Bicuspid Aortic Valve Alters Aortic Protein Expression Profile in Neonatal Coarctation Patients

Late complication rates after aortic coarctation repair in patients with or without a bicuspid aortic valve

OBJECTIVE

Patients with previously repaired aortic coarctation (CoA) are at risk of developing late surgical complications. Many patients with CoA also have a bicuspid aortic valve (BAV). We sought to determine in patients with repaired CoA whether the presence of BAV is associated with more cardiovascular reinterventions during follow-up.

METHODS

Adults with previously repaired simple CoA were recruited from our Adult Congenital Heart Disease database (Sydney, Australia). The incidence of complications relating to the 'CoA-site' (descending aortic aneurysm or dissection, or recoarctation) and the 'AV/AscAo' (aortic valve or ascending aortic pathology) that required intervention was compared between those with BAV ('CoA-BAV') and without BAV ('CoA-only').

RESULTS

Of 146 patients with repaired CoA, 101 (69%) had BAV. Age at CoA repair was similar (median 6.0 (IQR 0.5-14.0) years vs 5.0 (IQR 0.5-11.0) years, p=0.44), as was the distribution of repair types, with end-to-end repair the most common in both groups (45.9% vs 45.6%). At a median of 28 years following initial repair, a significantly higher proportion of patients with CoA-BAV required cardiovascular reintervention (45.5% vs 20.0%, p=0.003). Whereas 'CoA-site' complications were more common than 'AV/AscAo' complications in patients with CoA only (13.3% and 0%, respectively), patients with CoA-BAV had a high prevalence of both 'CoA-site' as well as 'AV/AscAo' complications (19.8% and 21.8%, respectively). Overall survival was similar (p=0.42).

CONCLUSION

In adults with repaired CoA, patients with CoA-BAV are more than twice as likely to require cardiovascular reintervention by early-to-mid-adult life compared with those with CoA alone. Despite this, no difference in survival outcomes was observed.

Bicuspid aortic valve: different clinical profiles for subjects with versus without repaired aortic coarctation

Objectives

A small proportion of patients undergoing bicuspid aortic valve (BAV) intervention have had prior repair of aortic coarctation (CoA). We aimed to describe phenotypic differences between BAV patients, comparing those with versus those without previous coarctation repair.

Methods

556 adults with BAV who had undergone aortic valve and/or ascending aortic surgery were identified, and relevant clinical and operative details were retrospectively analysed.

Results

Of the total cohort, 532 patients (95.7%) had isolated BAV (‘BAV-only’), and 24 (4.3%) had had a previous successful CoA repair (‘BAV-CoA’). The median age at surgery was significantly lower in BAV-CoA patients compared with BAV-only (median, IQR: 40 years, 26–57 vs 62 years, 51–69, p<0.001). Indications for surgery also differed, with BAV-CoA patients much more likely to undergo surgery for aortic regurgitation (BAV-CoA 38% vs BAV-only 13%, p<0.001); patients with isolated BAV were more likely to require surgery for aortic stenosis (BAV-only 75% vs BAV-CoA 50%, p<0.001). Two different BAV morphotypes were commoner in the BAV-CoA group; type 0 valves (24% vs 8%, p<0.05) and type 2 valves (12% vs 3%, p<0.05). The proportion of patients undergoing concomitant aortic surgery at the time of valve surgery were similar (BAV-only 38% vs BAV-CoA 42%, p=0.8).

Conclusion

In adult patients undergoing aortic valve surgery for BAV disease, those with a prior history of repaired CoA underwent surgery at a very much younger age, and a higher proportion required intervention for aortic regurgitation.

Changes in inflammation and oxidative stress signalling pathways in coarcted aorta triggered by bicuspid aortic valve and growth in young children

Neonates with coarctation of the aorta (CoA) combined with a bicuspid aortic valve (BAV) show significant structural differences compared to neonatal CoA patients with a normal tricuspid aortic valve (TAV). These effects are likely to change over time in response to growth. This study investigated proteomic differences between coarcted aortic tissue of BAV and TAV patients in children older than one month. Aortic tissue just proximal to the coarctation site was collected from 10 children (BAV; n=6, 1.9±1.7 years, TAV; n=4, 1.7±1.5 years, (mean ± SEM, P=0.92.) Tissue were snap frozen, proteins extracted, and the extracts used for proteomic and phosphoproteomic analysis using Tandem Mass Tag (TMT) analysis. A total of 1811 protein and 76 phosphoprotein accession numbers were detected, of which 40 proteins and 6 phosphoproteins were significantly differentially expressed between BAV and TAV patients. Several canonical pathways involved in inflammation demonstrated enriched protein expression, including acute phase response signalling, EIF2 signalling and macrophage production of IL12 and reactive oxygen species. Acute phase response signalling also demonstrated enriched phosphoprotein expression, as did Th17 activation. Other pathways with significantly enriched protein expression include degradation of superoxide radicals and several pathways involved in apoptosis. This work suggests that BAV CoA patients older than one month have an altered proteome consistent with changes in inflammation, apoptosis and oxidative stress compared to TAV CoA patients of the same age. There is no evidence of structural differences, suggesting the pathology associated with BAV evolves with age in paediatric CoA patients.

Identified plasma proteins related to vascular structure are associated with coarctation of the aorta in children

BACKGROUND

Coarctation of the aorta (CoA), presenting with local stenosis of the aorta is involved in many cardiovascular processes. However, there has been little research on the mechanism of coarctation of the aorta.

METHODS

Altered proteins were identified by isobaric tag for relative and absolute quantitation (iTRAQ) technology in 8 participants, and further analysed by heatmap, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) and Search Tool for the Retrieval of Interacting Gene (STRING). Of these, two vascular structure-related proteins were further validated by using enzyme-linked immunosorbent assay (ELISA) in a new cohort of CoA patients.

RESULTS

39 differentially expressed plasma proteins were first identified in patients with coarctation of the aorta by iTRAQ. Of these, fibulin-1 (FBLN1) and insulin-like growth factor-binding protein complex acid labile subunit (ALS) were considered candidates and further validation also showed that the level of FBLN1 in the CoA group (8.92 ± 2.36 μg/ml) was significantly higher compared with control group (6.13 ± 1.94 μg/ml), and the level of ALS in CoA children (348.08 ± 216.74 ng/ml) was significantly lower than the level in normal children (619.46 ± 274.08 ng/ml).

CONCLUSIONS

The differentially expressed proteins identified in the plasma from CoA patients indicated that they may play critical roles in CoA and that they could potentially be utilized as biomarkers for diagnosis. Altered vascular related proteins were associated with COA. These results provide a foundation for further understanding and studying the aetiology and pathogenesis of coarctation of the aorta.