Coronary Flow Reserve in Patients With Prior Spontaneous Coronary Artery Dissection and Recurrent Angina

BACKGROUND: A significant proportion of patients with spontaneous coronary artery dissection (SCAD) have ongoing chronic chest pain despite healing of their dissection. We sought to determine whether coronary microvascular dysfunction contributes to post‐SCAD chronic chest pain by performing coronary reactivity testing in the cardiac catheterization laboratory. METHODS AND RESULTS: Eighteen patients consented to coronary reactivity testing at least 3 months post‐SCAD. Coronary flow reserve (CFR) and index of microcirculatory resistance were measured in the previously affected SCAD artery and 1 non‐SCAD artery. CFR <2.5 was defined as diagnostic of coronary microvascular dysfunction. An abnormal index of microcirculatory resistance was defined as >25 units. Seventeen women underwent coronary reactivity testing (1 had chronic dissection and was excluded). All presented with myocardial infarction and 2 underwent coronary stenting during the initial SCAD event. Fibromuscular dysplasia was present in 70.6% upon screening renal, iliac, and cerebrovascular arteries. Twelve patients (70.6%) had CFR <2.5 and 13 (76.5%) had an index of microcirculatory resistance >25 in at least 1 artery. There was no difference in the frequency of a low CFR measurement between SCAD and non‐SCAD arteries. CONCLUSIONS: Among patients with chronic chest pain after an SCAD event, >70% had coronary microvascular dysfunction as indicated by abnormal CFR or index of microcirculatory resistance in at least 1 coronary artery on invasive coronary reactivity testing. Presence of coronary microvascular dysfunction in both SCAD and non‐SCAD arteries suggests that underlying microvascular abnormalities from vasculopathies such as coronary fibromuscular dysplasia may be the underlying etiology.