P5618Coronary flow capacity to identify stenosis associated with coronary flow improvement after coronary revascularization
Authors: Murai T , Van De Hoef T P , Stegehuis V E , Wijntjens G W M , Yonetsu T , Hoshino M , Kanaji Y , Lee T , Kirkeeide R L , Johnson N P , Kakuta T , Piek J J 
Published: October 2019

Abstract

Background
Coronary flow capacity (CFC) has recently been introduced as a comprehensive assessment of the coronary circulation by combining coronary flow reserve (CFR) and maximal coronary flow velocity to overcome the limitations of using CFR alone, and was reported to provide enhanced risk stratification compared with CFR. However, its potential to identify stenosis that would be associated with clinically relevant flow coronary flow improvement after revascularization has not been investigated.

Aims
The aim of this study is to quantify coronary flow changes after revascularization in relation to CFC and CFR.

Methods and results
Using a combined dataset of DEFINE FLOW and the Amsterdam UMC prospective ComboWire database, a total of 133 patients (135 vessels) with intermediate coronary artery lesions who underwent intracoronary physiologic assessment including intracoronary Doppler flow measurement before and after PCI were analyzed. The median values of fractional flow reserve (FFR) and CFR before PCI were 0.70 (Q1–3: 0.56–0.80) and 1.64 (Q1–3: 1.30–2.06). The number of lesions classified by CFC before PCI were 14 for normal CFC, 40 for mildly reduced CFC, 33 for moderately reduced CFC and 48 for severely reduced CFC. The lesions with larger impairment of CFC showed greater increase in coronary flow, and vice versa (median percent increase in coronary flow by revascularization: 4.2% for normal CFC; 25.9% for mildly reduced; 50.1% for moderately reduced; 145.5% for severely reduced, P<0.0001). Using the same CFR distribution based on CFC criteria showed that only lesions with severely reduced CFR showed a significantly higher coronary flow increase after PCI (−2.6% for CFR in the normal zone; 26.6% for CFR in the mildly reduced zone; 33.3% for CFR in the moderately reduced zone; 81.7% for CFR in the severely reduced zone, P=0.0007). Compared with the established CFR cut-off value of 2.0, moderate to severely reduced CFC showed higher specificity and positive predictive value (PPV) to predict at least 20% increase in coronary flow after PCI (specificity and PPV: 86.4% and 72.5% for ischemic CFC vs. 75.8% and 40% for CFR cut-off value 2.0). Multivariate logistic regression analysis revealed that the lesions with moderately or severely reduced CFC (odd ratio [OR] = 7.606 95%interconfidence interval [CI]: 2.834–20.412, P<0.001) and pre-PCI FFR (OR=0.0002, 95% CI: 0.0002–0.0204, P<0.001) were the independent predictors of coronary flow increase after PCI.

Conclusion
CFC showed a higher diagnostic efficiency for identification of lesions which benefit from revascularization compared to CFR with respect to coronary flow improvement. This study provides the physiological rational of revascularization for the lesions with moderately to severely reduced CFC from the perspective of coronary flow increase.

Acknowledgement/Funding
Philips Volcano