# Comparison of Fractional Flow Reserve and Resting Full-Cycle Ratio in the Functional Assessment of Coronary Artery Stenosis in Patients with Non-ST-Segment Elevation Acute Coronary Syndrome

## TL;DR

This study compares two methods for assessing heart artery blockages in patients with a specific type of heart condition and finds that one method is more variable when a certain artery is involved.

## Contribution

Identifies left anterior descending artery involvement as a key predictor of discrepancies between FFR and RFR measurements in NSTE-ACS patients.

## Key findings

- 80% concordance between fractional flow reserve (FFR) and resting full-cycle ratio (RFR) measurements.
- Left anterior descending artery (LAD) lesions showed significantly lower consistency between FFR and RFR compared to non-LAD lesions.
- LAD involvement independently predicts diagnostic discrepancies between FFR and RFR in NSTE-ACS patients.

## Abstract

This study investigated factors
influencing discrepancies between fractional flow reserve (FFR) and resting
full-cycle ratio (RFR) in the functional assessment of coronary
artery stenosis in patients with non-ST-segment elevation acute coronary
syndrome (NSTE-ACS).

We included 320 diseased
vessels from 253 consecutive patients with NSTE-ACS. Vessels were categorized
into four groups based on FFR ≤0.80 and RFR ≤0.89 thresholds: group
1 concordant negative (RFR–/FFR–), group 2 positive RFR and negative FFR
(RFR+/FFR–), group 3 negative RFR and positive FFR (RFR–/FFR+), and group 4
concordant positive (RFR+/FFR+). Univariate and multivariate logistic regression
analyses were conducted to identify predictors of diagnostic discrepancy between
FFR and RFR.

Of the 320 diseased vessels, 182 (56.9%) were in
group 1 (RFR–/FFR–), 33 (10.3%) in group 2 (RFR+/FFR–), 31 (9.7%) in group 3
(RFR–/FFR+), and 74 (23.1%) in group 4 (RFR+/FFR+). The concordance between FFR
and RFR was 80.0%. Notably, left anterior descending artery (LAD) lesions
exhibited significantly lower consistency compared to non-LAD lesions (p
= 0.001), with distinct differences in FFR and RFR values between these groups
(p
< 0.001). The presence of a LAD lesion emerged as an independent
predictor of diagnostic inconsistency between positive RFR and negative FFR
measurements (p = 0.001).

LAD involvement
independently predicts diagnostic discrepancies between FFR and
RFR in evaluating functional coronary artery stenosis in NSTE-ACS
patients.