Atherosclerosis is one of the main risk factors for spontaneous CAD. Hering and co-authors6 reported atherosclerotic plaque rupture in 35 of 42 spontaneous CAD patients.
Three patients in our series had multiple risk factors for atherosclerosis, such as hypertension, diabetes mellitus, hypercholesterolemia, and smoking. In these patients, atherosclerotic coronary artery stenosis was seen on angiography (Fig. 1).
Spontaneous coronary artery dissection accounts for up to one third of myocardial infarctions during pregnancy and post partum.7 More than two thirds of patients with spontaneous CAD present in the postpartum period, usually within 2 weeks of delivery.8 Multiparity and advanced age have been found to be associated with spontaneous CAD.8 Arterial wall changes occur under hormonal influence during pregnancy. These include smooth muscle proliferation, impaired collagen synthesis, and alterations in the protein and acid mucopolysaccharide content of media.9
Other possible risk factors include Marfan syndrome, Ehlers-Danlos syndrome, systemic lupus erythematosus, polyarteritis nodosa, hypereosinophilic syndromes, and Kawasaki disease.10 Spontaneous coronary artery dissection can also be associated with the use of cocaine, cyclosporine, and oral contraceptives.11,12 Our patients had no connective-tissue disorders or history of oral contraceptive administration.
However, there are several reports of spontaneous CAD among previously healthy people who had no apparent risk factors.13 Shear stress, with or without angiographically proven coronary plaques, is a possible explanation.14 This hypothesis is supported by several reports of spontaneous CAD in young to middle-aged people, occurring during or after such heavy exercise as aerobic exercise,13 running,14 weightlifting,15 baseball-playing,16 or even prolonged sneezing.17
The clinical presentation of spontaneous CAD may vary from unstable angina to myocardial infarction. The left anterior descending coronary artery is the artery most often involved (in about 75% of cases),8 whereas LMCA and multivessel dissection occur in 24% and 40% of cases, respectively.8 Most patients with LMCA dissection sustain myocardial infarction (vs only 50% of patients with RCA dissection).18 In our series, 5 patients had LMCA dissection (83%), and 1 had RCA dissection (17%).
What constitutes optimal management for spontaneous CAD is controversial. The decision to intervene surgically or per catheter depends on the clinical presentation, the patient's hemodynamic state, the site and extent of the dissection, and the number of vessels involved.2 Stable patients with spontaneous CAD that is limited to a single coronary artery dissection usually have a favorable long-term outcome and are candidates for conservative medical management.19 Thrombolytictherapy is controversial. Thrombolysis might dissolve the compressing intramural clot but might also expand the hematoma and thereby proliferate the dissection.20 Stenting seems to be an attractive option, for it can yield very good long-term results in symptomatic patients who have localized dissections.20 Coronary artery bypass grafting should be performed in patients with main stem or multivessel involvement or in those with hemodynamic instability.21 The cause of idiopathic spontaneous CAD—after such predisposing factors as hypertension, collagen disorders, intense physical effort, and contusive chest trauma have been eliminated—is still in debate. We recommend prompt coronary angiography in all acute coronary syndrome patients. Thrombolytic therapy may lead to myocardial ischemia and to worsened clinical status in patients who have coronary artery dissection. For young, healthy women who display symptoms of acute coronary syndrome, spontaneous CAD should be included in the differential diagnosis. Angiography and early intervention are essential in the treatment of these patients. Angioplasty and stenting may be preferred in single-vessel dissection. Finally, CABG should be performed in patients who have LMCA or multivessel dissection or who have undergone stenting without success.