Lipoprotein (a) is associated with increased risk of Abdominal Aortic Aneurysm.

Introduction: Lipoprotein(a) (Lp(a)) is a circulating apolipoprotein B (ApoB) containing particle that has been observationally linked to atherosclerotic cardiovascular disease and is the target of emerging therapeutics. Recent work has highlighted the role of circulating lipoproteins in abdominal aortic aneurysm (AAA). We sought to triangulate human observational and genetic evidence to evaluate the role of Lp(a) in AAA. Methods: We tested the association between circulating levels of Lp(a) and clinically diagnosed abdominal aortic aneurysms while controlling for traditional AAA risk factors and levels of ApoB using logistic regression among 795 individuals with and 374,772 individuals without AAA in the UK Biobank (UKB). Multivariable Mendelian randomization (MVMR) was used to test for putatively causal associations between Lp(a) and AAA controlling for ApoB. Genetic instruments for Lp(a) and ApoB were created from genome-wide association studies (GWAS) of Lp(a) and ApoB comprising 335,796 and 418,505 UKB participants, respectively. The instruments were tested for association with AAA using data from a GWAS of 39,221 individuals with and 1,086,107 without AAA. Results: Elevated Lp(a) levels were observationally associated with an increased risk of AAA (OR 1.04 per 10 nmol/L Lp(a); 95%CI 1.02-1.05; P<0.01). Clinically elevated Lp(a) levels (>150nmol/L) were likewise associated with an increased risk of AAA (OR 1.47; 95% CI 1.15-1.88; P < 0.01) when compared to individuals with Lp(a) levels <150nmol/L. MVMR confirmed a significant, ApoB-independent association between increased Lp(a) and increased risk of AAA (OR 1.13 per SD increase in Lp(a); 95%CI 1.02-1.24; P<0.02). Conclusion: Both observational and genetic analyses support an association between increased Lp(a) and AAA risk that is independent of ApoB. These findings suggest that Lp(a) may be a therapeutic target for AAA and drive the inclusion of AAA as an outcome in clinical trials of Lp(a) antagonists.

Genome-wide association meta-analysis identifies risk loci for abdominal aortic aneurysm and highlights PCSK9 as a therapeutic target.

Abdominal aortic aneurysm (AAA) is a common disease with substantial heritability. In this study, we performed a genome-wide association meta-analysis from 14 discovery cohorts and uncovered 141 independent associations, including 97 previously unreported loci. A polygenic risk score derived from meta-analysis explained AAA risk beyond clinical risk factors. Genes at AAA risk loci indicate involvement of lipid metabolism, vascular development and remodeling, extracellular matrix dysregulation and inflammation as key mechanisms in AAA pathogenesis. These genes also indicate overlap between the development of AAA and other monogenic aortopathies, particularly via transforming growth factor ß signaling. Motivated by the strong evidence for the role of lipid metabolism in AAA, we used Mendelian randomization to establish the central role of nonhigh-density lipoprotein cholesterol in AAA and identified the opportunity for repurposing of proprotein convertase, subtilisin/kexin-type 9 (PCSK9) inhibitors. This was supported by a study demonstrating that PCSK9 loss of function prevented the development of AAA in a preclinical mouse model.

Feasibility study to assess the delivery of a novel isometric exercise intervention for people with stage 1 hypertension in the NHS: protocol for the IsoFIT-BP study including amendments to mitigate the risk of COVID-19.

BACKGROUND: Hypertension  (HTN) affects approximately 25% of the UK population and is a leading cause of mortality. Associated annual health care costs run into billions. National treatment guidance includes initial lifestyle advice, followed by anti-hypertensive medication if blood pressure (BP) remains high. However, adoption and adherence to recommended exercise guidelines, dietary advice and anti-hypertensive medication is poor. Four short bouts of isometric exercise (IE) performed 3 days per week (d/wk) at home elicits clinically significant reductions in BP in those with normal to high-normal BP. This study will determine the feasibility of delivering personalised IE to patients with stage 1 hypertension for whom lifestyle changes would be recommended before medication within NHS primary care. METHODS: This is a randomised controlled feasibility study. Participants were 18+ years, with stage 1 hypertension, not on anti-hypertensive medication and without significant medical contraindications. Trial arms will be standard lifestyle advice (control) or isometric wall squat exercise and standard lifestyle advice. Primary outcomes include the feasibility of healthcare professionals to deliver isometric exercise prescriptions in a primary care NHS setting and estimation of the variance of change in systolic BP. Secondary outcomes include accuracy of protocol delivery, execution of and adherence to protocol, recruitment rate, attrition, perception of intervention viability, cost, participant experience and accuracy of home BP. The study will last 18 months. Sample size of 100 participants (50 per arm) allows for 20% attrition and 6.5% incomplete data, based upon 74 (37 each arm) participants (two-sided 95% confidence interval, width of 1.33 and standard deviation of 4) completing 4 weeks. Ethical approval IRAS ID is 274676. DISCUSSION: Before the efficacy of this novel intervention to treat stage 1 hypertension can be investigated in any large randomised controlled trial, it is necessary to ascertain if it can be delivered and carried out in a NHS primary care setting. Findings could support IE viability as a prophylactic/alternative treatment option. TRIAL REGISTRATION: ISRCTN13472393 , registered 18 August 2020.