Physiologic Assessment of Coronary Stenosis: Current Status and Future Directions

Accuracy of segment anything model for classification of vascular stenosis in digital subtraction angiography

BACKGROUND

This retrospective study evaluates the diagnostic performance of an optimized comprehensive multi-stage framework based on the Segment Anything Model (SAM), which we named Dr-SAM, for detecting and grading vascular stenosis in the abdominal aorta and iliac arteries using digital subtraction angiography (DSA).

MATERIALS AND METHODS

A total of 100 DSA examinations were conducted on 100 patients. The infrarenal abdominal aorta (AAI), common iliac arteries (CIA), and external iliac arteries (EIA) were independently evaluated by two experienced radiologists using a standardized 5-point grading scale. Dr-SAM analyzed the same DSA images, and its assessments were compared with the average stenosis grading provided by the radiologists. Diagnostic accuracy was evaluated using Cohen's kappa, specificity, sensitivity, and Wilcoxon signed-rank tests.

RESULTS

Interobserver agreement between radiologists, which established the reference standard, was strong (Cohen's kappa: CIA right = 0.95, CIA left = 0.94, EIA right = 0.98, EIA left = 0.98, AAI = 0.79). Dr-SAM showed high agreement with radiologist consensus for CIA (κ = 0.93 right, 0.91 left), moderate agreement for EIA (κ = 0.79 right, 0.76 left), and fair agreement for AAI (κ = 0.70). Dr-SAM demonstrated excellent specificity (up to 1.0) and robust sensitivity (0.67-0.83). Wilcoxon tests revealed no significant differences between Dr-SAM and radiologist grading (p > 0.05).

CONCLUSION

Dr-SAM proved to be an accurate and efficient tool for vascular assessment, with the potential to streamline diagnostic workflows and reduce variability in stenosis grading. Its ability to deliver rapid and consistent evaluations may contribute to earlier detection of disease and the optimization of treatment strategies. Further studies are needed to confirm these findings in prospective settings and to enhance its capabilities, particularly in the detection of occlusions.

Fractional Flow Reserve Implications for Clinical Decision Making in Coronary Artery Disease

Fractional flow reserve (FFR) is regarded as the gold standard for assessing the functional significance of coronary artery lesions. However, its utilization in clinical practice remains limited. This study aims to determine whether FFR results can influence treatment decisions for coronary artery disease compared to visual assessments of angiographic images. We conducted a retrospective study involving 63 patients diagnosed with either chronic coronary syndrome (n = 39, 61.9%) or acute coronary syndrome (n = 24, 38.1%) who underwent an FFR assessment. Three experienced interventional cardiologists (>300 PCI procedures/year) reevaluated 105 ambiguous coronary lesions in these patients, blinded to the FFR results. The objective was to assess lesion significance and determine the treatment strategy based on a visual angiographic evaluation. The three operators reached concordant agreement (≥two operators) to perform PCI in 60 (57.1%) of the evaluated lesions based on the angiographic assessment. Of these, nine lesions (15%) were deemed functionally non-significant by FFR (FFR > 0.80). Conversely, they agreed to defer PCI in 45 (42.9%) lesions, but 4 lesions (8.9%) were found to be functionally significant (FFR ≤ 0.80) and required a re-evaluation for PCI. Visual-guided decision making by interventional cardiologists shows variability and does not always align with the functional significance of coronary lesions as determined by FFR. Incorporating FFR into routine decision making could enhance treatment accuracy and patient outcomes.

Validity and correlation of quantitative flow ratio with fractional flow reserve for assessment of intermediate coronary lesions

BACKGROUND

The angiographic percent diameter stenosis (%DS) do not assess the physiological significance of epicardial coronary stenosis. The currently practised physiological indices require pressure wires with or without adenosine-induced hyperaemia. Quantitative flow ratio (QFR) is an angiography-based method to determine the functional significance of coronary stenosis. The present study aimed to analyse the diagnostic performance of QFR in comparison to fractional flow reserve (FFR) in intermediate coronary lesions.

MATERIALS AND METHODS

It was a single centre retrospective study to analyse the diagnostic performance of offline QFR with the previously performed FFR in the last six years. A total of 56 interrogated vessels were included for the analysis. Offline QFR analysis was performed and correlated with FFR values in the intermediate coronary stenoses.

RESULTS

The mean age of the study population was 62.4 ± 9.1 years, including 81% men. The left anterior descending artery (50%) was the most common analysed vessel followed by left circumflex (27%) and right coronary (21%) arteries. The mean % DS and % area stenosis were 45.25 ± 11.22% and 57.45% ± 16.25%, respectively. The mean FFR and QFR values were 0.83 ± 0.06 and 0.82 ± 0.10, respectively. A strong positive correlation was found between FFR and QFR with a Spearman correlation coefficient of 0.56. Receiver operating curve analysis for QFR and %DS with a FFR cut off value <0.80 showed an area under the curve of 0.97 and 0.77, respectively. The sensitivity, specificity and diagnostic accuracy of QFR were 87.5%, 95% and 92.8%, respectively. There was a discordance in four vessels (7.1%) between QFR and FFR.

CONCLUSION

QFR has a good diagnostic performance in comparison to the gold standard FFR for physiological assessment of intermediate lesions. Its performance is significantly better than the anatomical % DS (p < 0.001).

Fractional Flow Reserve: Patient Selection and Perspectives

The aim of this review was to discuss the current practice and patient selection for invasive FFR, new techniques to estimate invasive FFR and future of coronary physiology tests. We elaborate on the indication and application of FFR and on the contraindications and concerns in certain patient populations.