Prediction of post-intervention fractional flow reserve in diffuse or sequential coronary stenosis considering the residual trans-stent pressure gradient

Aims: Prediction of post-intervention fractional flow reserve (FFR) in a diffuse or sequential coronary lesion is difficult due to complex haemodynamic interactions between individual stenoses. Furthermore, the existence of a residual intra-stent pressure gradient makes the prediction difficult. We developed an equation predicting the post-intervention FFR in a diffuse/sequential lesion by considering intra-stent FFR gradient. The present study aims to validate the equation in an in vitro model and in clinical data. Methods and results: In the in vitro experiment, three sequential coronary stenoses were made with a collateral flow. The correlation coefficient of the predicted FFR and the actual post-intervention FFR was 0.99, and the absolute difference was 0.008±0.006 (n=50). In the clinical data analysis, the correlation coefficient was 0.41, and the absolute difference was 0.06±0.05 (n=67). We applied a fixed value of intra-stent FFR gradient and a collateral flow index so that the equation can be used in clinical practice. The correlation coefficient became 0.28 and the absolute difference became 0.06±0.06. Conclusions: In clinical practice, prediction of post-intervention FFR in a diffuse/sequential lesion is difficult even when residual intra-stent pressure gradient is considered.