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The introduction of wire-free microcirculatory resistance index from functional angiography (angio-IMR) promises swift detection of coronary microvascular dysfunction, however it has not been properly validated. We sought to validate angio-IMR against invasive IMR and PET derived microvascular resistance (MVR). Moreover, we studied if angio-IMR could aid in the detection of ischemia with non-obstructive coronary arteries (INOCA). In this investigator-initiated study symptomatic patients underwent [ 15 O]H 2 O positron emission tomography (PET) and invasive angiography with 3-vessel fractional flow reserve (FFR). Invasive IMR was measured in 40 patients. Angio-IMR and QFR were computed retrospectively. MVR was defined as the ratio of mean distal coronary pressure to PET derived coronary flow. PET and QFR/angio-IMR analyses were performed by blinded core labs. The right coronary artery was excluded. A total of 211 patients (mean age 61 ± 9, 148 (70%) male) with 312 vessels with successful angio-IMR analyses were included. Angio-IMR correlated moderately with invasive IMR (r = 0.48, p < 0.01), whereas no correlation was found between angio-IMR and MVR (r=-0.07, p = 0.25). Angio-IMR did not differ for vessels without obstructive coronary artery disease (CAD) (FFR-) but with reduced stress perfusion (PET+) compared to vessels without obstructive CAD (FFR-) with normal stress perfusion (PET-) (median 28.19 IQR 20.42-38.99 vs. 31.67 IQR 23.47-40.63, p = 0.40). Angio-IMR correlated moderately with invasively measured IMR, whereas angio-IMR did not correlate with PET derived MVR. Moreover, angio-IMR did not reliably identify patients with INOCA., Competing Interests: Declarations. Competing interests: RK, JT and JH are employees of Medis Medical Imaging. Disclosures: RK, JT and JH are employees of Medis Medical Imaging. JK has received consultancy fees from GE Healthcare and AstraZeneca and speaker fees from GE Healthcare, Bayer, Lundbeck, Boehringer-Ingelheim, Pfizer and Merck, outside of the submitted work. TvdH has received speaker fees and institutional research grants from Abbott and Philips. PK received research grants from HeartFlow Inc. The remaining authors have nothing to disclose., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Background: The applicability of quantitative flow ratio (QFR), a nonhyperemic, invasive coronary angiography-derived computation of fractional flow reserve (FFR), has not been studied in coronary artery bypass grafts. We sought to explore the correlation and diagnostic agreement between QFR and FFR in saphenous vein grafts (SVGs)., Methods and Results: A total of 129 prospectively included patients (mean age 73±8 years, 84% male) with prior coronary artery bypass grafting underwent invasive coronary angiography and pressure-derived functional assessment in 150 nonoccluded SVGs. QFR dedicated angiography images of the SVGs were acquired and used for offline QFR computation. The diagnostic performance of QFR was compared with 2-dimensional quantitative coronary angiography, using FFR as a reference. A threshold of ≤0.80 was used to define functional significance. QFR was successfully computed in 140 (93%) SVGs. We found a significant correlation between QFR and FFR (r=0.72, P <0.001). FFR indicated significant disease in 43 (31%) SVGs, whereas QFR analysis showed significant lesions in 53 (38%) bypass grafts. QFR exhibited a higher sensitivity and diagnostic accuracy compared with angiographic lesion assessment (84% versus 63%, P =0.030 and 83% versus 74%, P =0.036, respectively), whereas specificity did not differ (82% versus 79%, P =0.466). Lastly, QFR demonstrated a higher area under the receiver operating curve than quantitative coronary angiography (0.90 versus 0.82, P =0.008) for the detection of FFR-defined significant vein graft disease., Conclusions: This study shows the potential applicability of contemporary QFR computation in venous bypass grafts with a moderate correlation and good diagnostic accuracy compared with functional assessment using FFR.

Background: This study aimed to investigate the diagnostic value of comprehensive on-site coronary computed tomography angiography (CCTA) using stenosis and plaque measures and subtended myocardial mass (V sub ) for fractional flow reserve (FFR) defined hemodynamically obstructive coronary artery disease (CAD). Additionally, the incremental diagnostic value of off-site CT-derived FFR (FFR CT ) was assessed., Methods: Prospectively enrolled patients underwent CCTA followed by invasive FFR interrogation of all major coronary arteries. Vessels with ≥30% stenosis were included for analysis. On-site CCTA assessment included qualitative and quantitative stenosis (visual grading and minimal lumen area, MLA) and plaque measures (characteristics and volumes), and V sub . Diagnostic value of comprehensive on-site CCTA assessment was tested by comparing area under the curves (AUC). In vessels with available FFR CT , the incremental value of off-site FFR CT was tested., Results: In 236 vessels (132 patients), MLA, positive remodeling, non-calcified plaque volume, and V sub were independent on-site CCTA predictors for hemodynamically obstructive CAD (p < 0.05 for all). V sub /MLA 2 outperformed all these on-site CCTA parameters (AUC = 0.85) and V sub was incremental to all other CCTA predictors (p = 0.02). In subgroup analysis (n = 194 vessels), diagnostic performance of FFR CT and V sub /MLA 2 was similar (AUC 0.89 and 0.85 respectively, p = 0.25). Furthermore, diagnostic performance significantly albeit minimally increased when FFR CT was added to on-site CCTA assessment (ΔAUC = 0.03, p = 0.02)., Conclusions: In comprehensive on-site CCTA assessment, V sub /MLA2 demonstrated greatest diagnostic value for hemodynamically obstructive CAD and V sub was incremental to all evaluated CCTA indices. Additionally, adding FFR CT only minimally increased diagnostic performance, demonstrating that on-site CCTA assessment is a reasonable alternative to FFR CT ., Competing Interests: Declaration of competing interest Dr. Min serves as a consultant to Abbott Vascular, serves on the scientific advisory board of Arineta, and has an equity interest in MDDX. Dr. Leipsic has received research grants from GE Healthcare; and serves as a consultant and holds stock options in Circle CVI and HeartFlow. Dr. Taylor has an equity interest in and is an employee of HeartFlow. Dr. Knaapen has received unrestricted research grants from HeartFlow. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2020 [The Author/The Authors]. Published by Elsevier Inc. All rights reserved.)

Aims: This study aimed to evaluate associations between coronary collaterals and myocardial viability as assessed by quantitative cardiac magnetic resonance (CMR) imaging in patients with a chronic coronary total occlusion (CTO)., Methods and Results: A total of 218 patients with a CTO who underwent CMR between 2013 and 2018 were included. A concomitant collateral connection (CC) score 2 and Rentrop grade 3 defined well-developed collaterals in 146 (67%) patients, whereas lower CC scores or Rentrop grades characterised poorly developed collaterals. Dysfunctional myocardium (<3 mm segmental wall thickening [SWT]) and ≤50% late gadolinium enhancement (LGE) defined viability. Extensive scar (LGE >50%) was observed in only 5% of CTO segments. In the CTO territory, SWT was greater (3.72±1.51 vs 3.05±1.60 mm, p<0.01) and the extent of scar was less (7.0 [0.1-16.7] vs 13.1% [2.8-22.2], p=0.048) in patients having well-developed versus poorly developed collaterals. Viability was more prevalent in CTO segments among patients with poorly developed versus well-developed collaterals (44% vs 30% of segments, p<0.01), predominantly due to a higher prevalence of dysfunctional myocardium (51% vs 34% of segments, p<0.01) in the poorly developed collateral group., Conclusions: The infarcted area in myocardium subtended by a CTO is generally limited. Well-developed collaterals are associated with less myocardial scar and enhanced preserved function. However, viability was regularly present in patients with poorly developed collaterals.

Objectives: Quantitative flow ratio (QFR) computes fractional flow reserve (FFR) based on invasive coronary angiography (ICA). Residual QFR estimates post-percutaneous coronary intervention (PCI) FFR. This study sought to assess the relationship of residual QFR with post-PCI FFR.Methods: Residual QFR analysis, using pre-PCI ICA, was attempted in 159 vessels with post-PCI FFR. QFR lesion location was matched with the PCI location to simulate the performed intervention and allow computation of residual QFR. A post-PCI FFR < 0.90 was used to define a suboptimal PCI result.Results: Residual QFR computation was successful in 128 (81%) vessels. Median residual QFR was higher than post-PCI FFR (0.96 Q1-Q3: 0.91-0.99 vs. 0.91 Q1-Q3: 0.86-0.96, p < 0.001). A significant correlation and agreement were observed between residual QFR and post-PCI FFR (R = 0.56 and intraclass correlation coefficient = 0.47, p < 0.001 for both). Following PCI, an FFR < 0.90 was observed in 54 (42%) vessels. Specificity, positive predictive value, sensitivity, and negative predictive value of residual QFR for assessment of the PCI result were 96% (95% confidence interval (CI): 87-99%), 89% (95% CI: 72-96%), 44% (95% CI: 31-59%), and 70% (95% CI: 65-75%), respectively. Residual QFR had an accuracy of 74% (95% CI: 66-82%) and an area under the receiver operating characteristic curve of 0.79 (95% CI: 0.71-0.86).Conclusions: A significant correlation and agreement between residual QFR and post-PCI FFR were observed. Residual QFR ≥ 0.90 did not necessarily commensurate with a satisfactory PCI (post-PCI FFR ≥ 0.90). In contrast, residual QFR exhibited a high specificity for prediction of a suboptimal PCI result. [ABSTRACT FROM AUTHOR]

Background: Scan quality of imaging modalities affects diagnostic accuracy, the magnitude of its impact on CCTA, SPECT, and PET for diagnosis of significant coronary artery disease (CAD) has scarcely been investigated in a head-to-head comparative approach. Aim: To study the impact of scan quality on the diagnostic performance of CCTA, SPECT and PET for the diagnosis of CAD referenced by fractional flow reserve (FFR). Methods: This post-hoc analysis comprised 208 patients with suspected CAD, who underwent 256-slice CCTA, 99mTc-tetrofosmin SPECT and [15O]H2O PET prior to invasive coronary angiography in conjunction with three-vessel FFR measurements. Scans were analyzed in core laboratories and graded as scans of good, moderate or poor quality. A FFR ≤0.80 defined significant CAD. Results are presented on a per patient level. Results: Distribution of good, moderate and poor quality scans was as follows for CCTA; 137 (66%), 45 (22%), 27 (12%). SPECT and PET scans were graded as good, moderate and poor quality in 108 (52%), 79 (38%), 19 (10%) and 175 (86%), 27 (13%), 2 (1%) patients. Specificity (75%), positive predictive value (PPV, [71%]) and accuracy (80%) of good quality CCTA scans were significantly higher compared to moderate image quality scans, 31%, (p<0.001), 51% (p=0.050), and 67% (p=0.009), respectively (Figure 1A). Sensitivity or negative predictive value (NPV) of CCTA did not differ across scan quality groups (Figure 1A). Sensitivity of good quality SPECT scans was superior to moderate (76% vs 41%, p=0.001) and poor image quality scans (30%, p=0.003). A similar trend was seen with regard to accuracy and NPV of SPECT (Figure 1B). Scan quality did not influence diagnostic value of PET (Figure 1C). A comparison of diagnostic performance of good quality CCTA, SPECT and PET scans revealed a similar accuracy of 80%, 85%, and 85%, respectively (p=0.247). Similarly, area under the curves were 0.86, 0.81, and 0.88, respectively, with overlapping 95% confidence intervals. Conclusion: Diagnostic value of CCTA and SPECT was hampered by scan quality, while PET seemed not to be affected by scan quality. Exclusion of moderate and poor quality scans resulted in a high and comparable diagnostic performance of CCTA, SPECT and PET for the diagnosis of significant CAD. [ABSTRACT FROM AUTHOR]