Pericoronary adipose tissue attenuation index (FAI) – a new imaging biomarker and its diagnostic and prognostic utility: a systematic review and meta-analysis

Abstract Background Pericoronary fat attenuation index (FAI) on coronary computed tomography angiography (CCTA) imaging has been proposed as a sensitive marker of coronary vascular inflammation with prognostic value for major cardiovascular events. To date though there is no systematic review of the published literature and no meta-analyzed data of previously published results. Methods We performed a systematic review and meta-analysis according to the PRISMA guidelines. We systematically explored published literature in MEDLINE (Pubmed) before February 1, 2021 for studies assessing FAI in both diagnostic and prognostic clinical settings in patients with or without cardiovascular disease. The primary outcome was the mean difference in FAI attenuation between stable and unstable coronary plaques. The secondary outcome was the hazard ratio of high FAI values for future cardiovascular events. We calculated I2 to test heterogeneity. We used random effects modelling for the meta-analyses to assess the primary and secondary outcome. Results In total, 16 studies and 6,944 patients were included in this meta-analysis. FAI was significantly higher in unstable compared to stable plaques with a mean difference of 4.07 HU (95% CI: 1.10–7.89, I2=88%). Higher FAI values offered incremental prognostic value for major cardiovascular events (MACE) in studies with prospective follow-up (HR=3.29, 95% CI= 1.88–5.76, I2=75%). Conclusion FAI is a promising imaging biomarker that may be successfully be used for detection of coronary inflammation, discrimination between stable and unstable plaques and prognosis of future MACE. There is undeniable need of further studies to establish the utility of this biomarker in clinical practice in order to improve coronary plaque discrimination and cardiovascular risk prognostication. Funding Acknowledgement Type of funding sources: None.