Purpose: Quantitative ow ratio (QFR) is a recently proposed angiographic index that allows to assess the pressure loss in coronary arteries in a similar fashion as the accepted standard fractional ow reserve (FFR). The purpose of this study was to evaluate the diagnostic performance of QFR as compared to FFR, in a Latin-American population of patients with suspected ischaemic heart disease.Methods: QFR was retrospectively derived from coronary angiograms. The association, diagnostic performance, and continuous agreement of xed-ow QFR (fQFR) and contrast-ow QFR (cQFR) with FFR was assessed by continuous and dichotomous methods.Results: 90 vessels form 63 patients were nally included. The study comprised coronary stenoses of intermediate severity, both angiographically (diameter stenosis: 46.6 ± 12.8%) and physiologically [median FFR=0.86 (quartile 1-3, 0.76-0.89)]. The correlation of FFR with both fQFR [ρ=0.841, (95% CI: 0.767 to 0.893), p<0.001] and cQFR [ρ=0.833, (95% CI: 0.755 to 0.887), p<0.001] was strong. The diagnostic performance of cQFR was numerically better [area under the ROC curve of 0.92 (95% CI: 0.86 to 0.97, p<0.001)], with 0.80 as the optimal cQFR cut-off against FFR≤0.80. This 0.80 cQFR cut-off classi ed correctly 83.3% of total stenoses, with a sensitivity of 85.2% and speci city of 80.6%.Conclusions: QFR was strongly associated with FFR and exhibited a high diagnostic performance in this Latin-American population.