Derivation and validation of Pd/Pa in the assessment of residual ischemia post‐intervention: A prospective all‐comer registry

Background Measurement of post‐percutaneous coronary intervention (PCI) fractional flow reserve (FFR) demonstrates residual ischemia in a large percentage of cases deemed angiographically successful which, in turn, has been associated with worse long‐term outcomes. It has recently been shown that a resting pressure index, Pd/Pa, has prognostic value post stenting, however, its diagnostic value relative to FFR post‐PCI has not been evaluated. Methods The diagnostic accuracy of Pd/Pa in identifying ischemia (FFR≤0.80) pre‐ and post‐PCI was evaluated. Three patient subsets were analyzed. A reference pre‐PCI cohort of 1,255 patients (1,560 vessels) was used to measure the accuracy of pre‐PCI Pd/Pa vs. FFR. A derivation post‐PCI group of 574 patient (664 vessels) was then used to calculate the diagnostic accuracy of post‐PCI Pd/Pa vs. FFR. A final prospective validation cohort of 230 patients (255 vessels) was used to test and validate the diagnostic performance of post‐PCI Pd/Pa. Results Median Pd/Pa and FFR were 0.90 (IQR 0.90–0.98) and 0.80 (IQR 0.71–0.88) in the reference pre‐PCI model, 0.96 (IQR 0.93–1.00) and 0.87 (IQR 0.77–0.90) in the post‐PCI derivation model, and 0.94 (IQR 0.89–0.97) and 0.84 (IQR 0.77–0.90) in the post‐PCI validation model respectively. There was a strong linear correlation between Pd/Pa and FFR in all three models ( p < 0.0001). Using ROC analysis, the optimal Pd/Pa cutoff value to predict a FFR ≤ 0.80 was ≤0.92 (AUC 0.87) in the pre‐PCI model, ≤0.93 (AUC 0.85) in the post‐PCI derivation model, and ≤ 0.90 (AUC 0.91) in the post‐PCI validation model. Using a hybrid strategy of post‐PCI Pd/Pa and post‐PCI FFR when necessary (25% patients), overall diagnostic accuracy was improved to 95%. Conclusions Pd/Pa has excellent diagnostic accuracy for identifying ischemia post‐intervention. Using a hybrid strategy of post‐PCI Pd/Pa first, and FFR afterwards, if required, adenosine administration can be avoided in over 75% of physiologic assessments post intervention.