Multi-biomarker mortality prediction in patients with aortic stenosis undergoing valve replacement

Biomarkers as Prognostic Markers for Aortic Stenosis: A Review

Aortic stenosis (AS) is the most frequent valvular heart disease among the older individuals. Current guidelines indicate intervention for patients with symptomatic or fast progressive severe AS and asymptomatic patients with a reduced left ventricular (LV) ejection fraction by 50%. Interestingly, myocardial damage may have already happened by the time symptoms appear or LV function deteriorates. Serum biomarkers can be an early indicator to show LV function decline and AS progression even before clinical symptom onset. Studies have shown that cardiac biomarkers have prognostic value in patients with AS. Hence, cardiac biomarkers can be helpful in determining the optimum time to intervene. Transcatheter aortic valve replacement is a less invasive alternative to conventional surgical aortic valve replacement. The elevation of cardiac biomarkers at discharge has been associated with 2-year mortality after transcatheter aortic valve replacement. The correlation between biomarkers and AS-associated morbidity and mortality is an area to explore further. The authors of this review article have discussed the role of cardiac biomarkers in patients with AS for better risk stratification and identification of patients who would benefit from early intervention.

Low levels of circulating methylated IRX3 are related to worse outcome after transcatheter aortic valve implantation in patients with severe aortic stenosis

BACKGROUND

Aortic stenosis (AS) is one of the most common cardiac diseases and major cause of morbidity and mortality in the elderly. Transcatheter aortic valve implantation (TAVI) is performed in such patients with symptomatic severe AS and reduces mortality for the majority of these patients. However, a significant percentage dies within the first two years after TAVI, such that there is an interest to identify parameters, which predict outcome and could guide pre-TAVI patient selection. High levels of cardiac fibrosis have been identified as such independent predictor of cardiovascular mortality after TAVI. Promoter hypermethylation commonly leads to gene downregulation, and the Iroquois homeobox 3 (IRX3) gene was identified in a genome-wide transcriptome and methylome to be hypermethylated and downregulated in AS patients. In a well-described cohort of 100 TAVI patients in which cardiac fibrosis levels were quantified histologically in cardiac biopsies, and which had a follow-up of up to two years, we investigated if circulating methylated DNA of IRX3 in the peripheral blood is associated with cardiac fibrosis and/or mortality in AS patients undergoing TAVI and thus could serve as a biomarker to add information on outcome after TAVI.

RESULTS

Patients with high levels of methylation in circulating IRX3 show a significantly increased survival as compared to patients with low levels of IRX3 methylation indicating that high peripheral IRX3 methylation is associated with an improved outcome. In the multivariable setting, peripheral IRX3 methylation acts as an independent predictor of all-cause mortality. While there is no significant correlation of levels of IRX3 methylation with cardiac death, there is a significant but very weak inverse correlation between circulating IRX3 promoter methylation level and the amount of cardiac fibrosis. Higher levels of peripheral IRX3 methylation further correlated with decreased cardiac IRX3 expression and vice versa.

CONCLUSIONS

High levels of IRX3 methylation in the blood of AS patients at the time of TAVI are associated with better overall survival after TAVI and at least partially reflect myocardial IRX3 expression. Circulating methylated IRX3 might aid as a potential biomarker to help guide both pre-TAVI patient selection and post-TAVI monitoring.

Pathophysiology, emerging techniques for the assessment and novel treatment of aortic stenosis

Our perspectives on aortic stenosis (AS) are changing. Evolving from the traditional thought of a passive degenerative disease, developing a greater understanding of the condition's mechanistic underpinning has shifted the paradigm to an active disease process. This advancement from the 'wear and tear' model is a result of the growing economic and health burden of AS, particularly within industrialised countries, prompting further research. The pathophysiology of calcific AS (CAS) is complex, yet can be characterised similarly to that of atherosclerosis. Progressive remodelling involves lipid-protein complexes, with lipoprotein(a) being of particular interest for diagnostics and potential future treatment options.There is an unmet clinical need for asymptomatic patient management; no pharmacotherapies are proven to slow progression and intervention timing varies. Novel approaches are developing to address this through: (1) screening with circulating biomarkers; (2) development of drugs to slow disease progression and (3) early valve intervention guided by medical imaging. Existing biomarkers (troponin and brain natriuretic peptide) are non-specific, but cost-effective predictors of ventricular dysfunction. In addition, their integration with cardiovascular MRI can provide accurate risk stratification, aiding aortic valve replacement decision making. Currently, invasive intervention is the only treatment for AS. In comparison, the development of lipoprotein(a) lowering therapies could provide an alternative; slowing progression of CAS, preventing left ventricular dysfunction and reducing reliance on surgical intervention.The landscape of AS management is rapidly evolving. This review outlines current understanding of the pathophysiology of AS, its management and future perspectives for the condition's assessment and treatment.

Severe Aortic Valve Stenosis and Pulmonary Hypertension: A Systematic Review of Non-Invasive Ways of Risk Stratification, Especially in Patients Undergoing Transcatheter Aortic Valve Replacement

Patients with severe aortic valve stenosis and concomitant pulmonary hypertension show a significantly reduced survival prognosis. Right heart catheterization as a preoperative diagnostic tool to determine pulmonary hypertension has been largely abandoned in recent years in favor of echocardiographic criteria. Clinically, determination of echocardiographically estimated systolic pulmonary artery pressure falls far short of invasive right heart catheterization data in terms of accuracy. The aim of the present systematic review was to highlight noninvasive possibilities for the detection of pulmonary hypertension in patients with severe aortic valve stenosis, with a special focus on cardiovascular biomarkers. A total of 525 publications regarding echocardiography, cardiovascular imaging and biomarkers related to severe aortic valve stenosis and pulmonary hypertension were analyzed in a systematic database analysis using PubMed Central®. Finally, 39 publications were included in the following review. It was shown that the current scientific data situation, especially regarding cardiovascular biomarkers as non-invasive diagnostic tools for the determination of pulmonary hypertension in severe aortic valve stenosis patients, is poor. Thus, there is a great scientific potential to combine different biomarkers (biomarker scores) in a non-invasive way to determine the presence or absence of PH.

Novel predictive role for mid-regional proadrenomedullin in moderate to severe aortic stenosis

OBJECTIVE

We investigated the prognostic significance of selected known and novel circulating biomarkers in aortic stenosis (AS).

METHODS

N-terminal pro-BNP (NT-proBNP), high-sensitivity troponin-T (hsTnT), growth differentiation factor-15 (GDF-15), suppression of tumorigenicity-2 (ST2), mid-regional proadrenomedullin (MR-proADM) and mid-regional proatrial natriuretic peptide (MR-proANP) were measured in patients with moderate to severe AS, New York Heart Association (NYHA) class I-II and left ventricular ejection fraction ≥50%, recruited consecutively across five centres from 2011 to 2018. Their ability to predict both primary (all-cause mortality, heart failure hospitalisation or progression to NYHA class III-IV) and secondary (additionally incorporating syncope and acute coronary syndrome) outcomes was determined by competing risk analyses.

RESULTS

Among 173 patients with AS (age 69±11 years, 55% male, peak transaortic velocity (Vmax) 4.0±0.8 m/s), the primary and secondary outcomes occurred in 59 (34%) and 66 (38%), respectively. With aortic valve replacement as a competing risk, the primary outcome was determined consistently by the comorbidity index and each selected biomarker except ST2 (p<0.05), independent of NYHA class, Vmax, LV-global longitudinal strain and serum creatinine. MR-proADM had the highest discriminative value for both primary (subdistribution HR (SHR) 11.3, 95% CI 3.9 to 32.7) and secondary outcomes (SHR 12.6, 95% CI 4.7 to 33.5). Prognostic assessment of dual-biomarker combinations identified MR-proADM plus either hsTnT or NT-proBNP as the best predictive model for both clinical outcomes. Paired biomarker models were not superior to those including MR-proADM as the sole circulating biomarker.

CONCLUSION

MR-proADM most powerfully portended worse prognosis and should be further assessed as possibly the biomarker of choice for risk stratification in AS.

Impact of osteogenic activity on degenerative aortic valve disease in patients with osteoporotic hip fracture

BACKGROUND

Previous studies have proposed that osteogenic and apoptotic processes of valve interstitial cells contribute to the mineralization and then calcification of the aortic valve. Osteoblast-like cells subsequently mediate calcification of the aortic valve as part of a highly regulated process analogous to skeletal bone formation. The objective of this study was to evaluate the pathogenesis of the sclerotic/calcific changes in the aortic valve from histological and biological findings, and investigate the role of osteoblasts in the calcified pathway of aortic stenosis.

METHODS

Preoperative echocardiography in 550 consecutive patients with osteoporotic hip fracture were retrospectively examined (475 females, mean 25th-75th, 89 [85-93] years). One hundred sixteen patients were under medical treatment with anti-osteoporosis drugs. We evaluated the prevalence and degree of degenerative changes in the aortic valve and examined the associations of bone turnover biomarkers N-terminal pro-peptide of type 1 collagen (P1NP) and serum tartrate-resistant acid phosphatase (TRACP-5b) with degenerative calcific changes in the aortic valve.

RESULTS

Of 550 patients, 112 patients (20.9%) showed no leaflet calcification; 296 (53.8%), 1 leaflet calcification; and 142 (25.8%), 2 ≥ leaflets calcification. Significant (peak velocity ≥ 3.0m/s) Aortic stenosis was found in 43 patients (7.8%). In patients who were not taking anti-osteoporotic drugs, P1NP was higher in the 2 ≥ leaflets calcification group than in the other groups (p < 0.01). TRACP-5b was not significantly different among the three groups (p = 0.15).

CONCLUSIONS

Degenerative changes in the aortic valve were related to bone biomarker activation in osteoporotic hip fracture patients.

Biomarkers Associated with Mortality in Aortic Stenosis: A Systematic Review and Meta-Analysis

The optimal timing of aortic valve replacement (AVR) remains controversial. Several biomarkers reflect the underlying pathophysiological processes in aortic stenosis (AS) and may be of use as mortality predictors. The aim of this systematic review and meta-analysis is to evaluate the blood biomarkers utilised in AS and assess whether they associate with mortality. PubMed and Embase were searched for studies reporting baseline biomarker level and mortality outcomes in patients with AS. A total of 83 studies met the inclusion criteria and were systematically reviewed. Of these, 21 reporting brain natriuretic peptide (BNP), N-terminal pro B-type natriuretic peptide (NT-proBNP), Troponin and Galectin-3 were meta-analysed. Pooled analysis demonstrated that all-cause mortality was significantly associated with elevated baseline levels of BNP (HR 2.59; 95% CI 1.95–3.44; p < 0.00001), NT-proBNP (HR 1.73; 95% CI 1.45–2.06; p = 0.00001), Troponin (HR 1.65; 95% CI 1.31–2.07; p < 0.0001) and Galectin-3 (HR 1.82; 95% CI 1.27–2.61; p < 0.001) compared to lower baseline biomarker levels. Elevated levels of baseline BNP, NT-proBNP, Troponin and Galectin-3 were associated with increased all-cause mortality in a population of patients with AS. Therefore, a change in biomarker level could be considered to refine optimal timing of intervention. The results of this meta-analysis highlight the importance of biomarkers in risk stratification of AS, regardless of symptom status.