Endothelial nitric oxide synthase alterations are independent of turbulence in the aorta of patients with a unicuspid aortic valve

Reactivation of Oxidized Soluble Guanylate Cyclase as a Novel Treatment Strategy to Slow Progression of Calcific Aortic Valve Stenosis: Preclinical and Randomized Clinical Trials to Assess Safety and Efficacy

BACKGROUND

Pharmacological treatments for fibrocalcific aortic valve stenosis (FCAVS) have been elusive for >50 years. Here, we tested the hypothesis that reactivation of oxidized sGC (soluble guanylate cyclase), the primary receptor for nitric oxide, with ataciguat is a safe and efficacious strategy to slow progression of FCAVS.

METHODS

We used quantitative real-time reverse transcription polymerase chain reaction, Western blotting, and immunohistochemistry to characterize sGC signaling and the biological effects of ataciguat on signaling cascades related to nitric oxide, calcification, and fibrosis in excised human aortic valve tissue, aortic valve interstitial cells, and mouse aortic valves. We then conducted randomized, placebo-controlled phase I (14-day safety/tolerance) and phase II (6-month efficacy) trials in patients with moderate aortic valve stenosis.

RESULTS

In excised human tissue, we found robust losses in sGC signaling despite upregulation of sGC subunits. In vitro, ataciguat increased sGC signaling and reduced BMP2 (bone morphogenetic protein 2) signaling in aortic valve interstitial cells. In mice with established FCAVS, treatment with ataciguat attenuated BMP signaling and slowed progression of valve calcification and dysfunction. In a phase I, randomized, placebo-controlled trial, treatment with ataciguat for 2 weeks was safe and well tolerated in patients with moderate FCAVS (https://www.clinicaltrials.gov; Unique identifier: NCT02049203). In a separate phase II, randomized, placebo-controlled trial, treatment with ataciguat for 6 months slowed the progression of aortic valve calcification and tended to slow the progression of valvular and ventricular dysfunction in patients with moderate FCAVS (https://www.clinicaltrials.gov; Unique identifier: NCT02481258).

CONCLUSIONS

Collectively, this study highlights the therapeutic potential of the targeted restoration of the diseased/inactive form of sGC for treatment of FCAVS.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02049203. URL: https://www.clinicaltrials.gov; Unique identifier: NCT02481258.

Aortic Unicuspid Valve Surgery in a Young Patient: A Case Report

The patient was a 33-year-old male. He was noted to have a systolic murmur in the aortic valve region during childhood and underwent balloon valvuloplasty at a pediatric clinic. However, he was not followed up thereafter. Recently, he began experiencing exertional dyspnea and presented to our cardiology department. Detailed examinations, including echocardiography, revealed moderate aortic regurgitation and stenosis, and a unicuspid aortic valve was suspected morphologically. After discussing the findings with the patient, he opted for surgical treatment. The operation was performed under general anesthesia via a median sternotomy. Intraoperative inspection of the aortic valve confirmed a unicuspid morphology, consistent with the preoperative findings. The unicuspid valve was excised and replaced with a mechanical valve (St. Jude Medical (SJM) 25 mm). The surgery was completed without complications, and the postoperative course was uneventful. The patient was discharged home on postoperative day 10. Five years postoperatively, the patient remains asymptomatic and in good condition. Given the rarity of unicuspid aortic valve cases, this report is of significant clinical value.

A rare and unique case: aortic valve replacement in a young adult with a stenotic unicommissural unicuspid aortic valve

Unicuspid aortic valve (UAV) is a rare congenital cardiac anomaly. There are two forms of UAV, including unicuspid acommissural and unicuspid unicommissural. Definitive management for UAV is surgical intervention, but due to the rarity of UAV, the long-term surgical outcomes as well as overall prognosis are not known. Here, we present the case of a 19-year-old patient who was found to have a UAV prenatally and underwent a mechanical aortic valve replacement through an upper hemi-sternotomy due to elevated aortic stenosis gradients and presence of symptoms.

Layer-specific Nos3 expression and genotypic distribution in bicuspid aortic valve aortopathy

OBJECTIVES

We hypothesized that expression and activity of nitric oxide synthase-3 enzyme (Nos3) in bicuspid aortic valve (BAV) aortopathy are related to tissue layer and Nos3 genotype.

METHODS

Gene expression of Nos3 and platelet and endothelial cell adhesion molecule-1 (Pecam1) and NOS activity were measured in intima-containing media and adventitial specimens of ascending aortic tissue. The presence of 2 Nos3 single-nucleotide polymorphisms (SNPs; -786T/C and 894G/T) was determined for non-aneurysmal (NA) and aneurysmal patients with BAV (n = 40, 89, respectively); patients with tricuspid aortic valve (TAV) and aneurysm (n = 151); and NA patients with TAV (n = 100).

RESULTS

Elevated Nos3 relative to Pecam1 and reduced Pecam1 relative to a housekeeping gene were observed within intima-containing aortic specimens from BAV patients when compared with TAV patients. Lower Nos3 in the adventitia of aneurysmal specimens was noted when compared with specimens of NA aorta, independent of valve morphology. NOS activity was similar among cohorts in media/intima and decreased in the diseased adventitia, relative to control patients. Aneurysmal BAV patients exhibited an under-representation of the wild-type genotype for -786 SNP. No differences in genotype distribution were noted for 894 SNP. Primary intimal endothelial cells from patients with at least 1 C allele at -786 SNP exhibited lower Nos3 when compared with wild-type cells.

CONCLUSIONS

These findings of differential Nos3 in media/intima versus adventitia depending on valve morphology or aneurysm reveal new information regarding aneurysmal pathophysiology and support our ongoing assertion that there are distinct mechanisms giving rise to ascending aortopathy in BAV and TAV patients.