Abstract 18978: Resting Pressure Gradient (iFG) Instantaneous Wave-free ratio (iFR) for Non-culprit Stenosis Evaluation in Patients with Acute Coronary Syndromes. Preliminary Data from the FORECAST Study

Abstract

Background: The assessment of non-culprit stenoses is an important issue in ACS. Adenosine administration is currently required for functional evaluation of stenosis severity using the fractional flow reserve (FFR). An alternative adenosine-independent index of coronary stenosis, the instantaneous wave-free ratio (iFR), was recently introduced. Objective: Aim of the present study was to evaluate the trans-stenotic instantaneous wave-free pressure gradient (iFG), the instantaneous wave-free ratio (iFR) and the fractional flow reserve (FFR) in ACS patients. Methods: Intracoronary diastolic pressure was measured proximal and distal to the stenosis during the wave-free period with a pressure wire (Certus, St. Jude, USA) at baseline and upon iv adenosine administration (140 ug/kg/min). The data were acquired with a PowerLab (AD Instruments, USA) and analyzed with a LabChart 7. Results: A total of 71 stenoses were evaluated in the present study. iFR showed a correlation with FFR (r=0.61, p<0.001), while a proportional error was documented with the Bland-Altman analysis. At multivariate analysis, the localization of the evaluated stenosis within the coronary tree influenced the correlation of iFR with FFR (p=0.03). ROC analysis showed a promising diagnostic efficiency for detection of significant coronary stenosis with iFR (AUC=0.936; p<0.001) or iFG (AUC=0.944; p<0.001). Conclusions: The instant wave-free ratio (iFR) and the resting distal-to-proximal pressure gradient measured during the wave-free period (iFG) showed a good diagnostic performance for the assessment of non-culprit lesions in ACS, representing a promising and adenosine-independent alternative to standard fractional flow reserve (FFR).