Abstract 17034: Diagnostic Accuracy of Diastolic Pressure Ratio Using a Microcatheter: An Analysis of the ACIST-FFR Study

Abstract

Background: The diastolic pressure ratio (dPR) is a non-hyperemic index used to measure the ratio of distal coronary to aortic pressure during a diastolic portion of the cardiac cycle. dPR indices measured by a pressure wire have similar diagnostic accuracy as iFR for FFR. The accuracy of dPR using a microcatheter (MC) has not been defined. Methods: The ACIST-FFR study was a prospective, multicenter study of a pressure-monitoring MC in patients with stable CAD. Using an automated software algorithm, dPR with the MC was defined as the Pd/Pa at the location within the diastolic period that was 50% of the distance from the peak of one waveform to the peak of the next waveform, averaged over a 5-beat period. iFR with the MC was computed in the usual fashion by the core laboratory from the original pressure tracings. Results: A total of 161 paired data samples from 11 sites were analyzed. dPR was highly correlated with iFR (R 2 =0.992, AUC=0.998 with a mean bias of -0.0237 (95% CI, -0.0041 to -0.0011) and provided a sensitivity of 98%, specificity 96%, and diagnostic accuracy of 96.9%. The optimal cutpoint of dPR for FFR was 0.91 (AUC=0.886), which provided a sensitivity of 82%, specificity of 80%, and diagnostic accuracy of 81%. The diagnostic accuracy of iFR for FFR was 81%, with a sensitivity of 82%, and specificity 80%. Conclusions: With a MC system, a non-hyperemic diastolic pressure ratio is highly correlated with iFR, and provides similar diagnostic accuracy as iFR for FFR.