Nonculprit Stenosis Evaluation Using Instantaneous Wave-Free Ratio in Patients With ST-Segment Elevation Myocardial Infarction.

Objectives: The aim of this study was to examine the level of agreement between acute instantaneous wave-free ratio (iFR) measured across nonculprit stenoses in patients with ST-segment elevation myocardial infarction (STEMI) and iFR measured at a staged follow-up procedure.

Background: Acute full revascularization of nonculprit stenoses in STEMI is debated and currently guided by angiography. Acute functional assessment of nonculprit stenoses may be considered.

Methods: Immediately after successful primary culprit intervention for STEMI, nonculprit coronary stenoses were evaluated with iFR and left untreated. Follow-up evaluation with iFR was performed at a later stage. iFR <0.90 was considered hemodynamically significant.

Results: One hundred twenty patients with 157 nonculprit lesions were included. Median acute iFR was 0.89 (interquartile range [IQR]: 0.82 to 0.94; n = 156), and median follow-up iFR was 0.91 (interquartile range: 0.86 to 0.96; n = 147). Classification agreement was 78% between acute and follow-up iFR. The negative predictive value of acute iFR was 89%. Median time from acute to follow-up evaluation was 16 days (IQR: 5 to 32 days). With follow-up within 5 days after STEMI, no difference was observed between acute and follow-up iFR, and classification agreement was 89%. With follow-up ≥16 days after STEMI, acute iFR was lower than follow-up iFR, and classification agreement was 70%.

Conclusions: Acute iFR evaluation appeared valid for ruling out significant nonculprit stenoses in patients with STEMI undergoing primary percutaneous coronary intervention. The time interval from acute to follow-up iFR influenced classification agreement, suggesting that inherent physiological disarrangements during STEMI may contribute to classification disagreement.