Clinical implications of improved risk prediction of continuous FFRCT by accounting for adverse coronary atherosclerotic features.

PURPOSE: Fractional flow reserve (FFR) derived from coronary computed tomography angiography (FFRCT) is commonly used as a dichotomized index for risk stratification. We investigated the risk continuum of FFRCT on acute coronary syndrome (ACS) and its predictive value associated with coronary atherosclerotic features.

METHODS: Consecutive ambulatory patients who underwent coronary computed tomography angiography (CCTA) with subsequent FFRCT analysis by HeartFlow were included. Adverse plaque features were classified as mixed, non-calcified or diffuse plaque. The clinical outcome was the ACS spectrum of acute myocardial infarction or urgent revascularization due to unstable angina.

RESULTS: Among 1304 subjects included, 3912 vessels were analyzed. There was a gradual increase in the frequency of coronary stenosis [Formula: see text]50% and adverse plaque features in FFRCT categories of >0.90, 0.86-0.90, 0.81-0.85, 0.75-0.80 and <0.75 respectively (both p < 0.0001). During the mean follow-up period of 3.7 ± 1.8 years, 75 cases of ACS occurred. For every 0.05 unit decrease in FFRCT, there was an 18% increase in ACS risk (adjusted hazard ratio [HR] 1.18, 95% confidence interval [CI] 1.10-1.26). An additional 14% (HR 1.14, 95% CI 1.06-1.23) and 16% (HR 1.16, 95% CI 1.08-1.24) increase in ACS risk when coronary stenosis ≥50% or adverse plaque was present respectively. Likelihood ratio tests demonstrated improved ACS risk predictability by combining adverse coronary features with FFRCT.

CONCLUSION: Our results demonstrated a risk continuum of FFRCT for ACS supporting the value of FFRCT beyond dichotomized evaluation. ACS predictability from FFRCT was improved by accounting for adverse coronary atherosclerotic features which may have important clinical implications when FFRCT values are in borderline range.