Spontaneous coronary artery dissection causes

The exact etiology of spontaneous coronary artery dissection remains elusive; however, fibromuscular dysplasia and takotsubo cardiomyopathy have been considered as the potential cause of spontaneous coronary artery dissection. The underlying causes associated with SCAD include emotional stress, physical stress such as extreme valsalva maneuver, retching, vomiting, coughing, isometric exercise, history of using stimulant medications or illicit drugs, pregnancy, and connective tissue disorders.

Common causes associated with spontaneous coronary artery dissection (SCAD) include:^[1][2]

• Emotional stress
• Physical stress such as extreme valsalva maneuver, retching, vomiting, coughing, isometric exercise
• Using stimulant medications, illicit drugs
• Hormonal triggers such as pregnancy
• Inflammatory disorders such as systemic lupus erythematosus, sarcoidosis, Crohn’s disease, Ulcerative colitis , celiac disease, fibromuscular dysplasia (FMD), takotsubo cardiomyopathy (TCM)
• Connective tissue disorders such as vascular Ehlers–Danlos syndrome, marfan’s syndrome, Loeys–Dietz syndrome, cystic medial necrosis, systemic lupus erythematosus, polyarteritis nodosa, sarcoidosis, churg-Strauss syndrome, wegener’s granulomatosis, rheumatoid arthritis, giant cell arthritis

• FMD is a non-atherosclerotic vasculopathy characterized by thickening, fibrosis, and disarray of the arterial wall that primarily affects small and medium-sized vessels.
• The association between FMD and SCAD has been well described,^[3][4][5][6]
• The biological proof of causation has been supported by histopathologic reports.^[7][8][9]
• The presence of FMD may weaken the artery architecture and lead to aneurysm formation or coronary dissection.^[10]

• Both TCM and SCAD affect predominantly women and may be precipitated by emotional stress or strenuous exercise associated with sympathetic discharge.
• Numerous reports have described the concurrence of TCM and SCAD.^{[11][12][13][14][15]}
• In the setting of TCM, vigorous contraction of the left ventricular base in conjunction with the adjacent akinetic/dyskinetic segments could form a prerequisite anatomic/functional substrate for the causation of SCAD.^[16]
• The coronary dissection plane may develop as a result of excessive movement of the epicardial vessels and increased shear stress on the vessel wall at the hinge point between the hyperdynamic and dyskinetic/akinetic myocardium.^[17]
• The coronary arteries traversing the anterior or anterolateral wall would be more vulnerable to dissection as this region marks the transition point of the hyperdynamic basal segment and the remaining dyskinetic/akinetic left ventricular segments.
• Another plausible mechanism is that elevated catecholamine concentrations in TCM may cause epicardial coronary vasoconstriction and/or spasm, which in turn leads to increased arterial shear stress and subsequent intimal tear or disruption of vasa vasorum.^[18]
• The post-ischemic myocardial stunning associated with SCAD could lead to TCM,^[12], thus forming the “TCM begets SCAD, and SCAD begets TCM” vicious cycle.