Comparison of quantitative flow ratio, Pd/Pa and diastolic hyperemia-free ratio versus fractional flow reserve in non-culprit lesion of patients with non ST-segment elevation myocardial infarction.

Objectives: To investigate the correlation between quantitative flow ratio (QFR), Pd/Pa, diastolic hyperemia-free ratio (DFR) and fractional flow reserve (FFR, gold standard) in non-culprit lesion (NCL) of patients with non ST-segment elevation myocardial infarction (NSTEMI).

Background: The non-hyperemic pressure ratio (NHPR) and the angiography-based indexes have been developed to overcome the limitation of the use of the FFR.

Methods: Between January and December 2019, 184 NCL from 116 NSTEMI patients underwent physiologic assessment and were included in the study. NCLs were investigated with QFR, Pd/Pa, DFR, and FFR. Mean values of QFR, Pd/Pa, DFR and FFR were 0.85 ± 0.10, 0.92 ± 0.07, 0.93 ± 0.05 and 0.84 ± 0.07, respectively.

Results: DFR and FFR showed a good correlation (r = 0.76). Bland and Altman plot showed a mean difference of 0.080. DFR Diagnostic accuracy was 88%. The area under the ROC curve (AUC) for DFR was 0.946 (95%CI 0.90-0.97, p = .0001). Similar findings were reported for Pd/Pa (r = 0.73; mean difference 0.095, diagnostic accuracy 84%, AUC 0.909 [95%CI 0.85-0.94, p = .0001]) and QFR (r = 0.68; mean difference 0.01; diagnostic accuracy 88%, AUC 0.964 [95% CI 0.91-0.98, p = .0001]). FFR, QFR, Pd/Pa and DFR identified 31%, 32%, 30% and 32% potentially flow-limiting lesions, respectively.

Conclusions: In NSTEMI patients, QFR, Pd/Pa and DFR showed equivalence as compared to gold standard FFR in the discrimination of non-culprit lesions requiring revascularization.