Investigating the binding interaction of quinoline yellow with bovine serum albumin and anti-amyloidogenic behavior of ferulic acid on QY-induced BSA fibrils.

Protein aggregation induces profound changes in the structure along with the conformation of the protein, and is responsible for the pathogenesis of a number of neurodegenerative conditions such as Huntington's, Creutzfeldt-Jacob, Type II diabetes mellitus, Alzheimer's, etc. Numerous multi-spectroscopic approaches and in-silico experiments were utilized to investigate BSA's biomolecular interaction and aggregation in the presence of quinoline yellow. The present research investigation evaluated the interaction of BSA with the food colorant (QY) at two different pH (7.4 and 2.0). The development of the BSA-QY complex was established with UV visible and fluorescence spectroscopy. The quenching of fluorescence upon the interaction of BSA with QY revealed the static nature of quenching mechanism. The Kb value obtained from our result is 4. 54 × 10-4 M-1. The results from the competitive site marker study infer that quinoline yellow is binding with the sub-domain IB of bovine serum albumin, specifically on site III. Three-dimensional fluorescence and synchronous fluorescence spectroscopy were applied for monitoring the alterations in the microenvironment of BSA upon the addition of quinoline yellow. The results from turbidity and RLS studies showed that higher concentrations of QY (80-400 µM) triggered bovine serum albumin (BSA) aggregation at pH 2.0. At pH 7.4, QY couldn't manage to trigger bovine serum albumin aggregation, perhaps because of the repulsion between negatively charged dye (QY) and anionic bovine serum albumin. The results from far-UV CD, Congo Red, and scanning electron microscopy implicate that the QY-induced aggregates exhibit amyloid fibril-like structures. Molecular docking results revealed that hydrophobic interactions, hydrogen bonding, and Pi-Sulfur interactions contribute to QY-induced aggregation of BSA. Further, the amyloid inhibitory potential of ferulic acid (FA), a phenolic acid on QY-induced aggregation of BSA, has also been assessed. The QY-induced amyloid fibrils are FA-soluble, as confirmed by turbidity, RLS, and far-UV CD studies. Far-UV CD results showed that FA retains α helix and inhibits cross ß sheet formation when the BSA samples were pre-incubated with increasing concentrations of FA (0-500 µM). Our findings conclude that QY dye successfully stimulates BSA aggregation, but ferulic acid inhibits QY-induced aggregation of BSA. Thus, FA can serve as a therapeutic agent and can help in the treatment of various amyloid-related conditions.

Biophysical insight into anti-amyloidogenic nature of novel ionic Co(II)(phen)(H2O)4]+[glycinate]- chemotherapeutic drug candidate against human lysozyme aggregation.

In the recent past, there has been an ever-increasing interest in the search for metal-based therapeutic drug candidates for protein misfolding disorders (PMDs) particularly neurodegenerative disorders such as Alzheimer's, Parkinson's, Prion's diseases, and amyotrophic lateral sclerosis. Also, different amyloidogenic variants of human lysozyme (HL) are involved in hereditary systemic amyloidosis. Metallo-therapeutic agents are extensively studied as antitumor agents, however, they are relatively unexplored for the treatment of non-neuropathic amyloidoses. In this work, inhibition potential of a novel ionic cobalt(II) therapeutic agent (CoTA) of the formulation [Co(phen)(H2O)4]+[glycinate]- is evaluated against HL fibrillation. Various biophysical techniques viz., dye-binding assays, dynamic light scattering (DLS), differential scanning calorimetry (DSC), electron microscopy, and molecular docking experiments validate the proposed mechanism of inhibition of HL fibrillation by CoTA. The experimental corroborative results of these studies reveal that CoTA can suppress and slow down HL fibrillation at physiological temperature and pH. DLS and 1-anilino-8-naphthalenesulfonate (ANS) assay show that reduced fibrillation in the presence of CoTA is marked by a significant decrease in the size and hydrophobicity of the aggregates. Fluorescence quenching and molecular docking results demonstrate that CoTA binds moderately to the aggregation-prone region of HL (Kb = 6.6 × 104 M-1), thereby, inhibiting HL fibrillation. In addition, far-UV CD and DSC show that binding of CoTA to HL does not cause any change in the stability of HL. More importantly, CoTA attenuates membrane damaging effects of HL aggregates against RBCs. This study identifies inorganic metal complexes as a therapeutic intervention for systemic amyloidosis.

Natural compound plumbagin based inhibition of hIAPP revealed by Markov state models based on MD data along with experimental validations.

Human islet amyloid polypeptide (amylin or hIAPP) is a 37 residue hormone co-secreted with insulin from ß cells of the pancreas. In patients suffering from type-2 diabetes, amylin self-assembles into amyloid fibrils, ultimately leading to the death of the pancreatic cells. However, a research gap exists in preventing and treating such amyloidosis. Plumbagin, a natural compound, has previously been demonstrated to have inhibitory potential against insulin amyloidosis. Our investigation unveils collapsible regions within hIAPP that, upon collapse, facilitates hydrophobic and pi-pi interactions, ultimately leading to aggregation. Intriguingly plumbagin exhibits the ability to bind these specific collapsible regions, thereby impeding the aforementioned interactions that would otherwise drive hIAPP aggregation. We have used atomistic molecular dynamics approach to determine secondary structural changes. MSM shows metastable states forming native like hIAPP structure in presence of PGN. Our in silico results concur with in vitro results. The ThT assay revealed a striking 50% decrease in fluorescence intensity at a 1:1 ratio of hIAPP to Plumbagin. This finding suggests a significant inhibition of amyloid fibril formation by plumbagin, as ThT fluorescence directly correlates with the presence of these fibrils. Further TEM images revealed disappearance of hIAPP fibrils in plumbagin pre-treated hIAPP samples. Also, we have shown that plumbagin disrupts the intermolecular hydrogen bonding in hIAPP fibrils leading to an increase in the average beta strand spacing, thereby causing disaggregation of pre-formed fibrils demonstrating overall disruption of the aggregation machinery of hIAPP. Our work is the first to report a detailed atomistic simulation of 22 µs for hIAPP. Overall, our studies put plumbagin as a potential candidate for both preventive and therapeutic candidate for hIAPP amyloidosis.

Rationale and design of the CONFIRM2 (Quantitative COroNary CT Angiography Evaluation For Evaluation of Clinical Outcomes: An InteRnational, Multicenter Registry) study.

BACKGROUND: In the last 15 years, large registries and several randomized clinical trials have demonstrated the diagnostic and prognostic value of coronary computed tomography angiography (CCTA). Advances in CT scanner technology and developments of analytic tools now enable accurate quantification of coronary artery disease (CAD), including total coronary plaque volume and low attenuation plaque volume. The primary aim of CONFIRM2, (Quantitative COroNary CT Angiography Evaluation For Evaluation of Clinical Outcomes: An InteRnational, Multicenter Registry) is to perform comprehensive quantification of CCTA findings, including coronary, non-coronary cardiac, non-cardiac vascular, non-cardiac findings, and relate them to clinical variables and cardiovascular clinical outcomes. DESIGN: CONFIRM2 is a multicenter, international observational cohort study designed to evaluate multidimensional associations between quantitative phenotype of cardiovascular disease and future adverse clinical outcomes in subjects undergoing clinically indicated CCTA. The targeted population is heterogenous and includes patients undergoing CCTA for atherosclerotic evaluation, valvular heart disease, congenital heart disease or pre-procedural evaluation. Automated software will be utilized for quantification of coronary plaque, stenosis, vascular morphology and cardiac structures for rapid and reproducible tissue characterization. Up to 30,000 patients will be included from up to 50 international multi-continental clinical CCTA sites and followed for 3-4 years. SUMMARY: CONFIRM2 is one of the largest CCTA studies to establish the clinical value of a multiparametric approach to quantify the phenotype of cardiovascular disease by CCTA using automated imaging solutions.

Characterization of pH-induced conformational changes in recombinant DENV NS2B-NS3pro.

The increasing frequency of Dengue is a cause of severe epidemics and therefore demands strategies for effective prevention, diagnosis, and treatment. DENV-protease is being investigated as a potential therapeutic target. However, due to the flat and highly charged active site of the DENV-protease, designing orthosteric medicines is very difficult. In this study, we have done a thorough analysis of pH-dependent conformational changes in recombinantly expressed DENV protease using various spectroscopic techniques. Our spectroscopic study of DENV protease (NS2B-NS3pro) at different pH conditions gives important insights into the dynamicity of structural conformation. At physiological pH, the DENV-protease exists in a random-coiled state. Lowering the pH promotes the formation of alpha-helical and beta-sheet structures i.e. gain of secondary structure as shown by Far-UV CD. The light scattering and Thioflavin T (ThT)-binding assay proved the aggregation-prone tendency of DENV-protease at pH 4.0. Further, the confocal microscopy image intensity showed the amorphous aggregate formation of DENV protease at pH 4.0. Thus, the DENV protease acquires different conformations with changes in pH conditions. Together, these results have the potential to facilitate the design of a conformation destabilizer-based therapeutic strategy for dengue fever.

Left Atrial Thrombus in the Setting of Mitral Stenosis.

A 56-year-old man with no significant past medical history presented with exertional shortness of breath. Echocardiogram, cardiac magnetic resonance, and computed tomography showed mitral stenosis and a left atrial thrombus. Left atrial thrombus formation is a well-known complication of severe mitral stenosis that can lead to systemic thromboembolism. The patient underwent mitral valve replacement, left atrial thrombus resection, and left atrial appendage closure that resulted in significant improvement in breathing.

Relation of Gender to Atherosclerotic Plaque Characteristics by Differing Angiographic Stenosis Severity.

It is unknown whether gender influences the atherosclerotic plaque characteristics (APCs) of lesions of varying angiographic stenosis severity. This study evaluated the imaging data of 303 symptomatic patients from the derivation arm of the CREDENCE (Computed TomogRaphic Evaluation of Atherosclerotic Determinants of Myocardial IsChEmia) trial, all of whom underwent coronary computed tomographic angiography and clinically indicated nonemergent invasive coronary angiography upon study enrollment. Index tests were interpreted by 2 blinded core laboratories, one of which performed quantitative coronary computed tomographic angiography using an artificial intelligence application to characterize and quantify APCs, including percent atheroma volume (PAV), low-density noncalcified plaque (LD-NCP), noncalcified plaque (NCP), calcified plaque (CP), lesion length, positive arterial remodeling, and high-risk plaque (a combination of LD-NCP and positive remodeling ≥1.10); the other classified lesions as obstructive (≥50% diameter stenosis) or nonobstructive (<50% diameter stenosis) based on quantitative invasive coronary angiography. The relation between APCs and angiographic stenosis was further examined by gender. The mean age of the study cohort was 64.4 ± 10.2 years (29.0% female). In patients with obstructive disease, men had more LD-NCP PAV (0.5 ± 0.4 vs 0.3 ± 0.8, p = 0.03) and women had more CP PAV (11.7 ± 1.6 vs 8.0 ± 0.8, p = 0.04). Obstructive lesions had more NCP PAV compared with their nonobstructive lesions in both genders, however, obstructive lesions in women also demonstrated greater LD-NCP PAV (0.4 ± 0.5 vs 1.0 ± 1.8, p = 0.03), and CP PAV (17.4 ± 16.5 vs 25.9 ± 18.7, p = 0.03) than nonobstructive lesions. Comparing the composition of obstructive lesions by gender, women had more CP PAV (26.3 ± 3.4 vs 15.8 ± 1.5, p = 0.005) whereas men had more NCP PAV (33.0 ± 1.6 vs 26.7 ± 2.5, p = 0.04). Men had more LD-NCP PAV in nonobstructive lesions compared with women (1.2 ± 0.2 vs 0.6 ± 0.2, p = 0.02). In conclusion, there are gender-specific differences in plaque composition based on stenosis severity.

Prognostic value of global myocardial flow reserve in patients with history of coronary artery bypass grafting.

AIMS: It is not well understood whether positron emission tomography (PET)-derived myocardial flow reserve (MFR) is prognostic among patients with prior coronary artery bypass grafting (CABG). METHODS AND RESULTS: Consecutive patients with a clinical indication for PET were enrolled in the Houston Methodist DeBakey Heart and Vascular Center PET registry and followed prospectively for incident outcomes. The primary outcome was a composite of all-cause death, myocardial infarction (MI)/unplanned revascularization, and heart failure admissions. Cox proportional hazards models were used to study the association between MFR (<2 vs. ≥2) and incident events adjusting for clinical and myocardial perfusion imaging variables. The study population consisted of 836 patients with prior CABG; mean (SD) age 68 (10) years, 53% females, 79% Caucasian, 36% non-Hispanic, and 66% with MFR <2. Over a median (interquartile range [IQR]) follow-up time of 12 (4-24) months, there were 122 incident events (46 HF admissions, 28 all-cause deaths, 23 MI, 22 PCI/3 repeat CABG 90 days after imaging). In adjusted analyses, patients with impaired MFR had a higher risk of the primary outcome [hazard ratio (HR) 2.06; 95% CI 1.23-3.44]. Results were significant for admission for heart failure admissions (HR 2.92; 95% CI 1.11-7.67) but not for all-cause death (HR 2.01, 95% CI 0.85-4.79), or MI/UR (HR 1.93, 95% CI 0.92-4.05). CONCLUSION: Among patients with a history of CABG, PET-derived global MFR <2 may identify those with a high risk of subsequent cardiovascular events, especially heart failure, independent of cardiovascular risk factors and perfusion data.

Imaging for implementation of heart failure guidelines.

The classification of heart failure with implications for pharmacological therapeutic interventions rests on defining ejection fraction (EF) which is an imaging parameter. Imaging can provide diagnostic clues as to aetiology of heart failure; it can also guide and help assess response to treatment. Echocardiography, CMR, cardiac computed tomography, positron emission tomography, and Tc 99 m pyrophosphate scanning provide information about the aetiology of heart failure. Further, echocardiography plays the primary role in the evaluation of LV diastolic function and the estimation of left ventricular (LV) filling pressures both at rest and with exercise during diastolic stress testing. Heart failure guidelines recognize four stages (A, B, C, and D) for heart failure. Cardiac imaging along with risk factors and clinical status is needed for identifying these stages. There are joint societal echocardiographic guidelines by American Society of Echocardiography (ASE) of Echocardiography and European Association of Cardiovascular Imaging that are applicable to the imaging of heart failure patients. There are also separate guidelines for the evaluation of patients being considered for LV assist device implantation and for multimodality imaging of patients with heart failure and preserved EF. Cardiac catheterization is needed in patients whose haemodynamic status is uncertain after clinical and echocardiographic evaluation and to evaluate for coronary artery disease. Myocardial biopsy can identify the presence of myocarditis or specific infiltrative diseases when the findings by non-invasive imaging are not conclusive.

Mechanistic and biophysical insight into the inhibitory and disaggregase role of antibiotic moxifloxacin on human lysozyme amyloid formation.

Lysozyme amyloidosis is a systemic non-neuropathic disease caused by the accumulation of amyloids of mutant lysozyme. Presently, therapeutic interventions targeting lysozyme amyloidosis, remain elusive with only therapy available for lysozyme amyloidosis being supportive management. In this work, we examined the effects of moxifloxacin, a synthetic fluoroquinolone antibiotic on the amyloid formation of human lysozyme. The ability of moxifloxacin to interfere with lysozyme amyloid aggregation was examined using various biophysical methods like Rayleigh light scattering, Thioflavin T fluorescence assay, transmission electron microscopy and docking method. The reduction in scattering and ThT fluorescence along with extended lag phase in presence of moxifloxacin, suggest that the antibiotic inhibits and impedes the lysozyme fibrillation in concentration dependent manner. From ANS experiment, we deduce that moxifloxacin is able to decrease the hydrophobicity of the protein molecule thereby preventing aggregation. Our CD and DLS results show that moxifloxacin stabilizes the protein in its native monomeric structure, thus also showing retention of lytic activity upto 69% and inhibition of cytotoxicity at highest concentration of moxifloxacin. The molecular docking showed that moxifloxacin forms a stable complex of -7.6 kcal/mol binding energy and binds to the aggregation prone region of lysozyme thereby stabilising it and preventing aggregation. Moxifloxacin also showed disaggregase potential by disrupting fibrils and decreasing the ß-sheet content of the fibrils. Our current study, thus highlight the anti-amyloid and disaggregase property of an antibiotic moxifloxacin and hence sheds light on the future of antibiotics against protein aggregation, a hallmark event in many neurodegenerative diseases.

Coronary microvascular health in symptomatic patients with prior COVID-19 infection: an updated analysis.

AIMS: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with endothelial dysfunction. We aimed to determine the effects of prior coronavirus disease 2019 (COVID-19) on the coronary microvasculature accounting for time from COVID-19, disease severity, SARS-CoV-2 variants, and in subgroups of patients with diabetes and those with no known coronary artery disease. METHODS AND RESULTS: Cases consisted of patients with previous COVID-19 who had clinically indicated positron emission tomography (PET) imaging and were matched 1:3 on clinical and cardiovascular risk factors to controls having no prior infection. Myocardial flow reserve (MFR) was calculated as the ratio of stress to rest myocardial blood flow (MBF) in mL/min/g of the left ventricle. Comparisons between cases and controls were made for the odds and prevalence of impaired MFR (MFR < 2). We included 271 cases matched to 815 controls (mean ± SD age 65 ± 12 years, 52% men). The median (inter-quartile range) number of days between COVID-19 infection and PET imaging was 174 (58-338) days. Patients with prior COVID-19 had a statistically significant higher odds of MFR <2 (adjusted odds ratio 3.1, 95% confidence interval 2.8-4.25 P < 0.001). Results were similar in clinically meaningful subgroups. The proportion of cases with MFR <2 peaked 6-9 months from imaging with a statistically non-significant downtrend afterwards and was comparable across SARS-CoV-2 variants but increased with increasing severity of infection. CONCLUSION: The prevalence of impaired MFR is similar by duration of time from infection up to 1 year and SARS-CoV-2 variants, but significantly differs by severity of infection.

Partial Pericardial Agenesis.

Congenital absence of the pericardium is a rare anomaly, affecting the left pericardium (86%) more than the right, with male predilection distribution (3:1). In the majority of cases, the condition is asymptomatic. We describe a case of a 55-year-old female with a history of chronic hypercapnic respiratory failure secondary to restrictive lung disease who was referred to cardiovascular magnetic resonance (CMR) lab for shunt evaluation based on right ventricular pressure overload and paradoxical septal motion.

Tuning the aggregation behavior of human insulin in the presence of luteolin: An in vitro and in silico approach.

Protein misfolding and related formation of amyloid fibrils are associated with several conformational diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), prion diseases, and Diabetes mellitus, Type 2 (DM-II). Several molecules including antibiotics, polyphenols, flavonoids, anthraquinones, and other small molecules are implicated to modulate amyloid assembly. The stabilization of the native forms of the polypeptides and prevention of their misfolding and aggregation are of clinical and biotechnological importance. Among the natural flavonoids, luteolin is of great importance because of its therapeutic role against neuroinflammation. Herein, we have explored the inhibitory effect of luteolin (LUT) on aggregation of a model protein, human insulin (HI). To understand the molecular mechanism of the inhibition of aggregation of HI by LUT, we employed molecular simulation, UV-Vis, fluorescence, and circular dichroism (CD) spectroscopies along with the dynamic light scattering (DLS). The analysis of the tuning of the HI aggregation process by luteolin revealed that interaction of HI with LUT resulted in the decrease in binding of the various fluorescent dyes, such as thioflavin T (ThT) and 8-anilinonaphthalene-1-sulfonic acid (ANS) to this protein. Retention of the native-like CD spectra and resistance to the aggregation in the presence of LUT has confirmed the aggregation inhibitory potential of LUT. The maximum inhibitory effect was found at the protein-to-drug ratio of 1:12, and no significant change was observed beyond this concentration.

Biophysical insight into the anti-fibrillation potential of Glyburide for its possible implication in therapeutic intervention of amyloid associated diseases.

Protein aggregation is an underlying cause of many neurodegenerative diseases. Also, the overlapping pathological disturbances between neurodegenerative diseases and type-2 diabetes mellitus have urged the scientific community to explore potential of already available anti-diabetic medications in impeding amyloid formation too. Recent study brief out promising potential of an anti-diabetic drug Glyburide(GLY) as an inhibitor of amyloid fibrillation utilizing several biophysical techniques, computational methods and imaging tools. The mechanism of interaction was elucidated and the structural alterations in human serum albumin(HSA) as well as the microenvironment changes of its fluorophores(tryptophan, tyrosine) upon interacting with GLY were studied by spectroscopic techniques like Circular dichroism and synchronous fluorescence. Binding studies detailing about the GLY-HSA complex distance and the energy transfer efficiency was obtained by Fluorescence resonance energy transfer. For aggregation inhibition studies, the existence and size of aggregates formed in HSA and their inhibition by GLY was determined by Turbidity assay, Dynamic light scattering and Rayleigh light scattering along with dye binding assays. The ThT kinetics measurements analysis suggested that GLY deaccelerates fibrillation by decrement of apparent rate(Kapp) constant. The inhibitory effect of GLY might be attributed to native structure stabilization of HSA by obstruction into ß-sheet conversion as confirmed by CD spectroscopy results. Amyloid inhibition and suppression of amyloid-induced hemolysis by GLY was further delineated by TEM and SEM analysis respectively. All these findings for the first time report the new facet of the anti-amyloidogenic potential of GLY, making it a promising candidate to treat neurodegenerative diseases too in the near future.

Evaluating the inhibitory potential of natural compound luteolin on human lysozyme fibrillation.

Numerous pathophysiological conditions known as amyloidosis, have been connected to protein misfolding leading to aggregation of proteins. Inhibition of cytotoxic aggregates or disaggregation of the preformed fibrils is thus one of the important strategies in the prevention of such diseases. Growing interest and exploration of identification of small molecules mainly natural compounds can prevent or delay amyloid fibril formation. We examined the mechanism of interaction and inhibition of human lysozyme (HL) aggregates with luteolin (LT). Biophysical and computational approaches have been employed to study the effect of LT on HL amyloid aggregation. Transmission Electronic Microscopy, Thioflavin T fluorescence, UV-vis spectroscopy, and RLS demonstrates that LT inhibit HL fibril formation. ANS fluorescence and hemolytic assay was also employed to examine the effect of the LT on toxicity of HL aggregation. Docking and molecular dynamics results showed that LT interacted with HL via hydrophobic and hydrogen interactions, thus reducing fibrillation levels. These findings highlight the benefit of polyphenols as safe therapy for preventing amyloid related diseases.

Splenic switch-off in regadenoson 82Rb-PET myocardial perfusion imaging: assessment of clinical utility.

BACKGROUND: Splenic switch-off (SSO) is a phenomenon describing a decrease in splenic radiotracer uptake after vasodilatory stress. We aimed to assess the diagnostic utility of regadenoson-induced SSO. METHODS: We included consecutive patients who had clinically indicated Regadenoson Rb-82 PET-MPI for suspected CAD. This derivation cohort (no perfusion defects and myocardial flow reserves (MFR) ≥ 2) was used to calculate the splenic response ratio (SRR). The validation cohort was defined as patients who underwent both PET-MPI studies and invasive coronary angiography (ICA). RESULTS: The derivation cohort (n = 100, 57.4 ± 11.6 years, 77% female) showed a decrease in splenic uptake from rest to stress (79.9 ± 16.8 kBq⋅mL vs 69.1 ± 16.2 kBq⋅mL, P < .001). From the validation cohort (n = 315, 66.3 ± 10.4 years, 67% male), 28% (via SRR = 0.88) and 15% (visually) were classified as splenic non-responders. MFR was lower in non-responders (SRR; 1.55 ± 0.65 vs 1.76 ± 0.78, P = .02 and visually; 1.18 ± 0.33 vs 1.79 ± 0.77, P < .001). Based on ICA, non-responders were more likely to note obstructive epicardial disease with normal PET scans especially in patients with MFR < 1.5 (SRR; 61% vs 34% P = .05 and visually; 68% vs 33%, P = .01). CONCLUSION: Lack of splenic response based on visual or quantitative assessment of SSO may be used to identify an inadequate vasodilatory response.

Incremental prognostic value of digital positron emission tomography derived myocardial flow reserve: A prospective cohort study.

BACKGROUND: Positron Emission Tomography (PET) Myocardial Perfusion Imaging (MPI) is a robust diagnostic and prognostic test in patients with suspected or known coronary artery disease (CAD). We aimed to assess the incremental prognostic value of myocardial flow reserve (MFR) using the latest generation of digital PET scanners. METHODS: Consecutive patients with clinically indicated PET MPI for suspected or known CAD were included. Myocardial blood flow (MBF) in ml/min/g was obtained from dynamic images at rest and peak hyperemia, and the myocardial flow reserve (MFR) was calculated as the ratio of stress to rest MBF. Patients were followed from the date of PET imaging for the occurrence of the primary outcome (composite of all-cause death, myocardial infarction, and Percutaneous Coronary Intervention or Coronary Artery Bypass Graft occurring >90 days after imaging). Nested multivariable Cox regression models were used to assess the incremental prognostic role of MFR over traditional risk factors and PET relative perfusion parameters. RESULTS: The final cohort consisted of 3534 patients (mean age 67 ± 12 years, 48% female, 67% Caucasian, 53% obese, 55% hypertension, 32% diabetes, 42% dyslipidemia). During a median follow-up of 8.5 (3.0-15.4) months, 229 patients (6.5%, 6.4 per 1000 person-years) experienced the primary outcome. In nested multivariable Cox models, impaired MFR (MFR < 2) was significantly associated with the primary outcome (HR 2.9, 95% CI 2.0-4.1, p < 0.001) and significantly improved discrimination (Harrell's C 0.77, p = 0.002). CONCLUSION: MFR derived from digital PET scanners has an independent and incremental prognostic role in patients with suspected or known CAD.

AI Evaluation of Stenosis on Coronary CTA, Comparison With Quantitative Coronary Angiography and Fractional Flow Reserve: A CREDENCE Trial Substudy.

BACKGROUND: Clinical reads of coronary computed tomography angiography (CTA), especially by less experienced readers, may result in overestimation of coronary artery disease stenosis severity compared with expert interpretation. Artificial intelligence (AI)-based solutions applied to coronary CTA may overcome these limitations. OBJECTIVES: This study compared the performance for detection and grading of coronary stenoses using artificial intelligence-enabled quantitative coronary computed tomography (AI-QCT) angiography analyses to core lab-interpreted coronary CTA, core lab quantitative coronary angiography (QCA), and invasive fractional flow reserve (FFR). METHODS: Coronary CTA, FFR, and QCA data from 303 stable patients (64 ± 10 years of age, 71% male) from the CREDENCE (Computed TomogRaphic Evaluation of Atherosclerotic DEtermiNants of Myocardial IsChEmia) trial were retrospectively analyzed using an Food and Drug Administration-cleared cloud-based software that performs AI-enabled coronary segmentation, lumen and vessel wall determination, plaque quantification and characterization, and stenosis determination. RESULTS: Disease prevalence was high, with 32.0%, 35.0%, 21.0%, and 13.0% demonstrating ≥50% stenosis in 0, 1, 2, and 3 coronary vessel territories, respectively. Average AI-QCT analysis time was 10.3 ± 2.7 minutes. AI-QCT evaluation demonstrated per-patient sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 94%, 68%, 81%, 90%, and 84%, respectively, for ≥50% stenosis, and of 94%, 82%, 69%, 97%, and 86%, respectively, for detection of ≥70% stenosis. There was high correlation between stenosis detected on AI-QCT evaluation vs QCA on a per-vessel and per-patient basis (intraclass correlation coefficient = 0.73 and 0.73, respectively; P < 0.001 for both). False positive AI-QCT findings were noted in in 62 of 848 (7.3%) vessels (stenosis of ≥70% by AI-QCT and QCA of <70%); however, 41 (66.1%) of these had an FFR of <0.8. CONCLUSIONS: A novel AI-based evaluation of coronary CTA enables rapid and accurate identification and exclusion of high-grade stenosis and with close agreement to blinded, core lab-interpreted quantitative coronary angiography. (Computed TomogRaphic Evaluation of Atherosclerotic DEtermiNants of Myocardial IsChEmia [CREDENCE]; NCT02173275).