A novel mouse model of atherosclerotic plaque instability for drug testing and mechanistic/therapeutic discoveries using gene and microRNA expression profiling.

RATIONALE: The high morbidity/mortality of atherosclerosis is typically precipitated by plaque rupture and consequent thrombosis. However, research on underlying mechanisms and therapeutic approaches is limited by the lack of animal models that reproduce plaque instability observed in humans. OBJECTIVE: Development and use of a mouse model of plaque rupture that reflects the end stage of human atherosclerosis. METHODS AND RESULTS: On the basis of flow measurements and computational fluid dynamics, we applied a tandem stenosis to the carotid artery of apolipoprotein E-deficient mice on high-fat diet. At 7 weeks postoperatively, we observed intraplaque hemorrhage in ≈50% of mice, as well as disruption of fibrous caps, intraluminal thrombosis, neovascularization, and further characteristics typically seen in human unstable plaques. Administration of atorvastatin was associated with plaque stabilization and downregulation of monocyte chemoattractant protein-1 and ubiquitin. Microarray profiling of mRNA and microRNA (miR) and, in particular, its combined analysis demonstrated major differences in the hierarchical clustering of genes and miRs among nonatherosclerotic arteries, stable, and unstable plaques and allows the identification of distinct genes/miRs, potentially representing novel therapeutic targets for plaque stabilization. The feasibility of the described animal model as a discovery tool was established in a pilot approach, identifying a disintegrin and metalloprotease with thrombospondin motifs 4 (ADAMTS4) and miR-322 as potential pathogenic factors of plaque instability in mice and validated in human plaques. CONCLUSIONS: The newly described mouse model reflects human atherosclerotic plaque instability and represents a discovery tool toward the development and testing of therapeutic strategies aimed at preventing plaque rupture. Distinctly expressed genes and miRs can be linked to plaque instability.

Routine Protamine Administration for Bleeding in Transcatheter Aortic Valve Implantation: The ACE-PROTAVI Randomized Clinical Trial.

Importance: Vascular complications after transfemoral transcatheter aortic valve implantation (TAVI) remain an important cause of procedure-related morbidity. Routine reversal of anticoagulation with protamine at the conclusion of transfemoral TAVI could reduce complications, but data remain scarce. Objective: To evaluate the efficacy and safety of routine protamine administration after transfemoral TAVI. Design, Setting, and Participants: The ACE-PROTAVI trial was an investigator-initiated, double-blind, placebo-controlled randomized clinical trial performed at 3 Australian hospitals between December 2021 and June 2023 with a 1-year follow-up period. All patients accepted for transfemoral TAVI by a multidisciplinary heart team were eligible for enrollment. Interventions: Eligible patients were randomized 1:1 between routine protamine administration and placebo. Main Outcomes and Measures: The coprimary outcomes were the rate of hemostasis success and time to hemostasis (TTH), presented as categorical variables and compared with a χ2 test or as continuous variables as mean (SD) or median (IQR), depending on distribution. The major secondary outcome was a composite of all-cause death, major and minor bleeding complications, and major and minor vascular complications after 30 days, reported in odds ratios (ORs) with 95% CIs and P values. Results: The study population consisted of 410 patients: 199 patients in the protamine group and 211 in the placebo group. The median (IQR) patient age in the protamine group was 82 (77-85) years, and 68 of 199 patients receiving protamine (34.2%) were female. The median (IQR) patient age in the placebo group was 80 (75-85) years, and 89 of 211 patients receiving the placebo (42.2%) were female. Patients receiving up-front protamine administration had a higher rate of hemostasis success (188 of 192 patients [97.9%]) than patients in the placebo group (186 of 203 patients [91.6%]; absolute risk difference, 6.3%; 95% CI, 2.0%-10.6%; P = .006); in addition, patients receiving up-front protamine had a shorter median (IQR) TTH (181 [120-420] seconds vs 279 [122-600] seconds; P = .002). Routine protamine administration resulted in a reduced risk of the composite outcome in the protamine group (10 of 192 [5.2%]) vs the placebo group (26 of 203 [12.8%]; OR, 0.37; 95% CI, 0.1-0.8; P = .01). This difference was predominantly driven by the difference in the prevalence of minor vascular complications. There were no adverse events associated with protamine use. Conclusions and Relevance: In the ACE-PROTAVI randomized clinical trial, routine administration of protamine increased the rate of hemostasis success and decreased TTH. The beneficial effect of protamine was reflected in a reduction in minor vascular complications, procedural time, and postprocedural hospital stay duration in patients receiving routine protamine compared with patients receiving placebo. Trial Registration: anzctr.org.au Identifier: ACTRN12621001261808.

Transcatheter Aortic Valve Therapy for Bicuspid Aortic Valve Stenosis.

Transcatheter aortic valve implantation (TAVI) has become first-line treatment for older adults with severe aortic stenosis (AS), however, patients with bicuspid aortic valve (BAV) have been traditionally excluded from randomised trials and guidelines. As familiarity and proficiency of TAVI operators have improved, case-series and observational data have demonstrated the feasibility of successful TAVI in bicuspid aortic valve aortic stenosis (BAV-AS), however, patients with BAV-AS have several distinct characteristics that influence the likelihood of TAVI success. This review aims to summarise the pathophysiology and classification of BAV, published safety data, anatomical challenges and procedural considerations essential for pre-procedural planning, patient selection and procedural success of TAVI in BAV.

Coronary Artery Disease Risk Prediction in Patients With Severe Aortic Stenosis: Development and Validation of the Aortic Stenosis-Coronary Artery Disease (AS-CAD) Score.

Patients at a low risk of coronary artery disease (CAD) could be triaged to noninvasive coronary computed tomography angiogram instead of invasive coronary angiography, reducing health care costs and patient morbidity. Therefore, we aimed to develop a CAD risk prediction score to identify those who underwent transcatheter aortic valve implantation (TAVI) at a low risk of CAD. We enrolled 1,782 patients who underwent TAVI and randomized the patients to the derivation or validation cohort 2:1. The aortic stenosis-CAD (AS-CAD) score was developed using logistic regression, followed by separation into low- (score 0 to 5), intermediate- (6 to 10), or high-risk (>11) categories. The AS-CAD was validated initially through the k-fold cross-validation, followed by a separately held validation cohort. The average age of the cohort was 82 ± 7 years, and 41% (730 of 1,782) were female; 35% (630) had CAD. The male sex, previous percutaneous coronary intervention, stroke, peripheral arterial disease, diabetes, smoking status, left ventricular ejection fraction <50%, and right ventricular systolic pressure >35 mm Hg were all associated with an increased risk of CAD and were included in the final AS-CAD model (all p <0.03). Within the validation cohort, the AS-CAD score stratified those into low, intermediate, and high risk of CAD (p <0.001). Discrimination was good within the internal validation cohort, with a c-statistic of 0.79 (95% confidence interval 0.74 to 0.84), with similar power obtained using k-fold cross-validation (c-statistic 0.74 [95% confidence interval 0.70 to 0.77]). In conclusion, The AS-CAD score robustly identified those at a low risk of CAD in patients with severe AS. The use of AS-CAD in practice could avoid potential complications of invasive coronary angiogram by triaging low-risk patients to noninvasive coronary assessment using existing computed tomography data.

Resource implications following expansion of computed tomography coronary angiography: An Australian experience.

INTRODUCTION: To determine the downstream utilisation of Computed Tomography Coronary Angiography (CTCA) in a single Australian tertiary centre. METHODS: A single-centre retrospective study analysed 1460 patients undergoing CTCA between 1st January 2015 to 31st December 2018 at a tertiary hospital in Victoria, Australia, with a catchment area of 500,000 people. The coronary stenosis grading, plaque characteristics and coronary calcium score were identified. The downstream impact was assessed by measuring the number of stress echocardiograms, myocardial perfusion scans (MPS), invasive coronary angiograms and subsequent revascularisations. RESULTS: The number of CTCA's performed steadily increased from 59 in 2015 to 395, 461 and 545 in 2016, 2017 and 2018 respectively. Seven hundred and fifty-seven (52%) were females, and 703 (48%) males with 724 (50%) normal CTCA studies. The number of downstream stress echocardiogram performed each year was 2, 60, 46 and 16, respectively, accompanied by MPS numbers of 0, 21, 29, and 18. There were 9, 37, 57 and 64 invasive coronary angiograms with 1, 13, 19 and 22 corresponding revascularisations. Despite small increases in absolute numbers of patients presenting with chest pain (from 2678 in 2015 to 3660 in 2018), there was a significant increase in downstream further testing from 11 in 2015 to 98 in 2018. CONCLUSION: The use of CTCA expansion has resulted in an increase in downstream testing. Therefore, resource planning with regards to CTCA expansion will have to account for increased rates of functional testing, invasive angiography and revascularisation.

Near-infrared autofluorescence induced by intraplaque hemorrhage and heme degradation as marker for high-risk atherosclerotic plaques.

Atherosclerosis is a major cause of mortality and morbidity, which is mainly driven by complications such as myocardial infarction and stroke. These complications are caused by thrombotic arterial occlusion localized at the site of high-risk atherosclerotic plaques, of which early detection and therapeutic stabilization are urgently needed. Here we show that near-infrared autofluorescence is associated with the presence of intraplaque hemorrhage and heme degradation products, particularly bilirubin by using our recently created mouse model, which uniquely reflects plaque instability as seen in humans, and human carotid endarterectomy samples. Fluorescence emission computed tomography detecting near-infrared autofluorescence allows in vivo monitoring of intraplaque hemorrhage, establishing a preclinical technology to assess and monitor plaque instability and thereby test potential plaque-stabilizing drugs. We suggest that near-infrared autofluorescence imaging is a novel technology that allows identification of atherosclerotic plaques with intraplaque hemorrhage and ultimately holds promise for detection of high-risk plaques in patients.Atherosclerosis diagnosis relies primarily on imaging and early detection of high-risk atherosclerotic plaques is important for risk stratification of patients and stabilization therapies. Here Htun et al. demonstrate that vulnerable atherosclerotic plaques generate near-infrared autofluorescence that can be detected via emission computed tomography.

Transcatheter Tricuspid Valve Repair With a New Transcatheter Coaptation System for the Treatment of Severe Tricuspid Regurgitation: 1-Year Clinical and Echocardiographic Results.

OBJECTIVES: This study sought to describe the 1-year experience with the transcatheter FORMA system for severe tricuspid regurgitation (TR). BACKGROUND: Severe TR is associated with significant morbidity and mortality. Novel transcatheter therapies have been recently developed. METHODS: Eighteen patients underwent device implantation at 3 centers in Canada and Switzerland. Baseline characteristics, procedural, 30-day, and 1-year outcomes were prospectively evaluated using multimodality imaging and hemodynamic and clinical assessments. RESULTS: Procedural success was achieved in 16 (89%) patients. Unsuccessful procedures were because of right ventricular perforation requiring open surgery and device dislocation. At 1 year there were no deaths, significant arrhythmias, device infections, or dislocations. Thrombus was observed on 1 device at 4 months and there was 1 rehospitalization for heart failure. Among the 14 patients with successful device implantation and 1-year follow-up, 79% were in New York Heart Association functional class I/II (p < 0.001), the average 6-min walk test increased by 84 m (p = 0.03), and the Kansas City Cardiomyopathy Questionnaire heart failure score improved by 18 points (p = 0.02) compared with baseline. Echocardiography showed a reduction of TR from severe in 17 of 18 (94%) patients at baseline to moderate-severe or less in 11 of 16 patients (69%) by 30 days (p = 0.001) and 6 of 13 patients (46%) by 1 year (p = 0.01). The diameters of the tricuspid annulus and the right ventricle were reduced at 1 year (45.7 ± 4.8 mm to 42.1 ± 4.4 mm, p = 0.004; 54 ± 5.3 mm to 49.9 ± 4.3 mm, p = 0.02, respectively). CONCLUSIONS: Implantation of the FORMA system in high-risk patients with severe TR shows feasibility with a good mid-term safety profile. At 1 year, despite variable success in reducing echocardiographic TR grade, there were significant clinical improvements and reductions in right ventricular dimensions.

Biomarkers for AAA: Encouraging steps but clinical relevance still to be delivered.

Potential biomarkers have been investigated using proteomic studies in a variety of diseases. Some biomarkers have central roles in both diagnosis and monitoring of various disorders in clinical medicine, such as troponins, brain natriuretic peptide, and C-reactive protein. Although several biomarkers have been suggested in human abdominal aortic aneurysm (AAA), reliable markers have been lacking. In this issue, Moxon et al. [Proteomics Clin Appl. 2014, 8, 762-772] undertook a broad and systematic proteomic approach toward identification of biomarkers in a commonly used AAA mouse model (AAA created by angiotensin-II infusion). In this mouse model, apolipoprotein C1 and matrix metalloproteinase-9 were identified as novel biomarkers of stable AAA. This finding represents an important step forward, toward a clinically relevant role of biomarkers in AAA. This also encourages for further studies toward the identification of biomarkers (or their combinations) that can predict AAA progression and rupture, which would represent a major progress in AAA management and would establish an AAA biomarker as a much anticipated clinical tool.

Amyloid plaques dissociate pentameric to monomeric C-reactive protein: a novel pathomechanism driving cortical inflammation in Alzheimer's disease?

Beta-amyloid (Aß) plaques and local inflammation are central to the pathogenesis of Alzheimer's disease. Although an association between circulating pentameric C-reactive protein (pCRP) and Alzheimer's disease has been reported no pathomechanistic link has been established. We hypothesized that Aß plaques induce the dissociation of pCRP to individual monomers (mCRP), which possess strong pro-inflammatory properties not shared with pCRP and localizing inflammation to Alzheimer's plaques. pCRP was incubated with Aß plaques generated in vitro and with non-aggregated Aß(42) peptide. pCRP dissociation to mCRP was found only when co-incubated with Aß plaques. Furthermore, sections of frontal cortex from brains of patients with and without Alzheimer's disease were stained with antibodies specific for mCRP and pCRP. There was significantly more mCRP in the cortex of Alzheimer's disease patients (P ≤ 0.01). In contrast, there was no significant difference in pCRP staining. These findings establish that Aß plaques possess a previously unrecognized potential to dissociate pentameric CRP to monomeric CRP. The existence of mCRP but not pCRP in the brains of Alzheimer's disease patients strongly indicates that this newly described biological effect of Aß plaques is relevant in Alzheimer pathobiology; potentially localizing and amplifying inflammation via the strong pro-inflammatory effects of locally generated mCRP.