High immunoglobulin-M levels to oxidation-specific epitopes are associated with lower risk of acute myocardial infarction.

Immunoglobulin M (IgM) autoantibodies to oxidation-specific epitopes (OSEs) can be present at birth and protect against atherosclerosis in experimental models. This study sought to determine whether high titers of IgM titers to OSE (IgM OSE) are associated with a lower risk of acute myocardial infarction (AMI) in humans. IgM to malondialdehyde (MDA)-LDL, phosphocholine-modified BSA, IgM apolipoprotein B100-immune complexes, and a peptide mimotope of MDA were measured within 24 h of first AMI in 4,559 patients and 4,617 age- and sex-matched controls in the Pakistan Risk of Myocardial Infarction Study. Multivariate-adjusted logistic regression was used to estimate odds ratio (OR) and 95% confidence interval for AMI. All four IgM OSEs were lower in AMI versus controls (P < 0.001 for all). Males, smokers and individuals with hypertension and diabetes had lower levels of all four IgM OSE than unaffected individuals (P < 0.001 for all). Compared to the lowest quintile, the highest quintiles of IgM MDA-LDL, phosphocholine-modified BSA, IgM apolipoprotein B100-immune complexes, and MDA mimotope P1 had a lower OR of AMI: OR (95% confidence interval) of 0.67 (0.58-0.77), 0.64 (0.56-0.73), 0.70 (0.61-0.80) and 0.72 (0.62-0.82) (P < 0.001 for all), respectively. Upon the addition of IgM OSE to conventional risk factors, the C-statistic improved by 0.0062 (0.0028-0.0095) and net reclassification by 15.5% (11.4-19.6). These findings demonstrate that IgM OSE provides clinically meaningful information and supports the hypothesis that higher levels of IgM OSE may be protective against AMI.

Coming down the "chimney": Percutaneous coronary intervention on a post-transcatheter aortic valve replacement with valve-in-valve patient.

Accessing the coronary arteries post-transcatheter aortic valve replacement is a growing challenge. This is a case of a patient requiring percutaneous coronary intervention on a left circumflex artery after a TAVR valve-in-valve and a left main "chimney" stent, describing all the challenges met during the procedure.

Advances in treatment of chronic thromboembolic pulmonary hypertension.

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) is a progressive pulmonary vascular disease which can lead to right heart failure and death, if left untreated. CTEPH is caused by persistent obstruction of large, middle-sized, or distal pulmonary arteries due to limited thromboembolic resolution in the pulmonary vascular arterial tree. Every patient with CTEPH should undergo evaluation for Pulmonary Endarterectomy (PEA) after referral to institutions with an experienced multidisciplinary CTEPH team. Although management of distal thromboembolic lesions with PEA remains a challenge due to their difficult accessibility, limited distal CTEPH is not considered an absolute contraindication for PEA, as more expertise surgical teams operate on them successfully. Furthermore, in up to 30-50% of patients who undergo PEA, curative treatment is not achieved due to incomplete thrombi removal or extensive pulmonary microvascular disease. Medical therapies that target the underlying pulmonary microvascular disease can offer symptomatic and hemodynamic benefits, although they do not deal with the core mechanism of the disease which is the removal of thromboembolic material from pulmonary vasculature. Recent research has provided evidence suggesting balloon pulmonary angioplasty (BPA) is a reasonable treatment option for inoperable CTEPH and recurrent/persistent pulmonary hypertension after PEA. Advancements in diagnostic modalities and refinements of BPA technique have decreased the complication rate and increased its beneficial effects in hemodynamics, symptoms, right ventricular function and long-term survival. Ongoing trials and future prospective cohorts will provide evidence regarding the optimal selection of patients and lesions prone to BPA treatment along with hybrid therapeutic strategies combining pharmacological therapy, PEA and BPA, which can potentially change the standard of care in CTEPH.

Trends in testing and prevalence of elevated Lp(a) among patients with aortic valve stenosis.

BACKGROUND AND AIMS: Lipoprotein(a) [Lp(a)] is causally associated with aortic valve stenosis (AS) but Lp(a) testing among AS patients is not broadly incorporated into clinical practice. We evaluated trends in Lp(a) testing in an academic medical center. METHODS: Educational efforts and adding Lp(a) to the lipid panel on the electronic medical record (EMR) and pre-procedure order sets were used to increase awareness of Lp(a) as a risk factor in AS. Medical records at University of California San Diego Health (UCSDH) were analyzed from 2010 to 2020 to define the yearly frequency of first time Lp(a) testing in patients with diagnosis codes for AS or undergoing transcatheter aortic valve replacement (TAVR). RESULTS: Lp(a) testing for any indication increased over 5-fold from 2010 to 2020. A total of 3808 patients had a diagnosis of AS and 417 patients had TAVR. Lp(a) levels >30 mg/dL were present in 37% of AS and 35% of TAVR patients. The rates of Lp(a) testing in AS and TAVR were 14.0% and 65.7%, respectively. In AS, Lp(a) testing increased over time from 8.5% in 2010, peaking at 24.2% in 2017, and declining to 13.9% in 2020 (p < 0.001 for trend). Following implementation of EMR order-sets in 2016, Lp(a) testing in TAVR cases increased to a peak of 88.5% in 2018. CONCLUSIONS: Elevated Lp(a) is prevalent in AS and TAVR patients. Implementation of educational efforts and practice pathways resulted in increased Lp(a) testing in patients with AS. This study represents a paradigm that may allow increased global awareness of Lp(a) as a risk factor for AS.

Impact of the COVID-19 pandemic on interventional cardiology training in the United States.

OBJECTIVES: We sought to determine the effect of COVID-19 related reduction in elective cardiac procedures and acute coronary syndrome presentations on interventional cardiology (IC) training. BACKGROUND: The COVID-19 pandemic has significantly disrupted healthcare in the United States, including cardiovascular services. The impact of COVID-19 on IC fellow training in the United States has not been assessed. METHODS: The Society for Cardiovascular Angiography and Interventions (SCAI) surveyed IC fellows training in both accredited and advanced non-accredited programs, as well as their program directors (PD). RESULTS: Responses were received from 135 IC fellows and 152 PD. All respondents noted reductions in procedural volumes beginning in March 2020. At that time, only 43% of IC fellows had performed >250 PCI. If restrictions were lifted by May 15, 2020 78% of IC fellows believed they would perform >250 PCI, but fell to only 70% if restrictions persisted until the end of the academic year. 49% of IC fellows felt that their procedural competency was impaired by COVID-19, while 97% of PD believed that IC fellows would be procedurally competent at the end of their training. Most IC fellows (65%) noted increased stress at work and at home, and many felt that job searches and/or existing offers were adversely affected by the pandemic. CONCLUSION: The COVID-19 pandemic has substantially affected IC training in the United States, with many fellows at risk of not satisfying current program procedural requirements. These observations support a move to review current IC program requirements and develop mitigation strategies to supplement gaps in education related to reduced procedural volume.

Longitudinal Deformation of Distal Edge in a New-Generation Stent Caused by Guidewire Entrapment.

Longitudinal stent deformation, described in some older stent geometries, prompted design modifications such as reinforcing struts on the proximal end. However, distal edges of stents-also subject to longitudinal force-have not been reinforced. We report a case of guidewire entrapment that deformed the distal edge of a new-generation stent during percutaneous coronary intervention, and we describe our efforts to restore the stent to its initial length. This case highlights the risk of manipulating equipment beyond the position of a newly deployed stent, the ongoing potential for deformation of distal edges in newer stent platforms, and the advisability of treating distal lesions before proximal ones.

Apolipoprotein(a) isoform size, lipoprotein(a) concentration, and coronary artery disease: a mendelian randomisation analysis.

BACKGROUND: The lipoprotein(a) pathway is a causal factor in coronary heart disease. We used a genetic approach to distinguish the relevance of two distinct components of this pathway, apolipoprotein(a) isoform size and circulating lipoprotein(a) concentration, to coronary heart disease. METHODS: In this mendelian randomisation study, we measured lipoprotein(a) concentration and determined apolipoprotein(a) isoform size with a genetic method (kringle IV type 2 [KIV2] repeats in the LPA gene) and a serum-based electrophoretic assay in patients and controls (frequency matched for age and sex) from the Pakistan Risk of Myocardial Infarction Study (PROMIS). We calculated odds ratios (ORs) for myocardial infarction per 1-SD difference in either LPA KIV2 repeats or lipoprotein(a) concentration. In a genome-wide analysis of up to 17 503 participants in PROMIS, we identified genetic variants associated with either apolipoprotein(a) isoform size or lipoprotein(a) concentration. Using a mendelian randomisation study design and genetic data on 60 801 patients with coronary heart disease and 123 504 controls from the CARDIoGRAMplusC4D consortium, we calculated ORs for myocardial infarction with variants that produced similar differences in either apolipoprotein(a) isoform size in serum or lipoprotein(a) concentration. Finally, we compared phenotypic versus genotypic ORs to estimate whether apolipoprotein(a) isoform size, lipoprotein(a) concentration, or both were causally associated with coronary heart disease. FINDINGS: The PROMIS cohort included 9015 patients with acute myocardial infarction and 8629 matched controls. In participants for whom KIV2 repeat and lipoprotein(a) data were available, the OR for myocardial infarction was 0·93 (95% CI 0·90-0·97; p<0·0001) per 1-SD increment in LPA KIV2 repeats after adjustment for lipoprotein(a) concentration and conventional lipid concentrations. The OR for myocardial infarction was 1·10 (1·05-1·14; p<0·0001) per 1-SD increment in lipoprotein(a) concentration, after adjustment for LPA KIV2 repeats and conventional lipids. Genome-wide analysis identified rs2457564 as a variant associated with smaller apolipoprotein(a) isoform size, but not lipoprotein(a) concentration, and rs3777392 as a variant associated with lipoprotein(a) concentration, but not apolipoprotein(a) isoform size. In 60 801 patients with coronary heart disease and 123 504 controls, OR for myocardial infarction was 0·96 (0·94-0·98; p<0·0001) per 1-SD increment in apolipoprotein(a) protein isoform size in serum due to rs2457564, which was directionally concordant with the OR observed in PROMIS for a similar change. The OR for myocardial infarction was 1·27 (1·07-1·50; p=0·007) per 1-SD increment in lipoprotein(a) concentration due to rs3777392, which was directionally concordant with the OR observed for a similar change in PROMIS. INTERPRETATION: Human genetic data suggest that both smaller apolipoprotein(a) isoform size and increased lipoprotein(a) concentration are independent and causal risk factors for coronary heart disease. Lipoprotein(a)-lowering interventions could be preferentially effective in reducing the risk of coronary heart disease in individuals with smaller apolipoprotein(a) isoforms. FUNDING: British Heart Foundation, US National Institutes of Health, Fogarty International Center, Wellcome Trust, UK Medical Research Council, UK National Institute for Health Research, and Pfizer.

Control of angiogenesis by AIBP-mediated cholesterol efflux.

Cholesterol is a structural component of the cell and is indispensable for normal cellular function, although its excess often leads to abnormal proliferation, migration, inflammatory responses and/or cell death. To prevent cholesterol overload, ATP-binding cassette (ABC) transporters mediate cholesterol efflux from the cells to apolipoprotein A-I (apoA-I) and the apoA-I-containing high-density lipoprotein (HDL). Maintaining efficient cholesterol efflux is essential for normal cellular function. However, the role of cholesterol efflux in angiogenesis and the identity of its local regulators are poorly understood. Here we show that apoA-I binding protein (AIBP) accelerates cholesterol efflux from endothelial cells to HDL and thereby regulates angiogenesis. AIBP- and HDL-mediated cholesterol depletion reduces lipid rafts, interferes with VEGFR2 (also known as KDR) dimerization and signalling and inhibits vascular endothelial growth factor-induced angiogenesis in vitro and mouse aortic neovascularization ex vivo. Notably, Aibp, a zebrafish homologue of human AIBP, regulates the membrane lipid order in embryonic zebrafish vasculature and functions as a non-cell-autonomous regulator of angiogenesis. aibp knockdown results in dysregulated sprouting/branching angiogenesis, whereas forced Aibp expression inhibits angiogenesis. Dysregulated angiogenesis is phenocopied in Abca1 (also known as Abca1a) Abcg1-deficient embryos, and cholesterol levels are increased in Aibp-deficient and Abca1 Abcg1-deficient embryos. Our findings demonstrate that secreted AIBP positively regulates cholesterol efflux from endothelial cells and that effective cholesterol efflux is critical for proper angiogenesis.

Oxidation-specific biomarkers and risk of peripheral artery disease.

OBJECTIVES: The goal of this study was to examine the prospective association between oxidation-specific biomarkers, primarily oxidized phospholipids (OxPL) on apolipoprotein B-100-containing lipoproteins (OxPL/apoB) and lipoprotein (a) [Lp(a)], and risk of peripheral artery disease (PAD). We examined, as secondary analyses, indirect measures of oxidized lipoproteins, including autoantibodies to malondialdehyde-modified low-density lipoprotein (MDA-LDL) and apolipoprotein B-100 immune complexes (ApoB-IC). BACKGROUND: Biomarkers to predict the development of PAD are lacking. OxPL circulate in plasma, are transported by Lp(a), and deposit in the vascular wall and induce local inflammation. METHODS: The study population included 2 parallel nested case-control studies of 143 men within the Health Professionals Follow-up Study (1994 to 2008) and 144 women within the Nurses' Health Study (1990 to 2010) with incident confirmed cases of clinically significant PAD, matched 1:3 to control subjects. RESULTS: Levels of OxPL/apoB were positively associated with risk of PAD in men and women: pooled relative risk: 1.37, 95% confidence interval: 1.19 to 1.58 for each 1-SD increase after adjusting age, smoking, fasting status, month of blood draw, lipids, body mass index, and other cardiovascular disease risk factors. Lp(a) was similarly associated with risk of PAD (pooled adjusted relative risk: 1.36; 95% confidence interval: 1.18 to 1.57 for each 1-SD increase). Autoantibodies to MDA-LDL and ApoB-IC were not consistently associated with risk of PAD. CONCLUSIONS: OxPL/apoB were positively associated with risk of PAD in men and women. The major lipoprotein carrier of OxPL, Lp(a), was also associated with risk of PAD, reinforcing the key role of OxPL in the pathophysiology of atherosclerosis mediated by Lp(a).

Oxidized phospholipids on apoB-100-containing lipoproteins: a biomarker predicting cardiovascular disease and cardiovascular events.

Oxidative stress is a well-known etiologic factor in the development of cardiovascular disease. Oxidation of lipoproteins, and in particular of low density lipoprotein, is a necessary if not obligatory mechanism for the generation of macrophage-derived foam cells, the first major initiating factor in the development of an atherosclerotic plaque. Oxidation of lipoproteins does not result in the generation of a single, defined molecular species, but of a variety of oxidation-specific epitopes, such as oxidized phospholipids and malondialdehyde-lysine epitopes. Unique monoclonal antibodies have been developed to bind these well-defined epitopes, and have been used in in vitro assays to detect them on circulating lipoproteins present in plasma. This article will summarize the accumulating clinical data of one oxidation-specific biomarker, oxidized phospholipids (OxPL) on apoB-100 lipoproteins. Elevated levels of OxPL/apoB predict the presence and progression of coronary, femoral and carotid artery disease, are increased following acute coronary syndromes and percutaneous coronary intervention, and predict the development of death, myocardial infarction, stroke and need for revascularization in unselected populations. OxPL/apoB levels are independent of traditional risk factors and the metabolic syndrome, and enhance the risk prediction of the Framingham Risk Score. The OxPLs measured in this assay reflect the biological activity of the most atherogenic lipoprotein(a) (Lp(a)) particles, reflected in patients with high plasma Lp(a) levels with small apo(a) isoforms. The predictive value of OxPL/apoB is amplified by Lp(a) and phospholipases such as lipoprotein-associated phospholipase A(2) and secretory phospholipase A(2), which are targets of therapy in clinical trials. This assay has now been validated in over 10,000 patients and efforts are underway to make it available to the research and clinical communities.

Antisense oligonucleotide lowers plasma levels of apolipoprotein (a) and lipoprotein (a) in transgenic mice.

OBJECTIVES: This study sought to assess whether an antisense oligonucleotide (ASO) directed to apolipoprotein (a) [apo(a)] reduces apo(a) and lipoprotein (a) [Lp(a)] levels in transgenic mouse models. BACKGROUND: Elevated Lp(a) is a causal, independent, genetic risk factor for cardiovascular disease and myocardial infarction. Effective therapies to specifically lower plasma Lp(a) levels are lacking. METHODS: Three transgenic mouse models were utilized: 8K-apo(a) mice expressing 8 kringle IV (KIV) repeats with a single copy of KIV-2; 8K-Lp(a) mice expressing both the 8K apo(a) plus human apolipoprotein B-100; and 12K-apo(a) mice expressing a 12K apo(a) with 3 KIV-2 repeats. The mice were treated intraperitoneally with saline, a control ASO, or ASO 144367 directed to KIV-2 for 4 to 6 weeks. Apo(a), Lp(a), and oxidized phospholipids present on human apoB (OxPL/h-apoB) or apo(a) [OxPL/apo(a)] were measured at baseline and on and off therapy. RESULTS: ASO 144367 significantly reduced Lp(a) by 24.8% in 8K-Lp(a) mice, and reduced apo(a) levels by 19.2% in 8K-Lp(a) mice, 30.0% in 8K-apo(a) mice, and 86% in 12K-apo(a) mice; ASO 144367 also significantly reduced OxPL/apoB 22.4% in 8K-Lp(a) mice, and OxPL/apo(a) levels by 19.9% in 8K-Lp(a) mice, 22.1% in 8K-apo(a) mice, and 92.5% in 12K-apo(a) mice (p < 0.004, or less, for all). No significant changes occurred in Lp(a), apo(a), OxPL/apoB, or OxPL/apo(a) levels with control ASO or saline. CONCLUSIONS: This study documents the first specific therapy, to our knowledge, for lowering apo(a)/Lp(a) levels and their associated OxPL. A more potent effect was documented in mice expressing apo(a) with multiple KIV-2 repeats. Targeting liver expression of apo(a) with ASOs directed to KIV-2 repeats may provide an effective approach to lower elevated Lp(a) levels in humans.