Background and Objectives: This study was designed to compare novel functional coronary lesion severity index, hyperemic epicardial stenosis resistance index(hESRI), with fractional flow reserve(FFR) and with anatomic stenosis stenosis severity assessed by intravascular ultrasound(IVUS).
Methods: Forty-eight lesions of non-infarct related artery(46 LCA, 2 RCA) in 35 patients(28 male, mean age 57짹11) were studied. IVUS % area stenosis(IVUS-%AS), hESRI, FFR, and CFR were measured before and/or after coronary stenting. FFR and CFR were calculated as usual methods. hESRI was defined as the ratio of hyperemic trans-lesional pressure gradient to hyperemic average peak velocity(APV). Maximal coronary hyperemia was induced by intracoroanry adenosine bolus injection(32-48µg).
Results: Mean IVUS-%AS was 67.1짹17.6%, hESRI was 0.87짹0.81 mmHgm쨌cm^-1쨌sec, FFR was 0.74짹0.16 , and CFR was 2.56짹1.06. The correlation coefficient between IVUS-%AS with hESRI, FFR, and CFR were 0.825(p<0.001), 0.760(p<0.001), and 0.538(p<0.001), respectively. The agreement between IVUS-%AS with hESRI, FFR, and CFR were 87.5%, 91.7%, and 72.9%, on the cut-off value of 0.54, 0.77, and 1.6, respectively, when IVUS-%A���75% was considered as a significant anatomic epicardial stenosis. The area under curve(AUC) for hESRI(0.925짹0.045, sensitivity 89.5%, specificity 82.1%) and FFR(0.900짹0.044, sensitivity 94.7%, specificity 79.3%) were significantly higher than that of CFR(0.706.짹0.075, sensitivity 47.4%, specificity 93.1%)(p=0.002 and p=0.015, respectively). There was no significant difference in the area under curve between hESRI and FFR(p=0.517).
Conclusion: These results showed that hyperemic epicardial stenosis resistance index was comparable with fractional flow reserve for evaluation of functional coronary lesion severity and showed significant correlation with anatomic stenosis stenosis severity assessed by intravascular ultrasound in non-infarct related coronary artery