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Introduction: Epicardial adipose tissue (EAT) is a visceral fat deposit within the pericardial sac. The automated quantification of EAT volume is possible from routine CCTA scans via deep-learning. The use of automated EAT quantification for the assessment of cardiovascular disease (CVD) risk in addition to standard measures of obesity like BMI has not been fully explored. Purpose: To use deep-learning for automated segmentation of EAT from routine CCTA scans to assess the long-term CVD risk conveyed by EAT. Methods: A deep-learning automated EAT segmentation tool using a 3D Residual-U-Net neural network architecture for 3D volumetric segmentation of CCTA data was created and trained on over 2500 consecutive CCTAs from within the Oxford Risk Factors And Non Invasive Imaging (ORFAN) Study. External validation in 817 patients demonstrated excellent correlation between machine and human expert (CCC = 0.972). The prognostic value of deep-learning derived EAT volume was assessed against 5 years outcomes from the SCOTHEART trial (n=1588), with adjustment for CVD risk factors. An optimal cutoff was selected by identifying the EAT value that maximized the Youden’s J index (sum of sensitivity and specificity) for the three outcomes of interest - high risk was deemed to be EAT ≥ 170.5cm 3 . Results: There were 35 deaths (all-cause mortality), 35 non-fatal myocardial infarctions and 8 non-fatal strokes during the 5 years follow up period. By using multi-variable cox-regression, EAT volume was predictive of all-cause mortality (Figure 1A), non-fatal MI (Figure 1B), and non-fatal stroke (Figure 1C) independently from CVD risk factors. Conclusions: Automatically segmented EAT volume measured using a deep learning network, predicts 5-year all-cause mortality, heart attacks and stroke independently of BMI and clinical risk profile of the patients. This suggests that measures of visceral obesity will be of value in the interpretation of cardiovascular computed tomography.

Background: Non-invasive detection of vascular inflammation remains an unmet goal. We hypothesized that phenotypic changes in perivascular adipose tissue (PVAT) induced by vascular inflammation can be quantified using a new computed tomography angiography (CTA) methodology. Methods: In Arm 1, human PVAT adipocytes were cultured +/- inflammatory cytokines (n=7) or co-cultured with vascular tissue (+/-Angiotensin-II, n=6) to assess the effects of vascular inflammation on PVAT differentiation. In Arm 2, AT explants (epicardial, subcutaneous and thoracic AT) from 453 cardiac surgery patients were used in histology and gene expression studies to relate the ex vivo images with in vivo CT scan information (n=105) on the biology of the explants. In Arm 3, in 267 patients undergoing diagnostic CTA, PVAT attenuation (Fat Attenuation Index (FAI) defined as the average CT attenuation of AT), was analysed around the proximal right coronary artery. In Arm 4, PVAT FAI around unstable (culprit) and stable coronary plaques was calculated in 22 CAD patients undergoing CTA. Results: In Arm 1, Angiotensin-II (A) and proinflammatory cytokines (B) prevented lipid accumulation and adipocyte differentiation in cultured PVAT. In Arm 2, adipocyte size by histology was inversely correlated with FAI in vivo (C). Both FAI of AT explants (not shown) and FAI in-vivo (n=105) were negatively associated with epicardial AT differentiation as assessed by FABP4 expression (D). In Arm 3, PVAT FAI change over distance from RCA wall was significantly different in CAD compared to no CAD patients (E). In Arm 4, PVAT FAI was significantly increased around unstable plaques (F). Conclusions: Human vessels exert paracrine effects on surrounding PVAT, affecting local intracellular lipid accumulation in preadipocytes, which can then be monitored using a CT imaging approach. This novel methodology can be implemented in clinical practice to detect unstable plaques in the human coronary vasculature.

Background— Adiponectin is an adipokine with potentially important roles in human cardiovascular disease states. We studied the role of adiponectin in the cross-talk between adipose tissue and vascular redox state in patients with atherosclerosis. Methods and Results— The study included 677 patients undergoing coronary artery bypass graft surgery. Endothelial function was evaluated by flow-mediated dilation of the brachial artery in vivo and by vasomotor studies in saphenous vein segments ex vivo. Vascular superoxide (O 2 − ) and endothelial nitric oxide synthase (eNOS) uncoupling were quantified in saphenous vein and internal mammary artery segments. Local adiponectin gene expression and ex vivo release were quantified in perivascular (saphenous vein and internal mammary artery) subcutaneous and mesothoracic adipose tissue from 248 patients. Circulating adiponectin was independently associated with nitric oxide bioavailability and O 2 − production/eNOS uncoupling in both arteries and veins. These findings were supported by a similar association between functional polymorphisms in the adiponectin gene and vascular redox state. In contrast, local adiponectin gene expression/release in perivascular adipose tissue was positively correlated with O 2 − and eNOS uncoupling in the underlying vessels. In ex vivo experiments with human saphenous veins and internal mammary arteries, adiponectin induced Akt-mediated eNOS phosphorylation and increased tetrahydrobiopterin bioavailability, improving eNOS coupling. In ex vivo experiments with human saphenous veins/internal mammary arteries and adipose tissue, we demonstrated that peroxidation products produced in the vascular wall (ie, 4-hydroxynonenal) upregulate adiponectin gene expression in perivascular adipose tissue via a peroxisome proliferator-activated receptor-γ–dependent mechanism. Conclusions— We demonstrate for the first time that adiponectin improves the redox state in human vessels by restoring eNOS coupling, and we identify a novel role of vascular oxidative stress in the regulation of adiponectin expression in human perivascular adipose tissue.

Background— Tetrahydrobiopterin (BH 4 ) is a key regulator of endothelial nitric oxide synthase (eNOS) activity and coupling. However, the extent to which vascular and/or systemic BH 4 levels are altered in human atherosclerosis and the importance of BH 4 bioavailability in determining endothelial function and oxidative stress remain unclear. We sought to define the relationships between plasma and vascular biopterin levels in patients with coronary artery disease and to determine how BH 4 levels affect endothelial function, eNOS coupling, and vascular superoxide production. Methods and Results— Samples of saphenous veins and internal mammary arteries were collected from 219 patients with coronary artery disease undergoing coronary artery bypass grafting. We determined plasma and vascular levels of biopterins, vasomotor responses to acetylcholine, and vascular superoxide production in the presence and absence of the eNOS inhibitor N G -nitro- l -arginine methyl ester. High vascular BH 4 was associated with greater vasorelaxations to acetylcholine ( P 4 was associated with lower vasorelaxations in response to acetylcholine ( P P 4 was associated with reduced total and N G -nitro- l -arginine methyl ester–inhibitable superoxide, suggesting improved eNOS coupling. Finally, plasma but not vascular biopterin levels were correlated with plasma C-reactive protein levels ( P Conclusions— An inverse association exists between plasma and vascular biopterins in patients with coronary artery disease. Vascular but not plasma BH 4 is an important determinant of eNOS coupling, endothelium-dependent vasodilation, and superoxide production in human vessels, whereas plasma biopterins are a marker of systemic inflammation.

Introduction: Myocardial redox state is a strong determinant of heart biology. Epicardial adipose tissue (EpAT) is in close contact with the human heart and it is likely that by secreting a wide range of adipokines it may affect the biology of the underlying myocardium. Hypothesis: We hypothesised that EpAT volume may predict myocardial redox state and consequently myocardial function in ischaemic heart disease (IHD). Methods: We recruited 38 patients undergoing coronary artery bypass grafting surgery. Patients underwent transthoracic echocardiography to assess cardiac function and cardiac computerised tomography to determine the volume of EpAT, pericardial (PerAT) and subcutaneous (ScAT) AT, by using a strictly pre-defined protocol. Samples of right atrium appendage were collected during surgery and myocardial NADPH oxidase activity was assessed by lucigenin-enhanced chemiluminescence (using its substrate -NAPDH 100uM +/- its specific inhibitor VAS2870 40uM). Results: Increased EpAT volume index (EpAT volume/body surface area), but not PerAT or ScAT, was strongly associated with increased myocardial NADPH oxidase activity (Figure). EpAT volume index was not related with left ventricle (LV) mass index or LV systolic/diastolic function (p=NS for all). EpAT volume index was also unrelated to risk factors or body mass index (p=NS for all). Conclusions: These findings introduce the concept of a local cross-talk between EpAT and the underlying myocardium in humans. EpAT volume can be used as a surrogate of myocardial redox state, and this may have direct implications in risk stratification of patients undergoing coronary bypass surgery.

Background: GTP cyclohydrolase (GTPCH) is a key enzyme in biopterins synthesis, while tetrahydrobiopterin (BH4) is a regulator of eNOS coupling in vascular endothelium. A novel haplotype in GCH1 gene, combining dbSNPs: rs8007267G/A, rs3783641A/T and rs10483639C/G, affects GTPCH activity and biopterins levels in inflammatory cells. We examined the effect of this haplotype on vascular biopterins, eNOS coupling and redox state in human vessels from patients with coronary atherosclerosis. Methods: Samples of saphenous veins (SV) were obtained from 347 patients undergoing CABG. Vasorelaxations of SV to acetylcholine (ACh) and vascular O2- (± eNOS inhibitor LNAME) were determined. Biopterins were measured by HPLC. The haplotypes were defined as X (rs8007267A+ rs3783641T+ rs10483639G) or O (all other haplotypes). Results: The haplotype distribution was OO:245(71%), OX:95(27%) and XX:7(2%). Carriers of the X haplotype had lower plasma (Fig. a ) and vascular (Fig. b ) BH4. The X haplotype was associated with higher vascular O2- (XX+XO: 2.97±0.44 vs OO:1.90±0.10 RLU/Sec/mg, p ) suggesting eNOS uncoupling) and lower NO bioavailability (Fig. d ) in human vessels. The X haplotype was also associated with higher plasma ox-LDL (51.0±2.2 in XX+XO vs 44.2±1.4 U/L in OO p Conclusions: This novel haplotype on GCH1 gene regulates biopterins biosynthesis in both plasma and vascular endothelium. This haplotype also regulates eNOS coupling, O2- production and NO bioavailability in human vessels, and may play a role in atherogenesis.

Introduction: Tetrahydrobiopterin (BH4) is a regulator of endothelial nitric oxide synthase (eNOS) coupling but its synthesis is also stimulated by inflammation in experimental models. We defined for the first time, the relationships between plasma and vascular biopterins in patients with coronary artery disease, and we determined the impact of BH4 on endothelial function, eNOS coupling, and O2- production in human vessels. Methods : Paired samples of saphenous veins (SV) and internal mammary arteries (IMA) were obtained from 219 patients undergoing coronary bypass surgery. Vasomotor responses to acetylcholine (Ach) were determined ex-vivo and vascular O2- (± the eNOS inhibitor LNAME) was measured by chemiluminescence. Biopterins were measured by HPLC. Results: High vascular BH4 was associated with better vasorelaxations of SV to Ach, whereas high plasma BH4 was associated with worse vasorelaxations (Fig. a-b ). There was an inverse association between plasma and vascular biopterins (Fig c ). High vascular (but not plasma) BH4 was associated with lower O2-and less L-NAME inhibitable O2- (suggesting better eNOS coupling) in both SV and IMA (Fig c ). Finally, serum C-reactive protein was correlated with plasma biopterins (r=0.268, p=0.001) but not with vascular biopterins in SV (r=0.02, p=0.0857) or IMA (r=−0.044, p=0.717). Conclusions : There is an inverse association between plasma and vascular biopterins in patients with atherosclerosis. Vascular but not plasma BH4 is a modulator of NO bioavailability and eNOS coupling in human vessels, while plasma total biopterin is rather a marker of systemic inflammation, than a regulator of vascular function in vivo.