Diagnostic Performance of Quantitative Flow Ratio for the Assessment of Non-Culprit Lesions in Myocardial Infarction (QFR-OUTSMART): Systematic Review and Meta-Analysis.

Background: Quantitative flow ratio (QFR) analysis is a simple and non-invasive coronary physiological assessment method with evidence for evaluating stable coronary artery disease with correlation to fractional flow reserve (FFR). However, there is no evidence to recommend its use in non-culprit lesions (NCLs) in myocardial infarction (MI).

Methods: We performed a systematic review and meta-analysis using the PRISMA and PROSPERO statements. The study's primary objective was to assess the diagnostic accuracy of QFR in identifying functionally significant NCLs after MI based on invasive FFR and non-hyperemic pressure ratios as references. We obtained values of the area under the curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). We performed a leave-one-out sensitivity analysis for each study's impact on the overall effect.

Results: We included eight studies, with 713 patients and 920 vessels evaluated with QFR. The overall AUC was 0.941 (I² = 0.559, p < 0.002), with a sensitivity of 87.3%, a specificity of 89.4%, a PPV of 86.6%, and an NPV of 90.1%. Compared to FFR, we found an AUC of 0.957 (I² = 0.331, p < 0.194), a sensitivity of 89.6%, a specificity of 89.8%, a PPV of 88.3%, and an NPV of 91%. The sensitivity analysis showed a similar diagnostic performance in both studies.

Conclusions: QFR is effective in analyzing NCLs with a significant diagnostic yield compared to FFR, with an excellent AUC in MI patients. Performing prospective multicenter studies to characterize this population and reproduce our results is essential.