Endothelin (ET)-1 is a potent vasoconstrictor peptide originally isolated from endothelial cells. Its production is stimulated in a variety of different cell types under the influence of risk factors for cardiovascular disease and during the development of cardiovascular disease. Based on these observations and the biological effects induced by ET-1, including profound vasoconstriction, pro-inflammatory actions, mitogenic and proliferative effects, stimulation of free radical formation and platelet activation, ET-1 has been implicated as an important factor in the development of vascular dysfunction and cardiovascular disease. In the following the pathogenic role of ET-1, the mechanisms underlying the involvement of ET-1 for the development of vascular dysfunction and the potentially beneficial therapeutic effects of selective ET(A) and dual ET(A)/ET(B) receptor antagonists will be discussed. In particular the changes of pathophysiological importance mediated by ET-1 in clinical studies are reviewed. These changes may be of significance for the development of various cardiovascular diseases beyond pulmonary arterial hypertension which is the currently approved indication for ET receptor antagonists.

The clinical effect of routine oxygen therapy in patients with suspected acute myocardial infarction who do not have hypoxemia at baseline is uncertain. In this registry-based randomized clinical trial, we used nationwide Swedish registries for patient enrollment and data collection. Patients with suspected myocardial infarction and an oxygen saturation of 90% or higher were randomly assigned to receive either supplemental oxygen (6 liters per minute for 6 to 12 hours, delivered through an open face mask) or ambient air. A total of 6629 patients were enrolled. The median duration of oxygen therapy was 11.6 hours, and the median oxygen saturation at the end of the treatment period was 99% among patients assigned to oxygen and 97% among patients assigned to ambient air. Hypoxemia developed in 62 patients (1.9%) in the oxygen group, as compared with 254 patients (7.7%) in the ambient-air group. The median of the highest troponin level during hospitalization was 946.5 ng per liter in the oxygen group and 983.0 ng per liter in the ambient-air group. The primary end point of death from any cause within 1 year after randomization occurred in 5.0% of patients (166 of 3311) assigned to oxygen and in 5.1% of patients (168 of 3318) assigned to ambient air (hazard ratio, 0.97; 95% confidence interval [CI], 0.79 to 1.21; P=0.80). Rehospitalization with myocardial infarction within 1 year occurred in 126 patients (3.8%) assigned to oxygen and in 111 patients (3.3%) assigned to ambient air (hazard ratio, 1.13; 95% CI, 0.88 to 1.46; P=0.33). The results were consistent across all predefined subgroups. Routine use of supplemental oxygen in patients with suspected myocardial infarction who did not have hypoxemia was not found to reduce 1-year all-cause mortality. (Funded by the Swedish Heart–Lung Foundation and others; DETO2X-AMI ClinicalTrials.gov number, NCT01787110.)

Functional integrity of the vascular endothelium is of fundamental importance for normal vascular function. A key factor regulating endothelial function is the bioavailability of nitric oxide (NO). Recently, the enzyme arginase has emerged as an important regulator of NO production by competing for l-arginine, which is a substrate for both arginase and NO synthase. Increased activity of arginase may reduce the availability of l-arginine for NO synthase, thus reducing NO production, increasing formation of reactive oxygen species, and leading ultimately to endothelial dysfunction. Increased activity and expression of arginase have been demonstrated in several pathological cardiovascular conditions, including hypertension, pulmonary arterial hypertension, atherosclerosis, myocardial ischaemia, congestive heart failure, and vascular dysfunction in diabetes mellitus. Experimental studies have demonstrated that inhibition of arginase under these conditions increases NO bioavailability, reduces oxidative stress, improves vascular function, and protects against ischaemia–reperfusion injury. Initial clinical interventional studies are also promising. The purpose of this review is to discuss the role of arginase in cardiovascular pathologies, its contribution to the development of several cardiovascular disease states and the feasibility of using arginase inhibition as a therapeutic strategy.

Background: Observational and small, randomized studies suggest that influenza vaccine may reduce future cardiovascular events in patients with cardiovascular disease. Methods: We conducted an investigator-initiated, randomized, double-blind trial to compare inactivated influenza vaccine with saline placebo administered shortly after myocardial infarction (MI; 99.7% of patients) or high-risk stable coronary heart disease (0.3%). The primary end point was the composite of all-cause death, MI, or stent thrombosis at 12 months. A hierarchical testing strategy was used for the key secondary end points: all-cause death, cardiovascular death, MI, and stent thrombosis. Results: Because of the COVID-19 pandemic, the data safety and monitoring board recommended to halt the trial before attaining the prespecified sample size. Between October 1, 2016, and March 1, 2020, 2571 participants were randomized at 30 centers across 8 countries. Participants assigned to influenza vaccine totaled 1290 and individuals assigned to placebo equaled 1281; of these, 2532 received the study treatment (1272 influenza vaccine and 1260 placebo) and were included in the modified intention to treat analysis. Over the 12-month follow-up, the primary outcome occurred in 67 participants (5.3%) assigned influenza vaccine and 91 participants (7.2%) assigned placebo (hazard ratio, 0.72 [95% CI, 0.52–0.99]; P =0.040). Rates of all-cause death were 2.9% and 4.9% (hazard ratio, 0.59 [95% CI, 0.39–0.89]; P =0.010), rates of cardiovascular death were 2.7% and 4.5%, (hazard ratio, 0.59 [95% CI, 0.39–0.90]; P =0.014), and rates of MI were 2.0% and 2.4% (hazard ratio, 0.86 [95% CI, 0.50–1.46]; P =0.57) in the influenza vaccine and placebo groups, respectively. Conclusions: Influenza vaccination early after an MI or in high-risk coronary heart disease resulted in a lower risk of a composite of all-cause death, MI, or stent thrombosis, and a lower risk of all-cause death and cardiovascular death, as well, at 12 months compared with placebo. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT02831608.

Background—: Endothelial dysfunction plays an important role in the early development of atherosclerosis and vascular complications in type 2 diabetes mellitus. Increased expression and activity of arginase, metabolizing the nitric oxide substrate l -arginine, may result in reduced production of nitric oxide and thereby endothelial dysfunction. We hypothesized that inhibition of arginase activity improves endothelial function in patients with coronary artery disease (CAD) and type 2 diabetes mellitus. Methods and Results—: Three groups of subjects were included: 16 patients with CAD, 16 patients with CAD and type 2 diabetes mellitus (CAD+Diabetes), and 16 age-matched healthy control subjects. Forearm endothelium-dependent and endothelium-independent vasodilatation were assessed with venous occlusion plethysmography before and during intra-arterial infusion of the arginase inhibitor N ^ω -hydroxy-nor- l -arginine (nor-NOHA; 0.1 mg/min). Nor-NOHA was also coinfused with the nitric oxide synthase inhibitor ( N ^G -monomethyl L-arginine). The expression of arginase was determined in the internal mammary artery of patients undergoing bypass surgery. Nor-NOHA markedly increased endothelium-dependent vasodilatation (up to 2-fold) in patients with CAD+Diabetes and CAD ( P <0.001) but not in the control group. N ^G -monomethyl L-arginine completely inhibited the increase in endothelium-dependent vasodilatation induced by nor-NOHA. Endothelium-independent vasodilatation was slightly improved by nor-NOHA in the CAD+Diabetes group. Arginase I was expressed in vascular smooth muscle cells and endothelial cells, and arginase II was expressed in endothelial cells of patients with and without diabetes mellitus. Conclusions—: Arginase inhibition markedly improves endothelial function in patients with CAD and type 2 diabetes mellitus suggesting that increased arginase activity is a key factor in the development of endothelial dysfunction.