Exploring the Predictors of the Discrepancy Between Quantitative Flow Ratio and Fractional Flow Reserve Measurements

Background: Quantitative flow ratio is a novel technology for the functional assessment of intermediate coronary stenoses. The authors sought to explore the influence of diabe- tes mellitus on the application of quantitative flow ratio and predictors of discrepancies between quantitative flow ratio and fractional flow reserve. Methods: Quantitative flow ratio was calculated in 224 patients (317 vessels) who underwent fractional flow reserve measurement by professional technicians blinded to fractional flow reserve value. Patients were divided into the diabetes mellitus group and the non-diabetes mellitus group. The diagnostic performance of quantitative flow ratio was assessed using fractional flow reserve as a reference. Results: Good correlation and agreement between quantitative flow ratio and fractional flow reserve can be found in the diabetes mellitus group (r = 0.834, P < .001; mean difference: 0.007 +/- 0.108). Prior myocardial infarction showed a statistically significant association with increased classification discrepancy between quantitative flow ratio and fractional flow reserve [odds ratio 3.16 (95% confidence interval: 1.29-7.75), P = .01]. The area under the receiver-operating characteristic curve of quantitative flow ratio showed no significant difference in diabetes mellitus and non-diabetes mellitus groups, hemoglobin A1c >= 7% and hemoglobin A1c < 7% groups, diabetic duration > 10 years and diabetic duration < 10 years groups (area under receiver-operating characteristic curve: 0.90 (95% confidence interval: 0.84-0.94) vs. 0.92 (95% confidence interval: 0.87-0.96), P = .54; 0.89 (95% confidence interval: 0.81-0.95) vs. 0.92 (95% confidence interval: 0.81-0.97), P = .65; 0.88 (95% confidence interval: 0.79-0.94) vs. 0.89 (95% confidence interval: 0.79-0.96), P = .83; respectively). Conclusions: Clinical application of quantitative flow ratio is not limited to diabetic patients. The relationship between prior myocardial infarction and quantitative flow ratio needs to be further developed.