Mean Fractional Flow Reserve Research Articles

Diagnostic accuracy of automatic quantitative flow ratio for hemodynamic assessment of coronary artery stenosis: prospective observational study

Abstract Background Quantitative flow ratio (QFR) is a method for evaluating fractional flow reserve (FFR) without the use of an invasive coronary pressure wire or pharmacological hyperemic agent. Automatic QFR (auto QFR) is a recently developed, simpler method of calculating QFR that uses a patient-specific TIMI (Thrombolysis in Myocardial Infarction) frame count, but with automatically specified start and end frames. Although the previous studies demonstrated that contrast QFR is more accurate than fixed QFR, there is no evidence for auto QFR. Purpose The aim of this study was to evaluate the diagnostic performance of auto QFR, fixed QFR, and contrast QFR for the diagnosis of hemodynamically significant coronary stenosis defined by FFR ≤0.80. Methods This prospective, multicentre trial enrolled patients suspected with coronary artery disease undergoing diagnostic coronary angiography with an indication for to perform invasive FFR. QFR was calculated at a blinded core laboratory. The primary endpoint was the diagnostic accuracy of auto QFR, fixed QFR, and contrast QFR to determine hemodynamically significant coronary stenosis using invasive FFR (≤0.80) as a reference standard. Results A total of 325 vessels from 274 patients were analysed. Mean FFR was 0.82±0.09, mean auto QFR was 0.80±0.12, and mean contrast QFR was 0.82±0.11, respectively. The overall diagnostic accuracy for identifying an FFR of ≤0.80 was highest by contrast QFR (81.5%), followed by fixed QFR (79.1%), and auto QFR (77.5%). The AUC was higher for contrast QFR (AUC 0.885; 95% CI: 0.845-0.925) than fixed QFR (AUC 0.856; 95% CI: 0.812-0.900) or auto QFR (AUC 0.854; 95% CI: 0.806-0.901), but did not differ significantly between fixed QFR and auto QFR (Figure). Conclusions There was no significant difference in AUC between fixed and auto QFR, but the accuracy of contrast QFR was significantly higher compared to both QFRs. Auto QFR has the advantage of faster computation time while using patient-specific coronary flow, but accuracy still needs to be improved.

Single centre experience using vessel Fractional Flow Reserve (vFFR) and diagnostic performance compared with invasive Fractional Flow Reserve (FFR)

Abstract Background Fractional flow reserve (FFR) is a diagnostic gold standard in the functional assessment of coronary artery stenoses (1). Alternative invasive and non-invasive methods have been developed in an attempt to avoid limitations associated with FFR including added procedural risk, patient discomfort, time and cost. Vessel fractional flow reserve (vFFR) is a novel software using two angiographic projections to generate a 3D vessel reconstruction which has shown high diagnostic accuracy in predicting a positive FFR (2-4). Methods All patients undergoing coronary angiography between 01/10/2022 and 08/03/2023, where FFR was performed, were assessed. Patients were included where images met requirements necessary to use vFFR software. vFFR measurements were taken retrospectively by a single investigator and not used to inform patient care. Data were expressed as mean +/- standard deviation and %. The correlation of vFFR to FFR was compared using Pearson’s correlation coefficient. Receiving operator characteristic (ROC) area under the curve (AUC) analysis was used to determine diagnostic performance. Statistical analysis was performed using SPSS v27. Results 28 of 37 patients and 32 of 44 vessels were included and analysed with vFFR software. Excluded vessels were unsuitable due to insufficient frame rate or projection angulation during angiography. Mean age was 63 +/- 3.8 years and 75% of patients were male. Of 32 vessels assessed, 20 were LAD, 5 RCA, 5 LCx and 2 LMS. 29 of 32 vFFR values agreed with positive or negative FFR. Positive vFFR values were seen in all 15 vessels with positive FFR. 3 vessels received a positive vFFR where FFR values were negative. Mean vFFR was 0.76 +/- 0.1 and mean FFR was 0.81 +/- 0.09. vFFR correlated significantly with FFR (R=0.777, p<0.001). vFFR demonstrated good diagnostic accuracy in discriminating "positive" (>0.8) and "negative" (≤0.8) FFR with an AUC of 0.758 (95% CI 0.61-0.91, p<0.01). Conclusion vFFR correlated significantly with FFR and all positive FFR values also received positive vFFR values. vFFR demonstrated good diagnostic accuracy in predicting a positive FFR result. Thus, these data support a strategy of using a negative vFFR to avoid further testing.Pearson correlation of vFFR to invFFRROC curve: vFFR predicting invFFR

The evaluation of combined fractional flow reserve and dynamic SPECT in chronic total occlusion

BackgroundChronic total occlusion (CTO) is the most challenging subset in percutaneous coronary intervention (PCI), but the optimal selection of patients and indication for such procedures remain a subject of debate. We sought to investigate the role of physiological function in treatment decisions of CTO PCI by measuring fractional flow reserve (FFR) and Dynamic SPECT imaging in this study. MethodsAll the FFR of CTO vessel were measured before and immediately after CTO revascularization, and Dynamic SPECT imaging were detected before PCI in patients with an identified CTO. ResultsA total of 53 patients with single-vessel CTO lesions were included in this cohort study. The mean FFR value was 0.34 ± 0.09 at baseline. Immediately after successful CTO PCI, the FFR value significantly increased to 0.79 ± 0.11. The regional coronary flow reserve (CFR) of CTO vessels was 1.62 ± 0.64, which was significantly and positively correlated with the baseline FFR value (r = 0.607, p = 0.005). The area under the ROC curve of the baseline FFR for the detection of ischemia was 0.923 (p < 0.001). The diagnostic performance in terms of sensitivity and specificity was 83.3 % and 85.7 % for baseline FFR with a ROC-optimized cutoff value of 0.35. ConclusionsA significant correlation was found between the CFR derived from dynamic SPECT and baseline FFR. An FFR of <0.35 before CTO PCI can be taken as the cutoff for the presence of inducible ischemia, which was a useful index for therapy options.

Clinical outcomes of patients with deferred revascularisation based on fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) negative coronary artery lesions in Pakistani population.

To assess long-term clinical outcomes and factors associated with target vessel revascularisation in patients with deferred revascularisation based on negative fractional flow reserve and negative instantaneous wave-free ratio. The longitudinal, retrospective study was conducted from July 1, 2020, to January 1, 2022, at the Aga Khan University Hospital, Karachi, and comprised medical records from January 2012 to January 2020 of patients with deferred revascularisation having intermediate to severe coronary lesions on coronary angiogram and had negative fractional flow reserve >0.80 or instantaneous wave-free ratio >0.89 and had not undergone immediate or planned revascularisation on the basis of negative physiological assessment. Data was collected from the institutional records, while final follow-up was taken by reviewing the medical records or telephonic interviews regarding any major adverse cardiac event after the index procedure. Data was analysed using Stata 14.2. Of the 345 patients, 245(71%) were males. The overall mean age was 62±11 years. There were 194(56%) patients who presented with stable angina and 151(44%) presented with acute coronary syndrome. Mean fractional flow reserve was 0.87±0.04 and mean instantaneous wave-free ratio was 0.93±0.03. Multivessel disease was present in 223(65%) patients. Median follow-up period was 29 months (IQR: 24-36 months). Major adverse cardiovascular events occurred in 22(6%) patients, and target vessel revascularisation was required in 11(3%). Diabetes and percentage of stenosis were found to be independent predictors of major adverse cardiovascular events (p<0.05). Deferral of revascularisation and opting for medical treatment for coronary artery stenosis with higher fractional flow reserve or instantaneous wave-free ratio could be considered a safe and reasonable strategy.

Influence of Pathophysiological Patterns of Coronary Artery Disease on Immediate Percutaneous Coronary Intervention Outcomes.

Diffuse coronary artery disease (CAD) impacts the safety and efficacy of percutaneous coronary intervention (PCI). Pathophysiological CAD patterns can be quantified using fractional flow reserve (FFR) pullbacks incorporating the pullback pressure gradient (PPG) calculation. This study aimed to establish the capacity of PPG to predict optimal revascularisation and procedural outcomes. This prospective, investigator-initiated, single-arm, multicentre study enrolled patients with at least one epicardial lesion with an FFR ≤ 0.80 scheduled for PCI. Manual FFR pullbacks were employed to calculate PPG. The primary outcome of optimal revascularisation was defined as a post-PCI FFR ≥ 0.88. 993 patients with 1044 vessels were included. The mean FFR was 0.68 ± 0.12, PPG 0.62 ± 0.17, and post-PCI FFR 0.87 ± 0.07. PPG was significantly correlated with the change in FFR after PCI (r=0.65, 95% CI 0.61-0.69, p<0.001) and demonstrated excellent predicted capacity for optimal revascularisation (AUC 0.82, 95% CI 0.79-0.84, p<0.001). Conversely, FFR alone did not predict revascularisation outcomes (AUC 0.54, 95% CI 0.50-0.57). PPG influenced treatment decisions in 14% of patients, redirecting them from PCI to alternative treatment modalities. Periprocedural myocardial infarction occurred more frequently in patients with low PPG (<0.62) compared to those with focal disease (OR 1.71, 95% CI: 1.00-2.97). Pathophysiological CAD patterns distinctly affect the safety and effectiveness of PCI. The PPG showed an excellent predictive capacity for optimal revascularisation and demonstrated added value compared to a FFR measurement.

Fluid-filled versus sensor-tipped pressure guidewires for FFR and Pd/Pa measurement; PW-COMPARE study

BackgroundFluid-filled pressure guidewires are unaffected by the previously inevitable hydrostatic pressure gradient (HPG). This study aimed to compare simultaneous pressure measurements with fluid-filled and sensor-tipped pressure guidewires. MethodsFifty patients underwent fractional flow reserve (FFR) and Pd/Pa measurement with a fluid-filled and a sensor-tipped pressure guidewire simultaneously. To assess maneuverability, patients were randomized with respect to which pressure guidewire was used to cross the lesion first. Lateral fluoroscopy was used to estimate height difference between catheter tip and distal wire position (and thus HPG). Agreement between pressure measurements was studied. ResultsMeasurements were performed in LM (4% (n = 2)), LAD (44% (n = 22)), LCX (26% (n = 13)), and RCA (26% (n = 13)). Simultaneous pressure measurements showed excellent agreement (mean FFR difference − 0.01 ± 0.03 (r = 0.959, p < 0.001), mean Pd/Pa difference − 0.01 ± 0.04 (r = 0.929, p < 0.001)). FFR was ≤0.80 in 42.6% (n = 20) with fluid-filled FFR measurements versus 46.8% (n = 22) by sensor-tipped FFR measurements. Mean height difference was 15 ± 34 mm, and strongly dependent on the coronary artery (LAD 45 ± 10 mm, LCX −23 ± 16 mm, RCA −13 ± 17 mm). There was a strong correlation between height difference and difference in pressure ratios between sensor-tipped and fluid-filled pressure guidewires (FFR r = −0.850, p < 0.001; Pd/Par = −0.641, p < 0.001). Largest FFR differences were present in the LAD (−0.04 ± 0.02). After HPG correction, mean difference between HPG-corrected sensor-tipped FFR and fluid-filled FFR was 0.00 ± 0.02, mean Pd/Pa difference was 0.01 ± 0.03. ConclusionsThis study shows excellent overall correlation between FFR and Pd/Pa measurements with both pressure guidewires. Differences measured with fluid-filled and sensor-tipped pressure guidewires are vessel-specific and attributable to hydrostatic pressure gradients (NCT04802681).

Diagnostic performance of ultrasonic flow ratio versus quantitative flow ratio for assessment of coronary stenosis

BackgroundUltrasonic flow ratio (UFR) is a novel intravascular ultrasound (IVUS)-derived modality for fast computation of fractional flow reserve (FFR) without pressure wires and adenosine. AimsThis study was sought to compare the diagnostic performance of UFR and quantitative flow ratio (QFR), using FFR as the reference standard. MethodsThis is a retrospective study enrolling consecutive patients with intermediate coronary artery lesions (diameter stenosis of 30%–90% by visual estimation) for IVUS and FFR measurement. UFR and QFR were performed offline in a core-lab by independent analysts blinded to FFR. ResultsFrom December 2022 to May 2023, a total of 78 eligible patients were enrolled. IVUS and FFR measurements were successfully conducted in 104 vessels, finally 98 vessels with both FFR, UFR and QFR evaluation were analyzed. Mean FFR was 0.79 ± 0.12. UFR showed a strong correlation with FFR similar to QFR (r = 0.83 vs. 0.82, p = 0.795). Diagnostic accuracy of UFR was non-inferior to QFR (94% [89%–97%] versus 90% [84%–94%], p = 0.113). Sensitivity and specificity in identifying hemodynamically significant stenosis were comparable between UFR and QFR (sensitivity: 89% [79%–96%] versus 85% [74%–92%], p = 0.453; specificity: 97% [91%–99%] versus 95% [88%–99%], p = 0.625). The area under curve for UFR was 0.95 [0.90–0.98], non-inferior to QFR (difference = 0.021, p = 0.293), and significantly higher than minimum lumen area (MLA; difference = 0.13, p < 0.001). Diagnostic accuracy of UFR and QFR was not statically different in bifurcation nor non-bifurcation lesions. ConclusionsUFR showed excellent concordance with FFR, non-inferior to QFR, superior to MLA. UFR provides a potentiality for the integration of physiological assessment and intravascular imaging in clinical practice.

Diagnostic Performance of On-Site Automatic Coronary Computed Tomography Angiography-Derived Fractional Flow Reserve.

Fractional flow reserve (FFR) is an invasive standard method to identify ischemia-causing coronary artery disease (CAD). With the advancement of technology, FFR can be noninvasively computed from coronary computed tomography angiography (CCTA). Recently, a novel simpler method has been developed to calculate on-site CCTA-derived FFR (CT-FFR) with a commercially available workstation. A total of 319 CAD patients who underwent CCTA, invasive coronary angiography, and FFR measurement were included. The primary outcome was the accuracy of CT-FFR for defining myocardial ischemia evaluated with an invasive FFR as a reference. The presence of ischemia was defined as FFR ≤0.80. Anatomical obstructive stenosis was defined as diameter stenosis on CCTA ≥50%, and the diagnostic performance of CT-FFR and CCTA stenosis for ischemia was compared. Among participants (mean age 64.7±9.4 years, male 77.7%), mean FFR was 0.82±0.10, and 126 (39.5%) patients had an invasive FFR value of ≤0.80. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CT-FFR were 80.6% (95% confidence interval [CI], 80.5-80.7%), 88.1% (95% CI, 82.4-93.7%), 75.6% (95% CI, 69.6-81.7%), 70.3% (95% CI, 63.1-77.4%), and 90.7% (95% CI, 86.2-95.2%), respectively. CT-FFR had higher diagnostic accuracy (80.6% vs. 59.1%, p<0.001) and discriminant ability (area under the curve from receiver operating characteristic curve 0.86 vs. 0.64, p<0.001), compared with anatomical obstructive stenosis on CCTA. This novel CT-FFR obtained from an on-site workstation demonstrated clinically acceptable diagnostic performance and provided better diagnostic accuracy and discriminant ability for identifying hemodynamically significant lesions than CCTA alone.

Relationship of Coronary Angiography-Derived Radial Wall Strain With Functional Significance, Plaque Morphology, and Clinical Outcomes

BackgroundCoronary angiography-derived radial wall strain (RWS) is a newly developed index that can be readily accessed and describes the biomechanical features of a lesion. ObjectivesThe authors sought to investigate the association of RWS with fractional flow reserve (FFR) and high-risk plaque (HRP), and their relative prognostic implications. MethodsWe included 484 vessels (351 patients) deferred after FFR measurement with available RWS data and coronary computed tomography angiography. On coronary computed tomography angiography, HRP was defined as a lesion with both minimum lumen area <4 mm2 and plaque burden ≥70%. The primary outcome was target vessel failure (TVF), a composite of target vessel revascularization, target vessel myocardial infarction, or cardiac death. ResultsThe mean FFR and RWSmax were 0.89 ± 0.07 and 11.2% ± 2.5%, respectively, whereas 27.7% of lesions had HRP, 15.1% had FFR ≤0.80. An increase in RWSmax was associated with a higher risk of FFR ≤0.80 and HRP, which was consistent after adjustment for clinical or angiographic characteristics (all P < 0.05). An increment of RWSmax was related to a higher risk of TVF (HR: 1.23 [95% CI: 1.03-1.47]; P = 0.022) with an optimal cutoff of 14.25%. RWSmax >14% was a predictor of TVF after adjustment for FFR or HRP components (all P < 0.05) and showed a direct prognostic effect on TVF, not mediated by FFR ≤0.80 or HRP in the mediation analysis. When high RWSmax was added to FFR ≤0.80 or HRP, there were increasing outcome trends (all P for trend <0.001). ConclusionsRWS was associated with coronary physiology and plaque morphology but showed independent prognostic significance.

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

BackgroundFFRangio 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). MethodsThis 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. ResultsAmong 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. ConclusionIn 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.

Impact of revascularization on non-flow limiting lesions

Abstract Background Physiology-guided decision-making markedly improves outcomes in patients with coronary artery disease (CAD). The fractional flow reserve (FFR) and the coronary flow reserve (CFR) can be used to estimate the reduction in myocardial blood flow by a stenosis and both were validated against non-invasive modalities to identify ischemia. Nevertheless, discordance between FFR and CFR in stenosis classification occurs in 30-40%. Recent studies showed that patients with non-flow limiting lesions (abnormal FFR, normal CFR) deferred from revascularization had similar outcomes to those vessels that underwent revascularization. However, the direct impact of revascularization in these vessels remains unclear. Purpose We aimed to identify the impact of revascularization in vessels with non-flow limiting lesions (abnormal FFR and normal CFR). Methods We selected those patients with non-flow limiting lesions from the global ILIAS Registry, a comprehensive pooled data set of patients whom underwent clinically indicated coronary angiography and complete physiological assessment. The primary outcomes consist of the composite endpoints of MACE and TVF at 5-year follow-up. Results A total of N=526 patients were included in the current analysis. Mean age was 64±10 and 74% were men. The mean FFR was 0.79±0.09 and the mean CFR 2.38±1.12. Of these, 53% (N=276) underwent revascularization and (47%) had no revascularization of the target vessel during the index procedure. Both groups had a similarly increased risk for MACE and TVF at 5-years (HR 2.4 [95% CI 1.6 – 3.5] and HR 2.2 [95% CI 1.5 – 3.4] respectively, p&amp;lt;0.005 for both, and p=0.787 for the difference between both). Conclusions We found that revascularization did not impact the association between non-flow limiting lesions and MACE or TVF at 5-year follow-up. Although these results should be interpreted with caution, it indicates the need for a more inclusive assessment of coronary hemodynamic when considering revascularization therapy.Figure 1

Non-flow limiting non-culprit plaque characteristics in patients presenting with STEMI versus NSTEMI

Abstract Background Non-ST-elevation myocardial infarction (NSTEMI) and ST-elevation myocardial infarction (STEMI) are often considered distinct clinical entities. Although differences in culprit plaque characteristics have been described extensively, less is known about differences in non-culprit (NC) plaque characteristics. Purpose To compare plaque characteristics of fractional flow reserve (FFR)-negative NC lesions as assessed by optical coherence tomography (OCT) in STEMI and NSTEMI patients. Methods PECTUS-obs is a prospective, observational study in which 438 patients presenting with STEMI or NSTEMI underwent OCT of any intermediate FFR-negative NC lesion (defined as a FFR &amp;gt;0.80) after treatment of the infarct related artery. Quantitative and qualitative OCT analyses were performed by an independent core laboratory. A high risk plaque (HRP) was defined as the presence of ≥2 of the following prespecified criteria: 1) a lipid arc ≥90°, 2) a minimal fibrous cap thickness &amp;lt;65 µm, or 3) either cap rupture or thrombus presence. In the present sub-analysis, lesion-level plaque characteristics were compared between patients presenting with STEMI versus NSTEMI while accounting for within-patient clustering and correcting for prespecified clinical variables (age, history of myocardial infarction, diabetes, and estimated glomerular filtration rate (eGFR)). Results Among 420 patients with at least one analyzable OCT, 217 (51.7%) presented with STEMI and 203 (48.3%) with NSTEMI. Patients with STEMI were younger (mean age 62±10 vs 65±11 years, p=0.004) and less frequently had diabetes (11.1% vs 18.2%, p=0.037) and hypercholesterolemia (31.8% vs 41.6%, p=0.038). Baseline mean eGFR (84±19 vs 75±19 ml/min, p&amp;lt;0.001) and low density lipoprotein-cholesterol levels (3.2±1.2 vs 2.9±1.2, p=0.010) were higher in STEMI patients with fewer of these patients using lipid lowering therapy (18.9% vs 33.0%, p&amp;lt;0.001) before enrollment. A total of 494 NC lesions were analyzed, which were equally distributed in number and location between groups. The mean fractional flow reserve was 0.89±0.05 and was comparable between groups (p=0.26). Patients with STEMI had a smaller minimal lumen area (2.56±1.48 vs 2.84±1.58 mm2, p=0.031) and minimal lumen diameter (1.47±0.44 vs 1.55±0.45 mm, p=0.026) with a subsequent larger percentage area stenosis (64±15 vs 61±17%, p=0.022). Lipid plaques were more common in STEMI patients (81.7% vs 70.7%, p=0.006) and the maximal lipid arc more frequently was ≥90º (79.0% vs 69.0%, p=0.018). There was no difference in the presence of plaque ruptures (8.3% vs 11.2%, p=0.31) or HRP (32.9% vs 29.3%, p=0.40), whereas macrophage accumulation was more prevalent in STEMI patients (27.8% vs 18.2%, p=0.040). Conclusions FFR-negative NC lesions in patients with STEMI have smaller luminal dimensions, and more frequently harbor lipid plaques and macrophage accumulation. No difference was observed in the prevalence of HRP or plaque rupture.

Gender-related differences in absolute coronary flow and microvascular resistance in patients with angina and non-obstructed coronary arteries (ANOCA)

Abstract Background Women with angina more often have non-obstructive coronary artery disease (ANOCA) compared to males. Coronary microvascular dysfunction (CMD) is responsible for angina in a sizable proportion of ANOCA patients. Intracoronary continuous thermodilution allows direct quantification of absolute coronary flow (Q) and microvascular resistance (Rµ). Purpose To evaluate gender-related differences in the prevalence and pattern of CMD assessed with intracoronary continuous thermodilution in ANOCA patients. Specifically, we assessed resting and hyperemic Q (Qrest and Qhyper), R (Rµ,rest and Rµ,hyper), coronary flow reverse (CFR), and microvascular resistance reserve (MRR) in ANOCA patients stratified by gender. Methods Single-center, prospective study of patients with ANOCA. CMD was invasively assessed by intracoronary continuous thermodilution in the left anterior descending artery (LAD) and defined as CFR&amp;lt;2.5. Results A total of 118 patients (n=49 females and n= 69 males) were enrolled. The mean patient age was 65 years. The mean fractional flow reserve (FFR) was 0.85±0.04, with no difference between the 2 genders. There was no difference in Rµ,rest, Qrest and Qhyper between the two genders. However, Rµ,hyper were higher in females compared to males (p=0.003). Among patients with ANOCA, CMD was more prevalent in females (28% vs 22%, p=0.014). Yet, in both females and males with CMD, a higher Qrest was observed compared to patients without CMD. In male patients, also Qhyper was lower in CMD patients versus those without CMD. Conclusion Among patients with ANOCA and investigated with intracoronary continuous thermodilution, CMD appeared more prevalent in females compared to males. Females had higher microvascular Rµ,hyper compared to males. In both genders, CMD was characterized by higher Qrest, suggestive of functional rather than structural CMD.

Angiography-derived radial wall strain as a predictor of myocardial ischemia, high-risk plaque, and outcomes

Abstract Background Angiography-derived radial wall strain (RWS) is a novel method to assess the biomechanical characteristics of the underlying plaque. There is limited data regarding how the biomechanical attributes of atherosclerotic lesions relate to their physiologic and morphological attributes. Purpose This study aimed to investigate the association of RWS with myocardial ischemia and high-risk plaque, and their prognostic implication. Methods From the international CCTA-FFR registry, 484 deferred vessels underwent RWS analysis. Angiography-derived RWS was defined as relative changes of lumen diameter within the cardiac cycle, expressed as a percentage of the largest lumen diameter. Plaque characteristics were assessed in a coronary CT angiography core laboratory and high-risk plaque was defined as 3 or more high-risk plaque characteristics (HRPC) including minimum lumen area &amp;lt;4.0 mm2, plaque burden ≥70%, low-attenuation plaque, and positive remodeling. Functional significance of coronary lesion was assessed by invasively measured fractional flow reserve (FFR). The primary outcome was vessel-oriented composite outcome (VOCO), a composite of cardiac death, target vessel myocardial infarction, or target vessel revascularization at 5 years. All clinical outcomes were adjudicated by an independent clinical event committee. Results The mean FFR was 0.89±0.07, and that for maximum RWS (RWSmax) was 11.2±2.5%. RWS proportionally increased along with the decrease in FFR values, and the increase in the number of HRPC (Both p-for-trend &amp;lt;0.001). The proportion of vessels with FFR ≤0.80 and that of vessels with high-risk plaque increased in the order of RWSmax quartile group (Both p-for-trend &amp;lt;0.001) and these associations maintained after the adjustment of clinical characteristics (adjusted odds ratio [OR] 1.31, p value &amp;lt;0.001 for FFR ≤0.80; adjusted OR 1.24, p value &amp;lt;0.001 for high-risk plaque) and angiographic parameters (adjusted OR 1.24, p value &amp;lt;0.001 for FFR ≤0.80; adjusted OR 1.14, p value 0.012 for high-risk plaque). High RWSmax (&amp;gt;14.2%, optimal cut-off value for VOCO) was an independent predictor for VOCO after adjusting for diabetes and % diameter stenosis, FFR ≤0.8, or high-risk plaque (Figure 1). In a mediation analysis, RWS showed an independent effect from lesion-specific ischemia or high-risk morphological attributes in defining prognosis (Figure 2). Conclusion(s) Angiography-derived RWS was closely related to coronary physiologic and plaque morphological attributes, but was an independent predictor of clinical events. This novel index can provide additional prognostic implications over physiological severity or plaque characteristics in patients with coronary artery disease.Prognostic implications of high RWSMediation analysis

Abstract 18770: Understanding Patients’ Characteristics and Coronary Microvasculature: Early Insights From First US Coronary Microvascular Dysfunction Registry

Introduction: Coronary angiography falls short in accurately evaluating the coronary microcirculation. Fortunately, a new comprehensive invasive hemodynamic assessment method, which uses coronary flow reserve (CFR) and the index of microvascular resistance (IMR), provides enhanced diagnostic capabilities. Objective: We present our early real-world experience with invasive hemodynamic assessment of the coronary microvasculature in symptomatic patients with non-obstructive coronary artery disease (CAD) from the first US Coronary Microvascular Disease Registry (CMDR). Methods: The CMDR is a prospective, multi-center, standardized registry of patients with angina and non-obstructive CAD who underwent invasive hemodynamic assessment of the coronary microvasculature using the Coroventis CoroFlow Cardiovascular System (Abbott Laboratories, Chicago, Illinois). Comprehensive assessments, including resting full-cycle ratio (RFR), fractional flow reserve (FFR), CFR, and IMR, were performed on all patients. Results: The first 156 patients enrolled in the CMDR were analyzed; their mean age was 62.4 years and 65.6% were female. A substantial proportion (31.8%) of patients presented with a Canadian Cardiovascular Society Angina Score of 3 or 4. CMD was diagnosed in 39 of 154 patients (25.3%), with mean RFR of 0.89±0.43, mean FFR of 0.93±0.08, mean CFR of 1.8±0.9, and mean IMR of 36.26±19.23. None of the patients experienced in-hospital adverse events. Conclusions: Early results from CMDR patients show that invasive hemodynamic assessment of the coronary microvasculature is safe and effective for suspected CMD. Tailored medical therapy for microvascular angina was provided to diagnosed CMD patients. With ongoing patient enrollment, the CMDR aims to contribute valuable insights to the growing evidence base for CMD.

Diagnostic Performance of Intracoronary Optical Coherence Tomography-Modulated Quantitative Flow Ratio for Assessing Coronary Stenosis.

A novel method for fast computation of Murray law-based quantitative flow ratio (μQFR) from coregistered angiography and optical coherence tomography (OCT) was recently developed. This study aimed to evaluate the diagnostic performance of this OCT-modulated μQFR (OCT-μFR). Patients who underwent coronary angiography, OCT, and fractional flow reserve (FFR) were retrospectively enrolled. μQFR was computed from a single angiographic projection. Subsequently, OCT image pullback was coregistered with the angiogram, and OCT-μFR was calculated based on the coregistered data. The same cut-off value of 0.80 was used for OCT-μFR, μQFR, and FFR to define ischemia. A paired comparison of OCT-μFR and μQFR was performed in 269 vessels from 218 patients. The mean FFR was 0.81 ± 0.11, and 45.0% of vessels had an FFR ≤0.80. OCT-μFR showed a better correlation with FFR than μQFR (r = 0.83 vs 0.76, P = .018) and numerically higher diagnostic performance (area under the curve [AUC] = 0.95 vs 0.92, P = .057). Sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio for OCT-μFR to identify ischemia-causing stenosis were 89.3%, 93.2%, 91.5%, 91.4%, 13.2, and 0.1, respectively. In addition, OCT-μFR showed significantly higher diagnostic performance compared with μQFR in vessels with suboptimal angiographic image quality (AUC = 0.93 vs 0.87, P = .028) and tandem lesions (AUC = 0.94 vs 0.87, P = .017). Computation of OCT-μFR was feasible and accurately identified physiologically significant coronary stenosis with simultaneous morphological assessment. In vessels with suboptimal angiographic image quality or tandem lesions, OCT-μFR had a higher diagnostic performance than angiography-based μQFR.

Understanding Patient Characteristics and Coronary Microvasculature: Early Insights from the Coronary Microvascular Disease Registry

Coronary angiography has limitations in accurately assessing the coronary microcirculation. A new comprehensive invasive hemodynamic assessment method utilizing coronary flow reserve (CFR) and the index of microvascular resistance (IMR) offers improved diagnostic capabilities. This study aimed to present early real-world experience with invasive hemodynamic assessment of the coronary microvasculature in symptomatic patients with nonobstructive coronary artery disease (CAD) from the Coronary Microvascular Disease Registry, which is a prospective, multi-center registry that standardized the evaluation of patients with angina and nonobstructive CAD who underwent invasive hemodynamic assessment of the coronary microvasculature using the Coroventis CoroFlow Cardiovascular System. All patients underwent comprehensive invasive hemodynamic assessment. Analysis was performed on the first 154 patients enrolled in the Coronary Microvascular Disease Registry; their mean age was 62.4years and 65.6% were female. A notable proportion of patients (31.8%) presented with a Canadian Cardiovascular Society Angina Score of 3 or 4. Coronary microvascular dysfunction was diagnosed in 39 of 154 patients (25.3%), with mean fractional flow reserve of 0.89±0.43, mean resting full cycle ratio of 0.93±0.08, mean CFR of 1.8±0.9, and mean IMR of 36.26±19.23. No in-hospital adverse events were reported in the patients. This study demonstrates the potential of invasive hemodynamic assessment using CFR and IMR to accurately evaluate the coronary microvasculature in patients with nonobstructive CAD. These findings have important implications for improving the diagnosis and management of coronary microvascular dysfunction, leading to more targeted and effective therapies for patients with microvascular angina.

Multimodality OCT, IVUS and FFR evaluation of coronary intermediate grade lesions in women vs. men.

The pathophysiology of atherosclerotic plaque formation and its vulnerability seem to differ between genders due to contrasting risk profiles and sex hormones, however this process is still insufficiently understood. The aim of the study was to compare the differences between sexes regarding the optical coherence tomography (OCT), intravascular ultrasound (IVUS) and fractional flow reserve (FFR)-derived coronary plaque indices. In this single-center multimodality imaging study patients with intermediate grade coronary stenoses identified in coronary angiogram (CAG) were evaluated using OCT, IVUS and FFR. Stenoses were considered significant when the FFR value was ≤0.8. Minimal lumen area (MLA), was analyzed by OCT in addition to plaque stratification into fibrotic, calcific, lipidic and thin-cap fibroatheroma (TCFA). IVUS was used for evaluation of lumen-, plaque- and vessel volume, as well as plaque burden. A total of 112 patients (88 men and 24 women) with chronic coronary syndromes (CCS), who underwent CAG were enrolled. No significant differences in baseline characteristics were present between the study groups. The mean FFR was 0.76 (0.73-0.86) in women and 0.78 ± 0.12 in men (p = 0.695). OCT evaluation showed a higher prevalence of calcific plaques among women than men p = 0.002 whereas lipid plaques were more frequent in men (p = 0.04). No significant differences regarding minimal lumen diameter and minimal lumen area were found between the sexes. In IVUS analysis women presented with significantly smaller vessel area, plaque area, plaque volume, vessel volume (11.1 ± 3.3 mm2 vs. 15.0 ± 4.6 mm2 p = 0.001, 6.04 ± 1.7 mm2 vs. 9.24 ± 2.89 mm2 p < 0.001, 59.8 ± 35.2 mm3 vs. 96.3 (52.5-159.1) mm3 p = 0.005, 106.9 ± 59.8 mm3 vs. 153.3 (103-253.4) mm3 p = 0.015 respectively). At MLA site plaque burden was significantly greater for men than women (61.50 ± 7.7% vs. 55.5 ± 8.0% p = 0.005). Survival did not differ significantly between women and men (94.6 ± 41.9 months and 103.51 ± 36.7 months respectively; p = 0.187). The presented study did not demonstrate significant differences in FFR values between women and men, yet a higher prevalence of calcific plaques by OCT and lower plaque burden at the MLA site by IVUS was found in women vs. men.

Impact of diabetes mellitus on the diagnostic performance of fractional flow reserve in patients with severe aortic stenosis.

The validity of functional assessment of coronary artery disease with fractional flow reserve (FFR) and/or instantaneous wave-free ratio (iFR) in patients with severe aortic stenosis (AS) might be affected by AS per se and other factors, including diabetes mellitus. We aimed to evaluate the impact of diabetic status on FFR performance in severe AS. The functional significance of 416 stenoses of intermediate angiographic severity in 221 patients with severe AS was assessed with iFR and FFR. Patients treated with insulin or oral hypoglycemic agents were classified as diabetic patients. Of 221 enrolled patients, 68 (32.1%) patients were diabetic. A total of 128 (30.8%) lesions in patients with and 288 in patients without diabetes mellitus were assessed. The mean (SD) FFR was 0.85 (0.07), and iFR was 0.90 (0.04) with no difference between nondiabetic and diabetic patients. Good agreement between iFR and FFR was confirmed for non-diabetic (ICC, 0.83 [95% confidence interval, CI, 0.79-0.86]) and diabetic (ICC, 0.82 [95% CI, 0.76-0.87]) patients. Among patients without diabetes mellitus, the optimal cutoff value for FFR to detect iFR ≤0.89 was 0.81 with sensitivity and specificity of 96.6% and 100.0%. The optimal cutoff value for FFR to detect iFR ≤0.89 for diabetic patients was 0.83 with sensitivity and specificity of 98.0% and 100.0%. In patients with severe AS, FFR correlates well with iFR. However, the optimal threshold for FFR to identify significant ischemia (iFR ≤0.89) in those patients may differ from the standard threshold of FFR ≤0.80 and might be affected by the diabetic status.

A novel hybrid strategy of drug coated balloon and stent for coronary bifurcation lesions

Background. Provisional side branch (SB) stenting strategy is the default approach for the majority of bifurcation lesions, but outcomes of SB is suboptimal. Though drug coated balloon (DCB) improving SB outcomes attracts an increasing attention, sequence of DCB hasn’t yet been determined. We presented a novel hybrid strategy of DCB and stent for bifurcation lesions. Methods. With lesion preparation, DCB was persistently inflated in SB kissing with main branch (MB) stent deployment and balloon post-dilation of the bifurcation core. Proximal optimization technique was performed strictly not exceeding the bifurcation. Procedural and clinical adverse events were evaluated. Canadian Cardiovascular Society (CCS) angina classification was assessed at baseline and clinical follow-up. Results. Fourteen patients undergoing the hybrid technique from August 2020 to July 2021 were enrolled. The technique was successfully performed in all patients without rewiring or SB compromise. Minimal lumen diameter of SB increased from 0.60 ± 0.40 mm to 2.1 ± 0.2 mm while the percent stenosis decreased from 72.4 ± 17.9% to 19.6 ± 4.7%. In addition, intravascular ultrasound indicated comparable stent symmetry index and incomplete stent apposition between proximal and distal segments of stent. No further intervention was performed, and mean fractional flow reserve of SB (n = 12) was 0.88 ± 0.05. No major adverse cardiac events was noted in hospital and 12-month follow up. The mean CCS angina score was reduced by 84% (2.2 vs 0.4, p < .001). Conclusion. The hybrid strategy facilitates treatment of DCB and stent for bifurcation lesions, which appears to be feasible and acceptable in a short-term follow-up.