Pericoronary Fat Attenuation Index as an Emerging Imaging Biomarker of Vascular Inflammation in Spontaneous Coronary Artery Dissection: A Synthesis of Contemporary Evidence

Spontaneous coronary artery dissection (SCAD) is a well-recognized cause of acute coronary syndrome in patients without traditional risk factors for coronary artery disease, especially women. Pericoronary fat attenuation index (FAI) and pericoronary adipose tissue (PCAT) attenuation, quantified using coronary CT angiography, are novel noninvasive imaging surrogates of vascular inflammation. However, their significance for SCAD is unknown. This review presents a narrative analysis of published researches examining pericoronary fat stranding, FAI, or PCAT attenuation in SCAD. The literature on this topic consists of case reports, small case–control series, and prospective cohorts, which are highly heterogeneous with regard to imaging time point, vessels analyzed, and methodology used. There are reports of increased focal or pancoronary attenuation, persisting after the acute episode, and normalization along with healing of the vessel, as well as no difference between SCAD and control groups. Altogether, all these data suggest that pericoronary fat attenuation can be associated with predisposition to vascular inflammation, reaction to injury, healing process, or systemic vascular phenotypes. At the present time, FAI should be considered only as a research tool, but not as diagnostic or prognostic parameter. Prospective multicenter research with consistent protocol and serial imaging is needed.