Functional Flow Reserve (FFR) as a Surrogate Marker of Myocardial Viability: A Case Demonstration Highlighting the Forgotten Utility

Despite severe LAD ISR, FFR was nonsignificant (0.88), indicating the restricted microvascular bed and the limited demands in the LAD territory. No intervention was performed on the LAD. CMR confirmed extensive nonviable myocardium in the LAD distribution, corroborating the FFR findings. This case supports the use of FFR as a rapid, real-time, and practical tool for indirectly assessing myocardial viability, particularly when standard viability testing might be delayed or unavailable.