Coronary pressure measurement to assess the hemodynamic significance of serial stenoses within one coronary artery - Validation in humans

Background-When several stenoses are present within 1 coronary artery, the hemodynamic significance of each stenosis is influenced by the presence of the other(s), and the calculation of coronary and fractional flow reserve ( CFR and FFR) for each individual stenosis is confounded. Recently, we devel oped and experimentally validated a method to determine the true FFR of eac h stenosis as it would be after the removal of the other stenosis; the true FFR can be reliably predicted by coronary pressures measured before treatm ent at specific locations within the coronary artery using equations accoun ting for stenosis interaction. The aim of the present study was to test the validity of these equations in humans. Methods and Results-In this study of 32 patients with 2 serial stenoses in 1 coronary artery, relevant pressures were measured before the intervention , after the treatment of 1 stenosis, and after the treatment of both stenos es. The true FFR of each stenosis (FFRtrue) was directly measured after the elimination of the other stenosis and compared with the value predicted (F FRpred) from the initial pressure measurements before treatment. Although t he hyperemic gradient across 1 stenosis increased significantly (from 10+/- 7 to 19+/-11 mm Hg after treatment of the other stenosis), FFRpred was clos e to FFRtrue in all patients (0.78+/-0.12 versus 0.78+/-0.11 mm Hg; r=0.92; Delta%=4+0%). Without accounting for stenosis interaction, the value of FF R for each stenosis would have been significantly overestimated (0.85+/-0.0 8; P<0.01). Conclusions-Coronary pressure measurements made by a pressure win at maximu m hyperemia provide a simple, practical method for assessing the individual hemodynamic significance of multiple stenoses within the same artery.