Prognosis of CT-derived Fractional Flow Reserve in the Prediction of Clinical Outcomes.

PURPOSE

To examine the prognostic implication of fractional flow reserve (FFR) derived from coronary CT (FFR) in routine clinical practice.

MATERIALS AND METHODS

Patients referred for FFR analysis at a single center between October 2015 and June 2017 were retrospectively included and followed up for rates of invasive angiography and clinical events. Two hundred seven patients underwent successful FFR analysis with seven lost to follow-up, leaving 200 (mean age ± standard deviation, 62.4 years ± 10.0; 49 [24.5%] women) patients for analysis. At coronary CT angiography, patients were categorized as having significant stenosis (SS) in the presence of a diameter stenosis greater than or equal to 50% (hereafter, SS positive) and flow limitation in the presence of a postlesion (that is, FFR measured 2 cm to the distal aspect of the lesion) FFR less than 0.80 (hereafter, FFR positive). Vessel-oriented clinical events (VOCEs) were defined as vessel-related late revascularization (>90 days), myocardial infarction, and cardiac mortality.

RESULTS

At CT angiography, 130 (65%) studies were SS positive and 63 (31.5%) were FFR positive. At median follow-up of 477 days (range, 252-859 days), there were 26 VOCE end points in 22 patients: 22 revascularizations and four nonfatal myocardial infarctions. VOCE end points occurred in zero of 58 (0%) of SS-negative and FFR negative patients, in eight of 79 (10.1%) of SS-positive and FFR-negative patients, in zero of 12 (0%) of SS-negative and FFR-positive patients, and in 18 of 51 (35.3%) of SS-positive and FFR-positive patients (log-rank χ = 30.1; < .001). At multivariable Cox regression, both FFR (hazard ratio per 0.1 decrease, 1.54 [95% confidence interval: 1.1, 2.2] = .013) and stenosis (hazard ratio per unit increase, 2.16 [95% confidence interval: 1.25, 3.72] = .006) were independently associated with VOCE.

CONCLUSION

Stenosis and FFR are independent predictors of intermediate-term outcomes. In the absence of a stenosis greater than 50%, a positive FFR result is not associated with an increased intermediate risk.© RSNA, 2019See also commentary by Fairbairn and Bull in this issue.