Till Örebro universitet

BACKGROUND: Quantitative flow ratio (QFR) is an angiography-based approach for in-procedure functional evaluation of coronary artery lesions. We evaluated the diagnostic performance of QFR with instantaneous wave-free ratio (iFR) in non-culprit lesions (NCLs) in patients with ST-segment elevation myocardial infarction (STEMI) and with staged fractional flow reserve (FFR) as reference standard.

METHODS: This is a post-hoc analysis of the iSTEMI study. All NCLs were assessed with iFR in the acute setting and with iFR and FFR at staged (median 19 days) follow-up. QFR (Medis Medical Imaging bv., The Netherlands) was computed for all analyzable NCLs in a core lab by an investigator blinded to iFR and FFR results. Diagnostic cut-off values were 0.80 for QFR, 0.89 for iFR, and 0.80 for FFR.

RESULTS: A total of 156 NCLs in 120 patients were included in the iSTEMI study. Paired iFR and FFR data were available for 146 NCls in 112 patients. Of these, QFR analysis was feasible in 103 (71 %) lesions assessed in the acute setting. Mean acute QFR was 0.800.13, acute iFR was 0.860.12, and staged FFR was 0.800.11. With staged FFR as reference standard, diagnostic accuracy was 84% (95%CI: 76-90) for acute QFR and 73% (95%CI: 66-83) for acute iFR (p¼0.09), area under the receiver operating curve (AUC) was 0.89 (95%CI: 0.82-0.95) vs. 0.77 (95%CI: 0.68-0.87) (p¼0.02), sensitivity was 83% (95%CI: 69-92) vs. 85% (95%CI: 73-92) (p¼0.79), specificity was 84% (95%CI: 72-92) vs. 64% (95%CI: 53-75) (p¼0.11), positive predictive value was 81% (95%CI: 57-82) vs. 70% (95%CI: 57-82)(p¼0.06), and negative predictive value was 86% (95%CI: 76-95) vs. 84% (95%CI: 69-91)(p¼0.37), for acute QFR and acute iFR, respectively.

CONCLUSION: The diagnostic performance of acute QFR in post hocevaluation of NCLs in STEMI patients was at least similar to acuteassessment by iFR with staged procedure FFR as reference. QFR couldprovide an easy, safe and cost-effective solution to evaluate NCLs inthe acute phase, thus potentially reducing the number of unnecessaryfollow-up procedures.

CATEGORIES IMAGING: Physiologic Lesion Assessment.