Association of coronary inflammation with plaque vulnerability and fractional flow reserve in coronary artery disease.

Background: The fat attenuation index (FAI) measured using coronary computed tomography angiography (CCTA) enables the direct evaluation of pericoronary adipose tissue composition and vascular inflammation. We aimed to investigate the association of fractional flow reserve (FFR) and plaque vulnerability with coronary inflammation.

Methods: Patients with suspected coronary artery disease (CAD) who underwent CCTA and invasive FFR measurements within 90-day were included. A cloud-based medical device, CaRi-Heart, serves as a surrogate tool for evaluating coronary inflammation based on FAI by analyzing CCTA images. The correlations between CCTA-defined plaque characteristics, invasive coronary angiographic and physiologic assessments, and CaRi-Heart risk were analyzed. The primary endpoint was the patient-oriented composite outcome (POCO) consisting of all-cause death, any myocardial infarction, and any revascularization.

Results: A total of 564 patients (median age 67.0 years; 75.4 ​% men) were included. There were no significant differences in quantitative and qualitative plaque characteristics or FFR between the high- and low-CaRi-Heart risk groups (i.e., ≥5 ​% and <5 ​%). During the median follow-up of 3.2 years [1.13-4.73 years], CaRi-Heart risk ≥5 ​% was associated with a significantly higher rate of POCO compared to CaRi-Heart risk <5 ​% (0.9 ​% vs. 10.1 ​%, P ​= ​0.037). The CaRi-Heart risk was an independent predictor of POCO as a continuous (adjusted HR 1.016, 95 ​% CI 1.005-0.027, P ​= ​0.004) and categorical variable (CaRi-Heart risk ≥5 ​%, adjusted HR 2.949, 95 ​% CI 1.182-7.360, P ​= ​0.021), regardless of high-risk plaque characteristics and FFR.

Conclusion: Coronary inflammation risk assessed using CaRi-Heart risk provides independent prognostic information regardless of plaque vulnerability and physiologic stenosis in patients with CAD.