Case Presentation: A 42 year-old man with remote tobacco history and no other cardiac risk factors presented after an episode of substernal chest pain. One day prior to presentation, he ran three miles without chest pain or exertional dyspnea. On the day of presentation, he was testifying in court, which he described as an emotionally disturbing experience, when he developed severe left-sided chest pressure radiating to the left arm. At the time of first medical contact, vital signs were normal and physical exam was unremarkable. Initial cardiac troponin-I was 0.114 ng/mL and peaked at 1.389 ng/mL. Hemoglobin A1c was 5.6%, low-density lipoprotein was 91 mg/dL, and urine toxicology screen was negative. 12-lead electrocardiography revealed normal sinus rhythm without ST or T wave changes. Transthoracic echocardiography revealed normal left ventricular ejection fraction and wall motion.
Given the provisional diagnosis of non-ST elevation myocardial infarction (MI), the patient was administered aspirin, clopidogrel, and statin therapy, and invasive coronary angiography was performed. Angiography revealed type 1 spontaneous coronary artery dissection (SCAD) of a large obtuse marginal branch. The remainder of the coronary arteries were angiographically normal. No coronary intervention was performed and antiplatelet agents were continued. The patient had no further episodes of chest pain. CT angiography did not reveal evidence of fibromuscular dysplasia. Stress reduction techniques were reviewed and the patient was discharged on beta blocker therapy to reduce risk of recurrence or propagation of SCAD.
Discussion: SCAD is defined as a coronary artery dissection not associated with atherosclerosis, trauma, or iatrogenic causes. SCAD typically affects younger patients and women, but is relatively uncommon, accounting for only 0.16% to 4% of acute coronary syndromes (ACS). Given physicians’ lack of familiarity with the condition and angiographically subtle presentations, SCAD is frequently misdiagnosed.
SCAD is associated with unique precipitating factors, including extreme emotional stress, intense exercise, recreational drug use, and hormonal therapy. In a study of 168 patients with SCAD, over 50% reported a preceding emotional or physical stressor, and SCAD MI patients were more likely than non-SCAD MI patients to self-report anxiety and depression. SCAD is also associated with fibromuscular dysplasia (FMD). In a 2013 study of 50 patients with SCAD, 86% had FMD in at least one non-coronary territory. Renal, iliac, and cerebral arterial involvement was most common.
Conclusions: SCAD is often angiographically subtle and is not associated with traditional cardiovascular risk factors. Providers must maintain a high index of suspicion to establish the diagnosis.