Multi-ancestry genome-wide study identifies effector genes and druggable pathways for coronary artery calcification.

Coronary artery calcification (CAC), a measure of subclinical atherosclerosis, predicts future symptomatic coronary artery disease (CAD). Identifying genetic risk factors for CAC may point to new therapeutic avenues for prevention. Currently, there are only four known risk loci for CAC identified from genome-wide association studies (GWAS) in the general population. Here we conducted the largest multi-ancestry GWAS meta-analysis of CAC to date, which comprised 26,909 individuals of European ancestry and 8,867 individuals of African ancestry. We identified 11 independent risk loci, of which eight were new for CAC and five had not been reported for CAD. These new CAC loci are related to bone mineralization, phosphate catabolism and hormone metabolic pathways. Several new loci harbor candidate causal genes supported by multiple lines of functional evidence and are regulators of smooth muscle cell-mediated calcification ex vivo and in vitro. Together, these findings help refine the genetic architecture of CAC and extend our understanding of the biological and potential druggable pathways underlying CAC.

Transcatheter Tricuspid and Pulmonary Valve Repair and Replacement.

Severe tricuspid regurgitation (TR) is associated with significant mortality and morbidities. Currently, surgical tricuspid repair with annuloplasty is the gold standard treatment. However, the prohibitive risks of open surgery and increasing evidence that severe TR should be intervened on early has led to an outburst in the development and evolution of transcatheter tricuspid valve interventions (TTVI). These technologies are broadly categorized into direct suture annuloplasty devices, minimally invasive annuloplasty, direct ring annuloplasty devices, coaptation-based strategies, edge-to-edge repair devices, and transcatheter valve replacement. Each has its own set of advantages and limitations and have been tried, to varying degrees of success, in a myriad of pathoanatomic scenarios. Challenges faced in TTVI device and trial designs include heterogeneous patient populations, the need for quality imaging, variations of imaging requirements and anatomic criteria by device, hard-to-define clinical endpoints, and the poor prognosis carried by significant residual TR. Similar to tricuspid valve disease, pulmonic valve (PV) disease can occur on its own or secondary to a congenital heart defect, most commonly tetralogy of Fallot. Many patients with pulmonic stenosis or insufficiency often require repeat surgical interventions for other cardiac problems, highlighting the importance of developing transcatheter approaches to reduce the number of repeat open-heart surgeries required. Transcatheter PV replacement (TPVR) is growing in use and is the procedure of choice in patients with failed bioprostheses via valve-in-valve implantation. The Melody (Medtronic Inc., Minneapolis, Minnesota) and SAPIEN XT (Edwards Lifesciences Inc., Irvine, California) devices are the currently available TPVR technologies. Current limitations here include device kinking, the risk of stent fracture, anatomic difficulties, such as asymmetric right ventricular outflow tracts leading to poor landing zones and procedural risks of coronary artery and aortic root compression.

The Use of Transcatheter Devices for Mitral Repair and Replacement.

Recent advances in device design have resulted in a wide variety of transcatheter treatment options for patients with symptomatic mitral valve disease. Surgery remains the gold standard for patients with symptomatic, primary mitral regurgitation, while transcatheter devices can be considered in higher-risk patients. For secondary mitral regurgitation, optimal medical therapy and cardiac resynchronization are recommended. Recent evidence suggests that transcatheter alternatives may be considered as well. This review will provide an overview of current transcatheter mitral repair and replacement technologies. These include those that mimic open surgical procedures such as edge-to-edge repair, choral replacement, direct annuloplasty, and valve replacement.

HDAC9 is implicated in atherosclerotic aortic calcification and affects vascular smooth muscle cell phenotype.

Aortic calcification is an important independent predictor of future cardiovascular events. We performed a genome-wide association meta-analysis to determine SNPs associated with the extent of abdominal aortic calcification (n = 9,417) or descending thoracic aortic calcification (n = 8,422). Two genetic loci, HDAC9 and RAP1GAP, were associated with abdominal aortic calcification at a genome-wide level (P < 5.0 × 10-8). No SNPs were associated with thoracic aortic calcification at the genome-wide threshold. Increased expression of HDAC9 in human aortic smooth muscle cells promoted calcification and reduced contractility, while inhibition of HDAC9 in human aortic smooth muscle cells inhibited calcification and enhanced cell contractility. In matrix Gla protein-deficient mice, a model of human vascular calcification, mice lacking HDAC9 had a 40% reduction in aortic calcification and improved survival. This translational genomic study identifies the first genetic risk locus associated with calcification of the abdominal aorta and describes a previously unknown role for HDAC9 in the development of vascular calcification.

Optimal Treatment of Uncomplicated Type B Aortic Dissection: JACC Review Topic of the Week.

Historically, the gold standard for treating acute uncomplicated type B aortic dissection (TBAD) has been aggressive medical therapy to achieve optimal heart rate and blood pressure control. However, recent data have demonstrated that a significant proportion of patients with medically managed acute uncomplicated TBAD have late aorta-related complications, such as aneurysmal degeneration, that increase mortality and often necessitate surgical intervention. In this review, the authors review existing literature on uncomplicated TBAD and highlight contemporary surgical and medical strategies to manage this condition. Looking ahead, efforts are underway to identify and characterize a high-risk subgroup of acute uncomplicated TBAD patients who may benefit from early intervention.

Hepcidin Deficiency Protects Against Atherosclerosis.

Objective- Inflammatory stimuli enhance the progression of atherosclerotic disease. Inflammation also increases the expression of hepcidin, a hormonal regulator of iron homeostasis, which decreases intestinal iron absorption, reduces serum iron levels and traps iron within macrophages. The role of macrophage iron in the development of atherosclerosis remains incompletely understood. The objective of this study was to investigate the effects of hepcidin deficiency and decreased macrophage iron on the development of atherosclerosis. Approach and Results- Hepcidin- and LDL (low-density lipoprotein) receptor-deficient ( Hamp-/-/ Ldlr-/-) mice and Hamp+/+/ Ldlr-/- control mice were fed a high-fat diet for 21 weeks. Compared with control mice, Hamp-/-/ Ldlr-/- mice had decreased aortic macrophage activity and atherosclerosis. Because hepcidin deficiency is associated with both increased serum iron and decreased macrophage iron, the possibility that increased serum iron was responsible for decreased atherosclerosis in Hamp-/-/ Ldlr-/- mice was considered. Hamp+/+/ Ldlr-/- mice were treated with iron dextran so as to produce a 2-fold increase in serum iron. Increased serum iron did not decrease atherosclerosis in Hamp+/+/ Ldlr-/- mice. Aortic macrophages from Hamp-/-/ Ldlr-/- mice had less labile free iron and exhibited a reduced proinflammatory (M1) phenotype compared with macrophages from Hamp+/+/ Ldlr-/- mice. THP1 human macrophages treated with an iron chelator were used to model hepcidin deficiency in vitro. Treatment with an iron chelator reduced LPS (lipopolysaccharide)-induced M1 phenotypic expression and decreased uptake of oxidized LDL. Conclusions- In summary, in a hyperlipidemic mouse model, hepcidin deficiency was associated with decreased macrophage iron, a reduced aortic macrophage inflammatory phenotype and protection from atherosclerosis. The results indicate that decreasing hepcidin activity, with the resulting decrease in macrophage iron, may prove to be a novel strategy for the treatment of atherosclerosis.