Diagnostic Accuracy of Artificial Intelligence-Enhanced Ultrasonic Flow Ratio for On-Site Assessment of Coronary Stenosis.

Ultrasonic flow ratio (UFR) is a novel method for fast computation of fractional flow reserve (FFR) from intravascular ultrasound images. The objective of this study is to evaluate the diagnostic performance of UFR using wire-based FFR as the reference. Post hoc computation of UFR was performed in consecutive patients with both intravascular ultrasound and FFR measurement in a core lab while the analysts were blinded to FFR. A total of 167 paired comparisons between UFR and FFR from 94 patients were obtained. Median FFR was 0.80 (interquartile range, 0.68-0.89) and 50.3% had a FFR≤0.80. Median UFR was 0.81 (interquartile range, 0.69-0.91), and UFR showed strong correlation with FFR (r=0.87; P<0.001). The area under the curve was higher for UFR than intravascular ultrasound-derived minimal lumen area (0.97 versus 0.89, P<0.001). The diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio for UFR to identify FFR≤0.80 was 92% (95% CI, 87-96), 91% (95% CI, 82-96), 96% (95% CI, 90-99), 96% (95% CI, 89-99), 91% (95% CI, 93-96), 25.0 (95% CI, 8.2-76.2), and 0.10 (95% CI, 0.05-0.20), respectively. The agreement between UFR and FFR was independent of lesion locations (P=0.48), prior myocardial infarction (P=0.29), and imaging catheters (P=0.22). Intraobserver and interobserver variability of UFR analysis was 0.00±0.03 and 0.01±0.03, respectively. Median UFR analysis time was 102 (interquartile range, 87-122) seconds. UFR had a strong correlation and good agreement with FFR. The fast computational time and excellent analysis reproducibility of UFR bears the potential of a wider adoption of integration of coronary imaging and physiology in the catheterization laboratory.

Assessment of intermediate left main (LM) coronary artery stenosis remains clinically challenging. Wire-based fractional flow reserve (FFR) is considered the gold standard. Still, the use of intravascular ultrasound (IVUS)-derived functional indices, such as ultrasonographic flow ratio (UFR), is emerging as a potential non-wire alternative for physiological lesion assessment. Objective: To evaluate the diagnostic accuracy and efficacy of IVUS-based FFR (UFR) compared to wire-based FFR in patients with intermediate LM coronary artery stenosis. Methods: A prospective study was conducted at a tertiary care cardiology hospital from May 2024 to May 2025. A total of 100 adult patients with angiographically intermediate LM stenosis (defined as 50–70% diameter stenosis) were included. IVUS was performed using a motorized pullback device operating at 0.5 mm/s, from a distal point in the left coronary artery up to the aortic ostium. UFR was calculated based on IVUS pullback data. Wire-based FFR was recorded by positioning a pressure guidewire in the downstream coronary branches. The diagnostic performance of UFR was assessed using receiver operating characteristic (ROC) analysis, with wire-based FFR (cut-off &lt;0.80) as the reference standard. Results: There was a moderate correlation between UFR and FFR (r = 0.692, p &lt; 0.0001). UFR demonstrated a high area under the curve (AUC = 0.88; 95% CI: 0.91–0.99) for detecting functionally significant LM stenosis, outperforming angiography (AUC = 0.71, p &lt; 0.001) and minimum lumen area (MLA) measurement (AUC = 0.79, p = 0.11). The optimal UFR threshold showed a diagnostic accuracy of 83.2%, superior to MLA ≤ 4.5 mm² (59.1%) and comparable to MLA ≤ 6.0 mm² (81.4%). Sensitivity for UFR, MLA ≤ 4.5 mm², and MLA ≤ 6.0 mm² was 92.7%, 48.6%, and 85.8%, respectively. FFR-based specificity was 57.6%, with a positive predictive value of 85.5%, negative predictive value of 78.3%, favorable likelihood ratio (+LR) of 2.19 (95% CI: 1.16–4.34), and negative likelihood ratio (–LR) of 0.09 (95% CI: 0.05–0.52). Conclusion: IVUS-derived FFR (UFR) demonstrated high diagnostic accuracy and sensitivity, comparable or superior to wire-based FFR in identifying functionally significant intermediate LM stenosis. UFR may offer a reliable, less invasive alternative to pressure-wire-based assessment in select patients.

Intravascular optical coherence tomography (OCT) imaging provides limited information on the functional assessment of coronary stenosis. We evaluated a new approach to OCT image-based computation modeling, which can be used to estimate the fractional flow reserve (FFR) in patients with intermediate coronary stenosis. Ninety-two patients with intermediate diameter stenosis in the left anterior descending artery underwent both FFR measurement with pressure wires and OCT examination. Using the OCT data, a computational fluid dynamics algorithm was used to calculate the computational FFR (FFROCT). The diagnostic performance of the FFROCT was assessed based on the pressure wire-based FFR. The median FFR and FFROCT values were 0.86 (0.79-0.89) and 0.89 (0.82-0.94), respectively. The average diameter stenosis in quantitative coronary angiography and area stenosis in OCT were 58.1±13.4% and 67.5±13.5%, respectively. The FFROCT was better correlated to the FFR than were the anatomic variables (r=0.72; P<0.001 versus r=0.46; P<0.001 for minimal luminal diameter on quantitative coronary angiography or r=0.57; P<0.001 for minimal lumen area on OCT). When functionally significant stenosis was defined as an FFR cutoff value of ≤0.8, FFROCT resulted in 88.0% accuracy, 68.7% sensitivity, and 95.6% specificity. The positive and negative predictive values were 84.2% and 89.0%, respectively. The computation of FFROCT enables assessment not only of anatomic information, but also of the functional significance of intermediate stenosis. This measurement may be a useful approach for the simultaneous evaluation of the functional and anatomic severity of coronary stenosis.

The regional difference in severe coronary artery disease between fractional flow reserve and intravascular ultrasound

Diagnostic Accuracy of Angiography-Based Quantitative Flow Ratio Measurements for Online Assessment of Coronary Stenosis

Background Previous studies suggest that there are clinically relevant differences between women and men in patients with ischemic heart disease. However, little is known about the gender influence on the functional significance of coronary artery stenosis. Method A total of 1,032 lesions with available intravascular ultrasound (IVUS) and fractional flow reserve (FFR) were recruited from 11 international centers and 881 de novo lesions with intermediate stenosis located at the non-left main major epicardial coronary arteries (822 patients, male 70.6%) were included in this analysis. All data were analyzed at Seoul National University Data Management Core Laboratory. FFR ≤0.8 was considered functionally significant. Results Angiographic % diameter stenosis and reference diameter were 49.6±12.7 and 3.0±0.5 mm, respectively. Minimum luminal area (MLA) by IVUS was 3.12±1.34mm 2 . Mean FFR was 0.81±0.11 and 353 lesions (40.1%) were functionally significant. There were no differences in angiographic lesion severity and IVUS MLA between male and female patients (Table). However, compared to female patients, FFR was significantly lower in male (male: 0.81±0.11 vs. female: 0.83±0.10, P =0.010) and functionally significant stenosis was more frequent in male patients (FFR ≤0.8; male: 42.8% vs. female: 32.9%, P =0.007). The best cutoff value of angiographic % diameter stenosis to determine the functional significance was 49.4% in male and 53.0% in female patients. The best cutoff value of IVUS MLA was 3.25 mm 2 in male and 3.05 mm 2 in female patients. Conclusion Compared to male patients, female patients may have higher anatomical threshold for the functional significance of coronary artery stenosis.

Introduction. Multi-detector CT coronary angiography (CorCTA) has been introduced for coronary artery disease (CAD) detection and been validated against invasive angiography (XRA) and intravascular ultrasound (IVUS). However, the diagnostic accuracy of CorCTA-derived area stenosis (%AS), diameter stenosis (%DS), minimal lumen area (MLA) and minimal lumen diameter (MLD) have not been previously validated against fractional flow reserve (FFR). Methods. Twenty consecutive patients enrolled in a study of non-obstructive CAD underwent CorCTA and invasive FFR measurements within 2 weeks. Patients without prior CAD with visual intermediate stenoses (40–70%) by either XRA or CorCTA were eligible. CorCTA was performed on a 64-slice scanner. %AS, %DS, MLA and MLD were measured quantitatively with commercial software (SurePlaque; Vital Images). FFR was determined by averaging 3 independent measurements after intracoronary injection of adenosine. Statistical analysis was done using Analyse-It software. Results. CorCTA-derived values (mean±SD) in the group were as follows: %AS=43.8±21.3%, %DS=58.9±21.4%, MLA=3.9±3.0mm 2 , MLD=1.4±0.8mm, FFR=0.89±0.09. Two patients had flow-limiting stenoses by FFR. Table shows the area under the curve (AUC), optimal cutpoint, sensitivity, specificity, PPV and NPV for the parameters to predict non-flow-limiting FFR. All parameters performed well in predicting non-flow-limiting FFR as expressed by the AUC; these were highly significant. Values below stenosis cutpoints (%AS&lt;60%, %DS&lt;77%) and MLA&gt;3.0 mm 2 , MLD&gt;0.89 mm reliably excluded flow-limiting stenoses. Cutpoints were higher for %DS vs %AS (77% vs. 60%). Conclusions. To our knowledge, this is the first study to compare CorCTA to FFR. %AS, %DS, MLA and MLD performed very well in excluding hemodynamically significant stenoses. While%DS and MLD by CorCTA tend to overestimate the significance of stenosis, %AS and MLA correlate well to similar values derived from IVUS. Accuracy of CorCTA in Excluding Flow Limiting Stenoses As Measured by FFR

6113Gender differences in long-term outcomes in patients with deferred revascularization following fractional flow reserve assessment: international collaboration registry of physiologic evaluation

Diagnostic accuracy of vessel fractional flow reserve compared to conventional diagnostic tools in patients with coronary artery stenosis

Left ventricular end-diastolic pressure affects measurement of fractional flow reserve

The recently introduced ultrasonic flow ratio (UFR), is a novel fast computational method to derive fractional flow reserve (FFR) from intravascular ultrasound (IVUS) images. In the present study, we evaluate the diagnostic performance of UFR in patients with intermediate left main (LM) stenosis. This is a prospective, single center study enrolling consecutive patients with presence of intermediated LM lesions (diameter stenosis of 30%-80% by visual estimation) underwent IVUS and FFR measurement. An independent core laboratory assessed offline UFR and IVUS-derived minimal lumen area (MLA) in a blinded fashion. Both UFR and FFR were successfully achieved in 41 LM patients (mean age, 62.0 ± 9.9 years, 46.3% diabetes). An acceptable correlation between UFR and FFR was identified (r = 0.688, P < 0.0001), with an absolute numerical difference of 0.03 (standard difference: 0.01). The area under the curve (AUC) in diagnosis of physiologically significant coronary stenosis for UFR was 0.94 (95% CI: 0.87-1.01), which was significantly higher than angiographic identified stenosis > 50% (AUC = 0.66, P < 0.001) and numerically higher than IVUS-derived MLA (AUC = 0.82; P = 0.09). Patient level diagnostic accuracy, sensitivity and specificity for UFR to identify FFR ≤ 0.80 was 82.9% (95% CI: 70.2-95.7), 93.1% (95% CI: 82.2-100.0), 58.3% (95% CI: 26.3-90.4), respectively. In patients with intermediate LM diseases, UFR was proved to be associated with acceptable correlation and high accuracy with pressure wire-based FFR as standard reference. The present study supports the use of UFR for functional evaluation of intermediate LM stenosis.

P2720Diagnostic accuracy of Quantitative Flow Ratio (QFR) and Vessel Fractional Flow Reserve (vFFR) compared to Fractional Flow Reserve (FFR) based on 7.5 frames/second coronary angiography

Objective: In the present study, the association between red cell distribution width (RDW) with functional significance of intermediate coronary artery lesions was investigated. Materials and Methods: Two hundred and forty-six consecutive patients, 168 males and 78 females, who underwent fractional flow reserve (FFR) measurement for angiographically intermediate coronary stenosis (40-70% in quantitative coronary analysis) in the left anterior descending coronary artery were enrolled into the study. The functional significance of intermediate coronary artery lesions was determined by FFR measurement. An FFR value <0.75 was defined as functionally significant. Venous blood samples were taken within 48 h before the FFR measurement, and RDW levels were determined by a Coulter LH Series hematology analyzer. Logistic regression analysis was used to examine the association between functional significance in FFR measurement and other variables. Results: Of the 246 patients, 62 (25.2%) exhibited significant functional stenosis (FFR <0.75) in the FFR measurement. The mean RDW level was significantly higher in patients with significant stenosis (14.19 ± 0.73 vs. 13.69 ± 0.77, p < 0.001). In stepwise multivariate logistic regression analysis, RDW (OR = 2.489, 95% CI = 1.631-3.799, p < 0.001) and male gender (OR = 2.826, 95% CI = 1.347-5.928, p = 0.006) were independent predictors of significant functional stenosis. Conclusion: Increased RDW levels were associated with functional significance of angiographically intermediate coronary artery stenoses.

Comprehensive Assessment of Coronary Artery Stenoses: Computed Tomography Coronary Angiography Versus Conventional Coronary Angiography and Correlation With Fractional Flow Reserve in Patients With Stable Angina

Physiological disease pattern as assessed by PPGI in vessels with FFR and iFR discordance