Angiography-derived functional assessment of left main coronary stenoses.

OBJECTIVES: We aimed to evaluate the diagnostic accuracy of quantitative flow ratio (QFR) in left main (LM) coronary stenoses, using Fractional Flow Reserve (FFR) as reference. BACKGROUND: QFR has demonstrated a high accuracy in determining the functional relevance of coronary stenoses in non-LM. However, there is an important paucity of data regarding its diagnostic value in the specific anatomical subset of LM disease. METHODS: This is a retrospective, observational, multicenter, international, and blinded study including patients with LM stenoses. Cases with significant ostial LM disease were excluded. QFR was calculated from conventional angiograms at blinded fashion with respect to FFR. RESULTS: Sixty-seven patients with LM stenoses were analyzed. Overall, LM had intermediate severity, both from angiographic (diameter stenosis [%DS] 43.8 ± 11.1%) and functional perspective (FFR 0.756 ± 0.105). Mean QFR was 0.733 ± 0.159. Correlation between QFR and FFR was moderate (r = 0.590). Positive and negative predictive value, sensitivity and specificity were 85.4%, 64%, 85.4%, and 69.6% respectively. Classification agreement of QFR and FFR in terms of functional stenosis severity was 78.1%. Area under the receiver operating characteristics of QFR using FFR as reference was 0.82 [95% confidence interval [CI], 0.71-0.93], and significantly better than angiographic evaluation including %DS (area under the receiver-operating characteristic curve [AUC] 0.45 [95% CI, 0.32-0.58], p < 0.001) and minimum lumen diameter (AUC 0.60 [95% CI, 0.47-0.74], p < 0.001). CONCLUSIONS: Compared with FFR, QFR has acceptable diagnostic performance in determining the functional relevance of LM stenosis, being better than conventional angiographic assessment. Nonetheless, caution should be taken when applying functional angiography techniques for the assessment of LM stenosis given its particular anatomical characteristics.

Quantitative flow ratio vs. angiography-only guided PCI in STEMI patients: one-year cardiovascular outcomes.

BACKGROUND: Coronary physiology-guided PCIs are recommended worldwide. However, invasive coronary physiology methods prolong the procedure, create additional risks for the patients, and prolong the fluoroscopy time for an interventional cardiologist. Otherwise, there is a noninvasive coronary physiology evaluation method, QFR, that can be safely used even in STEMI patients. METHODS: A total of 198 patients admitted with STEMI and at least one intermediate (35-75%) diameter stenosis other than the culprit artery between July 2020 and June 2021 were prospectively included in this single-center study. All patients were randomized into one of two groups (1 - QFR-guided PCI; 2 - visual-estimation-only guided PCI). A 12-month follow-up with echocardiography, exercise stress test, and quality of life evaluation was performed in all included patients. For the QOF evaluation, the Seattle Angina Score Questionnaire was chosen. Statistical analysis was performed using the Kolmogorov-Smirnov test, Student's t-test, Mann-Whitney U test, Pearson's chi-squared test and Kaplan-Meier estimator. RESULTS: Ninety-eight (49.5%) patients were randomized to the first group, and 100 (50.5%) patients were included in the second group. Statistically, significantly more patients had a medical history of dyslipidemia (98 vs. 91, p = 0.002) and slightly better left ventricular ejection fraction (42.21 ± 7.88 vs. 39.45 ± 9.62, p = 0.045) in the QFR group. Six fewer patients required non-culprit artery revascularization within the 12-month FU in the QFR group (1.02% vs. 6%, p = 0.047). Survival analysis proved that patients in the Angio group had a more than 6-fold greater risk for death within a 12-month period after MI (OR 6.23, 95% CI 2.20-17.87, p = 0.006), with the highest mortality risk within the first two months after initial treatment. CONCLUSION: Using QFR in non-culprit lesions in patients with ST-elevation myocardial infarction reduces mortality and revascularization at the 12-month follow-up and improves the quality of life of the patient. TRIAL REGISTRATION: The study was approved by the Regional Bioethical Committee and conducted under the principles of the Helsinki Declaration and local laws and regulations.

Predictive value of intravascular ultrasound for the function of intermediate coronary lesions.

BACKGROUND: Intravascular ultrasound (IVUS) can provide detailed coronary anatomic parameters. The purpose of our study was to evaluate the parameters measured by IVUS for the prediction of intermediate coronary lesions function by referencing quantitative fraction ratio (QFR) ≤ 0.80 (vs. > 0.80). METHODS: Eighty four cases with 92 intermediate coronary lesions in vessels with a diameter ≥ 2.50 mm were enrolled. Paired assessment of IVUS and cQFR was available, and vessels with cQFR ≤ 0.8 were considered the positive reference standard. Logistic regression was used to select model variables by a maximum partial likelihood estimation test and receiver operating characteristic curve (ROC) analysis to evaluate the diagnostic value of different indices. RESULTS: Plaque burden (PB) and lesion length (LL) of IVUS were independent risk factors for the function of coronary lesions. The predictive probability P was derived from the combined PB and LL model. The area under the curve (AUC) of PB, (minimum lumen area) MLA, and LL and the predicted probability P are 0.789,0.732,0731, and 0.863, respectively (P < 0.01). The AUC of the predicted probability P was the biggest among them; the prediction accuracy of cQFR ≤ 0.8 was 84.8%, and the sensitivity of the diagnostic model was 0.826, specificity was 0. 725, and P < 0.01. CONCLUSION: PB and LL of IVUS were independent risk factors influencing the function of intermediate coronary lesions. The model combining the PB and LL may predict coronary artery function better than any other single parameter.

Diagnostic performance of intravascular ultrasound-based fractional flow reserve versus angiography-based quantitative flow ratio measurements for evaluating left main coronary artery stenosis.

OBJECTIVES: We compared the diagnostic performance of the ultrasonic flow ratio (UFR) and quantitative flow ratio (QFR) for left main coronary artery (LMCA) stenosis. BACKGROUND: Evaluation of LMCA stenosis remains challenging because of its complex pathogenesis and severity. Computing QFR allows rapid determination of fractional flow reserve (FFR) from coronary angiograms. A novel intravascular ultrasound (IVUS)-based FFR (UFR) allows rapid FFR computation from IVUS images. Neither of the computational approaches required a pressure wire or hyperemia induction. Previous studies have validated the good diagnostic accuracy of QFR and UFR in identifying hemodynamically significant coronary stenosis using FFR as the reference standard. METHODS: This retrospective observational study enrolled consecutive patients with intermediate-grade LMCA stenosis who underwent IVUS evaluation. UFR and QFR of all LMCA stenosis patients were assessed, their correlation and agreement were analyzed, and diagnostic performance of UFR in LMCA stenosis was evaluated. RESULTS: Eighty-three paired comparisons between UFR and QFR were obtained. UFR excellently correlated with QFR (r = 0.74, p < 0.01). The Bland-Altman plot showed good agreement between UFR and QFR (mean differences: 0.01 ± 0.05, p = 0.34). The area under the curve of UFR for identifying physiological LMCA stenosis was 0.97 (95% confidence interval [CI]: 0.93-1.00, p < 0.01). The overall UFR diagnostic accuracy was 0.95 (95% CI: 0.88-0.99). CONCLUSIONS: UFR showed excellent correlation and good agreement with QFR in LMCA stenosis assessment, indicating that it is highly feasible to use UFR for functional evaluation of LMCA stenosis.

A prospective multicenter validation study for a novel angiography-derived physiological assessment software: Rationale and design of the radiographic imaging validation and evaluation for Angio-iFR (ReVEAL iFR) study.

Angiography-derived physiological assessment of coronary lesions has emerged as an alternative to wire-based assessment aiming at less-invasiveness and shorter procedural time as well as cost effectiveness in physiology-guided decision making. However, current available image-derived physiology software have limitations including the requirement of multiple projections and are time consuming. METHODS/DESIGN: The ReVEAL iFR (Radiographic imaging Validation and EvALuation for Angio-iFR) trial is a multicenter, multicontinental, validation study which aims to validate the diagnostic accuracy of the Angio-iFR medical software device (Philips, San Diego, US) in patients undergoing angiography for Chronic Coronary Syndrome (CCS). The Angio-iFR will enable operators to predict both the iFR and FFR value within a few seconds from a single projection of cine angiography by using a lumped parameter fluid dynamics model. Approximately 440 patients with at least one de-novo 40% to 90% stenosis by visual angiographic assessment will be enrolled in the study. The primary endpoint is the sensitivity and specificity of the iFR and FFR for a given lesion compared to the corresponding invasive measures. The enrollment started in August 2019, and was completed in March 2021. SUMMARY: The Angio-iFR system has the potential of simplifying physiological evaluation of coronary stenosis compared with available systems, providing estimates of both FFR and iFR. The ReVEAL iFR study will investigate the predictive performance of the novel Angio-iFR software in CCS patients. Ultimately, based on its unique characteristics, the Angio-iFR system may contribute to improve adoption of functional coronary assessment and the workflow in the catheter laboratory.

Quantitative flow ratio for immediate assessment of nonculprit lesions in patients with ST-segment elevation myocardial infarction-An iSTEMI substudy.

OBJECTIVES: We evaluated the diagnostic performance of quantitative flow ratio (QFR) assessment of nonculprit lesions (NCLs) based on acute setting angiograms obtained in patients with ST-segment elevation myocardial infarction (STEMI) with QFR, fractional flow reserve (FFR), and instantaneous wave-free ratio (iFR) in the staged setting as reference. BACKGROUND: QFR is an angiography-based approach for the functional evaluation of coronary artery lesions. METHODS: This was a post-hoc analysis of the iSTEMI study. NCLs were assessed with iFR in the acute setting and with iFR and FFR at staged (median 13 days) follow-up. Acute and staged QFR values were computed in a core laboratory based on the coronary angiography recordings. Diagnostic cut-off values were ≤0.80 for QFR and FFR, and ≤0.89 for iFR. RESULTS: Staged iFR and FFR data were available for 146 NCLs in 112 patients in the iSTEMI study. Among these, QFR analysis was feasible in 103 (71%) lesions assessed in the acute setting with a mean QFR value of 0.82 (IQR: 0.73-0.91). Staged QFR, FFR, and iFR were 0.80 (IQR: 0.70-0.90), 0.81 (IQR: 0.71-0.88), and 0.91 (IQR: 0.87-0.96), respectively. Classification agreement of acute and staged QFR was 93% (95%Cl: 87-99). The classification agreement of acute QFR was 84% (95%CI: 76-90) using staged FFR as reference and 74% (95%CI: 65-83) using staged iFR as reference. CONCLUSIONS: Acute QFR showed a very good diagnostic performance with staged QFR as reference, a good diagnostic performance with staged FFR as reference, and a moderate diagnostic performance with staged iFR as reference.

Q-site inhibitor induced ROS production of mitochondrial complex II is attenuated by TCA cycle dicarboxylates.

The impact of complex II (succinate:ubiquinone oxidoreductase) on the mitochondrial production of reactive oxygen species (ROS) has been underestimated for a long time. However, recent studies with intact mitochondria revealed that complex II can be a significant source of ROS. Using submitochondrial particles from bovine heart mitochondria as a system that allows the precise setting of substrate concentrations we could show that mammalian complex II produces ROS at subsaturating succinate concentrations in the presence of Q-site inhibitors like atpenin A5 or when a further downstream block of the respiratory chain occurred. Upon inhibition of the ubiquinone reductase activity, complex II produced about 75% hydrogen peroxide and 25% superoxide. ROS generation was attenuated by all dicarboxylates that are known to bind competitively to the substrate binding site of complex II, suggesting that the oxygen radicals are mainly generated by the unoccupied flavin site. Importantly, the ROS production induced by the Q-site inhibitor atpenin A5 was largely unaffected by the redox state of the Q pool and the activity of other respiratory chain complexes. Hence, complex II has to be considered as an independent source of mitochondrial ROS in physiology and pathophysiology.

Head-to-head comparison of two angiography-derived fractional flow reserve techniques in patients with high-risk acute coronary syndrome: A multicenter prospective study.

BACKGROUND: FFRangio and QFR are angiography-based technologies that have been validated in patients with stable coronary artery disease. No head-to-head comparison to invasive fractional flow reserve (FFR) has been reported to date in patients with acute coronary syndromes (ACS). METHODS: This study is a subset of a larger prospective multicenter, single-arm study that involved patients diagnosed with high-risk ACS in whom 30-70% stenosis was evaluated by FFR. FFRangio and QFR - both calculated offline by 2 different and blinded operators - were calculated and compared to FFR. The two co-primary endpoints were the comparison of the Pearson correlation coefficient between FFRangio and QFR with FFR and the comparison of their inter-observer variability. RESULTS: Among 134 high-risk ACS screened patients, 59 patients with 84 vessels underwent FFR measurements and were included in this study. The mean FFR value was 0.82 ± 0.40 with 32 (38%) being ≤0.80. The mean FFRangio was 0.82 ± 0.20 and the mean QFR was 0.82 ± 0.30, with 27 (32%) and 25 (29%) being ≤0.80, respectively. The Pearson correlation coefficient was significantly better for FFRangio compared to QFR, with R values of 0.76 and 0.61, respectively (p = 0.01). The inter-observer agreement was also significantly better for FFRangio compared to QFR (0.86 vs 0.79, p < 0.05). FFRangio had 91% sensitivity, 100% specificity, and 96.8% accuracy, while QFR exhibited 86.4% sensitivity, 98.4% specificity, and 93.7% accuracy. CONCLUSION: In patients with high-risk ACS, FFRangio and QFR demonstrated excellent diagnostic performance. FFRangio seems to have better correlation to invasive FFR compared to QFR but further larger validation studies are required.

The relationship between glycemic risk and longitudinal changes in total physiological atherosclerotic burden in patients with coronary artery disease.

Background: The effects of glycemic status on coronary physiology have not been well evaluated. This study aimed to investigate changes in coronary physiology by using angiographic quantitative flow ratio (QFR), and their relationships with diabetes mellitus (DM) and glycemic control status. Methods: This retrospective cohort study included 530 patients who underwent serial coronary angiography (CAG) measurements between January 2016 and December 2021 at Tongji Hospital of Tongji University. Based on baseline and follow-up angiograms, 3-vessel QFR (3V-QFR) measurements were performed. Functional progression of coronary artery disease (CAD) was defined as a change in 3V-QFR (Δ3V-QFR = 3V-QFRfollow-up - 3V-QFRbaseline) ≤-0.05. Univariable and multivariable logistic regression analyses were applied to identify the independent predictors of coronary functional progression. Subgroup analysis according to diabetic status was performed. Results: During a median interval of 12.1 (10.6, 14.3) months between the two QFR measurements, functional progression was observed in 169 (31.9%) patients. Follow-up glycosylated hemoglobin (HbA1c) was predictive of coronary functional progression with an area under the curve (AUC) of 0.599 [95% confidence interval (CI): 0.546-0.651; P<0.001] in the entire population. Additionally, the Δ3V-QFR values were significantly lower in diabetic patients with HbA1c ≥7.0% compared to those with well-controlled HbA1c or non-diabetic patients [-0.03 (-0.09, 0) vs. -0.02 (-0.05, 0.01) vs. -0.02 (-0.05, 0.02); P=0.002]. In a fully adjusted multivariable logistics analysis, higher follow-up HbA1c levels were independently associated with progression in 3V-QFR [odds ratio (OR), 1.263; 95% CI: 1.078-1.479; P=0.004]. Furthermore, this association was particularly strong in diabetic patients (OR, 1.353; 95% CI: 1.082-1.693; P=0.008) compared to patients without DM. Conclusions: Among patients with established CAD, on-treatment HbA1c levels were independently associated with progression in physiological atherosclerotic burden, especially in patients with DM.

Comprehensive Angiography-Derived Functional Assessment of Epicardial and Microvascular Coronary Disease. Correlation With Non-invasive Myocardial Stress Imaging.

Coronary angiography (CA) is poorly correlated with non-invasive myocardial stress imaging (NSI) and myocardial ischemia is often observed in patients with unobstructed coronary arteries. Moreover, the diagnostic performance of combined epicardial and microcirculatory angiography-derived physiological assessment and its correlation with NSI remains unknown. A total of 917 coronary vessels in 319 patients who underwent both CA and NSI were included in this multicenter observational retrospective analysis. Quantitative flow ratio (QFR) and angiography-derived index of microcirculatory resistance (IMRangio) analyses were performed to estimate coronary epicardial and microcirculatory function respectively. NSI demonstrated evidence of myocardial ischemia in 76% of the cases. IMRangio (36 [22 to 50] vs 29 [21 to 41], p <0.001) was significantly higher and QFR (0.92 [0.78 to 0.99] vs 0.97 [0.91 to 0.99], p <0.001) was significantly lower in vessels subtending ischemic territories. Overall, the diagnostic accuracy of QFR was moderate (area under the curve of receiver operating characteristic [AUCROC] 0.632 [95% confidence interval [CI] 0.589 to 0.674], p <0.0001) but it was higher in patients with normal microcirculatory function (AUCROC = 0.726 [95% CI 0.669 to 0.784], p <0.0001, p Value for AUCROC comparison = 0.009). Combined QFR/IMRangio assessment provided incremental diagnostic performance compared with the evaluation of epicardial or microcirculatory districts in isolation (p Value for AUC comparison <0.0001) and it was able to identify the predominant mechanism of myocardial ischemia in 77% of the patients with positive NSI. Our study suggests the value of a combined angiography-derived assessment of epicardial and microvascular function for the definition of the predominant mechanism of myocardial ischemia in patients with suspected coronary artery disease.

Association between the insufficient improvement of the quantitative flow ratio and worsening outcomes in ST-segment elevated myocardial infarction: a multicentre prospective cohort study.

Background: Improved coronary physiological function after percutaneous coronary intervention (PCI) has been shown to improve prognosis in stable ischaemic heart disease, but has not yet been explored in ST-segment elevated myocardial infarction (STEMI). The study sought to determine whether an improvement in the quantitative flow ratio (QFR) could improve the prognosis of STEMI patients undergoing primary PCI. Methods: Patients diagnosed with STEMI who were receiving primary PCI were recruited for the study. Those with thrombolysis in myocardial infarction (TIMI) flow <2 after wiring were excluded. The ΔQFR was calculated using the following formula: ΔQFR = post-PCI QFR - pre-stent QFR. The primary endpoint was the composite event, including recurrent myocardial infarction (MI) and acute heart failure (AHF). Results: In total, 515 STEMI patients with a median follow-up of 364 days were enrolled in the study. Based on the cut-off value from the receiver operator characteristic (ROC) curve, the patients were divided into the following two groups: the lower ΔQFR group (≤0.25, N=332); and the normal ΔQFR group (>0.25, N=183). Patients with a lower ΔQFR had a relatively higher rate of MI/AHF (10.5% vs. 4.4%, P=0.019) and AHF (7.2% vs. 2.7%, P=0.044). A lower ΔQFR was significantly associated with a higher incidence of MI/AHF [hazard ratio (HR) =2.962, 95% confidence interval (CI): 1.358-6.459, P=0.006, respectively] after adjusting for potential confounders. Pre-stent angiographic microvascular resistance [odds ratio (OR) =1.027, 95% CI: 1.022-1.033, P<0.001] and the stent-to-vessel diameter ratio <1.13 (OR =1.766, 95% CI: 1.027-3.071, P=0.04) were independent predictors of a lower ΔQFR. Conclusions: An insufficient improvement in the QFR contributes to worsening outcomes and might be a useful tool for risk stratification in STEMI.

Operator decision-making in angiography-only guided revascularization for lesions not indicated for FFR: a QFR-based functional assessment in chronic coronary syndrome.

Background: Discordance between coronary angiographic findings and invasive functional significance is well-established. Yet, the prevalence of this mismatch in an era increasingly utilizing invasive functional assessments, such as fractional flow reserve (FFR), remains unclear. This study examines the extent of such discrepancies in current clinical practice. Methods: This single-center prospective registry included consecutive patients with chronic coronary syndrome (CCS) who underwent elective coronary angiography, with or without revascularization. Coronary angiograms deemed not requiring FFR due to clear anatomical distinctions, either anatomically severe indicating a need for revascularization or mild suggesting no need for intervention, were selected for evaluation. These were then subjected to post-hoc analysis by three independent operators who were blinded to the definitive treatment strategies. Importantly, the post-hoc analysis was conducted in two distinct phases: firstly, a re-evaluation of coronary stenosis, and secondly, a separate functional assessment, each carried out independently. Coronary stenosis severity was assessed visually, while functional relevance was determined by quantitative flow ratio (QFR), calculated using a computational fluid dynamics algorithm applied to angiographic images. Analysis focused on discrepancies between QFR-based functional indications and revascularization strategies actually performed. Results: In 191 patients, 488 vessels were analyzed. Average diameter stenosis (DS) was 37 ± 34%, and QFR was 0.87 ± 0.15, demonstrating a moderate correlation (r = -0.84; 95% CI: -0.86 to -0.81, p < 0.01). Agreement with QFR at conventional anatomical cutoffs was 88% for 50% DS and 91% for 70% DS. Mismatches between revascularization decisions and QFR indications occurred in 10% of cases. Discrepancies were more frequent in the left anterior descending artery (14%) compared to the left circumflex (6%) and the right coronary artery (9%; p = 0.07). Conclusion: In a cardiac-center where FFR utilization is high, discordance between coronary angiography and functional significance persists, even when operators are confident in their decisions not to use functional interrogation. This gap, most evident in the left anterior descending artery, highlights the potential need for integrated angiography-based functional assessments to refine revascularization decisions in CCS.

Application of AMR in evaluating microvascular dysfunction after ST-elevation myocardial infarction.

BACKGROUND: A guidewire-free angiography-derived microcirculatory resistance (AMR) derived from Quantitative flow ratio (QFR) exhibits good diagnostic accuracy for assessing coronary microvascular dysfunction (CMD), but there are no relevant studies supporting the specific application of AMR in patients with ST-elevation myocardial infarction (STEMI). The study aims to evaluate CMD in patients with STEMI using the AMR index. METHODS: This study included patients with STEMI who underwent percutaneous coronary intervention (PCI) from June 1, 2020 to September 28, 2021. All patients were divided into two groups: the CMD (n = 215) and non-CMD (n = 291) groups. After matching, there were 382 patients in both groups.1-year follow-up major adverse cardiac events (MACEs) were evaluated. RESULTS: After matching, the primary endpoint was achieved in 41 patients (10.7%), with 27 and 14 patients in the CMD and non-CMD groups, respectively (HR 1.954 [95% CI 1.025-3.726]; 14.1% versus 7.3%, p = .042). Subgroup analysis revealed that 18 patients (4.7%) were readmitted for heart failure, with 15 and 3 in the CMD and non-CMD groups, respectively (HR 5.082 [95% CI 1.471-17.554]; 7.9% versus 1.6%, p = .010). Post-PCI AMR ≥ 250 was significantly associated with a higher risk of the primary endpoint and was its independent predictor (HR 2.265 [95% CI 1.136-4.515], p = .020). CONCLUSION: The retrospective use of AMR with a cutoff value of ≥250 after PCI in patients with STEMI can predict a significant difference in the 1-year MACE rates when compared with a propensity score-matched group with normal AMR.

Standardized angiographic projections allow evaluation of coronary artery side branches with quantitative flow ratio (QFR).

Quantitative flow ratio (QFR) is a novel, software-based noninvasive method for the quantitative evaluation of coronary physiology. QFR results correlate with invasive FFR measurements in the three main epicardial coronary arteries. However, QFR data for the evaluation of coronary side branches (SB) are scarce. The evaluation of QFR-performance of SB was retrospective and prospective. Eighty-seven patients with suspected chronic coronary syndrome, who received angiography using routine core lab projections, were retrospectively analyzed. On the second part 37 patients, who received angiography using recommended standardized coronary angiography projections, were prospectively analyzed. Quantitative analysis was performed for SB with a maximum lumen diameter proximal of ≥2 mm based on quantitative coronary angiography (QCA) by two certified experts with the software QAngio XA 3D 3.2. Using routine projections, QFR computation in 55 % of the SB were obtained (123 out of 224). Using standardized projections, 85 % of SB were computed by QFR (64 out of 75; p < 0.001 vs routine projections). The fluoroscopy time for recommended projections was not significantly different as opposed to routine projections (3.75 ± 2.2 vs. 4.58 ± 3.00 min, p = 2.6986). Using the standardized projections was associated with a higher amount of contrast medium (53.44 ± 24.23 vs. 87.95 ± 43.73 ml, p < 0.01), longer overall procedure time (23.23 ± 16.35 vs. 36.14 ± 17.21 min, p < 0.01) and a higher dose area product (1152.28 ± 576.70 vs. 2540.68 ± 1774.07 cGycm2, p < 0.01). Our study shows that the blood flow of the vast majority of coronary SB can be determined non-invasively by QFR in addition to the main epicardial coronary arteries when standardized projections are used.

Accuracy of the angiography-based quantitative flow ratio in intermediate left main coronary artery lesions and comparison with visual estimation.

BACKGROUND: Revascularization of left main coronary artery (LMCA) stenosis is mostly based on angiography. Indices based on angiography might increase accuracy of the decision, although they have been scarcely used in LMCA. The objective of this study is to study the diagnostic agreement of QFR (quantitative flow ratio) with wire-based fractional flow reserve (FFR) in LMCA lesions and to compare with visual severity assessment. METHODS: In a series of patients with invasive FFR assessment of intermediate LMCA stenoses we retrospectively compared the measured value of QFR with that of FFR and the estimate of significance from angiography. RESULTS: 107 QFR studies were included. The QFR intra-observer and inter-observer agreement was 87% and 82% respectively. The mean QFR-FFR difference was 0.047 ± 0.05 with a concordance of 90.7%, sensitivity 88.1%, specificity 92.3%, positive predictive value 88.1% and negative predictive value 92.3%. All these values were superior to those observed with the visual estimation which showed an intra- and inter-observer agreement of 73% and 72% respectively, besides 78% with the FFR value. The low diagnostic performance of the visual estimation and the acceptable performance of the QFR index measurement were observed in all subgroups analysed. CONCLUSIONS: QFR allows an acceptable estimate of the FFR obtained with intracoronary pressure guidewire in intermediate LMCA lesions, and clearly superior to the assessment based on angiography alone. The decision to revascularize patients with moderate LMCA lesions should not be based solely on the degree of angiographic stenosis.

Prognostic Value of Post-PCI Angiography-Derived Fractional Flow Reserve: A Systematic Review and Meta-Analysis of Cohort Studies.

The post-percutaneous coronary intervention (post-PCI) fractional flow reserve (FFR) can detect suboptimal PCI or residual ischemia and potentially lead to fewer adverse clinical outcomes. We sought to investigate the predictive value of the angiography-derived FFR for adverse cardiovascular events in patients after PCI. We conducted a comprehensive search of electronic databases, MEDLINE, EMBASE, and the Cochrane Library, for studies published until March 2023 that investigated the prognostic role of angiography-derived fractional flow reserve values after PCI. We investigated the best predictive ability of the post-PCI angiography-derived FFR and relative risk (RR) estimates with 95% confidence intervals (CIs) between post-PCI angiography-derived FFR values and adverse events. Thirteen cohort studies involving 6961 patients (9719 vascular lesions; mean follow-up: 2.2 years) were included in this meta-analysis. The pooled HR of the studies using specific cut-off points for post-PCI angiography-derived FFR was 4.13 (95% CI, 2.92-5.82) for total cardiovascular events, while the pooled HRs for target vessel revascularization, cardiac death, target vessel myocardial infarction, and target lesion revascularization were 6.87 (95% CI, 4.93-9.56), 6.17 (95% CI, 3.52-10.80), 3.98 (95% CI, 2.37-6.66) and 6.27 (95% CI, 3.08-12.79), respectively. In a sensitivity analysis of three studies with 1789 patients assessing the predictive role of the post-PCI angiography-derived FFR as a continuous variable, we found a 58% risk reduction for future adverse events per 0.1 increase in the post-PCI angiography-derived FFR value. In conclusion, post-PCI angiography-derived FFR is an effective tool for predicting adverse cardiovascular events and could be potentially used in decision making, both during PCI and in the long-term follow-up.

Quantitative flow ratio-based outcomes in patients undergoing transcatheter aortic valve implantation quaestio study.

Background: Coronary artery disease (CAD) is common in patients with aortic valve stenosis (AS) ranging from 60% to 80%. The clinical and prognostic role of coronary artery lesions in patients undergoing Transcatheter Aortic Valve Implantation (TAVI) remains unclear. The aim of the present observational study was to estimate long-term clinical outcomes by Quantitative Flow Ratio (QFR) characterization of CAD in a well-represented cohort of patients affected by severe AS treated by TAVI. Methods: A total of 439 invasive coronary angiographies of patients deemed eligible for TAVI by local Heart Teams with symptomatic severe AS were retrospectively screened for QFR analysis. The primary endpoint of the study was all-cause mortality. The secondary endpoint was a composite of cardiovascular mortality, stroke/transient ischemic attack (TIA), acute myocardial infarction (AMI), and any hospitalization after TAVI. Results: After exclusion of patients with no follow-up data, coronary angiography not feasible for QFR analysis and previous surgical myocardial revascularization (CABG) 48/239 (20.1%) patients had a QFR value lower or equal to 0.80 (QFR + value), while the remaining 191/239 (79.9%) did not present any vessel with a QFR positive value. In the adjusted Cox regression analysis, patients with positive QFR were independently associated with an increased risk of all-casual mortality (Model 1, HR 3.47, 95% CI, 2.35-5.12; Model 2, HR 5.01, 95% CI, 3.17-7.90). In the adjusted covariate analysis, QFR+ involving LAD (37/48, 77,1%) was associated with the higher risk of the composite outcome compared to patients without any positive value of QFR or non-LAD QFR positive value (11/48, 22.9%). Conclusions: Pre-TAVI QFR analysis can be used for a safe, simple, wireless functional assessment of CAD. QFR permits to identify patients at high risk of cardiovascular mortality or MACE, and it could be considered by local Heart Teams.

Coronary Angiography Upgraded by Imaging Post-Processing: Present and Future Directions.

Advances in computer technology and image processing now allow us to obtain from angiographic images a large variety of information on coronary physiology without the use of a guide-wire as a diagnostic information equivalent to FFR and iFR but also information allowing for the performance of a real virtual percutaneous coronary intervention (PCI) and finally the ability to obtain information to optimize the results of PCI. With specific software, it is now possible to have a real upgrading of invasive coronary angiography. In this review, we present the different advances in this field and discuss the future perspectives offered by this technology.

1-Year Patency of Biorestorative Polymeric Coronary Artery Bypass Grafts in an Ovine Model.

Many attempts have been made to inhibit or counteract saphenous vein graft (SVG) failure modes; however, only external support for SVGs has gained momentum in clinical utility. This study revealed the feasibility of implantation, and showed good patency out to 12 months of the novel biorestorative graft, in a challenging ovine coronary artery bypass graft model. This finding could trigger the first-in-man trial of using the novel material instead of SVG. We believe that, eventually, this novel biorestorative bypass graft can be one of the options for coronary artery bypass graft patients who have difficulty harvesting SVG.

Angiographic Lesion Discordance in Women Presenting With Ischemic Heart Disease: Comparison of Visual Assessment, Quantitative Coronary Angiography, and Quantitative Flow Ratio.

BACKGROUND: Although visual assessment of stenosis severity is routinely used to guide coronary revascularization, there are concerns about its accuracy, especially in women, who present a higher variability in coronary anatomy and ischemic heart disease (IHD). The aim of this study was to assess whether quantitative coronary angiography (QCA) and quantitative flow ratio (QFR) could provide better discrimination of coronary stenosis severity and functional significance than visual assessment alone in women with IHD. METHODS: Coronary angiography was performed in a cohort of women with ischemic symptoms and non-invasive stress perfusion imaging. Visual assessment was done by blinded operators in clinical practice, while QCA and QFR were analyzed in an independent core laboratory. RESULTS: Ninety-nine consecutive patients with 101 lesions were included in the registry, and QFR was successfully measured in 81 lesions (80.2%). Visual assessment provided higher readings of angiographic severity than QCA in 50.5% (n = 51) of lesions. Mean absolute difference between QCA and visual assessment was significantly higher in lesions with >70% diameter stenosis (DS) (25.3 ± 7.3%), compared with both the 40%-55% (9.3 ± 6.8%; P<.001) and the <40% groups (7.0 ± 6.0%; P<.001). QFR was >0.80 in 33.3% of lesions with visually defined >70% DS, while all lesions with QCA-defined >70% DS had QFR ≤0.80. CONCLUSIONS: Interventional cardiologists' visual assessment results in a higher degree of coronary stenosis than QCA. Among women with ischemic symptoms and non-invasive stress perfusion imaging, additional lesion assessment by QCA and QFR may improve operators' ability to determine which patients and lesions will benefit from coronary revascularization.