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

BACKGROUND

Fractional Flow Reserve (FFR) is widely employed to determine the functional severity of stenoses in epicardial coronary arteries. However, its potential to serve as a surrogate for myocardial viability in infarcted territories remains underutilized.

AIMS: To illustrate the utility of FFR in assessing myocardial viability and guiding revascularization decisions in patients with angiographically severe coronary lesions and questionable myocardial viability.

METHODS

This is a demonstrative case of a middle-aged male with previous anterior ST-elevation myocardial infarctions (STEMIs) and prior in-stent restenosis (ISR) in the left anterior descending (LAD) artery. During an index admission for inferior STEMI, severe ISR in the LAD was observed. FFR was performed to assess functional significance and indirectly infer viability of the LAD territory, hence driving appropriate revascularization decisions. Subsequent cardiac magnetic resonance (CMR) imaging was used to validate the findings.

RESULTS

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.