Peri-coronary fat may be a "game-changer" in cardiovascular risk prediction: JACC study

The "holy grail" in coronary artery disease (CAD) research is the early identification of patients at increased risk to experience myocardial infarction (MI). In the latest issue of JACC Imaging, van Diemen et al have shown the prognostic value of pericoronary adipose tissue (PCAT) computed tomography attenuation (PCATa) in cardiovascular risk prediction. The benefits of this assessment extend beyond routine quantitative coronary computed tomography angiography (CCTA)-derived plaque volume and positron emission tomography determined ischemia.

As coronary inflammation plays a central role in the atherosclerotic process and in the rupture of vulnerable, predominantly nonobstructive plaque ultimately resulting in MI, its early detection might significantly improve cardiovascular risk stratification and targeted anti-inflammatory treatment. So far, the noninvasive detection of coronary artery inflammation remains challenging.

Due to its anatomic and biologic associations with the coronary arteries, recent research suggests that pericoronary adipose tissue (PCAT) is asscoiated with coronary inflammation and enables better prediction of future cardiac events.

The present single-center study assessed in a retrospective fashion the prognostic value of PCAT CT attenuation beyond quantitative plaque volume and ischemia among 539 patients with suspected CAD who underwent coronary CTA and [15O]H2O PET perfusion imaging.

Imaging assessment included coronary artery calcium score (CACS), presence of obstructive CAD (≥50% stenosis) and high-risk plaques (HRPs), total plaque volume (TPV), calcified/noncalcified plaque volume (CPV/NCPV), PCATa, and myocardial ischemia. The endpoint was a composite of death and nonfatal myocardial infarction. Prognostic thresholds were determined for quantitative CCTA variables.

The authors found that all plaque variables and the presence of myocardial ischemia were associated with the composite endpoint, with stronger association to outcome compared with right coronary artery (RCA) PCAT attenuation.

RCA PCAT CT attenuation above scanner-specific thresholds was associated with worse prognosis, and retained its prognostic value even after adjustment for imaging variables and clinical characteristics associated with the endpoint. Left anterior descending artery and circumflex artery PCATa were not related to outcome.

The trial thus demonstrated that increased RCA PCAT CT attenuation is a possible marker of global coronary inflammation and its prognostic value extends beyond coronary CTA-derived parameters linked to plaque burden, vulnerability, and myocardial ischemia.

This non-invasive assessment can easily be retrospectively quantified from available images without additional contrast agent or radiation exposure.

"Together with CTA-derived assessment of luminal and structural characteristics of the coronary wall, implementing analyses of the PCAT CT attenuation or the FAI (fat attenuation index) as a potential sensor of coronary inflammation might represent to date the most promising and applicable imaging approach to predict cardiovascular risk", noted Goeller et al in an accompanying editorial.

Thus pericoronary fat detection can be a game-changer in refining the cardiovascular risk prediction using non-invasive modalities. Large prospective trials are warranted to deliver conclusive data that might pave the way toward a "novel marker" in the search of the "vulnerable patient".

Source: JACC Cardiovascular Imaging: DOI: 10.1016/j.jcmg.2021.03.025