Fractional Flow Reserve Assessment Research Articles

Sex Differences in Fractional Flow Reserve Utilization

Background: The literature review shows that female patients are more frequently underdiagnosed or suffer from delayed diagnosis. Recognition of sex-related differences is crucial for implementing strategies to improve cardiovascular outcomes. We aimed to assess sex-related disparities in the frequency of fractional flow reserve (FFR)-guided procedures in patients who underwent angiography and/or percutaneous coronary intervention (PCI). Methods: We have derived the data from the national registry of percutaneous coronary interventions and retrospectively analyzed the data of more than 1.4 million angiography and/or PCI procedures [1,454,121 patients (62.54% men and 37.46% women)] between 2014 and 2022. The logistic regression analysis was conducted to explore whether female sex was associated with FFR utilization. Results: The FFR was performed in 61,305 (4.22%) patients and more frequently in men than women (4.15% vs. 3.45%, p < 0.001). FFR was more frequently assessed in females with acute coronary syndrome than males (27.75% vs. 26.08%, p < 0.001); however, women with chronic coronary syndrome had FFR performed less often than men (72.25% vs. 73.92%, p < 0.001). Females with FFR-guided procedures were older than men (69.07 (±8.87) vs. 65.45 (±9.38) p < 0.001); however. less often had a history of myocardial infarction (MI) (24.79% vs. 36.73%, p < 0.001), CABG (1.62% vs. 2.55%, p < 0.005) or PCI (36.6% vs. 24.79%, p < 0.001) compared to men. Crude comparison has shown that male sex was associated with a higher frequency of FFR assessment (OR = 1.2152–1.2361, p < 0.005). Conclusions: Despite a substantial rise in FFR utilization, adoption in women remains lower than in men. Female sex was found to be an independent negative predictor of FFR use.

Long-Term Outcomes of Fractional Flow Reserve-Guided Percutaneous Coronary Intervention of Moderate Lesions in Patients with Chronic Coronary Syndrome

Background: Fractional flow reserve (FFR) is crucial to evaluating coronary artery stenosis in patients diagnosed with chronic coronary syndrome (CCS). By assessing the severity of stenosis, FFR assists in determining whether percutaneous coronary intervention (PCI) is necessary. Methods: Conducted at Tehran Heart Center from 2013 through 2017, this cohort study involved 52,248 CCS patients who underwent coronary angiography. Among them, 598 symptomatic individuals, despite receiving comprehensive medical treatment, underwent FFR assessment. Subsequently, 225 patients with positive FFR (≤0.80) underwent PCI, while 373 patients received solely medical treatment. The patients were monitored for 3 years to evaluate primary and secondary endpoints. Results: After 3 years, the PCI group demonstrated a lower incidence of the primary composite endpoint, consisting of all-cause mortality, nonfatal myocardial infarction, repeat target vessel/lesion revascularization (TVR/TLR), and coronary artery bypass graft surgery, than the medical treatment group (HR, 0.85; 95% CI, 0.74 to 0.98; P=0.012). Additionally, urgent TVR/TLR significantly decreased in the PCI group (HR, 0.56; 95% CI, 0.42 to 0.74; P<0.001). Conclusion: FFR-guided PCI demonstrated effectiveness in reducing long-term major adverse cardiac events, primarily by lowering the incidence of TVR/TLR. The results emphasize the significance of FFR-guided PCI in addressing stenosis rather than alleviating ischemia.

Prognostic significance of compliance with fractional flow reserve guidance on diverse vessel-related clinical outcomes.

In patients underwent fractional flow reserve (FFR) assessment, a noteworthy proportion of adverse events occur in vessels in which FFR has not been measured. However, the effect of these non-target vessel-related events on the evaluation of FFR-related benefits remains unknown. In this retrospective study, vessels subjected to FFR measurement were grouped as FFR-based approach and non-compliance with FFR based on whether they received FFR-based treatment. Using inverse probability of treatment weighting (IPTW) to account for potential confounding, we investigated the association between compliance with FFR and 5-year target vessel failure (TVF) non-target vessel failure (NTVF) and vessel-oriented composite endpoints (VOCEs). Of the 1,119 vessels, 201 did not receive FFR-based treatment. After IPTW adjustment, a significantly lower hazard of TVF was observed in the FFR-based approach group (HR: 0.56; 95% CI: 0.34-0.92). While, the intergroup difference in hazard of NTVF (HR: 1.02; 95% CI: 0.45-2.31) and VOCEs (HR: 0.69; 95% CI: 0.45-1.05) were nonsignificant. In patients with CAD subjected to FFR, the FFR-based treatment yields a sustained clinical benefit in terms of the risks of target vessel-related events. The dilution of non-target vessel-related events renders the difference favoring the FFR-based approach nonsignificant.

Predictive value of plaque characteristics for identification of lesions causing ischemia

BackgroundFunctional assessment using fractional flow reserve (FFR) and anatomical assessment using optical coherence tomography (OCT) are used in clinical practice for patients with intermediate coronary stenosis. Moreover, coronary computed tomography angiography (CTA) is a common noninvasive imaging technique for evaluating suspected coronary artery disease before being referred for angiography. This study aimed to investigate the association between FFR and plaque characteristics assessed using coronary CTA and OCT for intermediate coronary stenosis. MethodsBased on a prospective multicenter registry, 159 patients having 339 coronary lesions with intermediate stenosis were included. All patients underwent coronary CTA before being referred for coronary angiography, and both FFR measurements and OCT examinations were performed during angiography. A stenotic lesion identified with FFR ≤0.80 was deemed diagnostic of an ischemia-causing lesion. The predictive value of plaque characteristics assessed using coronary CTA and OCT for identifying lesions causing ischemia was analyzed. ResultsStenosis severity and plaque characteristics on coronary CTA and OCT differed between lesions that caused ischemia and those that did not. In multivariate analysis, low attenuation plaque on coronary CTA (odds ratio [OR]=2.78; P=0.038), thrombus (OR=5.13; P=0.042), plaque rupture (OR=3.25; P=0.017), and intimal vasculature on OCT (OR=2.57; P=0.012) were independent predictors of ischemic lesions. Increasing the number of these plaque characteristics offered incremental improvement in predicting the lesions causing ischemia. ConclusionsComprehensive anatomical evaluation of coronary stenosis may provide additional supportive information for predicting the lesions causing ischemia.

Hemodynamic Insights into Combined Fractional Flow Reserve and Instantaneous Wave-Free Ratio Assessment Through Quantitative [15O]H2O PET Myocardial Perfusion Imaging.

In patients evaluated for obstructive coronary artery disease (CAD), guidelines recommend using either fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR) to guide coronary revascularization decision-making. The hemodynamic significance of lesions with discordant FFR and iFR measurements is debated. This study compared [15O]H2O PET-derived absolute myocardial perfusion between vessels with concordant and discordant FFR and iFR measurements. Methods: We included 197 patients suspected of obstructive CAD who had undergone [15O]H2O PET perfusion imaging and combined FFR/iFR interrogation in 468 vessels. Resting myocardial blood flow (MBF), hyperemic MBF, and coronary flow reserve (CFR) were compared among 4 groups: FFR low/iFR low (n = 79), FFR high/iFR low (n = 22), FFR low/iFR high (n = 22), and FFR high/iFR high (n = 345). Predefined [15O]H2O PET thresholds for ischemia were 2.3 mL·min-1·g-1 or less for hyperemic MBF and 2.5 or less for CFR. Results: Hyperemic MBF was lower in the concordant low (2.09 ± 0.67 mL·min-1·g-1), FFR high/iFR low (2.41 ± 0.80 mL·min-1·g-1), and FFR low/iFR high (2.40 ± 0.69 mL·min-1·g-1) groups compared with the concordant high group (2.91 ± 0.84 mL·min-1·g-1) (P < 0.001, P = 0.004, and P < 0.001, respectively). A lower CFR was observed in the concordant low (2.37 ± 0.76) and FFR high/iFR low (2.64 ± 0.84) groups compared with the concordant high group (3.35 ± 1.07, P < 0.01 for both). However, for vessels with either low FFR or low iFR, quantitative hyperemic MBF and CFR values exceeded the ischemic threshold in 38% and 49%, respectively. In addition, resting MBF exhibited a negative correlation with iFR (P < 0.001) and was associated with FFR low/iFR high discordance compared with concordant low FFR/low iFR measurements, independent of clinical and angiographic characteristics, as well as hyperemic MBF (odds ratio [OR], 0.41; 95% CI, 0.26-0.65; P < 0.001). Conclusion: We found reduced myocardial perfusion in vessels with concordant low and discordant FFR/iFR measurements. However, FFR/iFR combinations often inaccurately classified vessels as either ischemic or nonischemic when compared with hyperemic MBF and CFR. Furthermore, a lower resting MBF was associated with a higher iFR and the occurrence of FFR low/iFR high discordance. Our study showed that although combined FFR/iFR assessment can be useful to estimate the hemodynamic significance of coronary lesions, these pressure-derived indices provide a limited approximation of [15O]H2O PET-derived quantitative myocardial perfusion as the physiologic standard of CAD severity.

A Convolutional-Transformer Model for FFR and iFR Assessment from Coronary Angiography.

The quantification of stenosis severity from X-ray catheter angiography is a challenging task. Indeed, this requires to fully understand the lesion's geometry by analyzing dynamics of the contrast material, only relying on visual observation by clinicians. To support decision making for cardiac intervention, we propose a hybrid CNN-Transformer model for the assessment of angiography-based non-invasive fractional flow-reserve (FFR) and instantaneous wave-free ratio (iFR) of intermediate coronary stenosis. Our approach predicts whether a coronary artery stenosis is hemodynamically significant and provides direct FFR and iFR estimates. This is achieved through a combination of regression and classification branches that forces the model to focus on the cut-off region of FFR (around 0.8 FFR value), which is highly critical for decision-making. We also propose a spatio-temporal factorization mechanisms that redesigns the transformer's self-attention mechanism to capture both local spatial and temporal interactions between vessel geometry, blood flow dynamics, and lesion morphology. The proposed method achieves state-of-the-art performance on a dataset of 778 exams from 389 patients. Unlike existing methods, our approach employs a single angiography view and does not require knowledge of the key frame; supervision at training time is provided by a classification loss (based on a threshold of the FFR/iFR values) and a regression loss for direct estimation. Finally, the analysis of model interpretability and calibration shows that, in spite of the complexity of angiographic imaging data, our method can robustly identify the location of the stenosis and correlate prediction uncertainty to the provided output scores.

Combined Assessment of Fractional Flow Reserve and Coronary Flow Velocity Reserve after Drug-Eluting Stent Implantation

Coronary flow velocity reserve (CFVR) can be measured noninvasively using stress transthoracic Doppler echocardiography (S-TDE). The prognostic significance of S-TDE-derived CFVR after percutaneous coronary intervention (PCI) remains unknown. The aim of this study was to investigate the prognostic value of post-PCI CFVR and its additional efficacy to fractional flow reserve (FFR) in patients undergoing elective PCI. A retrospective study was conducted involving 187 consecutive patients with chronic coronary syndrome who underwent elective PCI guided by FFR for the left anterior descending coronary artery. Pre- and post-PCI wire-based FFR and CFVR assessments of the left anterior descending coronary artery using S-TDE were performed in all patients. The association between post-PCI clinical and physiologic parameters and major adverse cardiac events (MACE), defined as a composite of cardiac death, myocardial infarction, heart failure, and unplanned remote target vessel revascularization, was evaluated. Three-quarters of patients exhibited CFVR increase after PCI, while all patients showed FFR improvement. During a median follow-up period of 1.5years, MACE occurred in 21 patients (11.2%). Among clinical demographics, patients with MACE had higher levels of N-terminal pro-brain natriuretic peptide compared with those without MACE (median, 615pg/mL [interquartile range, 245-1,500pg/mL] vs 180pg/mL [interquartile range, 70-559pg/mL]; P=.010). Post-PCI S-TDE-derived CFVR was lower in patients with MACE, while post-PCI FFR showed a nonsignificant tendency to be lower in patients with MACE. In a multivariable analysis, higher NT-proBNP (adjusted hazard ratio, 1.33; 95% CI, 1.02-1.74; P=.038), post-PCI CFVR ≤ 2.0 (adjusted hazard ratio, 2.93; 95% CI, 1.16-7.40; P=.023), and post-PCI FFR ≤ 0.82 (adjusted hazard ratio, 3.93; 95% CI, 1.52-10.18; P=.005) were independently associated with MACE. In patients with chronic coronary syndrome who underwent successful elective PCI for left anterior descending coronary artery, the combined assessment of S-TDE-derived post-PCI CFVR and post-PCI FFR provided a significant association with the occurrence of MACE.

Effects of guiding catheter on franctional flow reserve and non-hyperemic pressure ratios for the assessment of coronary artery stenoses

Abstract Aims Non-hyperemic pressure-derived Indexes (NHPI) provide diagnostic efficacy equivalent to fractional flow reserve (FFR) to guide percutaneous coronary interventions. In the Disengage (Determination of Fractional Flow Reserve in Intermediate Coronary Stenosis With Guiding Catheter Disengagement) registry, selective decannulation of the guiding catheter (GC) within the coronary ostium during FFR assessment was associated with a significant overall decrease in FFR, particularly when the stenosis was located in the proximal and middle coronary segments. So far it is unclear what influence the selective cannulation of the catheter in the coronary artery ostium has on the NHPI. This prospective registry aimed to evaluate the influence of GC engagement within the coronary ostium on FFR and NHPI values. Methods and results In the DISENGAGE@Rest (Determination of Fractional Flow Reserve in Intermediate Coronary Stenosis With Guiding Catheter Disengagement) 133 patients with 164 intermediate coronary artery stenoses (40-90%) were enrolled. We evaluated: 1) the impact of GC engagement within the coronary ostium on FFR and NHPI values; 2) implications for clinical decision making; 3) the relationship between coronary physiology indices and study site (proximal, middle and distal coronary segments). Disengagement of GC was associated with a significant decrease in FFR (FFReng, 0.85±0.07 vs. FFRdis, 0.83±0.07; p&amp;lt; .001), Pd/Pa (Pd/Paeng, 0.94±0.05 vs. Pd/Padis, 0.93±0.05; p&amp;lt; .001) and RFR values (RFReng, 0.91±0.07 vs. RFRdis, 0.90±0.07; p= .018). This significant decrease in invasive physiologic indexes was driven by a significant increase in mean Pa value (Pa eng, 93±15 mm Hg vs. Pa dis, 97±15 for FFR; P &amp;lt; .001; Pa eng, 94±15 mm Hg vs Pa dis, 96±15 for Pd/Pa; P &amp;lt; .001 Pa eng, 95±15 mm Hg vs Pa dis, 97±15 for RFR; P &amp;lt; .001), without changes in mean Pd value. In 24 (15%), 12 (7%) and 17 (10%) lesions, FFR, RFR and Pd/Pa values, respectively, shifted below the cut-off point after GC disengagement with changes in clinical decision-making. There was a significant FFR change, but no NHPI, across different segments (ΔFFReng–FFRdis proximal 0.04±0.03 vs. ΔFFReng–FFRdis middle 0.02±0.02 vs. ΔFFReng–FFRdis distal 0.03±0.04; p= .018). Conclusions The results confirm a significant overall decrease in FFR after GC disengagement and extend this to Pd/Pa and RFR. In case of proximal coronary artery disease, GC disengagement should be performed in order not to underestimate the hemodynamic significance of the lesion under examination.

Changes in cardiac electrical biomarker with hyperaemic stress: an experimental perspective

Abstract Background "Cardiac electrical biomarker" (CEB) is a numerical index measured by the Vectraplex ECG (vECG) System with Vectraplex AMI software that measures changes in the cardiac electrical field vectors from dipolar to multipolar during myocardial ischemia. CEB performs well in detecting NSTEMI and STEMI against physician adjudicated diagnosis. Purpose To assess changes in CEB during adenosine stress induced ischaemia. Method Thirty-three patients, in the VECTRA-PCI trial, with normal surface ECG (sECG) had CEB measured before (CEB0), at maximal hyperaemia (CEBh)) and 1-(CEB1), 2-(CEB2) and 3-(CEB3) hours after standard fractional flow reserve (FFR) assessment using intravenous adenosine. vECGs were adjudicated for quality by 2 blinded observers. vECGs with artefacts and arrhythmias were discarded and CEBs from best traces were analysed. Forty-nine individuals with non-cardiac chest pain, without past medical history or risk factors for CAD, on no medications, normal ECGs, normal blood profile acted as controls. CEBs (median, IQR) were compared using appropriate tests. Results FFR was normal (&amp;gt;/=0.80) (nFFR) in 25 and ischaemic (&amp;lt;0.80) (iFFR) in 8 patients. CEB0 in nFFR and iFFR groups were similar to each other (p=0.785) (Fig 1) and to controls (30.0; IQR 17.0-44.0, vs nFFR: p=0.057, vs iFFR: p=0.241). Compared to CEB0, CEBh was higher in nFFR (p=0.014) (Fig 1A) and iFFR (p=0.016) groups (Fig 1B). CEBh in iFFR (126.0; 109.5-216.0) higher than nFFR (44.0; 27.8-104.8), (p=0.039). In nFFR group, CEB1, 2 and 3, though numerically lower, were statistically similar to CEBh and CEB0 (Fig 1A) suggesting quick recovery. In iFFR group CEB1 was similar to and CEB2 and 3 were lower than CEBh (Fig 1B) suggesting a slower recovery of CEB. Both CEBh and change from CEB0 to CEBh (δCEB0-h), but not CEB0, predicted ischaemic FFR with similar accuracy (p=0.570) (Fig 2). CEBh &amp;gt;96 and δCEB0-h &amp;gt;28 had similar sensitivity of 87.5% with specificity of 68% and 80% respectively. Conclusion Obstructive coronary atheroma is associated with higher CEB than non-obstructive atheroma under hyperaemic stress. Both CEBh and δCEB0-h accurately predict ischaemic FFR with higher specificity of δCEB0-h. This is the first study to measure CEB changes with hyperaemic stress in patients with coronary artery disease and could have potential for wider clinical application. Figure 1. Changes in the CEB during and after hyperaemic stress in patients with normal (A) and ischaemic (B) FFR. Figure 2. Area under the ROC curve to determine the diagnostic accuracy of pre-procedural CEB, hyperaemic CEB and change in CEB from baseline to hyperaemia in determining ischaemic FFR.Fig 1. Changes in CEB with stress.Fig 2. CEB for ischaemic FFR

Abstract 11776: Sex Differences in Coronary Artery Disease Characteristics Among Patients With Type 2 Myocardial Infarction: Results From the Prospective DEFINE-Type 2 MI Study

Background: Type 2 Myocardial Infarction (T2MI) is a result of coronary supply and demand imbalance and is associated with a poor prognosis. It is crucial to identify potential sex-based differences in the prevalence and nature of coronary artery disease (CAD) within this specific population. Retrospective analyses are limited by selection bias, unequal proportions of male and female subjects, and lack of angiographic definition. Hypothesis: In patients with T2MI, women and men will have unique characteristics. Aim: To evaluate sex-based differences in presentation, prevalence/characteristics of CAD and clinical management of T2MI. Methods: In a single-center prospective study, patients with strictly adjudicated T2MI underwent coronary computed tomography angiography and Fractional Flow Reserve (FFR CT ) and quantitative plaque assessment was performed. Results: Of 50 study participants enrolled, 50% were women. Women with T2MI were older than men with T2MI (72.2 ± 10.1 vs. 64 ± 11.3 years; p = 0.009) but otherwise had similar baseline characteristics. A broad and similar mix of T2MI precipitants were present among both sexes. Ischemic ST depression was more common in women (64% vs. 32%; p = 0.05) while men were more likely to have T wave inversion (68% vs. 36%; p = 0.05). Women and men had comparable CAC scores (median [Q1, Q3] 152 [45, 762] vs. 234 [56, 422]; p = 0.07). Prevalence of any CAD (100% vs. 84%; p = 0.12), obstructive CAD (28% vs. 24%; p = 1.0), and hemodynamically significant focal stenosis with FFR CT &lt; 0.80 (64% vs. 56%; p = 0.08) were similar between men and women. While total plaque volumes were similar between men and women, women had significantly lower levels of low-attenuation plaque (median [Q1, Q3]: 3 [1,7] vs. 9 [3, 14]; p = 0.03). Men and women did not significantly differ in percentile of plaque burden. Both sexes showed comparable increases in the utilization of aspirin (OR = 0.67; p = 0.53), beta blockers (OR = 0.76; p = 0.71), and statins (OR = 0.22; p = 0.08) by discharge. Conclusions: This prospective study of using FFRCT in T2MI identifies similarities and differences in clinical presentation and CAD characteristics of T2MI in both men and women. These findings may be helpful in improving the identification and management of T2MI.

The importance of baseline fractional flow reserve to detect significant coronary artery stenosis in different patient populations.

Fractional flow reserve (FFR) assessment compares the blood flow on either side of a blockage in the coronary artery and indicates how severe the stenosis is in the artery. Intravenous adenosine is widely used to achieve conditions of stable hyperaemia for the measurement of FR. However, intravenous adenosine affects both systemic and coronary vascular beds differentially. Therefore, FFR has some limitations, such as the side effects of adenosine and the long procedure time. In addition, there are not enough studies on the evaluation of the baseline ratio of distal coronary pressure to aortic pressure (Pd/Pa) according to standard cut-off values in coronary stenosis under special clinical conditions. This study aimed to assess the diagnostic power of the baseline FFR value for critical coronary stenosis and to determine its predictive value in special patient groups. This retrospective study included 158 patients, who were stratified as Q1 (< 0.89), Q2 (0.89-0.92), Q3 (0.93-0.95) and Q4 (> 0.95) based on baseline FFR values. The baseline Pd/Pa value, the change in adenosine FFR and the raw FFR change were recorded. Its predictive value was also calculated for specific patient groups. The threshold value of baseline FFR level for predicting critical stenosis was ≤ 0.92 with a sensitivity of 92.8% and a specificity of 82% (upper limit of Q2 cartilage). Patients with a baseline FFR value ≤ 0.92 had a 58.4-fold greater likelihood of a critical outcome compared with patients with a baseline FFR value > 0.92 (OR: 58.4; 95% CI: 20.3-124.6). In patients with a baseline FFR ≤ 0.92, the Q1 group had a 10.23-fold higher odds of critical stenosis compared with the Q2 group (OR: 10.23; 95% CI: 2.14-48.84). The same values had similar diagnostic power for all specific patient groups. The baseline FFR value could be used to predict critical coronary stenosis in our patients and had similar value for predicting lesion severity in all the subgroups.

Оценка фракционного резерва кровотока при эндоваскулярном лечении пациентов с хроническим коронарным синдромом и многососудистым поражением коронарного русла

To evaluate the impact of fractional flow reserve (FFR) assessment on the choice of the myocardial revascularization strategy in patients with ischemic heart disease and multivessel coronary artery disease and to compare the long-term outcomes of complete functional or anatomical revascularization.

The Impact of Age on the Physiological Assessment of Borderline Coronary Stenoses.

Background and Objectives: Coronary angiography is the gold standard for diagnosing coronary artery disease (CAD). In the case of borderline changes, patients require further diagnosis through ischemia assessment via one of the recommended methods of invasive evaluation. This study aimed to assess whether clinical factors influence the risk of a positive result in invasive myocardial ischemia assessment and if these potential factors change with the patient's age and the consistency of ischemia assessment. Materials and Methods: Data were collected retrospectively on all consecutive patients hospitalized in the University Hospital in Krakow between 2020 and 2021, on whom physiological assessments of coronary circulation were performed. Patients were divided into two groups: patients aged 60 or younger and patients older than 60. Results: Despite the older patients having more risk factors for CAD, their physiological assessment results of borderline lesions were similar to those of the younger patients. Positive fractional flow reserve (FFR) assessments were obtained from almost 50% of vessels. In the younger patients, cigarette use and type 2 diabetes mellitus increased the risk of a positive FFR result by 3.5 and 2.5 times, respectively. In the older patients, male gender and peripheral vascular disease significantly increased the risk of a positive FFR by 2.5 and 2 times, respectively. Conclusions: Clinical characteristics of patients undergoing physiological assessment of borderline coronary stenosis varied significantly by age. Refining the definition of borderline lesions to include age, gender, and other factors may improve the identification of patients who would benefit from physiological assessment and coronary revascularization.

Impact of Post-PCI FFR Stratified by Coronary Artery

BackgroundLow fractional flow reserve (FFR) after percutaneous coronary intervention (PCI) has been associated with adverse clinical outcomes. Hitherto, this assessment has been independent of the epicardial vessel interrogated. ObjectivesThis study sought to assess the predictive capacity of post-PCI FFR for target vessel failure (TVF) stratified by coronary artery. MethodsWe performed a systematic review and individual patient-level data meta-analysis of randomized clinical trials and observational studies with protocol-recommended post-PCI FFR assessment. The difference in post-PCI FFR between left anterior descending (LAD) and non-LAD arteries was assessed using a random-effect models meta-analysis of mean differences. TVF was defined as a composite of cardiac death, target vessel myocardial infarction, and clinically driven target vessel revascularization. ResultsOverall, 3,336 vessels (n = 2,760 patients) with post-PCI FFR measurements were included in 9 studies. The weighted mean post-PCI FFR was 0.89 (95% CI: 0.87-0.90) and differed significantly between coronary vessels (LAD = 0.86; 95% CI: 0.85 to 0.88 vs non-LAD = 0.93; 95% CI: 0.91-0.94; P < 0.001). Post-PCI FFR was an independent predictor of TVF, with its risk increasing by 52% for every reduction of 0.10 FFR units, and this was mainly driven by TVR. The predictive capacity for TVF was poor for LAD arteries (AUC: 0.52; 95% CI: 0.47-0.58) and moderate for non-LAD arteries (AUC: 0.66; 95% CI: 0.59-0.73; LAD vs non-LAD arteries, P = 0.005). ConclusionsThe LAD is associated with a lower post-PCI FFR than non-LAD arteries, emphasizing the importance of interpreting post-PCI FFR on a vessel-specific basis. Although a higher post-PCI FFR was associated with improved prognosis, its predictive capacity for events differs between the LAD and non-LAD arteries, being poor in the LAD and moderate in the non-LAD vessels.

Clinical and hemodynamic characteristics of patients with intermediate coronary lesions selected for elective percutaneous coronary intervention

The aim – to identify clinical, angiographic and hemodynamic factors, having impact upon the decision on percutaneous coronary intervention (PCI) in stable coronary artery disease (SCAD) patients with intermediate subepicardial coronary lesions, in clinical settings. Materials and methods. The cross-sectional single-center study analyzed clinical and instrumental data from 123 SCAD patients (mean age 62 ± 9 years; 90 (73.2 %) males) and intermediate (50–90 %) stenotic subepicardial coronary lesions (by invasive coronary angiography [ICA]). The enrolled sample included 74 (60.2 %) patients with an assessment of ICA-derived fractional flow reserve (FFR). The studied parameters were analyzed in the groups of decision not to perform (PCI(–); n = 30 [24.4 %]) and to perform PCI (PCI(+); n = 93 [75.6 %]). Results. The positive decision on PCI was more frequent in patients with stable angina ІII and ІI CCS class, as compared to those without angina (93 %, 79 % і 46 %, respectively; рtrend &lt; 0.001). PCI was considered to be appropriate in all patients with FFR &lt; 0.8 (46 of 74 (62 %) cases). The more advanced hemodynamic compromise of coronary lesions was associated with the higher maximum degree of coronary artery stenosis. Multivariable logistic regression analysis revealed a more pronounced coronary stenosis (at least, in one subepicardial coronary artery territory) was independently associated with the PCI(+) decision (stenosis 80–90 % vs. 70–79 %; 70–79 % vs. 60–69 %; 60–69 % vs. 50–59 %: odds ratio 26 (95 % confidence interval 8–87); р &lt; 0.001). Conclusions. A degree of coronary artery stenosis was a key factor impacting upon a positive decision on PCI in SCAD patients with intermediate (50–90 %) coronary lesions. There is a need for the broader implementation of non-invasive diagnostic tests and the tools for a quantitative assessment of myocardial ischemia in patients with intermediate pretest probability of coronary stenosis, including those with previous PCI.

Fractional flow reserve in assessment of intermediate non-culprit lesions in acute myocardial infarction

Context: Percutaneous coronary intervention (PCI) of intermediate non-culprit arteries can reduce death or heart attack risk in patients with acute myocardial infarction and multivessel coronary artery disease. Aims: To compare the effectiveness of fractional flow reserve (FFR)-guided PCI with angiography-guided PCI for intermediate non-culprit lesions in patients with acute myocardial infarction and multivessel coronary artery disease. Methods: In this cohort study, acute myocardial infarction patients with multivessel coronary artery disease who had successful percutaneous coronary intervention of the culprit artery were divided into group of patients receiving FFR-guided PCI (FFR≤0.80, n = 31) and group of patients receiving angiography-guided PCI (diameter stenosis of 50-90%, n = 62) for lesions in non-culprit arteries. These two groups were followed for at least 1 year for major adverse cardiovascular events. Results: There was no statistically significant difference in major cardiovascular events between FFR-guided percutaneous coronary intervention group and angiography-guided percutaneous coronary intervention group. However, FFR-guided percutaneous coronary intervention group had a lower mortality rate compared to the angiography-guided percutaneous coronary intervention group (3.2% vs. 4.8%). Additionally, there were no reported cases of myocardial infarction in angiography-guided PCI group, while angiography-guided PCI group had a rate of 1.6%. Conclusions: This study found that it remains uncertain whether FFR-guided PCI is superior than angiography-guided PCI for intermediate non-culprit lesions in patients with acute myocardial infarction and multivessel coronary artery disease.

Current Reimbursement Landscape of Artificial Intelligence

One of the biggest hurdles to widespread adoption of new procedures and technology such as artificial intelligence (AI) algorithms is payment and coverage policy. Noninvasive assessment of coronary fractional flow reserve is one AI imaging algorithm that will successfully achieve reimbursement through multiple pathways of CMS payment mechanisms in 2024. CMS is the largest provider of health care in the United States. Understanding how this AI algorithm is paid through the different fee schedules will help to understand the challenges CMS has in paying for new services and innovation in the United States.

Particularities of coronary physiology in patients with atrial fibrillation: insights from combined pressure and flow indices measurements.

Symptoms suggestive of myocardial ischemia are frequently encountered in patients with atrial fibrillation (AF) even in the absence of obstructive coronary artery disease. Nevertheless, an in-depth characterisation of coronary physiology in patients with AF is currently lacking. We aim to provide an insight into the characteristics of coronary physiology in AF, by performing simultaneous invasive measurements of coronary flow- and pressure- indices in a real-life population of patients with AF and indication of coronary angiography. This is a prospective open label study including patients with permanent or persistent AF and indication of coronary angiography showing intermediate coronary stenosis requiring routine physiological assessment (n = 18 vessels from 14 patients). We measured FFR (fractional flow reserve), and Doppler-derived coronary flow indices, including CFR (coronary flow reserve) and HMR (hyperaemic microvascular resistance). From the analysed vessels, 18/18 vessels (100%) presented a pathological CFR (<2.5), indicative of coronary microvascular dysfunction (CMD), and 3/18 (17%) demonstrated obstructive epicardial coronary disease (FFR ≤ 0.8). A large proportion of vessels (15/18; 83%) showed discordant FFR/CFR with preserved FFR and low CFR. 47% of the coronary arteries in patients with AF and non-obstructive epicardial coronary disease presented structural CMD (HMR ≥ 2.5 mmHg/cm/s), and were associated with high BMR and an impaired response to adenosine. Conversely, vessels from patients with AF and non-obstructive epicardial coronary disease with functional CMD (HMR < 2.5 mmHg/cm/s) showed higher bAPV. The permanent AF subpopulation presented increased values of HMR and BMR compared to persistent AF, while structural CMD was more often associated with persistent symptoms at 3 months, taking into account the limited sample size of our study. Our findings highlight a systematically impaired CFR in patients with AF even in the absence of obstructive epicardial coronary disease, indicative of CMD. In addition, patients with AF presented more prevalent structural CMD (HMR ≥ 2.5 mmHg/cm/s), characterized by reduced hyperaemic responses to adenosine, possibly interfering with the FFR assessment.

Vessel-Specific Outcomes of Deferred Revascularization Following Negative Fractional Flow Reserve

Variations in myocardial supply area and hydrostatic pressure gradients result in greater likelihood of positive fractional flow reserve (FFR) in the left anterior descending (LAD) compared with the circumflex (Cx) and right coronary artery (RCA). However, the same FFR threshold for deferral of revascularization is applied to all arteries, without evidence that this results in equivalent outcomes. We assessed vessel-specific outcomes of deferred revascularization for the 3 major coronary arteries based on FFR > 0.8. In this retrospective study, data were obtained on consecutive patients who underwent indicated FFR assessment across 2 tertiary institutions. Patients with deferred revascularization were followed for 36 months for the primary end point of vessel-specific target lesion failure (TLF). Of 1,916 major coronary arteries (1,579 patients), the odds ratio of positive FFR was highest in the LAD (odds ratio 3.36, p<0.001). In total, 867 vessels (733 patients) with FFR > 0.8 had complete 3-year medical record follow-ups. The TLF rate for deferred vessels was 10.21%, 11.52%, and 10.96% for the LAD, Cx, and RCA respectively. In a multivariate analysis, there was no significant difference in the odds of TLF for the 0.84 (0.53 to 1.33, p=0.459), 1.17 (0.68 to 2.01, p=0.582), and 1.11 (0.62 to 2.00, p=0.715) in the LAD, Cx, and RCA, respectively. In a multivariate analysis, diabetes mellitus was the only baseline characteristic significantly associated at risk of TLF (1.43 [1.01 to 2.02], p=0.043). In conclusion, despite greater likelihood of positive FFR in the LAD, the FFR threshold for deferred revascularization resulted in equivalent outcomes in all 3 major coronary arteries, and patients with diabetes mellitus may represent a group that requires aggressive surveillance and risk factor modification after deferred revascularization.

Automated quantitative myocardial perfusion cardiac magnetic resonance with artificial intelligence-based arterial input function correction versus fractional flow reserve

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Wellcome Trust. Background Quantitative myocardial perfusion cardiac magnetic resonance (QP-CMR) is gaining importance in clinical practice due to the increasing availability of automated processing software. However, a significant obstacle in the widespread deployment of QP-CMR is the accurate estimation of the arterial input function (AIF), as this is precluded by the non-linear relationship between observed MR signal and the concentration of contrast agent. Modern solutions favour a dual-saturation acquisition sequence, acquiring specific low-resolution images with a short saturation time to minimise the signal saturation of the AIF. However, this approach is limited by the availability of the pulse sequence. Recently, the AI-AIF has been proposed (1), which uses an artificial intelligence (AI)-based correction of the AIF, without the need for a dual-sequence or dual-bolus acquisition. Purpose In this work, we compare QP-CMR values, quantified with the AI-AIF versus the invasive reference standard: fractional flow reserve (FFR), to identify diagnostically significant coronary artery disease (CAD), as defined by FFR &amp;lt; 0.80. Methods This study enrolled 18 patients (mean age 65 (± 11), 8 female) who underwent stress perfusion CMR (Philips Achieva 3T) and invasive FFR assessment of at least one coronary artery. Perfusion was quantified in a fully-automated manner with motion compensation (2) and AI-based segmentation and processing (3), using a Fermi function-constrained deconvolution. Fully automated pixelwise perfusion maps were generated, and further subdivided into 16 myocardial segments. Segments were assigned to their respective perfusion territory (4) and the QP value for a territory is given as the mean of its two lowest segments. Receiver operating characteristic (ROC) analysis was performed to identify cut-off thresholds and report the diagnostic accuracy of the proposed approach. Results The overall mean QP-CMR value was 2.29 ml/min/g (± 0.32). Figure 1 shows QP maps and FFR values for 3 example patients. The mean QP-CMR value was 2.09 ml/min/g (± 0.36) in patients with significant CAD and 2.95 ml/min/g (± 0.48) in patients without significant CAD. In total, 28 vessels underwent FFR assessment with 12 vessels in 10 patients being positive for significant CAD (FFR &amp;lt; 0.80). The mean QP-CMR value in FFR-positive coronary territories was 1.76 ml/min/g (± 0.37). The ROC curves are shown in Figure 2 on a per-vessel (left) and per-patient (right) level. The optimal QP threshold on a per-vessel level is 2.11 ml/min/g and on a per-patient level is 1.96 ml/min/g. Conclusion QP-CMR is feasible with the AI-AIF and does not require dual-sequence acquisition or a dual contrast injection. The QP values derived after the AI-based correction of the AIF show good agreement with FFR assessment of epicardial coronary disease. However, due to the limited sample size, further work is required to confirm these findings.