Resonance Raman study of oxoiron(IV) porphyrin π-cation radical complex: Porphyrin ligand effect on ν(Fe=O) frequency

Resonance Raman (rR) spectroscopy has been applied to study the nature of the iron-oxo (Fe=O) moiety of oxoiron(IV) porphyrin π-cation radical complex (CompI). While the axial ligand effect on the nature of the Fe=O moiety has been studied with rR spectroscopy, the porphyrin ligand effect has not been studied well. Here, we investigated the porphyrin ligand effect on the Fe=O moiety with rR spectroscopy. The porphyrin ligand effect was modulated by the electron-withdrawing effect of the porphyrin substituent at the meso-position. This study shows that the frequency of the Fe=O stretching band, ν(Fe=O), hardly change even when the electron-withdrawing effect of the porphyrin substituent changes. This result is further supported by theoretical calculation of CompI. The natural atomic charge analysis reveals that the oxo and axial ligands work to buffer the electron-withdrawing effect of the porphyrin substituent. The electron-withdrawing porphyrin substituent shifts an electron population from the ferryl iron to the porphyrin, but the decreased electron population on the ferryl iron is compensated by the shift of the electron population from the oxo ligand and the axial ligand. The shift of the electron population makes the Fe-axial ligand bond length short, but the Fe=O bond length unchanged, resulting in the invariable ν(Fe=O) frequency.

How does multi-reference computation change the catalysis chemistry? DFT and CASPT2 studies of the Cu-catalysed coupling reactions between aryl iodides and β-diketones

The molecular mechanism of a Cu-catalysed coupling reaction was theoretically studied using density functional theory (DFT) and the complete active space self-consistent field method followed by the second-order perturbation theory (CASSCF/CASPT2) to investigate the effects of the strong electron correlation of the Cu centre on the reaction profile. Both DFT and CASSCF/CASPT2 calculations showed that the catalytic cycle proceeds via an oxidative addition (OA) reaction, followed by a reductive elimination (RE) reaction, where OA is the rate-determining step. Although the DFT-calculated activation energies of the OA and RE steps are highly dependent on the choice of functionals, the CASSCF/CASPT2 results are less affected by the choice of DFT-optimised geometries. Therefore, with a careful assessment based on the CASSCF/CASPT2 single-point energy evaluation, an optimal choice of the DFT geometry is of good qualitative use for energetics at the CASPT2 level of theory. Based on the changes in the electron populations of the 3d orbitals during the OA and RE steps, the characteristic features of the DFT-calculated electronic structure were qualitatively consistent with those calculated using the CASSCF method. Further electronic structure analysis by the natural orbital occupancy of the CASSCF wavefunction showed that the ground state is almost single-reference in this system and the strong electron correlation effect of the Cu centre can be dealt with using the MP2 or CCSD method, too. However, the slightly smaller occupation numbers of the 3dπ orbital in the course of reactions suggested that the electron correlation effect of the Cu(III) centre appears through the interaction between the 3dπ orbital and the C-I antibonding σ* orbital in the OA step, and between the 3dπ orbital and the Cu-C antibonding σ* orbital in the RE step.

Electric field effect of positive and negative charges of substituents on electronic structure and reactivity of oxoiron(IV) porphyrin π-cation radical complex

Electric field effect by the positive and negative changes near the active site is an important factor for controlling the reactivity of metalloenzymes. Previously, we reported that the positive charge of the N-methyl-2-pyridinium cation increases the reactivity of oxoiron(IV) porphyrin π-cation radical complex (Compound I), due to the attractive Coulomb interaction with electrons in Compound I. To further investigate the electric field effect, we study here the effect of the negative charge of the sulfonate group on the electronic structure and reactivity using Compound I of meso-tetrakis(2,4,6-trimethyl-3-sulfonatophenyl)porphyrin (TMPS-I). Although Compound I has been known as a very unstable complex, TMPS-I is very stable in 0.1 M acetate buffer at pH = 6. The half-life of TMPS-I is estimated to be 6.9 × 10³ s, which is the longest in Compound I previously reported. The redox potential of TMPS-I is estimated to be 0.76 V vs SCE in phosphate buffer, pH = 10. Kinetic analysis with stopped-flow technique indicates TMPS-I is less reactive than Compounds I reported previously. However, ¹H NMR and EPR spectra of TMPS-I are very close to those of Compounds I reported previously. The DFT calculations show that the orbital energy of Compound I is drastically altered by the positive and negative charges on the meso-phenyl group, suggesting the electric field effect. The difference of the reactivity of Compound I can be rationalized with the change of the orbital energy caused by the intramolecular electric field effect of the positive and negative charges.

Density Functional Study on the Photopolymerization of Styrene Using Dinuclear Ru-Pd and Ir-Pd Complexes with Naphthyl-Substituted Ligands

A density functional study was performed to investigate the mechanism of the photocatalytic reactivity of styrene polymerization using dinuclear Ru-Pd and Ir-Pd catalytic complexes. In previous experiments with these catalysts, the reactivity increased, and more polymer products were yielded compared to dimers under visible light irradiation. The best catalytic reactivity was obtained using an Ir-Pd complex containing naphthyl substituents at the phenyl ligands coordinated to Ir (Ir-Pd1). In contrast, Ir-Pd2, an isomer of Ir-Pd1, containing naphthyl substituents at the pyridine ligands, did not show good reactivity, which may be related to the stability of the excited state of the catalytic complexes. In this study, we calculated the radiative lifetimes of these catalytic complexes and Ir-Pd1 had the longest lifetime; this result was consistent with the experimental results. The longest lifetime of the Ir-Pd1 was attributed to the destabilization of the highest occupied molecular orbital (HOMO) energy by π*-π* interactions between the naphthyl and phenyl ligands. Further, this destabilization of the HOMO energy afforded a small energy gap between the HOMO and lowest unoccupied molecular orbital, enhancing the metal-to-ligand charge transfer to the bridging ligand between Ir and Pd. Additionally, we focused on the reaction of the second insertion of styrene, which was identified as the rate-determining step of the polymerization cycle in a previous study. The singlet-triplet crossing points of the intermediates were estimated, and the barrier heights of the intersystem crossing were much lower than those in the thermal paths, which explained the efficiency of the photocatalytic reactivity in the experiment.

Theoretical Study on the Vapochromic Ni(II)-Quinonoid Complex: One-Dimensional Stacking Structure-Based Color Switching

Vapochromic crystals of Ni(II)-quinonoid complexes were theoretically investigated using density functional theory (DFT) calculations. Kato et al. previously reported that the purple crystals of a four-coordinate Ni(II)-quinonoid complex (1P) exhibited vapochromic characteristics upon exposure to methanol gas, resulting in orange crystals of the six-coordinate methanol-bound complex (1O) [Angew. Chem., Int. Ed.2017, 56, 2345-2349]. However, the authors did not characterize the crystal structure of 1P. In the present study, we computationally predicted the crystal structure of 1P by performing a crystal structure search with classical force-field computations followed by optimization using DFT calculations. The simulated powder X-ray diffraction pattern of the DFT-optimized structure agreed with experimental observations, indicating that our predicted crystal structure is reliable. Investigation of the optimized crystal structure of 1P revealed that its color change arose from changes in its 1D-band structure, which consists of Ni 3d orbitals and quinonoid π-orbitals. Intermolecular interactions were weakened upon the binding of methanol to the Ni(II) center in 1O. Consequently, the intermolecular 3d-π interaction in 1P lowered the band gap and induced the red-shifting of the monomeric four-coordinate Ni(II)-quinonoid complex. Meanwhile, the obtained absorption spectrum of 1O closely corresponded to that of the monomeric six-coordinate Ni(II)-quinonoid complex. Our study provides a new strategy for accurately predicting molecular crystal structures and reveals a new insight into vapochromism based on band structure color switching.

the diagnostic value of left-anterior-descending artery velocity assessed by transthoracic Doppler echocardiography for microvascular dysfunction in stenotic left-anterior-descending artery

Background

Index of microcirculatory resistance (IMR) has been used as a clinical measure of microvascular function. Transthoracic Doppler echocardiography (TDE) can provide information on the functional status of coronary artery circulation. This study aims to assess the diagnostic value of left-anterior-descending artery (LAD) flow velocity by TDE for microvascular dysfunction.

Methods

Consecutive patients who were scheduled for elective percutaneous coronary intervention (PCI) for LAD lesions were prospectively enrolled in the single tertiary-care center between April 2020 and July 2021. Pre-PCI LAD diastolic peak velocity (DPV) by TDE at rest and hyperemia were measured. By invasive coronary angiography, quantitative coronary angiography and invasive wire-based physiological indices including fractional flow reserve (FFR) and index of microcirculatory resistance (IMR) were measured.

Results

A total of 104 patients were studied. Median FFR and IMR values were 0.70 (0.60–0.74) and 20.68 (14.92–31.69), respectively. No significant relationship was observed between FFR and IMR. The prevalence of microvascular dysfunction defined as IMR≥25 was 39.4%. Basal DPV was 25 (20–33) cm/sec, and hyperemic DPV was 51 (41–67) cm/sec. In lesions with IMR≥25, reference diameter (RD) was significantly greater [2.63 (2.22–3.19) mm vs 2.39 (2.09–2.66) mm, p=0.019], basal DPV was lower [26 (18–29) cm/sec vs 29 (22–37) cm/sec, p=0.022)] and hyperemic DPV was lower [49 (19–54) cm/sec vs 56 (42–70) cm/sec, p=0.023] compared to lesions with IMR<25. ROC analysis showed basal DPV and RD are significant predictors of IMR≥25 [basal DPV: AUC 0.633 (0.525–0.742), best cutoff 29cm/sec RD: AUC 0.636 (0.523–0.750), best cutoff 2.84mm]. Multivariable logistic regression analysis showed basal DPV<29cm/sec and RD>2.84mm are independent predictors for IMR≥25 [Odds ratio: 3.08 (1.22–7.78), p=0.017; odds ratio 4.40 (1.55–12.50), p=0.005].

Conclusion

Basal DPV by non-invasive pre-PCI TDE and reference diameter can predict lesions with coexisting microvascular dysfunction in LAD territory with functionally significant lesions without the need of vasodilator-induced hyperemia and a wire-based invasive physiological measurement.

Funding Acknowledgement

Type of funding sources: None.

Prognostic implications of unrecognized myocardial infarction before elective percutaneous coronary intervention

Background

A non-negligible proportion of myocardial infarction (MI) is not clinically recognized and unrecognized myocardial infarction (UMI) is associated with adverse outcomes.

Purpose

To determine the prevalence and prognostic significance of UMI by delayed-enhancement cardiac magnetic resonance (DE-CMR) before elective percutaneous coronary intervention (PCI).

Methods

In this prospective, single-center study, 236 patients with stable coronary artery disease undergoing elective and uncomplicated PCI were studied. All patients underwent DE-CMR before PCI. The prevalence of UMI was evaluated and the association of clinical and CMR-derived variables with primary MACE, defined as cardiovascular death, nonfatal MI, hospitalization for heart failure, unplanned late revascularization, and ischemic stroke was investigated.

Results

In the final analysis of 213 patients, 63 patients (29.6%) showed UMI. Target territory UMI was observed in 38 (17.8% of total, 60.3% of patients with UMI). UMI was significantly associated with sex, diabetes mellitus, left ventricular ejection fraction, SYNTAX score and fractional flow reserve in target vessels. During follow-up periods (median, 23 months), MACE was observed in 17 (27.0%) of patients with UMI, and 17 (11.3%) without (P=0.001). In a multivariable model, UMI (hazard ratio [HR] 2.18, 95% confidential interval, 1.10–4.33, P=0.001) remained as an independent predictor of MACE. Kaplan–Meier analysis indicated that the presence of UMI was significantly associated with higher incidence of MACE.

Conclusions

The prevalence of UMI in patients undergoing elective PCI was 29.6%. UMI was independently associated with an increased risk of MACE after successful PCI. Given the non-negligible prevalence and potential clinical significance of UMI, clinical studies comparing PCI and guideline directed medical therapy (GDMT) versus GDMT only strategy might have to take the presence of UMI into consideration.

Funding Acknowledgement

Type of funding sources: None.

Prognostic implication of unrecognized myocardial infarction in patients with non-ST-segment-elevation acute coronary syndrome

Background

Prognostic value of unrecognized non-infarct-related territory (non-IR) myocardial infarction (UMI) in patients with non-ST-segment-elevation acute coronary syndrome (NSTE-ACS) remains to be elucidated.

Purpose

This study sought to evaluate the prevalence of non-IR UMI and its prognostic value in patients with first NSTE-ACS presentation.

Methods

This retrospective single-center analysis was conducted in patients with NSTE-ACS without prior history of coronary artery disease, who underwent uncomplicated urgent percutaneous coronary intervention (PCI) within 48 hours of admission between August 2014 and January 2018. All patients underwent postprocedural cardiac magnetic resonance imaging (CMR) within 30 days after PCI. Non-IR UMI was defined as the presence of non-IR delayed gadolinium enhancement with an ischemic distribution pattern. We investigated the association of non-IR UMI, other CMR findings and baseline clinical characteristics with major adverse cardiac events (MACE), defined as all-cause death, non-fatal myocardial infarction, ischemic stroke, late revascularization and hospitalization for congestive heart failure.

Results

A total of 168 NSTE-ACS patients were included (124 males (73.8%); 66±11 years). Non-IR UMI was detected in 28 patients (16.7%). During a median follow-up of 32 months (15–58), MACE occurred in 10 (35.7%) patients with non-IR UMI, and 20 (14.3%) patients without (P=0.013). Patients with MACE showed higher frequency of non-IR UMI in RCA territory and multi vessel disease, higher level of NT-proBNP at admission, higher Genisini score, and greater extent of UMI. Cox's proportional hazards analysis showed that the presence of non-IR UMI was an independent predictor of MACE (HR 2.34, 95% CI 1.02–5.37, P=0.045), after adjusting confounding factors, such as multi vessel disease and serum levels of NT-proBNP at admission. The discriminant efficacy (IDI and NRI) of predicting MACE was significantly improved when the presence of non-IR UMI added to the reference clinical risk model. Kaplan-Meier analysis revealed that patients with non-IR UMI were significantly associated with poor prognosis. (Figure 1).

Conclusions

In patients with NSTE-ACS undergoing urgent PCI, the prevalence of non-IR UMI was 16.7%. Non-IR UMI provided prognostic information independent of conventional risk factors.

Funding Acknowledgement

Type of funding sources: None.

Identification of coronary plaque rupture or erosion by preprocedural computed tomography angiography in patients with non-st-segment elevation acute coronary syndrome

Background

The frequent pathological cause of acute coronary thrombosis is plaque rupture or erosion. A previous CT angiographic study failed to discriminate OCT-defined intact fibrous cap culprit lesions (IFC lesions) from those with ruptured fibrous cap (RFC group) in patients with acute coronary syndrome (ACS) and chronic coronary syndrome.

Objectives

This study aimed to evaluate the diagnostic efficacy of preprocedural coronary CT imaging to identify optical coherence tomography (OCT)-defined plaque rupture or erosion at culprit lesions in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS).

Methods

Consecutive patients with suspected NSTE-ACS who underwent preprocedural non-contrast CT and CT angiography (CCTA) were studied. Patients with at least one lesion with more than 50% stenosis at the proximal segment on CCTA were subsequently assessed by invasive coronary angiography and OCT. ALL CT and OCT examination were performed within 24 hours from presentation. The diagnosis of intact fibrous cap or ruptured fibrous cap was made by OCT for the angiographically most severely stenosed lesion. Cases of ambiguous OCT diagnosis such as massive thrombosis or calcified nodule precluding the fibrous cap assessment were excluded from the final analysis.

Results

In the final analysis of 176 patients, OCT identified 87 RFC plaques and 89 IFC plaques for the culprit lesions, respectively. In IFC group, lower prevalence of diabetes mellitus (24.7% vs. 41.4%, P=0.025) and lower peak cardiac marker elevation (CPK, 159 vs. 272 U/L, P<0.001) were observed. On CT, the prevalence of low attenuation plaque, positive remodeling, napkin ring sign, spotty calcification, calcium score (CAC), and culprit vessel pericoronary adipose tissue attenuation (FAI) were all significantly low in IFC group. Multivariate regression analysis to predict IFC at culprit lesions revealed that the absence of low attenuation plaque, the absence of napkin ring sign, zero CAC, and low FAI were independent predictors of IFC. When stratified by the number of these 4 CT factors, the presence of IFC were stratified as 0%, 23.6%, 50%, 77.8%, and 100% (P<0.001), respectively. Adding non-contrast CT factor of zero CAC to the reference model including age, sex, DM, EF, low attenuation plaque, napkin ring sign, and FAI, can increase the incremental discriminatory and reclassification performance for the prediction of IFC (C-statistic 0.828 NRI: 0.37, 95% CI: 0.095–0.646, P=0.008 and IDI: 0.042, 95% CI: 0.012–0.071, P=0.005).

Conclusions

Preprocedural comprehensive CT imaging including CAC and pericoronary adipose tissue inflammation could identify IFC or RFC culprit lesions defined by OCT. Further studies are needed to confirm our preliminary results and if CT imaging in NSTE-ACS provides prognostic information or specific therapeutic approach such as conservative therapy or non-stenting strategy before invasive angiography.

Funding Acknowledgement

Type of funding sources: None.

Diagnostic value of computed tomography myocardial perfusion to detect coexisting microvascular dysfunction in patients with obstructive epicardial coronary disease

Background

The usefulness of computed tomography myocardial perfusion (CTP) to assess hemodynamically significant epicardial coronary artery lesions has been previously reported. However, the diagnostic value of quantitative evaluation of absolute coronary flow by CTP to detect microvascular dysfunction remains unknown.

Purpose

The aim of study is to assess the diagnostic value of CTP to evaluate coronary microvascular dysfunction (CMD) in patients with significant epicardial coronary stenosis, and to analyze the predicting factors for lesions with CMD.

Methods

Sixty-eight chronic coronary syndrome patients with de novo single functionally significant stenosis (Fractional flow reserve [FFR] <0.80) were investigated. CMD was defined by the index of microcirculatory resistance (IMR) ≥25. Clinical characteristics and CTP findings were compared between the two groups with and without CMD (CMD, n=29, non-CMD, n=39, respectively). The computed tomography angiography (CCTA) assessment included CTP findings and quantitative and qualitative assessment of plaques.

Results

In wire-based analysis, FFR, coronary flow reserve (CFRwire) and IMR were 0.68 (0.59–0.74), 1.71 (1.24–2.88), and 22.6 (15.1–34.5), respectively.

In CTP analysis, culprit territory regional absolute myocardial blood flow (MBF) at rest (rest-MBF) and hyperemia (hyperemic-MBF) were evaluated semi-automatically. CTP-derived CFR (CFRCTP) was calculated as hyperemic-MBF divided by rest-MBF. Rest and hyperemic-MBF and CFRCTP were 0.83 (0.64–1.03) ml/min/g, 2.14 (1.30–2.92) ml/min/g, and 2.19 (1.44–3.37).

In the lesions with CMD, hyperemic-MBF was significantly lower than those without CMD (1.68 [0.84–2.44] vs 2.31 [1.67–3.34] ml/min/g, p=0.015) and the prevalence of CFRCTP<2.0 was higher in the lesions with CMD than those without CMD (62.1% vs 28.2%, p=0.007).

CCTA analysis showed that fibrofatty and necrotic core component (FFNC) volume was greater in the lesions with CMD than in the lesions without CMD (31.8 [19.0–48.9] vs 25.1 [17.2–32.1] mm3, p=0.045). The multivariable logistic regression analysis, hyperemic-MBF and FFNC volume were independent predictors for lesions with CMD (Odds ratio [OR] 0.583 [0.355–0.958], p=0.033 and OR 1.040 [1.010–1.070], p=0.018).

Conclusion

Quantitative assessment of absolute coronary flow by CTP and comprehensive plaque analysis by CCTA may help detect coexisting subtended microvascular dysfunction in patients with functionally significant epicardial coronary lesions. Further studies are needed to elucidate the clinical significance of coexisting CMD in CCS patients.

Funding Acknowledgement

Type of funding sources: None.

Multimodality coronary imaging to predict non-culprit territory unrecognized myocardial infarction assessed by cardiac magnetic resonance in non-ST-elevation acute coronary syndrome

Objectives

This study sought to assess the predictors of coherence tomography (OCT) and coronary computed tomography angiographic (CCTA) findings for non-infarct-related (non-IR) territory unrecognized myocardial infarction (UMI) in patients with first non-ST-elevation acute coronary syndrome (NSTE-ACS) presentation.

Background

UMI detected by cardiac magnetic resonance (CMR) is associated with adverse outcomes in patients with both acute coronary syndrome and chronic coronary syndrome. However, the association between the presence of UMI and findings of multimodality coronary imaging remains unknown.

Methods

We investigated 69 patients with a first clinical episode of NSTE-ACS, who underwent pre-PCI 320-slice CCTA, uncomplicated urgent percutaneous coronary intervention (PCI) with OCT assessment within 48 hours of admission, and post-PCI CMR. UMI was assessed on late gadolinium enhancement (LGE-CMR) by identifying regions of hyperenhancement with an ischemic distribution pattern in non-IR territories (non-IR UMI).

Results

Non-IR UMI was detected in 11 patients (15.9%). ROC analysis revealed the optimal cut-off value of PCATA in culprit vessel for predicting the presence of non-IR UMI were −71.3. Lower ejection fraction, higher Gensini score, high pericoronary inflammation (>−71.3), OCT-defined culprit lesion plaque rupture (OCT-PR), and OCT-defined culprit lesion cholesterol crystal (OCT-CC) were significantly associated with the presence of non-IR UMI (Figure 1A). OCT findings are shown in Figure 1B. Patients with non-IR UMI had a higher prevalence of OCT-PR and OCT-CC than those without. Compared with patients without non-IR UMI, the prevalence of high pericoronary inflammation was higher in patients with non-IR UMI (Figure 1C). When the total cohort was divided into four groups according to the numbers of aforementioned OCT-derived risk factors and PCATA, patients with all of these UMI risk factors showed 46.2% (6/13) prevalence of non-IR UMI, whereas none of 15 patients without these factors showed non-IR UMI (Figure 1D).

Conclusions

When culprit lesion showed OCT-PR, OCT-CC, and high PCATA, about half of these patients are likely to have non-IR UMI. The integrated CCTA and OCT assessment may help identify the presence of non-IR UMI, potentially providing prognostic information in first NSTE-ACS patients.

Funding Acknowledgement

Type of funding sources: None.

Prognostic implications of fractional flow reserve and coronary flow reserve after newer-generation drug-eluting stent implantation

Background

FFR after percutaneous coronary intervention (PCI) has been reported to provide prognostic information. However, limited data are available regarding the prognostication by CFR in patients treated with elective PCI using newer generation DES.

Purpose

This study aimed to assess the prognostic value of post-procedural fractional flow reserve (FFR) and coronary flow reserve (CFR) after newer-generation drug-eluting stent implantation (DES).

Methods

A total of 466 stenoses in 466 patients underwent FFR-guided PCI. FFR and CFR measurements before and after PCI by a pressure-temperature sensor-tipped wire were performed. Follow-up data were studied to determine the predictors of target vessel failure (TVF), defined as death, target vessel-related nonfatal myocardial infarction, and unplanned clinically driven target vessel late revascularization. Prognostic value of post-PCI CFR was compared with that of FFR or FFR/CFR combination.

Results

After PCI completion, 13.7% showed post-PCI FFR ≤0.80 and 44.2% exhibited post-PCI CFR <2.5. Discordant results were observed in 42.5% (198/466). During 2.7 (1.8–3.3) years follow-up, 57 (12.2%) TVF were documented. The multivariable Cox proportional hazard regression analysis revealed that post-PCI FFR and post-PCI CFR were independent prognostic factors. ROC analysis revealed that the optimal cut-off values of post-PCI FFR and CFR values were 0.85 and 2.26, respectively. Significant differences in TVF were detected according to post-PCI FFR (≤0.85 vs >0.85: 17.8% vs 8.9%, P<0.05) and post-PCI CFR (≤2.26 vs >2.26: 20.5% vs 7.2%, P<0.01), although the reclassification ability for TVF was improved only with post-PCI CFR (net reclassification index 0.598; P<0.01; integrated discrimination index 0.038; P<0.01), but not with post-PCI FFR, in comparison with the clinical model. Compared with patients with FFR >0.85, those with post-PCI FFR ≤0.85 and CFR ≤2.26 showed significantly higher risk of TVF (8.9% vs 28.9%, P<0.01, HR 4.24, 95% CI 2.40–7.50, P<0.01), whereas those with post-PCI FFR <0.85 and CFR >2.26 had similar TVF risk (8.9% vs 9.2%, P=1.00, HR 1.01, 95% CI 0.47–2.16, P=0.97).

Conclusions

After PCI completion with newer-generation DES, discordant results between FFR and CFR were observed in 42.5%. Compared with post-PCI CFR, post-PCI FFR provided limited reclassification ability for TVF. Among patients with lower post-PCI FFR, only patients with lower post-PCI CFR showed significantly higher risk of TVF than those with higher post-PCI FFR.

Funding Acknowledgement

Type of funding sources: None.

Prevalence and culprit lesion plaque characteristics on optical coherence tomography in patients with non-st-segment elevation acute coronary syndrome with zero coronary calcification on coronary CTA

Background

CAC evaluated by non-contrast computed tomography is a marker of atherosclerosis. However, the characteristic features of CCTA and optical coherence tomography (OCT) of culprit lesions in patients with NSTE-ACS showing zero CAC remain unknown.

Objectives

This study aimed to assess the prevalence and characteristic features of culprit lesions on coronary CT angiography (CCTA) and optical coherence tomography (OCT) in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) showing zero coronary artery calcium (CAC).

Methods

A total of 176 consecutive patients with NSTE-ACS who underwent preprocedural CCTA and OCT were studied. Patients were divided into two groups according to their CAC (zero-CAC and non-zero-CAC groups). Baseline characteristics, CCTA and OCT findings were compared between these two groups.

Results

The prevalence of patients with zero-CACS was 15.9% (28/176). Patients in zero CAC group were younger (mean age, 55 vs. 65 years, P<0.001) and had a lower prevalence of diabetes (10.7 vs 37.2%, P=0.012) than non-zero CAC group. In zero CAC group, the lower prevalence of napkin ring sign (3.5% vs. 28.4%, P=0.028), smaller LV mass index (77.7 vs. 83.9, P=0.04), lower prevalence on spotty calcification (0 vs. 83.8%, P<0.001), lower epicardial fat volume (111.3 vs. 142.6 cm3, P=0.025), and lower pericoronary adipose tissue attenuation (−71.5 vs. −70.2 HU, P=0.07) on CCTA were observed. On OCT, the frequency of plaque erosion (82.1 vs. 44.6%, P<0.001) was significantly higher in zero-CACS group. The prevalence of lipid-rich plaque (46.4 vs. 86.5%, P<0.001), thin-cap fibroatheroma (17.9 vs. 46%, P=0.006), macrophage accumulation (46.4 vs. 81.8%, P<0.001) and cholesterol crystal (7 vs. 41.9%, P<0.001) were all significantly lower in zero-CAC group.

Conclusions

Zero CAC NSTE-ACS was not rare. Zero-CAC NSTE-ACS was characterized by specific phenotypes defined by the combined assessment of CCTA and OCT. Further studies are warranted if these characteristics of NSTE-ACS on preprocedural imaging studies provide prognostic information or guidance of a specific therapeutic approach.

Funding Acknowledgement

Type of funding sources: None.

Relationship between OCT-derived plaque characteristics, CTA-derived coronary inflammation, and CMR-derived global coronary flow reserve in patients with acute coronary syndrome

Background

The presence of layered plaque is suggestive of recurrent thrombotic events. However, the impact of layered plaque detected by optical coherence tomography (OCT) on coronary inflammation and coronary flow reserve remains unclear.

Purpose

We aimed to investigate the association of OCT-derived layered plaque with pericoronary adipose tissue inflammation assessed by coronary computed tomography angiography (cCTA) and global coronary flow reserve (G-CFR) assessed by cardiac magnetic resonance imaging (CMR) in patients with acute coronary syndrome (ACS).

Methods

We investigated 88 patients with first ACS who underwent preprocedural cCTA and OCT imaging of the culprit lesion, and CMR after percutaneous coronary intervention (PCI). All patients were divided into four groups according to the OCT-derived culprit plaque characteristics: layered vs. non-layered plaque; and plaque rupture vs. plaque erosion. Coronary inflammation was assessed by the mean value of pericoronary adipose tissue (PCAT) attenuation (−190 to −30 HU) of the three major coronary vessels. G-CFR was obtained by quantifying absolute coronary sinus flow at rest and during maximum hyperemia. CCTA and CMR findings were compared between the groups.

Results

In a total of 88 patients, layered plaque [L] with plaque rupture [PR] was observed in 25 patients, layered plaque with plaque erosion [PE] was observed in 26 patients, non-layered plaque [NL] with PR was observed in 23 patients, and non-layered plaque with PE was observed in 14 patients, respectively. Three-vessel-PCAT attenuation value (L-PR vs. L-PE vs. NL-PR vs. NL-PE; −68.13±6.18 vs. −69.01±6.72 vs. −69.76±4.04 vs. −74.61±5.63 HU, P=0.009) and culprit vessel PCAT attenuation value (L-PR vs. L-PE vs. NL-PR vs. NL-PE; −66.39±7.38 vs. −68.94±8.06 vs. −70.01±5.76 vs. −75.45±6.60 HU, P=0.003) showed the graded difference between the four groups. G-CFR value also showed the graded difference between the four groups (L-PR vs. L-PE vs. NL-PR vs. NL-PE; 2.26 [1.80–2.87] vs. 2.24 [1.72–3.13] vs. 2.97 [2.24–3.83] vs. 3.18 [2.67–4.08], P=0.022).

Conclusions

The presence of layered plaque at the culprit lesion was associated with high PCATA and low G-CFR in patients with ACS. Detection of layered plaque may indicate increased pericoronary inflammation and impaired coronary flow reserve, potentially providing the risk stratification in patients with ACS.

Funding Acknowledgement

Type of funding sources: None.

Mechanistic insights into the selectivity of norcarane oxidation by oxoMn(V) porphyrin complexes

OxoMn(V) porphyrin complexes perform competitive hydroxylation, desaturation, and radical rearrangement reactions using diagnostic substrate norcarane. Initial C-H cleavage proceeds through the two hydrogen abstraction steps from the two adjacent carbon on the norcarane, then the selective reaction is performed to generate various products. Using density functional theory calculations, we show that the hydroxylation and desaturation reactions are triggered by a rate-determining H-abstraction step, whereas the rate-determining step for the radical rearrangement is located at the rebound step ( TS2 ). We find that the  endo- 2  reaction is favorable over other reactions, which is consistent with the experimental result. Furthermore, the competitive pathways for norcarane oxidation depend on the non-covalent interaction between norcarane and porphyrin-ring, and orbital energy gaps between donor and acceptor orbitals because of stable or unstable acceptor orbital. The stereo- and regio-selectivities of norcarane oxidation are hardly sensitive to the zero-point energy and thermal free energy corrections.

Rate-Limiting Step of Epoxidation Reaction of the Oxoiron(IV) Porphyrin π-Cation Radical Complex: Electron Transfer Coupled Bond Formation Mechanism

Epoxidation reactions catalyzed by high-valent metal-oxo species are key reactions in various biological and chemical processes. Because the redox potentials of alkenes are higher than those of most high-valent metal-oxo species, the electron transfer (ET) from the alkene to the high-valent metal-oxo species in the epoxidation reaction is endergonic and must be coupled with another exergonic process. To reveal the mechanism of the ET, we performed a Marcus plot analysis for the epoxidation reaction of the oxoiron(IV) porphyrin π-cation radical complex (compound I) with alkene. The Marcus plots can be simulated with a linear line with the gradient of 0.50 when the redox potential of compound I varies and 0.07 when the redox potential of alkene varies. These results indicate that the ET process is involved in the rate-limiting step and coupled with the following O-C bond formation process: ET coupled bond formation mechanism. The DFT calculations support this conclusion and disclose the details of the mechanism. As the alkene comes close to the oxo ligand, the energy of the highest occupied molecular orbital (HOMO) of the alkene increases and the energy for the ET becomes small enough to allow the ET. Finally, the ET occurs from the HOMO of the alkene to the porphyrin π-radical orbital. The shift of one electron from the HOMO of the alkene by the ET simultaneously results in the O-C half bond formation between the oxo ligand and the alkene. The ET process itself is still endergonic and reversible, but the bond formation coupled with the ET changes the overall process to exergonic and irreversible. We also discuss the similarity with the aromatic hydroxylation reaction and the relevance to the epoxidation reactions of other metal-oxo complexes and peracid.

Insights into the electronic structure and mechanism of norcarane hydroxylation by OxoMn(V) porphyrin complexes: A density functional theory study

Norcarane hydroxylation by neutral [PorMn(V)O-L] (L═OH^- , F^- ) and cationic [PorMn(V)O-L]⁺ (L═H₂ O, imidazole) oxoMn(V) porphyrin complex models has been investigated by density functional theory calculations to better understand the reaction mechanism and electronic structure. We found that the energy barriers of norcarane hydroxylation by cationic oxoMn(V) porphyrin complexes are lower than those by neutral oxoMn(V) porphyrin complexes. This indicates that cationic oxoMn(V) porphyrin complexes enhance norcarane hydroxylation compared with neutral oxoMn(V) porphyrin complexes. According to electronic structure analysis, in the C─H activation step, electron transfer occurs through initial interaction between the σ_CH and rich-oxygen π(Mn═O) orbitals to form real donor orbitals, followed by transfer to the acceptor π*(Mn═O) orbitals. Moreover, single electron shifts from norcarane (CH) to Mn atom during C─H activation. The positive charge of the cationic complex stabilizes the acceptor orbital more than the donor orbital, reducing the energy gap between these orbitals, thus lowering the reaction barrier.

Synthesis, characterization, and reactivity of oxoiron(IV) porphyrin π-cation radical complexes bearing cationic N-methyl-2-pyridinium group

Electronic charge near the active site is an important factor for controlling the reactivity of metalloenzymes. Here, to investigate the effect of the cationic charge near the heme in heme proteins, we synthesized new iron porphyrin complexes (1 and 2) having cationic 3-methyl-N-methyl-2-pyrdinium group and N-methyl-2-pyridinium group at one of the four meso-positions, respectively. The N-methyl-2-pyridinium groups could be introduced by Stille coupling used palladium catalysts. Oxoiron(IV) porphyrin π-cation radical complexes (Compound I) of 1 (1-CompI) and 2 (2-CompI) are soluble in most organic solvents, allowing direct comparison of their electronic structure and reactivity with Compound I of tetramesitylporphyrin (3-CompI) and tetrakis-(2,6-dichlorophenyl)porphyrin (4-CompI) under the same conditions. Spectroscopic data for 1-CompI are close to those for 3-CompI, but the redox potential for 1-CompI is close to that of 4-CompI. Kinetic analysis of the epoxidation reactions shows that 1-CompI and 2-CompI are (~250-fold) more reactive than 3-CompI, and comparable to 4-CompI. DFT calculations allow to propose that the positive shift of the redox potential and the enhanced reactivity of 1-CompI and 2-CompI is induced by the intramolecular electric field effect of N-methyl-2-pyridinium cation, not by the electron-withdrawing effect.

Density Functional Study on Compounds to Accelerate the Electron Capture Decay of 7Be

In radionuclide compounds undergoing electron capture (EC) decay, the electron density at the nucleus (ρ(0)) and half-life of the nucleus are inversely proportional. Thus, the decay can be accelerated by changing the chemical or physical conditions. A previous study reported a 1.1-1.5% reduction in the half-life of ⁷Be encapsulated in C₆₀ compared with ⁷Be metal. However, ⁷Be was inserted into the fullerene using the rebound energy of the nuclear reaction, which may not be a practical method. This paper elucidates the mechanism of ρ(0) change in various Be compounds from density functional calculations and attempts to propose better systems that show faster EC decay (larger ρ(0)) and/or that are easier to generate than Be in C₆₀. In typical Be compounds, ρ(0) decreases because Be donates electrons to other atoms through chemical bonds and, thus, is not effective. Among the various Be-encapsulated fullerenes (C₂₀-C₁₈₀), the largest increase in ρ(0) was obtained for C₅₀ fullerene, but the magnitude was almost similar to that of C₆₀. As new systems, we propose Be-encapsulated rare gas solids, which would be generated only by applying high pressure. An increase in ρ(0) from Be metal in the range 2-10%, which depends on the lattice constant, is obtained.

Prognostic value of peri-coronary adipose tissue attenuation and whole vessel and lesion plaque quantification on Coronary Computed Tomography Angiography

Background

Peri-coronary adipose tissue attenuation expressed by fat attenuation index (FAI) on coronary CT angiography (CCTA) reflects peri-coronary inflammation and is associated with cardiac mortality. CCTA also provides two-dimensional and three-dimensional quantification of the individual component of atherosclerotic plaque and entire vessel. The atherosclerotic burden or disease extent in entire epicardial coronary arteries provides prognostic information in patients with coronary artery disease.

Purpose

This study sought to explore the prognostic significance of FAI values and whole vessel and lesion plaque quantification on CCTA in stable patients with intermediate epicardial stenosis evaluated by fractional flow reserve (FFR).

Methods

A total of 277 patients (277 lesions) with intermediate coronary stenosis who underwent FFR measurement and CCTA were studied. FAI was assessed by the crude analysis of the mean CT attenuation value (−190 to −30 Hounsfield units; higher values indicating inflammation) on CCTA. CT findings including whole vessel and lesion plaque quantification, and target vessel myocardial mass were investigated. Major adverse cardiovascular outcome (MACE) was defined as all cause death, cardiac death, myocardial infarction, unplanned revascularization, and heart failure requiring admission. Survivals from MACE were assessed.

Results

The mean FAI and the median FFR values were −71.6 and 0.77, respectively. FFR values were weakly albeit significantly correlated with FAI values. (r=−0.016, P=0.008.) MACE was occurred 43 (15.5%) patients during 5 years F-up. ROC analyses revealed that best cut-off value of FAI to predict MACE was −73.1. Kaplan-Meier analysis revealed that lesions with FAI ≥−73.1 had a significantly higher risk of MACE. (Chi-square 5.5, P=0.019) FFR values and the percutaneous coronary intervention were not predictive of MACE. Multivariate COX proportional hazards regression analysis revealed that age, remodeling index, and lesions with FAI ≥−73.1 were independent predictors of MACE.

Conclusion

The peri-coronary inflammation evaluated by FAI and CT remodeling index enhances cardiac risk prediction in chronic coronary syndrome patients with intermediate lesions. Non-invasive comprehensive CT assessment may help identify high risk patients of subsequent clinical events and provide enhanced patient management.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): This study was supported in part by an unrestricted research grant from St. Jude Medical (Abbot Vascular, Santa Clara, CA, USA). The company had no role in study design, conduct, data analysis or manuscript preparation.

Prognostic value of unrecognized myocardial infarction and hyperemic coronary sinus flow in patients undergoing elective percutaneous coronary intervention

Background

Cardiac magnetic resonance (CMR) imaging is a useful instrument for the assessment of pathological and functional conditions without the need for ionizing radiation, radioactive tracers, or intravascular catheterization. Both unrecognized myocardial infarction (UMI) and impaired global myocardial blood flow (g-MBF) have been reported to be strongly associated with worse outcome in patients with cardiovascular disease. However, their combined efficacy remains undetermined.

Purpose

We sought to assess the prognostic value of the presence of UMI and pre-procedural hyperemic g-MBF evaluated by phase-contrast cine magnetic resonance imaging (PC-CMR) in patients with chronic coronary syndrome who underwent elective percutaneous coronary intervention (PCI).

Methods

A total of 177 patients with de novo functionally significant stenosis who underwent pre-PCI CMR and PCI between September, 2016 and March, 2019 were retrospectively studied. UMI was defined as a scar detected by late gadolinium enhancement (LGE) without previously diagnosed MI. g-MBF was assessed by quantifying coronary sinus flow using PC-CMR at rest and hyperemic state. The predictors of major adverse cardiac events (MACE; cardiac death, nonfatal myocardial infarction, clinically driven unplanned revascularization, or hospitalization for congestive heart failure) during follow-up were investigated.

Results

UMI was detected in 40 (27.7%) patients and rest and maximal hyperemic g-MBF evaluated by the coronary sinus flow obtained by PC-CMR were 0.95 ml/min/g and 2.26 ml/min/g, respectively. During the median follow-up of 26 months, cardiovascular death occurred in 1 patient (0.6%), nonfatal myocardial infarction occurred in 4 patients (2.3%), and clinically driven revascularization and hospitalization due to congestive heart failure occurred in 25 patients (14.1%) and 3 patients (1.7%) patients, respectively. In patients with MACE, hyperemic g-MBF was significantly lower and the prevalence of UMI were significantly higher compared with those without MACE (1.94 ml/min/g vs 2.36 ml/min/g P=0.014; 48.3% vs 23.6%, P=0.011). Cox proportional hazards model indicated that impaired hyperemic g-MBF (<2.00 ml/min/g) and the presence of UMI were significant predictors of MACE (HR 2.22, 95% CI 1.060–4.640, P=0.034; HR 2.660, 95% CI 1.290–5.470, P=0.008). During follow-up, cardiac event-free survival was significantly worse in patients with impaired hyperemic g-MBF (<2.00 ml/min/g) and UMI (log-rank χ2=11.0, P=0.010).

Conclusion

In patients with chronic coronary syndrome undergoing elective PCI, the combined assessment of UMI and hyperemic g-MBF obtained by preprocedural noninvasive CMR may provide significant prognostic information.

Funding Acknowledgement

Type of funding source: None

Diagnostic value of myocardial perfusion CT to detect coexisting microvascular dysfunction in patients with obstructive epicardial coronary disease

Background

The usefulness of computed tomography myocardial perfusion (CTP) to assess hemodynamically significant coronary artery lesions has been previously reported. However, the diagnostic value of quantitative evaluation of regional absolute coronary flow by CTP to detect microvascular dysfunction remains unknown.

Purpose

The aim of study is to assess the diagnostic value of preprocedural CTP to detect coexisting microvascular dysfunction with functionally significant epicardial stenosis in patients with chronic coronary syndromes.

Methods and results

Thirty-three chronic coronary syndrome patients with de novo single functionally significant stenosis (Fractional flow reserve [FFR]<0.80) who underwent noncomplicated PCI were investigated. In CTP analysis, regional myocardial blood flow (MBF) at rest (rest-MBF) and hyperemia (hyperemic-MBF) were evaluated semi-automatically. Clinical characteristics, pressure-temperature sensor-chipped wire-based information and CTP findings were compared between groups with and without microvascular dysfunction defined by the index of microcirculatory resistance (IMR) (IMR≥25, n=17, IMR<25, n=16, respectively).

The determinants of coexistence of microvascular dysfunction and functional epicardial stenosis were determined. In invasive wire-based analysis, FFR, coronary flow reserve (CFRwire) and IMR were 0.68 (0.57–0.72), 1.61 (1.00–1.98), and 26.7 (19.3–39.4) respectively.

In CTP analysis, rest and hyperemic-MBF and CFR derived from CTP (CFRCTP; calculated as hyperemic-MBF/rest-MBF) were 2.00 (1.31–2.35) ml/min/g, 4.03 (2.11–5.44) ml/min/g, and 2.09 (1.49–2.09) respectively.

In the lesions with IMR>25, hyperemic-MBF was significantly lower than that in IMR<25 (3.42 [1.89–4.34] vs 4.50 [3.44–5.99], p=0.031), although there was no significant difference in regional rest-MBF and CFRCTP (1.75 [1.31–2.24] vs 2.05 [1.35–2.46], p=0.439, and 1.83 [1.21–2.11] vs 2.61 [1.91–2.91], p=0.101 respectively). Receiver operating characteristic curve analysis of hyperemic-MBF detecting IMR>25 showed area under the curve of 0.72 (0.54–0.90), sensitivity of 47% and specificity of 94%.

Conclusion

Quantitative assessment of absolute coronary flow by CTP may help detect coexisting microvascular dysfunction in patients with significant epicardial stenotic lesions.

Funding Acknowledgement

Type of funding source: None

Prognostic value of fat attenuation index of pericoronary adipose tissue surrounding left anterior descending artery on coronary computed tomography angiography

Background

Recent studies reported the association between elevated fat attenuation index (FAI) of pericoronary adipose tissue (PCAT) on coronary computed tomography angiography (CTA) and worse cardiac outcomes.

Purpose

We investigated the prognostic value of increased FAI-defined coronary inflammation status in patients with coronary artery disease.

Methods

Three-hundred fifty-eight patients (127 acute coronary syndromes [ACS], 231 stable coronary artery disease) with left anterior descending artery (LAD) as a culprit vessel who underwent coronary CTA were retrospectively studied. The FAI defined as the mean CT attenuation value of PCAT (−190 to −30 Hounsfield Unit [HU]) was measured at the proximal 40-mm segment of LAD. All subjects were divided into two groups according to the median value of FAI in the LAD. The association between the incidence of major adverse cardiac events (MACE) including all-cause death, myocardial infarction, heart failure, target and non-target vessel revascularization were evaluated.

Results

In a total of 358 patients, median FAI values surrounding the LAD was −71.46 (interquartile range, −77.10 to −66.34) HU. Thirty-eight patients (10.6%) experienced MACE during the follow-up period (median, 818 days). Kaplan-Meier analysis revealed that high FAI-LAD (>−71.46 HU [median]) was significantly associated with the incidence of MACE (log-rank test, chi-square = 4.183, P=0.041) (Figure).

Conclusions

In patients with coronary artery disease with culprit LAD lesions, elevated FAI of PCAT surrounding the LAD was associated with worse clinical outcomes. Assessment of FAI may have a potential for potential for non-invasive risk-stratification by coronary CTA.

Kaplan-Meier analysis for MACE

Funding Acknowledgement

Type of funding source: None

Impact of neoatherosclerosis observed at very late phase after coronary stent implantation on subsequent adverse events

Background

Despite the reduction in late thrombotic events with newer generation coronary stents, late stent failure remains a concern following stent implantation. Neoatherosclerosis (NA) is a cause of in-stent restenosis and acute thrombotic occlusion originating from the stented segment by disruption of the in-stent atheroma. Although the clinical impact of NA at 1 year has been reported, clinical significance of NA observed at very later phase remains to be determined. We sought to investigate the association between optical coherence tomography (OCT) findings at very late phase after stenting and subsequent clinical outcomes.

Methods

A total of 195 patients with 316 stents (including 74 bare metal stents, 48 first-generation DES, and 194 second-generation DES) without stent failure who underwent OCT examination at >3 years (4.9 [3.9- 5.8] years) after stent implantation according to the prespecified protocol were investigated. OCT analysis included the presence of lipid-laden neointima, macrophage, malapposition, thrombus, and plaque rupture within the stents. NA was defined as having lipid-laden neointima. The criteria for the diagnosis of NA were signal-poor region in continuous flames, lipid length longer than 0.3 mm, and invisible stent strut at NA site. Quantitative OCT measurement included lipid length (LL), lipid arc, minimum lumen area (MLA) at the stented segment and minimum stent area (MSA). Major adverse cardiac events (MACE) including all-cause death, non-fatal myocardial infarction, and clinically driven revascularization were assessed. MACE-free survival rate was compared between patients with stent showing NA (NA group) and those without NA (non-NA group). Furthermore, in per-stent basis analysis, stent failure including remote revascularization and stent thrombosis of the stent after follow-up OCT examination was assessed.

Results

NA was identified in 50 stents (15.8%) in 38 patients (19.5%). During the median follow-up period of 2.1 [1.0- 2.8] years after OCT examination, 15 MACEs (7.7%) were captured in the total cohort, of which stent failure was observed in 5 stents (5/316, 1.6%). In patient-based analysis, patients with NA had more frequent MACE than those without (18.0% vs 5.1%, p=0.01). Kaplan-Meier analysis revealed that significantly higher MACE rate was detected in NA group than in non-NA group (χ2=5.4, Log-rank p=0.02). In stent-based analysis, NA stents had more frequent stent failure than those without (8.0% vs 0.4%, p=0.002)

Conclusions

NA observed by OCT at >3 years after implantation were associated with subsequent worse clinical outcomes in both patient and stent-based analysis. NA at the very late phase after stenting might be the therapeutic target of secondary prevention and OCT examination at very late phase after stenting may help identify high risk patients of subsequent MACE.

Funding Acknowledgement

Type of funding source: None

Prognostic value of coronary flow capacity assessed by coronary sinus flow obtained by phase contrast cine-magnetic resonance imaging in patients with acute coronary syndrome

Background

The concept of coronary flow capacity (CFC) originated from positron emission tomography has been reported to provide prognostic information. Phase contrast cine-magnetic resonance imaging (PC-CMR) of the coronary sinus (CS) is a promising approach for quantifying global coronary sinus flow (CSF) and global coronary flow reserve (g-CFR) without the need for ionizing radiation, radioactive tracers, or intravascular catheterization.

Purpose

We evaluated the prognostic value of postprocedural CFC by quantifying CSF using PC-CMR in patients with acute coronary syndrome (ACS) treated with primary or urgent percutaneous coronary intervention (PCI).

Methods

This study prospectively but nonconsecutively enrolled 569 ACS patients who underwent uncomplicated primary (for ST-segment elevation myocardial infarction (STEMI)) or urgent PCI within 48 hours of symptom onset (for non-ST elevation acute coronary syndrome (NSTE-ACS)). Breath-hold PC-CMR images of CS were acquired to assess absolute CSF at rest and during maximum hyperemia within 30 days after culprit lesion PCI and revascularization of functionally significant non-culprit lesions. The entire cohort was stratified by the CFC according to the thresholds of hyperemic CSF and g-CFR. Impaired CFC was defined as a severely-reduced CFC in the present study. The association of CFC and baseline clinical characteristics with major adverse cardiac events (all-cause death, nonfatal myocardial infarction, hospitalization for congestive heart failure or stroke) was investigated.

Results

In the final analysis of 502 patients (Male 417 (83.1%), mean age was 67 [58, 73]) and 310 patients (82.3%) with STEMI and 192 patients (38.2%) with NSTE-ACS were studied. In a total cohort, rest and maximal hyperemic CSF and corrected G-CFR were 0.93 [0.68, 1.24] ml/min/g, 2.08 [1.44, 2.77] ml/min/g, and 2.21 [1.58, 3.05], respectively. During a median follow-up of 28 months, MACE occurred in 53 patients (all-cause death: 19, nonfatal myocardial infarction: 16, late revascularization: 59, hospitalization for congestive heart failure: 9, stroke: 9). Cox proportional hazards analysis showed that corrected G-CFR and impaired CFC were both independent predictors of MACE. (hazard ratio (HR), 0.61, 95% confidence interval (CI): 0.45–0.82, p=0.001; HR, 3.51, 95% CI: 1.79–6.86, p≤0.001, respectively). Cardiac event-free survival was significantly worse in patients with impaired CFC (log-rank χ2=22.9, P<0.001). Net reclassification index (NRI) and integrated discrimination improvement (IDI) were both significantly improved when impaired CFC was added to the clinical risk model for predicting MACE.

Conclusions

In ACS patients successfully revascularized with primary or urgent PCI, CFC categorization stratified by noninvasive PC-CMR provided significant prognostic information independent of infarction size, conventional risk factors and g-CFR.

Funding Acknowledgement

Type of funding source: None

Association between near-infrared spectroscopy defined lipid rich plaque and pericoronary adipose tissue inflammation on computed tomography angiography

Background

A recent study has shown that lipid-rich plaque (LRP) detected by near-infrared spectroscopy (NIRS) is a significant predictor of future adverse events. Pericoronary adipose tissue inflammation (FAI; fat attenuation index) evaluated by computed tomography angiography (CTA) has also been reported to be linked with cardiac events. The relationship between NIRS-defined LRP and FAI remains to be determined.

Methods

A total of 82 de novo culprit lesions in 82 patients with chronic coronary syndromes (CCS) who underwent perprocedural CTA and NIRS was retrospectively studied. FAI was assessed by the crude analysis of the mean CT attenuation value (−190 to −30 Hounsfield units; higher values indicating inflammation) of pericoronary adipose tissue. Plaque morphology was assessed by coronary CTA and grey-scale intravascular ultrasound (IVUS). NIRS-defined LRP was defined as a maximum lipid core burden index (LCBI) in 4 mm ≥400. Relationship between NIRS-defined LRP, CTA/grey-scale IVUS findings, and FAI was assessed. Univariate and multivariate logistic regression analyses were performed to determine the predictors for NIRS-derived LRP.

Results

NIRS-defined LRP was observed in 35 (42.6%) patients. Maximum LCBI showed modest correlations both with FAI (r=0.29, p-value=0.007) and CT-derived remodeling index (r=0.51, p<0.001). Receiver operating characteristic (ROC) curve analysis revealed that the best cut-off values of FAI and CT-derived remodeling index for predicting NIRS-defined LRP were −70.7 (AUC: 0.65, 95% CI: 0.53–0.71, P<0.05) and 1.11 (AUC: 0.74, 95% CI: 0.63–0.86, P<0.01), respectively. Multivariate logistic regression analysis showed FAI ≥−70.7 (odds ratio [OR]: 4.27; 95% CI: 1.28–14.3; p-value = 0.02) and CT-derived remodeling index (OR: 10.7; 95% CI: 2.99–32.2; p-value <0.001) were independent predictors of the presence of NIRS-defined LRP, whereas there was no statistically significant and independent predictor of IVUS-derived factors for NIRS-defined LRP. When stratified according to the presence or absence of FAI ≥−70.7 and CT-derived remodeling index ≥1.11, 93% of the lesions showed NIRS-derived LRP when both factors were present, and NIRS-derived LRP was safely ruled out (88%) when both factors were absent.

Conclusions

FAI of the culprit lesion in CCS was an independent predictor of NIRS-defined LRP, supporting the notion that local pericoronary adipose tissue inflammation may correlate to the presence of LRP. Comprehensive assessment of coronary CTA including FAI evaluation may provide a highly accurate information with high sensitivity and specificity for identifying high risk lesions potentially leading to future cardiac events.

Funding Acknowledgement

Type of funding source: None

Clinical significance of the periaortic adipose tissue inflammation in patients with abdominal aortic aneurysms

Background

Recent studies have reported the association between periaortic adipose tissue volumes identified by multi-detector computed tomography (MDCT) and the periaortic adipose tissue inflammation (PATI) identified by positron emission tomography, which may suggest the link between perivascular inflammation and aortic dilation. However, clinical significance of the PATI identified by MDCT remains elusive in patients with asymptomatic abdominal aortic aneurysm (AAA).

Methods

A total of 77 patients with AAA (diameter >30mm) who underwent the initial and follow-up MDCT examinations were studied retrospectively. PATI was assessed by the crude analysis of the mean CT attenuation value (−190 to −30 Hounsfield units; higher values indicating inflammation). The AAA progression (AP) was defined as the growth of AAA diameter >5.0mm/year from the initial to follow-up. Univariate and multivariate logistic regression analysis were performed to determine the predictors for AP.

Results

AP was observed in 19 (24.7%) patient, the median initial AAA diameter was 38.9 (32.7–42.9) mm, and the median progression of AAA diameter was 3.1 (1.5–4.9) mm/year. The initial AAA diameter (odds ratio [OR]: 1.16; 95% confidence interval [CI]: 1.05–1.28; p-value=0.001) and the initial PATI (OR: 1.12; 95% CI: 1.05–1.20; p-value=0.004) were independent predictors of AP. PATI of −71.08 at initial MDCT and the initial AAA diameter of 37.7mm were the best cut-off value to predict AP. Receiver operating characteristic curve analysis revealed that the best cut-off values of PATI at initial MDCT and the initial AAA diameter for predicting AP were −71.08 (AUC: 0.68, 95% CI: 0.50–0.82) and 37.7 (AUC: 0.71, 95% CI: 0.59–0.84), respectively. Addition of the initial AAA diameter to PATI at initial MDCT significantly increased the accuracy for discriminating AP (net reclassification improvement; 95% CI: 0.67 [0.17–1.17]; p-value = 0.007, integrated discrimination improvement; 95% CI: 0.14 [0.04–0.24]; p-value =0.007).

Conclusions

PATI was an independent and significant predictor of aortic dilation, supporting the notion that local adipose tissue inflammation may contribute to aortic remodeling. Comprehensive assessment of MDCT including PATI evaluation may provide a highly accurate information for identifying high risk lesions potentially leading to future AAA rupture.

Funding Acknowledgement

Type of funding source: None

Impact of pericoronary inflammation assessed by coronary computed tomography angiography on the progression of aortic valve calcification

Background

Aortic valve calcification (AVC) has been known as an independent predictor for adverse cardiovascular events and all-cause mortality. Previous studies demonstrated that AVC was associated with aortic valve inflammation and atherosclerosis. However, the relationship between the progression of AVC and pericoronary inflammation remains undetermined.

Purpose

The purpose of this study was to evaluate the impact of the pericoronary inflammation on the progression of AVC.

Methods

A total of 107 patients with suspected or known chronic coronary syndromes who underwent clinically indicated serial 320-slice coronary computed tomography angiography (CTA) at Tsuchiura Kyodo General Hospital from January 2011 to June 2019 were retrospectively studied. Pericoronary inflammation was assessed by pericoronary adipose tissue attenuation (PCATA) defined as the mean CT attenuation value of PCATA (−190 to −30 Hounsfield units [HU]) on proximal 40 mm segments of coronary arteries. AVC was quantified by Agatston score on CTA. The mean aortic attenuation (HU Aorta) and the standard deviation (SD) in the region of interest at the level of the sinotubular junction was measured. AVC was defined as the threshold for calcium detection (mean HU Aorta + 2SD). AVC index was calculated as follows: (follow-up/baseline) AVC divided by follow-up period. AVC progression was defined as newly-developed AVC at follow-up or an increased AVC index during follow-up. All patients were divided into two groups according to the presence or absence of AVC progression, and clinical characteristics and CT findings were compared between these two groups.

Results

AVC progression was observed in 26 patients (24.3%) between 2 serial CT examinations (median, 34 months). There was no significant difference in age, gender and the prevalence of other cardiovascular risk factors between the 2 groups. Patients in AVC progression group were associated with higher prevalence of elevated PCATA-LAD, higher LV mass index at baseline and the initial AVC presence. Receiver-operating characteristic curve analysis revealed that the optimal cut off value of PCATA-LAD for predicting AVC progression was −68.26 HU (area under the curve 0.605; 95% confidence interval [CI], 0.465–0.745). Multivariable logistic regression analysis revealed that baseline PCATA-LAD ≥−68.26 HU (odds ratio [OR], 3.12; 95% CI, 1.04–9.35, p=0.042) and the presence of baseline positive AVC (OR, 6.84; 95% CI, 2.34–20.0, p=0.0004) were independent predictors of AVC progression.

Conclusions

The increased pericoronary inflammation and the presence of AVC may help identify patients with high risk for future AVC progression.

Funding Acknowledgement

Type of funding source: None

DFT insight into axial ligand effects on electronic structure and mechanistic reactivity of oxoiron(iv) porphyrin

A series of DFT studies on the epoxidation reactions of olefins by oxoiron(iv) porphyrin cation radical complexes are performed in this work, to elucidate the axial ligand effects on the electronic features and reaction mechanism in detail. We analyzed the molecular orbitals, spin populations, and Mulliken charges along the intrinsic reaction coordinate route. From the findings, we confirmed that the interaction between the axial ligand and the oxoiron(iv) porphyrin is strong and the initial changes in the electronic structures occur early during the reaction, which further enhances the reactivity toward olefin epoxidation. More importantly, the patterns of the electron transfer from olefin to oxoiron(iv) porphyrin were impacted by the axial ligand. The pattern of successive electron transfer from Fe-O to porphyrin and then from C[double bond, length as m-dash]C to Fe-O for oxoiron(iv) porphyrin in case of fluorine and acetate axial ligands, whereas the pattern of electron transfer occurs from C[double bond, length as m-dash]C to porphyrin for oxoiron(iv) porphyrin in case of chlorine and nitrate axial ligands during the epoxidation reaction of the olefins. We also determined the intersystem crossing between the quartet and sextet spin states occurring at the second transition state (TS2) by the analysis of the two-dimensional potential energy surface.

Time-dependent DFT study of the K-edge spectra of vanadium and titanium complexes: effects of chloride ligands on pre-edge features

X-ray absorption near edge structures (XANES) of vanadium and titanium complexes were investigated with time-dependent density functional theory (TDDFT).

P3578Determinants of visual-functional mismatches as assessed by coronary angiography and 3-D angiography-based quantitative flow ratio

Background

Quantitative flow ratio (QFR) is a novel three-dimensional quantitative coronary angiography (QCA)-based computational index that can estimate fractional flow reserve (FFR) without pharmacologically induced hyperemia or the use of a pressure wire.

Purpose

We aimed to evaluate the determinants of visual-functional mismatches between conventional two-dimensional QCA and QFR.

Methods

A total of 504 de novo intermediate-to-severe lesions from 504 patients with stable angina who underwent angiographical and physiological assessments were analyzed. All lesions were divided into four groups based on the significance of visual (QCA-diameter stenosis [DS] >50% and ≤50%) and functional (QFR <0.80 and ≥0.80) stenosis severity. Patient characteristics, angiographic findings, QFR computations, and physiological indices were compared among the four groups.

Results

Among 504 lesions, 153 lesions (30.4%) showed concordantly negative (DS ≤50% and QFR >0.80) and 170 lesions (33.7%) showed concordantly positive (DS >50% and QFR ≤0.80) visual and functional assessments. Among 181 lesions (35.9%) with discordant results, 75 lesions (14.9%) showed a mismatch (DS >50% and QFR >0.80) and 106 lesions (21.0%) showed a reverse mismatch (DS ≤50% and QFR ≤0.80), respectively. Reverse mismatch was associated with smaller reference diameter (odds ratio [OR] 0.561; P=0.036), greater DS (OR 1.039, P=0.013), lower coronary flow reserve (CFR) (OR 0.571, P<0.001, non-diabetes mellitus (OR 2.141, P=0.013) and lower ejection fraction (OR 0.961, P=0.011). Mismatch was associated with smaller DS (OR 0.914, P<0.001), shorter lesion length (OR 0.894, P=0.001), higher CFR (OR 1,633, P<0.001), and lower estimated glomerular filtration rate (OR, 0.968, P=0.001). Lesion location and the index of microcirculatory resistance was not associated with the prevalence of reverse mismatch or mismatch.

Conclusions

There was a high prevalence of visual-functional mismatches between QCA-DS and QFR, and CFR was an important functional factor of mismatches. Our results suggested the difference between predictors of reported visual-functional mismatches of QCA/FFR and those of QCA/QFR.

P2705Hybrid QFR-FFR decision making strategy for revascularization

Background

Measurement of the fractional flow reserve (FFR) has become a standard practice for revascularization decision-making in evaluating the functional significance of angiographically intermediate epicardial coronary stenosis. The quantitative flow ratio (QFR) is a novel method for rapid computational estimation of FFR without pressure wire and vasodilator drugs.

Purpose

Nevertheless, the evidence was shown the clinical better outcome of coronary revascularization stratified by FFR, the adoption of FFR remains low. We hypothesized that combined QFR and FFR hybrid strategy could improve the physiological assessment without pressure wire and drugs.

Methods and results

We performed a post-hocanalysis of 549 vessels with angiographically intermediate stenosis in 549 patients who underwent measurement of FFR. The median FFR and QFR values were 0.81 (0.73–0.87) and 0.79 (0.74–0.87), respectively.The ischemic threshold was defined as 0.80 for both QFR and FFR measures. The diagnostic sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the QFR for predicting an FFR of ≤0.80 were 86.2%, 71.9%, 78.9%, 74.5%, and 84.5%, respectively. The area under the receiver operating characteristic curve using the cut-off threshold of ≤0.80 for the FFR was 0.85 (95% confidence interval [CI], 0.81–0.88) for the QFR.In total, 433 (78.9%) and 116 (21.1%) lesions showed concordant and discordant FFR and QFR functional classifications, respectively. A hybrid QFR-FFR strategy was developed, by allowing deferral when QFR values providing negative predictive value greater than 90% and treat others when QFR values greater than that showing 90% positive predictive value, with adenosine being given only to patients with QFR in between those values. For the FFR cut-off (0.8), an QFR of <0.73 could be used to confirm treatment (PPV of 90.7%), while an QFR value of >0.83 could be used to defer revascularization (NPV of 90.0%). When QFR values fall between 0.73 and 0.84, adenosine is given for hyperemic induction and the FFR cut-off of 0.8 is used to guide revascularization. This hybrid QFR-FFR approach has a 95% agreement with an FFR-only decision making, and 285 lesions (51.9%) would have obviated the need of a pressure wire and adenosine.

Hybrid QFR-FFR strategy

Conclusions

A hybrid QFR-FFR strategy for coronary revascularization could reduce the need of a pressure wire and vasodilator drugs, which may increase the penetration of functional assessment of coronary lesions.

P5619Comparison of different resting physiological indices: are diastolic pressure ratio and resting full-cycle ratio equal?

Background

Previous reports showed all diastolic resting indexes tested were virtually identical to the instantaneous wave-free ratio (iFR). Although RFR has been also reported to be diagnostically equivalent to iFR, no comparisons have been reported about the prevalence and characteristics of discordance in diagnosis between diastolic pressure ratio (dPR) and resting full-cycle ratio (RFR).

Purpose

This study sought to determine the coronary pressure characteristics of lesions classified as discordant between dPR and RFR in angiographically intermediate stenoses.

Methods

We recruited 532 patients with 668 intermediate (angiographically stenosis between 30% to 70% severity) coronary lesions undergoing FFR assessment and analyzed DICOM pressure tracings of resting state (dPR and RFR) using a fully automated off-line software algorithm in a blind fashion. Diagnostic performance of dPR and RFR was evaluated using FFR as a reference. Furthermore, we investigated similarity and difference between dPR and RFR.

Results

Median FFR was 0.81 with an interquartile range of 0.74 to 0.87. RFR was highly correlated to dPR (R2=0.94, p<0.001), with a mean bias of 0.012 (95% limits of agreement −0.008 to 0.031). The diagnostic performance of RFR versus dPR was diagnostic accuracy 95.4%, sensitivity 100.0%, specificity 91.6%, positive predictive value 90.6%, negative predictive value 100.0%). Using the binary cut-off of dPR ≤0.89 as a cut-off value, RFR showed near identical agreement according to ROC curve analysis (AUC: 0.996, 95% CI: 0.994–0.999, p<0.001). Although dPR and RFR demonstrated equivalent performance against FFR ≤0.8 (79.5% vs. 79.3% accuracy; p=0.960; area under the receiver-operating characteristic curve: 0.869 vs. 0.870; p=0.528), RFR disagreed with dPR in 4.6% (31 of 668). When all lesions (668 vessels) were divided into groups according to the concordance and discordance between dPR and RFR: RFR+/dPR+ (298 vessels, n=240), RFR+/dPR– (31 vessels, n=31 patients), RFR-/dPR- (339 vessels, n=259). There was no lesion showing RFR-/dPR+. The prevalence of ischemia was tended to be higher in lesions evaluated by RFR (49.3% vs 44.6%, P=0.100) when using FFR ≤0.80 as a reference standard. An overall significant difference in the prevalence of FFR ≤0.80 and the FFR values were detected among these 3 groups. Furthermore, pairwise comparison also revealed the prevalence of FFR >0.80 and the FFR values were significantly lower in RFR+/dPR– than in RFR-/dPR-, and significantly higher in RFR+/dPR– than in RFR+/dPR+. (P<0.001 and P<0.001, respectively)

Conclusion

Significant difference in FFR values was observed according to dPR/RFR agreement and disagreement. Revascularization decision making might defer according to the resting index used. Compared with RFR, lesions might be more frequently deferred when dPR was used to assess physiological significance.

Acknowledgement/Funding

None

P2704The association between global coronary flow reserve and coronary inflammation assessed by attenuation index on computed tomography in patients with stable angina pectoris

Background

Impaired global coronary flow reserve (G-CFR) is known to predict worse outcomes in patients with coronary artery disease. Phase contrast cine-magnetic resonance imaging (PC-CMR) of the coronary sinus (CS) is a promising approach for quantifying coronary sinus flow (CSF) and G-CFR without the need for ionizing radiation, radioactive tracers, or intravascular catheterization. Although G-CFR impairment is previously reported to be linked with endothelium dysfunction and progression of atherosclerosis, the association of perivascular adipose tissue inflammation with myocardial coronary flow remains to be determined.

Purpose

We evaluated the association between G-CFR by quantifying CSF using PC-CMR and the extent of coronary inflammation evaluated by perivascular adipose tissue inflammatory status using CT to assess if coronary inflammation is linked with G-CFR in patients with stable angina pectoris (SAP) treated with elective percutaneous coronary intervention (PCI).

Methods

The study enrolled 74 SAP patients with single denovo lesion who underwent coronary CT angiography and PC-CMR within 90 days before coronary intervention. Proximal 40-mm segments of all three major epicardial coronary vessels were traced and examined. Coronary inflammation was assessed by the CT fat attenuation index of perivascular adipose tissue (FAI-PVAT) defined as the mean attenuation of the perivascular adipose tissue (−190 to −30 Hounsfield units (HU)) in a layer of tissue within a radial distance from the outer coronary artery wall equal to the diameter of the vessel. CMR images were also acquired to assess absolute CSF at rest and during maximum hyperemia before elective PCI. The patients were divided into 4 groups according to the number of inflamed vessels as defined by showing FAI ≥−70.1 HU.

Results

In the final analysis of 69 patients (mean age 67, Male 45 (65.2%)), 18, 19, 20, 12 patients exhibited none, 1, 2, 3 inflamed vessels with FAI ≥−70.1 HU, respectively. Rest and maximal hyperemic CSF and corrected G-CFR were 1.28 [0.76,1.55] vs 1.47 [1.11, 1.81] vs 1.30 [0.94, 1.64] vs 1.27 [1.11, 2.00] ml/min/g; P=0.49, 3.50 [2.84, 5.25] vs 3.28 [2.62, 4.31] vs 3.11 [2.16, 3.63] vs 2.37 [1.40, 2.98] ml/min/g; P=0.049, 3.57 [2.17, 4.54] vs 2.25 [1.73, 3.49] vs 2.26 [1.64, 3.38] vs 1.89 [0.89, 2.32]; P=0.023, respectively. G-CFR and hyperemic CSF were both significantly lower in the group with larger number of inflamed vessels.

Conclusions

In SAP patients with significant coronary artery stenosis, G-CFR obtained by PC-CMR significantly associated with the prevalence of inflamed vessels detected by coronary CT. The extent of coronary inflammation may influence global coronary endothelium dysfunction, resulting in decreased G-CFR.

P5617Repeatability of instantaneous wave-free ratio in comparison with fractional flow reserve

Background

Instantaneous wave-free ratio (iFR) has been recently introduced as an adenosine free alternative for fractional flow reserve (FFR) to assess the functional significance of epicardial coronary stenosis. Little is known, however, regarding the repeatability and stability of iFR in comparison with FFR.

Purpose

The aim of this study was to evaluate the repeatability of iFR and compare it to that of FFR.

Methods

Patients with stable coronary artery disease who underwent physiological assessment twice within 90 days were enrolled. Repeated measurements were performed at diagnostic and therapeutic catheterization in about 70% of studied population. The remaining patients were measured twice for non-culprit lesion assessment at primary PCI and subsequent non-culprit and ischemia-documented lesion PCI. The calculation of iFRmatlab from DICOM pressure tracing data of resting state was performed using a fully automated off-line software algorithm in a blind fashion. FFR values were also measured by a fully automated algorithm in the same core laboratory by using hyperemic pressure tracing data. The repeatability of the two indices were evaluated and compared. The inter-rater agreement between iFRmatlab and FFR values of two measurements was assessed by κ coefficient. The pressure rate product during each assessment was also documented and evaluated.

Results

Ninety-three lesions from 92 patients were included in the study. The time interval between the two assessments was 38.4±19.0 days. iFRmatlab and FFR both showed significant correlation within the two assessments (iFRmatlab: r=0.75, 95% confidence interval, 0.64 to 0.83; mean difference, −0.006 [−0.18 to −0.01], FFR: r=0.86, 95% confidence interval, 0.79 to 0.90; mean difference, 0.004 [−0.07 to 0.03]). The inter-rater agreement of functional ischemia for iFRmatlab and FFR were κ=0.449 and κ=0.732, respectively. Although the prevalence of functional ischemia during the first and second assessment were consistent for both indices (iFRmatlab: 70.0%/67.7%, FFR: 86.0%/ 86.0%), significant difference was observed in the prevalence of clinical disagreement on the diagnosis of functional ischemia (FFR=0.80, iFR=0.89 used as cut-off values, respectively) between the first and second assessment among the two indices (iFRmatlab: 6.5%, FFR: 23.7%, p=0.002). iFRmatlab was significantly associated with pressure rate product during the examination compared to FFR (iFRmatlab: r= −0.25, 95% confidence interval, −0.43 to −0.04, P=0.018, FFR: r=−0.08, 95% confidence interval, −0.28 to −0.13, p=0.467).

Conclusion

Our results suggested that iFRmatlab showed lower repeatability and reliability for decision making compared to FFR. The instability of iFRmatlab potentially derives at least in part from its association with heart rate and blood pressure product.

P2703Impact of subtended myocardial mass on the assessment of functional ischemia as evaluated by FFR and QFR

Background

The fractional flow reserve (FFR) becomes a standard practice for revascularization decision-making in evaluating the functional significance of angiographically intermediate epicardial coronary stenosis. The quantitative flow ratio (QFR) is a novel method for rapid computational estimation of FFR without pressure wire and hyperemic induction. FFR has been reported to be associated with not only epicardial stenosis but also subtended myocardial mass (Vsub). In contrast, the relationship between QFR and Vsub has not been clarified.

Purpose

We sought to examine if subtended myocardial mass (Vsub) assessed by coronary computed tomography showed a significant relationship with QFR in comparison with FFR.

Methods and results

We performed a post-hoc analysis of 152 territories (LAD 116, RCA 25 and LCX 11 lesions) with angiographically intermediate-to-severe stenosis in 152 patients who underwent FFR assessment. The median FFR and QFR values were 0.76 (0.64–0.84) and 0.76 (0.72–0.83), respectively. The median diameter stenosis (%DS) and minimum lumen diameter (MLD) were 54.5 (43.9–64.2) and 1.2 (0.9–1.6), respectively. In total, 123 (80.9%) and 29 (19.1%) lesions showed concordant and discordant FFR and QFR functional classifications, respectively. The ability of Vsub/MLD2 to discriminate lesions with FFR≤0.80 and QFR≤0.80 was assessed compared with QCA data. FFR values were associated with Vsub (R=0.37, P<0.001). In contrast, a trend albeit no significant linear relationshipwas detected between QFR and Vsub (R=0.15, P=0.060). The area under the curve (AUC) of Vsub/MLD2 predicting FFR≤0.80 (0.88: 95% confidence interval [CI], 0.83–0.94)was significantly better than that of MLD (0.80: 95% [CI], 0.72–0.88) (P<0.001). On the other hand, the AUC of Vsub/MLD2 predicting QFR≤0.80 (0.82: 95% [CI], 0.75–0.90) was similar to that of MLD (0.80: 95% [CI], 0.72–0.87) (P=0.276). Multivariate analysis showed that the value of Vsub/MLD2 was an independent predictor of FFR≤0.80 (odds ratio [OR]: 1.09, 95% [CI]: 1.03–1.15, P=0.002), whereas it was not an independent predictor of QFR≤0.80.

Conclusions

Subtended cardiac mass volume derived from CT segmentation improved the diagnostic performance of angiography-derived parameters to identify ischemia-producing lesions when FFR used as a reference standard, whereas QFR showed non-significant relationship with subtended cardiac mass.