30-Day Outcomes With the Portico Transcatheter Heart Valve: Insights From a Multi-Centre Australian Observational Study.

BACKGROUND: Transcatheter aortic valve implantation (TAVI) is an established therapy for the treatment of aortic valve disease in appropriately selected patients. Previous studies using the self-expanding Portico transcatheter heart valve (THV), (Abbott Structural Heart, St Paul, MN, USA) have demonstrated the technical feasibility of this system albeit in the hands of relatively inexperienced Portico users. The objective of this study was to assess the real-world safety and efficacy of the Portico THV (with and without the FlexNav delivery system, Abbott Structural Heart) at the 30-day timepoint in an Australian cohort. METHODS AND RESULTS: This study was a retrospective real-world cohort analysis of 269 consecutive patients with severe aortic valve disease who underwent TAVI at multiple centres within Australia between February 2015 and April 2021. Of the 269 patients, 51.7% were female, mean Society of Thoracic Surgeons (STS) score was 5.2 (±6.8) and 98.5% had successful implantations. Thirty (30)-day post-implantation all-cause mortality was observed in one (0.4%) patient, major vascular complications in two (0.7%) patients, more-than-mild paravalvular leak in six (2.2%) patients and requirement for new permanent pacemaker implantation in 27 (10.2%) patients. Haemodynamic parameters at 30 days included mean effective orifice area (EOA) of 2.3 (±0.9) cm2 and mean aortic valve gradient (AVG) of 9.6 (±6.2) mmHg. CONCLUSION: This analysis of the Portico THV in a real-world setting suggested that the system is associated with satisfactory safety and efficacy parameters. Previously published datasets may not have found similar findings owing to lower operator experience with the Portico THV system.

Changes in R-wave amplitude at implantation are associated with gender and orientation of insertable cardiac monitor: observations from the confirm Rx™ body posture and physical activity study.

BACKGROUND: Insertable cardiac monitors (ICMs) are small subcutaneously implanted devices that detect changes in R-wave amplitudes (RWAs), effective in arrhythmia-monitoring. Although ICMs have proven to be immensely successful, electrical artefacts are frequent and can lead to misdiagnosis. Thus, there is a growing need to sustain and increase efficacy in detection rates by gaining insight into various patient-specific factors such as body postures and activities. METHODS: RWAs were measured in 15 separate postures, including supine, lying on the right-side (RS) or left-side (LS) and sitting, and two separate ICM orientations, immediately after implantation of Confirm Rx™ ICM in 99 patients. RESULTS: The patients (53 females and 46 males, mean ages 66.62 ± 14.7 and 66.40 ± 12.25 years, respectively) had attenuated RWAs in RS, LS and sitting by ~ 26.4%, ~ 27.8% and ~ 21.2% respectively, compared to supine. Gender-based analysis indicated RWAs in RS (0.32 mV (0.09-1.03 mV), p < 0.0001) and LS (0.37 mV (0.11-1.03 mV), p = 0.004) to be significantly attenuated compared to supine (0.52 mV (0.20-1.03 mV) for female participants. Similar attenuation was not evident for male participants. Further, parasternally oriented ICMs (n = 44), attenuated RWAs in RS (0.37 mV(0.09-1.03 mV), p = 0.05) and LS (0.34 mV (0.11-1.03 mV), p = 0.02) compared to supine (0.48 mV (0.09-1.03 mV). Similar differences were not observed in participants with ICMs in the 45°-relative-to-sternum (n = 46) orientation. When assessing the combined effect of gender and ICM orientation, female participants demonstrated plausible attenuation in RWAs for RS and LS postures compared to supine, an effect not observed in male participants. CONCLUSION: This is the first known study depicting the effects on RWA due to body postures and activities immediately post-implantation with an overt impact by gender and orientation of ICM. Future work assessing the cause of gender-based differences in RWAs may be critical. TRIAL REGISTRATION: Clinical Trials, NCT03803969. Registered 15 January 2019 - Retrospectively registered, https://clinicaltrials.gov/NCT03803969.

High-density lipoproteins attenuate high glucose-impaired endothelial cell signaling and functions: potential implications for improved vascular repair in diabetes.

BACKGROUND: Abnormalities of endothelial cell function are proposed to be a critical factor underlying adverse cardiovascular outcomes in the setting of hyperglycaemia. While high-density lipoproteins (HDL) have been demonstrated to be cardioprotective, the impact on the endothelium in hyperglycaemia has not been fully elucidated. METHODS: Human umbilical vein endothelial cells (HUVECs) were exposed to high-glucose conditions using dextrose, the main isoform of glucose, and native HDL. HUVEC proliferation and migration were determined. The key signalling pathways that regulate endothelial cell function were also characterized. RESULTS: Increasing concentrations of dextrose resulted in significant reductions in HUVEC proliferation, this was attenuated by coincubation with HDL. In support of this, HDL was also found to rescue dextrose impaired expression of PCNA and the activation (phosphorylation) of the key transcription factor for proliferation ERK. Dextrose also dose-dependently inhibited HUVEC migration, which was mitigated by co-incubation with HDL. Consistent with this, HDL prevented dextrose-induced inhibition of p38 phosphorylation, responsible for cell migration. Finally, phosphorylation of the pro-survival transcription factor Akt was dose-dependently inhibited by dextrose, however, this was completely rescued by co-administration with HDL. CONCLUSION: Dextrose-induced hyperglycaemia causes the impairment of endothelial cell proliferation and migration and inhibits the activation of ERK, p38 and Akt pathways. The protective effects of HDL in this milieu highlights the potential for HDL to improve vascular repair in patients with impaired glucose homeostasis.

Clinical trials with cholesteryl ester transfer protein inhibitors.

PURPOSE OF REVIEW: Inhibition of cholesteryl ester transfer protein (CETP) has received considerable interest by virtue of its favorable effects on atherogenic and protective lipid parameters. The impact of CETP inhibitors in large clinical outcome trials will be reviewed. RECENT FINDINGS: Population and genetic studies demonstrate that low CETP activity associates with lower rates of cardiovascular events. Inhibiting CETP activity in animal models has a favorable impact on experimental atherosclerosis. Although the first CETP inhibitor to advance to an outcome trial proved to have adverse clinical effects and the next agent, a more modest inhibitor, was clinically futile, there continues to be immense interest in the potential to develop nontoxic, potent CETP inhibitors to reduce cardiovascular risk. SUMMARY: The current status of CETP inhibitors in the context of large outcomes trials will be reviewed.

CETP Inhibition in CVD Prevention: an Actual Appraisal.

By virtue of their effects on low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and cellular cholesterol efflux, there is considerable interest in the potential use of pharmacological inhibitors of cholesteryl ester transfer protein (CETP) as a novel approach for cardiovascular disease prevention. This is supported by observations from genetic and animal studies suggesting that less CETP activity has favorable cardiovascular effects. Despite the adverse effects of the first CETP inhibitor to move forward in clinical development, torcetrapib, there remains considerable interest in developing alternative CETP inhibitors without the off-target effects of torcetrapib. The clinical development programs leading to a number of promising CETP inhibitors will be reviewed.

Acute high-density lipoprotein therapies.

PURPOSE OF REVIEW: Increasing interest has focused on the strategies that target the atheroprotective properties of HDL in order to reduce cardiovascular risk. The potential impact of strategies to acutely promote HDL functionality will be reviewed. RECENT FINDINGS: Population and animal studies suggest that HDLs have a protective impact on atherosclerotic plaque. However, the failure of recent clinical trials of HDL cholesterol-raising agents has raised concerns that this may not be a viable strategy to reduce cardiovascular risk. Increasing attention has highlighted the importance of the functional quality, as opposed to quantity, of HDL with evidence of impaired HDL function in the setting of acute coronary syndromes (ACSs). The finding that infusing HDL in patients with recent acute ischemic events promotes the rapid regression of coronary atherosclerosis suggests a potentially useful strategy for ACS patients, although this remains to be fully established in large clinical outcome trials. SUMMARY: Infusing HDL has favorable effects on coronary atherosclerosis in ACS patients, suggesting a potentially beneficial therapeutic strategy to acutely promote HDL functionality.

Liver ABCA1 deletion in LDLrKO mice does not impair macrophage reverse cholesterol transport or exacerbate atherogenesis.

OBJECTIVE: Hepatic ATP binding cassette transporter A1 (ABCA1) expression is critical for maintaining plasma high-density lipoprotein (HDL) concentrations, but its role in macrophage reverse cholesterol transport and atherosclerosis is not fully understood. We investigated atherosclerosis development and reverse cholesterol transport in hepatocyte-specific ABCA1 knockout (HSKO) mice in the low-density lipoprotein (LDL) receptor KO (LDLrKO) C57BL/6 background. APPROACH AND RESULTS: Male and female LDLrKO and HSKO/LDLrKO mice were switched from chow at 8 weeks of age to an atherogenic diet (10% palm oil, 0.2% cholesterol) for 16 weeks. Chow-fed HSKO/LDLrKO mice had HDL concentrations 10% to 20% of LDLrKO mice, but similar very low-density lipoprotein and LDL concentrations. Surprisingly, HSKO/LDLrKO mice fed the atherogenic diet had significantly lower (40% to 60%) very low-density lipoprotein, LDL, and HDL concentrations (50%) compared with LDLrKO mice. Aortic surface lesion area and cholesterol content were similar for both genotypes of mice, but aortic root intimal area was significantly lower (20% to 40%) in HSKO/LDLrKO mice. Although macrophage (3)H-cholesterol efflux to apoB lipoprotein-depleted plasma was 24% lower for atherogenic diet-fed HSKO/LDLrKO versus LDLrKO mice, variation in percentage efflux among individual mice was <2-fold compared with a 10-fold variation in plasma HDL concentrations, suggesting that HDL levels, per se, were not the primary determinant of plasma efflux capacity. In vivo reverse cholesterol transport, resident peritoneal macrophage sterol content, biliary lipid composition, and fecal cholesterol mass were similar between both genotypes of mice. CONCLUSIONS: The markedly reduced plasma HDL pool in HSKO/LDLrKO mice is sufficient to maintain macrophage reverse cholesterol transport, which, along with reduced plasma very low-density lipoprotein and LDL concentrations, prevented the expected increase in atherosclerosis.

Comorbidities and Symptom Status in Moderate and Severe Aortic Stenosis: A Multicenter Clinical Cohort Study.

Background: Symptoms associated with severe aortic stenosis (AS) are used to guide management. Objectives: The purpose of this study was to examine the pattern of symptoms, comorbidities, and cardiac damage in moderate and severe AS. Methods: A total of 846,198 echocardiographic investigations from 330,940 individuals aged >18 years were selected for the most recent echocardiogram, moderate or severe AS (mean gradient 20.0-39.9 mm Hg, aortic valve peak gradient 3.0-3.9 m/s and aortic valve area >1.0 cm2; or ≥ 40.0 mm Hg, ≥4.0 m/s or ≤1.0 cm2, respectively), and a cardiologist consultation. Natural Language Processing was applied to letters to extract comorbidities, dyspnea, chest pain, and syncope. Patients with prior aortic valve replacement were excluded. Results: 2,213 patients (0.7% overall, 32.8% females) had moderate and 3,416 (1.0%, 47.3% females) had severe AS. Comorbidities were common, including hypertension, (56.6% moderate AS, 53.1% severe AS, P = 0.01), coronary disease (46.0% and 46.8%, respectively, P = 0.58) and atrial fibrillation (29.6% and 34.8%, respectively, P < 0.001). Symptoms were also common in both moderate (n = 915, 41.3%) and severe (n = 1,630, 47.7%) AS (P < 0.001). Comorbidities were more likely in symptomatic vs asymptomatic patients (P < 0.001). Dyspnea was more likely in severe AS, whereas angina and syncope were similar in moderate vs severe AS. In multivariable analysis, only dyspnea was associated with severe (vs moderate) AS (OR: 1.73, 95% CI: 1.41-2.13, P < 0.001). In both adjusted and unadjusted models, the degree of cardiac damage did not relate to presence of any symptoms but was associated with AS severity. Conclusions: Dyspnea is common in both moderate and severe AS, is associated with comorbidities and is not related to the degree of cardiac damage. Symptom-guided management decisions in AS may need revision.

Early vs. Late Readmission following Percutaneous Coronary Intervention: Predictors and Impact on Long-Term Outcomes.

BACKGROUND: Readmissions within 1 year after percutaneous coronary intervention (PCI) are common (18.6-50.4% in international series) and a burden to patients and health services, however their long-term implications are not well characterised. We compared predictors of 30-day (early) and 31-day to 1-year (late) unplanned readmission and the impact of unplanned readmission on long-term clinical outcomes post-PCI. METHODS: Patients enrolled in the GenesisCare Cardiovascular Outcomes Registry (GCOR-PCI) from 2008 to 2020 were included in the study. Multivariate logistic regression analysis was performed to identify predictors of early and late unplanned readmission. A Cox proportion hazards regression model was used to explore the impact of any unplanned readmission during the first year post-PCI on the clinical outcomes at 3 years. Finally, patients with early and late unplanned readmission were compared to determine which group was at the highest risk of adverse long-term outcomes. RESULTS: The study comprised 16,911 consecutively enrolled patients who underwent PCI between 2009-2020. Of these, 1422 patients (8.5%) experienced unplanned readmission within 1-year post-PCI. Overall, the mean age was 68.9 ± 10.5 years, 76.4% were male and 45.9% presented with acute coronary syndromes. Predictors of unplanned readmission included increasing age, female gender, previous CABG, renal impairment and PCI for acute coronary syndromes. Unplanned readmission within 1 year of PCI was associated with an increased risk of MACE (adjusted HR 1.84 (1.42-2.37), p < 0.001) and death over a 3-year follow-up (adjusted HR 1.864 (1.34-2.59), p < 0.001) compared with those without readmission within 1-year post-PCI. Late compared with early unplanned readmission within the first year of PCI was more frequently associated with subsequent unplanned readmission, MACE and death between 1 and 3 years post-PCI. CONCLUSIONS: Unplanned readmissions in the first year following PCI, particularly those occurring more than 30 days after discharge, were associated with a significantly higher risk of adverse outcomes, such as MACE and death at 3 years. Strategies to identify patients at high risk of readmission and interventions to reduce their greater risk of adverse events should be implemented post-PCI.

Early outcomes following integration of computed tomography (CT) coronary angiography service in an established cardiology practice in disease management.

BACKGROUND: Computed tomography coronary angiography (CTCA) is an established modality for the diagnosis and assessment of cardiovascular disease. However, price and space pressure have mostly necessitated outsourcing CTCA to external radiology providers. Advara HeartCare has recently integrated CT services within local clinical networks across Australia. This study examined the benefits of the presence (integrated) or absence (pre-integrated) of this "in-house" CTCA service in real-world clinical practice. METHODS: De-identified patient data from electronic medical records were used to create an Advara HeartCare CTCA database. Data analysis included clinical history, demographics, CTCA procedure, and 30-day outcomes post-CTCA from two age-matched cohorts: integrated (n â€‹= â€‹495) and pre-integrated (n â€‹= â€‹456). RESULTS: Data capture was more comprehensive and standardised across the integrated cohort. There was a 21% increase in referrals for CTCA from cardiologists observed for the integration cohort vs. pre-integration [n â€‹= â€‹332 (72.8%) pre-integration vs. n â€‹= â€‹465 (93.9%) post-integration, p â€‹< â€‹0.0001] with a parallel increase in diagnostic assessments including blood tests [n â€‹= â€‹209 (45.8%) vs. n â€‹= â€‹387 (78.1%), respectively, p â€‹< â€‹0.0001]. The integrated cohort received lower total dose length product [Median 212 (interquartile range 136-418) mGy∗cm vs. 244 (141.5, 339.3) mGy∗cm, p â€‹= â€‹0.004] during the CTCA procedure. 30-days after CTCA scan, there was a significantly higher use of lipid-lowering therapies in the integrated cohort [n â€‹= â€‹133 (50.5%) vs. n â€‹= â€‹179 (60.6%), p â€‹= â€‹0.04], along with a significant decrease in the number of stress echocardiograms performed [n â€‹= â€‹14 (10.6%) vs. n â€‹= â€‹5 (11.6%), p â€‹= â€‹0.01]. CONCLUSION: Integrated CTCA has salient benefits in patient management, including increased pathology tests, statin usage, and decreased post-CTCA stress echocardiography utilisation. Our ongoing work will examine the effect of integration on cardiovascular outcomes.

Sex Differences in Baseline Characteristics Do Not Predict Early Outcomes after Percutaneous Coronary Intervention: Results from the Australian GenesisCare Cardiovascular Outcomes Registry (GCOR).

OBJECTIVE: The effect of baseline differences between men and women on early outcomes after percutaneous coronary intervention (PCI). DESIGN, SETTING, PARTICIPANTS: This is an observational study of all participants in the GenesisCare Cardiovascular Outcomes Registry, undergoing PCI. The registry holds data for both emergency and elective procedures. Data was collected on 10,989 consecutive patients from 12 Australian Private Hospitals, including baseline demographics, co-morbidities, risk factors, PCI procedures, and lesion characteristics. MAIN OUTCOME MEASURES: Outcome was measured for complications (in-hospital death, peri-procedural myocardial infarctions, and bleeding events), at discharge and at 30-days for death, myocardial infarction, target lesion revascularisation (TLR), major adverse cardiac events (MACE), and unplanned readmissions. RESULTS: Women represented 23% of the study population, were significantly older, with a higher rate of hypertension and hyperlipidaemia. Heart failure was more common in women and was associated with a significantly higher average ejection fraction than in men. Women had a lower rate of pre-existing coronary artery disease (CAD), had less complex CAD, and needed fewer stents. Periprocedural complications were similar, but major bleeding was more common in women. The 30-day outcome was similar between men and women for death, myocardial infarction, target lesion revascularisation (TLR), major adverse cardiovascular events (MACE), and unplanned readmissions. CONCLUSIONS: Although significant differences were observed between women and men in both clinical presentation and complexity of disease, the 30-day outcome was similar for death and MACE. Women had a higher rate of major bleeding events, and lower adherence to statins and dual antiplatelet therapy (DAPT).

The Association of Sex with Unplanned Cardiac Readmissions following Percutaneous Coronary Intervention in Australia: Results from a Multicentre Outcomes Registry (GenesisCare Cardiovascular Outcomes Registry).

Background and aim: Unplanned cardiac readmissions in patients with percutaneous intervention (PCI) is very common and is seen as a quality indicator of in-hospital care. Most studies have reported on the 30-day cardiac readmission rates, with very limited information being available on 1-year readmission rates and their association with mortality. The aim of this study was to investigate the impact of biological sex at 1-year post-PCI on unplanned cardiac readmissions. Methods and results: Patients enrolled into the GenesisCare Cardiovascular Outcomes Registry (GCOR-PCI) from December 2008 to December 2020 were included in the study. A total of 13,996 patients completed 12 months of follow-up and were assessed for unplanned cardiac readmissions. All patients with unplanned cardiac readmissions in the first year of post-PCI were followed in year 2 (post-PCI) for survival status. The rate of unplanned cardiac readmissions was 10.1%. Women had a 29% higher risk of unplanned cardiac readmission (HR 1.29, 95% CI 1.11 to 1.48; p = 0.001), and female sex was identified as an independent predictor of unplanned cardiac readmissions. Any unplanned cardiac readmission in the first year was associated with a 2.5-fold higher risk of mortality (HR 2.50, 95% CI 1.67 to 3.75; p < 0.001), which was similar for men and women. Conclusion: Unplanned cardiac readmissions in the first year post-PCI was strongly associated with increased all-cause mortality. Whilst the incidence of all-cause mortality was similar between women and men, a higher incidence of unplanned cardiac readmissions was observed for women, suggesting distinct predictors of unplanned cardiac readmissions exist between women and men.

Health-Related Quality of Life (HRQoL) and the Effect on Outcome in Patients Presenting with Coronary Artery Disease and Treated with Percutaneous Coronary Intervention (PCI): Differences Noted by Sex and Age.

Background and aim: poor quality of life (QoL) has been identified as an independent risk factor for mortality and major cardiac events (MACE) in patients with cardiovascular disease (CVD). The aim of this study was to assess health-related quality of life (HRQoL) at baseline and its association with outcome in patients with coronary artery disease presenting for percutaneous coronary intervention (PCI). The outcome was measured by mortality and MACE at 1-year, and whether there was any difference for sex and different age groups. Methods and results: all patients prospectively enrolled into the GenesisCare Outcome Registry (GCOR) over a 11-year period were included in the study. The EQ-5D-5L and VAS patient survey were used for assessment of baseline HRQoL. Of the 15,198 patients, only 6591 (43.4%) completed the self-assessment. Women had significantly more impairment of all five dimensions of the EQ-5D-5L survey, and their self-reported QoL was significantly lower than men (68.3 in women vs. 71.9 in men, p < 0.001). Poor QoL was strongly associated with increased mortality (HR 2.85; 95% CI 1.76 to 4.62, p < 0.001) and MACE (HR 1.40; 95% CI 1.10 to 1.79, p = 0.01). A similar trend was noted for women and men, but did not reach significance in women due to the smaller number of female patients. Conclusion: poor HRQoL is associated with subsequent mortality and MACE in patients undergoing PCI. By not assessing quality of life as a standard of care, an opportunity is lost to identify high-risk patients who may benefit from targeted interventions to improve health outcomes.

Long-Term Outcomes of Contemporary Percutaneous Coronary Intervention with the Xience Drug-Eluting Stent: Results from a Multicentre Australian Registry.

Introduction: Several large registries have evaluated outcomes after percutaneous coronary intervention (PCI) in the USA, however there are no contemporary data regarding long-term outcomes after PCI, particularly comparing new generation drug-eluting stents (DES) with other stents in Australia. Additionally, approval of new-generation drug-eluting stents (DES) is almost exclusively based on non-inferiority trials comparing outcomes with early generation DES, and there are limited data comparing safety and efficacy outcomes of new-generation DES with bare metal stents (BMS). This study reports in-hospital and long-term outcomes after PCI with the Xience DES from a large national registry, the GenesisCare Outcomes Registry (GCOR). Methods: The first 1500 patients consecutively enrolled from January 2015 to January 2019 and treated exclusively with either Xience DES or BMS and eligible for 1-year follow-up were included. Baseline patient and procedural data, major adverse cardiovascular events (MACE) in-hospital, at 30 days and 1-year, and medications were reported and analysed with respect to Xience DES (n = 1000) or BMS (n = 500) use. Results: In this cohort the mean age was 68.4 ± 10.7 years, 76.9% were male, 24.6% had diabetes mellitus and 45.9% presented with acute coronary syndromes. Of the overall cohort of 4765 patients from this period including all DES types, and patients who received multiple DES or a combination of DES and BMS, DES were exclusively used in 3621 (76.0%) patients, and BMS were exclusively used in 596 (12.5%). In comparison to international cohorts, adverse clinical event rates were low at 30 days in terms of mortality (0.20%), target lesion revascularisation (TLR, 0.27%) and MACE (0.47%), and at 12 months for mortality (1.26%) TLR (1.16%) and MACE (1.78%). Conclusions: Clinical practice and long-term outcomes of PCI with the Xience DES in Australia are consistent with international series. Recent trends indicate DES use has increased in parallel with good outcomes despite an increasingly complex patient and lesion cohort.

R-wave amplitude changes with posture and physical activity over time in an insertable cardiac monitor.

Background: Insertable cardiac monitors (ICMs) are accepted tools in cardiac arrhythmia management. Consistent R-wave amplitude (RWA) is essential for optimal detection. Objectives: Assess RWAs with posture/activities at insertion and at 30 days. Methods: Participants (n = 90) with Confirm Rx™ ICM had RWAs measured in different postures (supine, right-side [RS], left-side [LS], sitting, and standing) and defined physical activities (including isometric push [IPUSH] and pull) at 2 time points. ICMs were inserted in 45° to sternum and parasternal orientations. Results: There were significant reductions at insertion with RS, LS, sitting, or standing vs supine (reference position) (all P < .05). At 30 days, significant changes only occurred with LS and sitting (P < .05). Sex had an effect on RWAs, with females having significant variability at insertion (supine vs RS, LS, sitting, standing, and IPUSH; all P < .05). Males showed large RWA interpatient variabilities but minimal differences between positions vs supine. At 30 days, RS, LS, and sitting positions remained significant for females (P < .05), while in males RWAs were higher than at insertion for most postures and activities. The orientation 45° to sternum had consistently higher RWAs vs parasternal orientation at both time points (P < .0001). In females, ICM orientation had no significant effect on RWAs; however, in males the 45° to sternum produced higher RWAs. ICM movement from the insertion site showed no correlation with RWA changes. Conclusion: The mean RWAs were higher at 30 days with less interparticipant and interpostural variability; males had higher RWAs compared to females; 45° to sternum orientation had higher RWAs; and ICM migration from the insertion site did not affect RWAs.

Targeted deletion of hepatocyte ABCA1 leads to very low density lipoprotein triglyceride overproduction and low density lipoprotein hypercatabolism.

Loss of ABCA1 activity in Tangier disease (TD) is associated with abnormal apoB lipoprotein (Lp) metabolism in addition to the complete absence of high density lipoprotein (HDL). We used hepatocyte-specific ABCA1 knock-out (HSKO) mice to test the hypothesis that hepatic ABCA1 plays dual roles in regulating Lp metabolism and nascent HDL formation. HSKO mice recapitulated the TD lipid phenotype with postprandial hypertriglyceridemia, markedly decreased LDL, and near absence of HDL. Triglyceride (TG) secretion was 2-fold higher in HSKO compared with wild type mice, primarily due to secretion of larger TG-enriched VLDL secondary to reduced hepatic phosphatidylinositol 3-kinase signaling. HSKO mice also displayed delayed clearance of postprandial TG and reduced post-heparin plasma lipolytic activity. In addition, hepatic LDLr expression and plasma LDL catabolism were increased 2-fold in HSKO compared with wild type mice. Last, adenoviral repletion of hepatic ABCA1 in HSKO mice normalized plasma VLDL TG and hepatic phosphatidylinositol 3-kinase signaling, with a partial recovery of HDL cholesterol levels, providing evidence that hepatic ABCA1 is involved in the reciprocal regulation of apoB Lp production and HDL formation. These findings suggest that altered apoB Lp metabolism in TD subjects may result from hepatic VLDL TG overproduction and increased hepatic LDLr expression and highlight hepatic ABCA1 as an important regulatory factor for apoB-containing Lp metabolism.

Combined therapy of dietary fish oil and stearoyl-CoA desaturase 1 inhibition prevents the metabolic syndrome and atherosclerosis.

BACKGROUND: Stearoyl-CoA desaturase 1 (SCD1) is a critical regulator of energy metabolism and inflammation. We have previously reported that inhibition of SCD1 in hyperlipidemic mice fed a saturated fatty acid (SFA)-enriched diet prevented development of the metabolic syndrome, yet surprisingly promoted severe atherosclerosis. In this study we tested whether dietary fish oil supplementation could prevent the accelerated atherosclerosis caused by SCD1 inhibition. METHODS AND RESULTS: LDLr(-/-), ApoB(100/100) mice were fed diets enriched in saturated fat or fish oil in conjunction with antisense oligonucleotide (ASO) treatment to inhibit SCD1. As previously reported, in SFA-fed mice, SCD1 inhibition dramatically protected against development of the metabolic syndrome, yet promoted atherosclerosis. In contrast, in mice fed fish oil, SCD1 inhibition did not result in augmented macrophage inflammatory response or severe atherosclerosis. In fact, the combined therapy of dietary fish oil and SCD1 ASO treatment effectively prevented both the metabolic syndrome and atherosclerosis. CONCLUSIONS: SCD1 ASO treatment in conjunction with dietary fish oil supplementation is an effective combination therapy to comprehensively combat the metabolic syndrome and atherosclerosis in mice.

Omega-3 fatty acids ameliorate vascular inflammation: A rationale for their atheroprotective effects.

BACKGROUND AND AIMS: Clinical trials have demonstrated reductions in major adverse cardiovascular events with purified high-dose eicosapentaenoic acid (EPA), independent of effects on lipids. We aimed to investigate whether omega-3 fatty acids reduce vascular inflammation, a critical mediator of atherosclerosis, and hypothesised that EPA is superior to docosahexaenoic acid (DHA). METHODS: In a double-blind randomised controlled trial and cell-culture study, 40 healthy volunteers were supplemented with 4 g daily of either EPA, DHA, fish oil (2:1 EPA:DHA), or placebo for 30 days. Serum was incubated with TNF-stimulated human umbilical vein endothelial cells (HUVECs), and markers of acute vascular inflammation (AVI) were measured. The effects of EPA, DHA (600 mg/kg/day), olive oil, or no treatment were also measured in preclinical models of [1] AVI using a periarterial collar (C57Bl/6J; n = 40 mice) and [2] atherosclerosis where ApoE-/- mice (n = 40) were fed a 16-week atherogenic diet. RESULTS: EPA supplementation reduced expression of C-C motif chemokine ligand 2 (CCL2) by 25% compared to placebo (p = 0.03). In the AVI model, EPA reduced vascular expression of VCAM1 by 43% (p = 0.02) and CCL2 by 41% (p = 0.03). Significant inverse correlations were observed between EPA levels and vascular expression of VCAM1 (r = -0.56, p = 0.001) and CCL2 (r = -0.56, p = 0.001). In ApoE-/- mice, EPA reduced aortic expression of Il1b by 44% (p = 0.04) and Tnf by 49% (p = 0.04), with similar inverse correlations between EPA levels and both Il1b (r = -0.63, p = 0.009) and Tnf (r = -0.50, p = 0.04). CONCLUSIONS: Supplementation with EPA, more so than DHA, ameliorates acute and chronic vascular inflammation, providing a rationale for the cardiovascular benefit observed with high dose omega-3 fatty acid administration.

Tissue-specific roles of ABCA1 influence susceptibility to atherosclerosis.

OBJECTIVE: The ATP-binding cassette transporter, subfamily A, member 1 (ABCA1) plays a key role in HDL cholesterol metabolism. However, the role of ABCA1 in modulating susceptibility to atherosclerosis is controversial. METHODS AND RESULTS: We investigated the role of ABCA1 in atherosclerosis using a combination of overexpression and selective deletion models. First, we examined the effect of transgenic overexpression of a full-length human ABCA1-containing bacterial artificial chromosome (BAC) in the presence or absence of the endogenous mouse Abca1 gene. ABCA1 overexpression in the atherosclerosis-susceptible Ldlr(-/-) background significantly reduced the development of atherosclerosis in both the presence and absence of mouse Abca1. Next, we used mice with tissue-specific inactivation of Abca1 to dissect the discrete roles of Abca1 in different tissues on susceptibility to atherosclerosis. On the Apoe(-/-) background, mice lacking hepatic Abca1 had significantly reduced HDL cholesterol and accelerated atherosclerosis, indicating that the liver is an important site at which Abca1 plays an antiatherogenic role. In contrast, mice with macrophage-specific inactivation of Abca1 on the Ldlr(-/-) background displayed no change in atherosclerotic lesion area. CONCLUSIONS: These data indicate that physiological expression of Abca1 modulates the susceptibility to atherosclerosis and establish hepatic Abca1 expression as an important site of atheroprotection. In contrast, we show that selective deletion of macrophage Abca1 does not significantly modulate atherogenesis.

Inhibition of stearoyl-coenzyme A desaturase 1 dissociates insulin resistance and obesity from atherosclerosis.

BACKGROUND: Stearoyl-coenzyme A desaturase 1 (SCD1) is a well-known enhancer of the metabolic syndrome. The purpose of the present study was to investigate the role of SCD1 in lipoprotein metabolism and atherosclerosis progression. METHODS AND RESULTS: Antisense oligonucleotides were used to inhibit SCD1 in a mouse model of hyperlipidemia and atherosclerosis (LDLr(-/-)Apob(100/100)). In agreement with previous reports, inhibition of SCD1 protected against diet-induced obesity, insulin resistance, and hepatic steatosis. Unexpectedly, however, SCD1 inhibition strongly promoted aortic atherosclerosis, which could not be reversed by dietary oleate. Further analyses revealed that SCD1 inhibition promoted accumulation of saturated fatty acids in plasma and tissues and reduced plasma triglyceride, yet had little impact on low-density lipoprotein cholesterol. Because dietary saturated fatty acids have been shown to promote inflammation through toll-like receptor 4, we examined macrophage toll-like receptor 4 function. Interestingly, SCD1 inhibition resulted in alterations in macrophage membrane lipid composition and marked hypersensitivity to toll-like receptor 4 agonists. CONCLUSIONS: This study demonstrates that atherosclerosis can occur independently of obesity and insulin resistance and argues against SCD1 inhibition as a safe therapeutic target for the metabolic syndrome.