Biomarkers in Aortic Stenosis: A Systematic Review

Adipokines are possible risk markers for aortic stenosis requiring surgery

OBJECTIVES

Aortic stenosis (AS) is the most prevalent valvular heart disease among adults. The adipocyte-derived hormones, leptin and adiponectin, have profound metabolic actions. We examined whether these adipokines are independently associated with future aortic valve replacement (AVR).

DESIGN

In this longitudinal case-control study, we identified 336 cases who had undergone AVR due to AS, and who had previously participated in population-based health surveys. Two referents were matched to each case and leptin and adiponectin concentrations were analysed from stored baseline survey samples. Uni- and multivariable logistic regression analyses were used to estimate the risk of future AVR. An additional cohort was identified for validation including 106 cases with AVR and 212 matched referents.

RESULTS

Median age (interquartile range (IQR)) in years at survey was 59.9 (10.4) and at surgery 68.3 (12.7), and 48% were women. An elevated concentration of leptin was not associated with future AVR (odds ratio [95% confidence interval]) (1.10 [0.92-1.32]), although leptin was associated with a higher risk in patients with coronary artery disease (CAD) having more than 5 years between survey and AVR (1.41 [1.08-1.84]). Adiponectin was not associated with higher risk for future AVR (0.95 [0.82-1.11]), although after stratification for age, higher levels were associated with reduced risk for AVR in persons aged ≥60 years at surgery (0.79 [0.64-0.98]). In the validation study, leptin was associated with future AVR whereas adiponectin was not. None of the associations remained significant after adjustment for body mass index (BMI).

CONCLUSIONS

The adipokine leptin may promote the development of AS.

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.

B-type natriuretic peptide and N-terminal Pro-B-type natriuretic peptide in severe aortic stenosis: a comprehensive literature review

B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-pro BNP) are cardiac biomarkers that are released in response to increased ventricular and atrial wall stress. Aortic stenosis (AS) leads to hemodynamic changes and left ventricular hypertrophy and may be associated with natriuretic peptide levels. Several studies have shown that increased natriuretic peptide levels are correlated with AS severity and can predict the need for intervention. It can be useful in risk stratification, monitoring follow-up, and predicting cardiovascular outcomes of patients with severe AS. This paper aims to summarize the evidence of the role of BNP and NT-pro BNP in AS, before and after intervention.

Association of high-sensitivity troponin T with outcomes in asymptomatic non-severe aortic stenosis: a post-hoc substudy of the SEAS trial

BACKGROUND

High-sensitivity Troponin T (hsTnT), a biomarker of cardiomyocyte overload and injury, relates to aortic valve replacement (AVR) and mortality in severe aortic stenosis (AS). However, its prognostic value remains unknown in asymptomatic patients with AS. We aimed to investigate if an hsTnT level >14 pg/mL (above upper limit of normal 99th percentile) is associated with echocardiographic AS-severity, subsequent AVR, ischaemic coronary events (ICE), and mortality in asymptomatic patients with non-severe AS.

METHODS

In this post-hoc sub-analysis of the multicentre, randomised, double-blind, placebo-controlled SEAS trial (ClinicalTrials.gov, NCT00092677), we included asymptomatic patients with mild to moderate-severe AS. We ascertained baseline and 1-year hsTnT concentrations and examined the association between baseline levels and the risk of the primary composite endpoint, defined as the first event of all-cause mortality, isolated AVR (without coronary artery bypass grafting (CABG)), or ICE. Multivariable regressions and competing risk analyses examined associations of hsTnT level >14 pg/mL with clinical correlates and 5-year risk of the primary endpoint.

FINDINGS

Between January 6, 2003, and March 4, 2004, a total of 1873 patients were enrolled in the SEAS trial, and 1739 patients were included in this post-hoc sub-analysis. Patients had a mean (SD) age of 67.5 (9.7) years, 61.0% (1061) were men, 17.4% (302) had moderate-severe AS, and 26.0% (453) had hsTnT level >14 pg/mL. The median hsTnT difference from baseline to 1-year was 0.8 pg/mL (IQR, -0.4 to 2.3). In adjusted linear regression, log(hsTnT) did not correlate with echocardiographic AS severity (p = 0.36). In multivariable Cox regression, a hsTnT level >14 pg/mL vs. hsTnT ≤14 pg/mL was associated with an increased risk of the primary composite endpoint (HR, 1.41; 95% CI, 1.18-1.70; p = 0.0002). In a competing risk model of first of the individual components of the primary endpoint, a hsTnT level >14 pg/mL was associated with ICE risk (HR 1.71; 95% CI, 1.23-2.38; p = 0.0013), but not with isolated AVR (p = 0.064) or all-cause mortality (p = 0.49) as the first event.

INTERPRETATION

hsTnT level is within the reference range (≤14 pg/mL) in 3 out of 4 non-ischaemic patients with asymptomatic mild-to-moderate AS and remains stable during a 1-year follow-up regardless of AS-severity. An hsTnT level >14 pg/mL was mainly associated with subsequent ICE, which suggest that hsTnT concentration is primarily a risk marker of subclinical coronary atherosclerotic disease.

FUNDING

Merck & Co., Inc., the Schering-Plough Corporation, the Interreg IVA program, Roche Diagnostics Ltd., and Gangstedfonden. Open access publication fee funding provided by prof. Olav W. Nielsen and Department of Cardiology, Bispebjerg University Hospital, Denmark.

Prognostic role of pre- and postinterventional myocardial injury in patients undergoing transcatheter aortic valve implantation

BACKGROUND

Chronic pre-procedural and acute post-procedural myocardial injury are frequently observed in patients with aortic stenosis undergoing transcatheter aortic valve implantation (TAVI). The aim of our study was to investigate the prognostic role of high sensitivity cardiac troponins (hs-cTns) elevation before and after TAVI.

METHODS

106 patients with severe aortic stenosis who underwent TAVI were enrolled. High sensitivity cardiac troponin T (hs-cTnT) was measured before and after TAVI (6, 24, 48, 72 hours). Post-procedural myocardial damage was defined as a 15-fold rise in hs-cTnT upper reference limit (URL) after TAVI. The clinical endpoints were all cause death, cardiovascular death and re-hospitalization at 24 months follow-up.

RESULTS

Before TAVI, hs-cTnT median value was 0.03 μg/L (2.3±2.1 fold over URL). After TAVI procedure, myocardial damage (MD), as defined by VARC-2 criteria, was observed in 40 patients (38%) (MD group). In our population, logarithmically transformed hs-cTnTs were independently associated with all-cause mortality at 24 months F/U (pre-TAVI hs-cTnT: Hazard ratio [HR] 2.2, 95% confidence interval [CI]: 1.1 to 4.4, P=0.027). No significant differences were observed between the MD and non-MD groups for the three endpoints of all cause death (p log rank: 0.15), cardiovascular death (p log rank: 0.86) and re-hospitalization (p log rank: 0.87).

CONCLUSIONS

Only baseline hs-cTnT levels correlated with outcomes at 24 months of follow-up. Chronic pre-procedural myocardial injury significantly affects prognosis after TAVI.

Coronary Artery Disease and Aortic Valve Stenosis: A Urine Proteomics Study

Coronary artery disease (CAD) and the frequently coexisting aortic valve stenosis (AVS) are heart diseases accounting for most cardiac surgeries. These share many risk factors, such as age, diabetes, hypertension, or obesity, and similar pathogenesis, including endothelial disruption, lipid and immune cell infiltration, inflammation, fibrosis, and calcification. Unsuspected CAD and AVS are sometimes detected opportunistically through echocardiography, coronary angiography, and magnetic resonance. Routine biomarkers for early detection of either of these atherosclerotic-rooted conditions would be important to anticipate the diagnosis. With a noninvasive collection, urine is appealing for biomarker assessment. We conducted a shotgun proteomics exploratory analysis of urine from 12 CAD and/or AVS patients and 11 controls to identify putative candidates to differentiate these diseases from healthy subjects. Among the top 20 most dysregulated proteins, TIMP1, MMP2 and vWF stood out, being at least 2.5× increased in patients with CAD/AVS and holding a central position in a network of protein-protein interactions. Moreover, their assessment in an independent cohort (19 CAD/AVS and 10 controls) evidenced strong correlations between urinary TIMP1 and vWF levels and a common cardiovascular risk factor - HDL (r = 0.59, p < 0.05, and r = 0.64, p < 0.01, respectively).

Models and Techniques to Study Aortic Valve Calcification in Vitro, ex Vivo and in Vivo. An Overview

Aortic valve stenosis secondary to aortic valve calcification is the most common valve disease in the Western world. Calcification is a result of pathological proliferation and osteogenic differentiation of resident valve interstitial cells. To develop non-surgical treatments, the molecular and cellular mechanisms of pathological calcification must be revealed. In the current overview, we present methods for evaluation of calcification in different ex vivo, in vitro and in vivo situations including imaging in patients. The latter include echocardiography, scanning with computed tomography and magnetic resonance imaging. Particular emphasis is on translational studies of calcific aortic valve stenosis with a special focus on cell culture using human primary cell cultures. Such models are widely used and suitable for screening of drugs against calcification. Animal models are presented, but there is no animal model that faithfully mimics human calcific aortic valve disease. A model of experimentally induced calcification in whole porcine aortic valve leaflets ex vivo is also included. Finally, miscellaneous methods and aspects of aortic valve calcification, such as, for instance, biomarkers are presented.

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.

Aortic valve disease in diabetes: Molecular mechanisms and novel therapies

Valve disease and particularly calcific aortic valve disease (CAVD) and diabetes (DM) are progressive diseases constituting a global health burden for all aging societies (Progress in Cardiovascular Diseases. 2014;56(6):565: Circulation Research. 2021;128(9):1344). Compared to non‐diabetic individuals (The Lancet. 2008;371(9626):1800: The American Journal of Cardiology. 1983;51(3):403: Journal of the American College of Cardiology. 2017;69(12):1523), the diabetic patients have a significantly greater propensity for cardiovascular disorders and faster degeneration of implanted bioprosthetic aortic valves. Previously, using an original experimental model, the diabetic‐hyperlipemic hamsters, we have shown that the earliest alterations induced by these conditions occur at the level of the aortic valves and, with time these changes lead to calcifications and CAVD. However, there are no pharmacological treatments available to reverse or retard the progression of aortic valve disease in diabetes, despite the significant advances in the field. Therefore, it is critical to uncover the mechanisms of valve disease progression, find biomarkers for diagnosis and new targets for therapies. This review aims at presenting an update on the basic research in CAVD in the context of diabetes. We provide an insight into the accumulated data including our results on diabetes‐induced progressive cell and molecular alterations in the aortic valve, new potential biomarkers to assess the evolution and therapy of the disease, advancement in targeted nanotherapies, tissue engineering and the potential use of circulating endothelial progenitor cells in CAVD.

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.

Predicting and measuring mortality risk after transcatheter aortic valve replacement

Introduction: Over the last decade, transcatheter aortic valve replacement (TAVR) has emerged as a treatment option for most patients with severe symptomatic aortic stenosis (AS). With growing indications and exponential increase in the number of TAVR procedures, it is important to be able to accurately predict mortality after TAVR.Areas covered: Herein, we review the surgical and TAVR-specific mortality prediction models (MPMs) and their performance in their original derivation and external validation cohorts. We then discuss the role of other important risk assessment tools such as frailty, echocardiographic parameters, and biomarkers in patients, being considered for TAVR.Expert opinion: Conventional surgical MPMs have suboptimal predictive performance and are mis-calibrated when applied to TAVR populations. Although a number of TAVR-specific MPMs have been developed, their utility is also limited by their modest discriminative ability when applied to populations external to their original derivation cohorts. There is an unmet need for robust TAVR MPMs that accurately predict post TAVR mortality. In the interim, heart teams should utilize the currently available TAVR-specific MPMs in conjunction with other prognostic factors, such as frailty, echocardiographic or computed tomography (CT) imaging parameters, and biomarkers for risk assessment of patients, being considered for TAVR.

Additive prognostic value of carbohydrate antigen-125 over frailty in patients undergoing transcatheter aortic valve replacement

BACKGROUND

To evaluate the additive prognostic value of myocardial, inflammatory, and renal biomarkers according to frailty status in patients undergoing transcatheter aortic valve replacement (TAVR) for aortic stenosis (AS).

METHODS

A total of 111 subjects who underwent TAVR at Hospital Italiano de Buenos Aires, Argentina between January 2016 and December 2018 were retrospectively reviewed. Plasma levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP), high sensitivity troponin T (hs-cTnT), C-reactive protein (CRP), cystatin-c (Cys-C) and carbohydrate antigen-125 (CA-125) were assessed prior to TAVR. Frailty status was assessed according to the fried physical frailty phenotype (FPFP). The primary endpoint was defined as all-cause death and/or readmission for worsening congestive heart failure (CHF) within the first year after TAVR.

RESULTS

Of the 111 patients included, 48/111 (43%) were considered to be "frail" according to the FPFP. Among biomarkers, we found CA-125 to be strongly associated with the primary endpoint (p = .006). CA-125 ≥ 18.2 U/ml was present in 41% and was associated with a higher rate of the primary endpoint (31% vs. 9%; p = .003). After multivariable adjustment, CA-125 ≥ 18.2 U/ml (hazard ratio [HR] 3.17; p = .024) was the only independent predictor of the primary endpoint. Finally, the inclusion of CA-125 to frailty significantly improved C-index (0.68-0.74; p < .05), and provided a Net Reclassification Improvement (NRI) of 0.34 (95% CI 0.19-0.49, p = .031), largely through reductions in risk estimates among pre-frail and frail patients.

CONCLUSIONS

CA-125, a tumor biomarker, outperformed frailty for predicting the primary endpoint within the first year after TAVR.

Elevated high-sensitivity troponin T levels at 1-year follow-up are associated with increased long-term mortality after TAVR

Background

Elevated pre-procedural high-sensitivity troponin T (hs-TnT) levels predict adverse outcomes in patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR). It is unknown whether elevated troponin levels still provide prognostic information during follow-up after successful TAVR. We evaluated the long-term implications of elevated hs-TnT levels found at 1-year post-TAVR.

Methods and results

The study included 349 patients who underwent TAVR for severe AS from 2010–2019 and for whom 1-year hs-TnT levels were available. Any required percutaneous coronary interventions were performed > 1 week before TAVR. The primary endpoint was survival time starting at 1-year post-TAVR. Optimal hs-TnT cutoff for stratifying risk, identified by ROC analysis, was 39.4 pg/mL. 292 patients had hs-TnT < 39.4 pg/mL (median 18.3 pg/mL) and 57 had hs-TnT ≥ 39.4 pg/mL (median 51.2 pg/mL). The high hs-TnT group had a higher median N-terminal pro-B-type natriuretic peptide (NT-proBNP) level, greater left ventricular (LV) mass, higher prevalence of severe diastolic dysfunction, LV ejection fraction < 35%, severe renal dysfunction, and more men compared with the low hs-TnT group. All-cause mortality during follow-up after TAVR was significantly higher among patients who had hs-TnT ≥ 39.4 pg/mL compared with those who did not (mortality rate at 2 years post-TAVR: 12.3% vs. 4.1%, p = 0.010). Multivariate analysis identified 1-year hs-TnT ≥ 39.4 pg/mL (hazard ratio 2.93, 95% CI 1.91–4.49, p < 0.001), NT-proBNP level > 300 pg/mL, male sex, an eGFR < 60 mL/min/1.73 m² and chronic obstructive pulmonary disease as independent risk factors for long-term mortality after TAVR.

Conclusions

Elevated hs-TnT concentrations at 1-year after TAVR were associated with a higher long-term mortality.

Graphic abstract

Periprocedural Changes of NT-proBNP Are Associated With Survival After Transcatheter Aortic Valve Implantation

Background

Cardiovascular biomarkers constitute promising tools for improved risk stratification and prediction of outcome in patients undergoing transcatheter aortic valve implantation. We examined the association of periprocedural changes of NT‐proBNP (N‐terminal pro–B‐type natriuretic peptide) with survival after transcatheter aortic valve implantation.

Methods and Results

NT‐proBNP levels were measured in 704 patients before transcatheter aortic valve implantation and at discharge. Patients were grouped as responders and nonresponders depending on an NT‐proBNP–based ratio (postprocedural NT‐proBNP at discharge/preprocedural NT‐proBNP). Overall, 376 of 704 patients showed a postprocedural decrease in NT‐proBNP levels (NT‐proBNP ratio <1). Responders and nonresponders differed significantly regarding median preprocedural (2822 versus 1187 pg/mL, P<0.001) and postprocedural (1258 versus 3009 pg/mL, P<0.001) NT‐proBNP levels. Patients in the nonresponder group showed higher prevalence of atrial fibrillation (47.0% versus 39.4%, P=0.042), arterial hypertension (94.2% versus 87.5%, P=0.002), renal impairment (77.4% versus 69.1%, P=0.013), and peripheral artery disease (24.4% versus 14.6%, P=0.001). In contrast, patients in the responder group had higher prevalence of moderately reduced left ventricular ejection fraction (17.3% versus 11.0%, P=0.017), lower calculated aortic valve area (0.7 versus 0.8 cm², P<0.001), and higher mean pressure gradient (41 versus 35 mm Hg, P<0.001). Median follow‐up was 22.6 months. Kaplan–Meier analysis showed a highly significant survival benefit for the responder group compared with the nonresponder group (log‐rank test, P<0.001).

Conclusions

A ratio based on periprocedural changes of NT‐proBNP is a simple tool for better risk stratification and is associated with survival in patients after transcatheter aortic valve implantation.

Low and elevated B-type natriuretic peptide levels are associated with increased mortality in patients with preserved ejection fraction undergoing transcatheter aortic valve replacement: an analysis of the PARTNER II trial and registry

Aims

B-type natriuretic peptide (BNP) is a cardiac neurohormone that is secreted in response to ventricular volume expansion and pressure overload. There are conflicting data regarding the association between BNP levels and outcomes after transcatheter aortic valve replacement (TAVR). We therefore sought to assess the association between baseline BNP and adverse outcomes in patients with symptomatic, severe aortic stenosis (AS), and left ventricular ejection fraction (LVEF) ≥50%, undergoing TAVR in the PARTNER 2 Trial and Registry.

Methods and results

A total of 1782 patients were included in the analysis, and BNP was evaluated both as a continuous log-transformed value and by a priori categories: low (&lt;50 pg/mL), normal (≥50 and &lt;100 pg/mL), moderately elevated (≥100 and &lt;400 pg/mL), or markedly elevated (≥400 pg/mL). Clinical outcomes from discharge to 2 years were compared between patients according to their baseline BNP level, using Kaplan–Meier event rates and multivariable Cox proportional hazards regression models. After adjustment, spline curves revealed a non-linear association between log-transformed BNP and all-cause and cardiovascular mortality in which both the lowest and highest values were associated with increased mortality. Two-year all-cause mortality rates for those with low (n = 86), normal (n = 202), moderately elevated (n = 885), and markedly elevated (n = 609) baseline BNP were 20.0%, 9.8%, 17.7%, and 26.1%, respectively. In adjusted models, compared to a normal baseline BNP, low [adjusted hazard ratio (HR) 2.6, 95% confidence interval (CI) 1.3–5.0, P-value 0.005], moderately elevated (adjusted HR 1.6, 95% CI 1.0–2.6, P-value 0.06), and markedly elevated (adjusted HR 2.1, 95% CI 1.3–3.5, P-value 0.003) BNP were associated with increased all-cause mortality, driven by cardiovascular mortality.

Conclusions

In a large cohort of patients with severe symptomatic AS and preserved LVEF undergoing TAVR, all-cause and cardiovascular mortality rates at 2 years were higher in patients with low and markedly elevated BNP levels.

Clinical Trial Registration

https://clinicaltrials.gov/ unique identifier #NCT01314313, #NCT02184442, #NCT03222128, and #NCT03222141.

Aortic Stenosis Prognostication in Patients With Type 2 Diabetes: Protocol for Testing and Validation of a Biomarker-Derived Scoring System

Background

Type 2 diabetes mellitus (T2DM) has been established as an important independent risk factor for aortic stenosis. T2DM patients present with a higher degree of valve calcification and left ventricular dysfunction compared to patients without diabetes. This may be due to an increase in incidence and severity of myocardial fibrosis. Currently, there is no reliable method of determining the optimal timing of intervention for a patient with asymptomatic aortic stenosis or predicting when a patient will become symptomatic. Research into serum biomarkers to predict subclinical onset and track progression of aortic stenosis is hampered by the multimodal nature of the pathological processes ultimately responsible for aortic stenosis.

Objective

The aim of this study is to prove that an approach using a combination of serum biomarkers and the echocardiographic parameter global longitudinal strain (GLS) can be used to establish baseline status of fibrocalcific aortic valve disease, predict rate of progression, and quantitatively assess any regression of these processes following aortic valve replacement in patients with T2DM.

Methods

Validated serum biomarkers for the separate processes of calcification, inflammation, oxidative stress and fibrosis can be used to quantify onset and rate of progression of aortic stenosis. This, in combination with the echocardiographic parameter GLS, can be compared with other objective investigations of calcification and fibrosis with the aim of developing a quick, noninvasive one-stop assessment of aortic stenosis in patients with T2DM. The serum biomarkers BNP (B-type natriuretic peptide), Gal-3 (Galectin-3), GDF-15 (growth differentiation factor-15), sST2 (soluble suppression of tumorigenicity 2), OPG (osteoprotegerin), and microRNA 19b and 21 will be sampled from patients undergoing aortic valve replacement (with and without T2DM), patients with T2DM but without aortic valve disease and healthy volunteers. These patients will also undergo computed tomography (CT) scans for calcium scoring, magnetic resonance imaging (MRI) to quantify myocardial fibrosis, and myocardial strain imaging with speckle-tracking echocardiography. Samples of calcified native aortic valve and a biopsy of ventricular myocardium will be examined histologically to determine the quantity and distribution of calcification and fibrosis, and the secretome of these tissue samples will also be analyzed for levels of the same biomarkers as in the serum samples. All patients will be followed up with in 3 months and 12 months for repeat blood sampling, echocardiography, and CT and MRI imaging to assess disease progression or regression. The results of tissue analysis and CT and MRI scanning will be used to validate the findings of the serum biomarkers and echocardiographic assessment.

Results

Using all of the information gathered throughout the study will yield a ranking scale for use in the clinic, which will provide each patient with a fibrocalcific profile. This can then be used to recommend an optimal time for intervention.

Conclusion

A reliable, validated set of serum biomarkers combined with an inexpensive bedside echocardiographic examination can now form the basis of a one-stop outpatient-based assessment service, which will provide an accurate risk assessment in patients with aortic stenosis at first contact.

International Registered Report Identifier (IRRID)

PRR1-10.2196/13186

Clinical Implications of Serum Biomarkers of Cardiac Stress in Aortic Stenosis

PURPOSE OF REVIEW

The purpose of this review is to outline the relationship between serum biomarkers of cardiac stress and the pathophysiologic progression of aortic stenosis, to identify studies exploring the utility of biomarkers in the risk stratification and management of patients with aortic stenosis, and to highlight the biomarkers most practical to management of patients with aortic stenosis.

RECENT FINDINGS

Several biomarkers have been identified that reflect various aspects of the pathogenesis of calcific aortic stenosis, subsequent hemodynamic obstruction leading to myocardial remodeling, oxidative stress and injury, and concomitant systemic inflammation. These markers are associated with adverse outcomes in aortic stenosis and offer incremental value in risk prediction over traditional clinical assessment for aortic stenosis. NTproBNP and troponin are the most rigorously studied serum biomarkers in aortic stenosis, and only NTproBNP is currently reflected in any major guideline on aortic stenosis management. Serum biomarkers show promise in guiding management of aortic stenosis, but still require significant prospective investigation before they can be incorporated in major guidelines.

Impact of Left Ventricular Diastolic Dysfunction and Biomarkers on Pulmonary Hypertension in Patients with Severe Aortic Stenosis

Background: Severe aortic stenosis (AS) complicated by pulmonary hypertension (PH) is associated with poor outcomes after surgical aortic valve replacement (AVR). There is still scarce information about predictors of secondary PH in this group of patients. Objectives: The aim of this study was to investigate the prognostic impact of biomarkers together with conventional Doppler echocardiographic parameters of left ventricular diastolic function on elevated pulmonary systolic pressure (PSP) in severe AS patients before surgical AVR. Methods: Sixty patients with severe isolated AS (aortic valve area <1 cm²) underwent echocardiography, N-terminal pro B-type natriuretic peptide (NT-proBNP) and growth differentiation factor-15 (GDF-15) measurements before AVR. PSP, left ventricular ejection fraction (LV EF), parameters of LV diastolic function (E/E’ ratio, mitral valve deceleration time (MV DT) and left atrial (LA) volume) were evaluated. PH was defined as an estimated PSP ≥ 45 mmHg. Results: Of the 60 patients, 21.7% with severe isolated AS had PH with PSP ≥ 45 mmHg (58.5 ± 11.2 mmHg). LV EF did not differ between groups and was not related to an elevated PSP (50 ± 8 vs. 49 ± 8%, p = 0.58). Parameters of LV diastolic dysfunction (E/E’ ratio > 14 (OR 6.00; 95% CI, 1.41–25.48; p = 0.009), MV DT ≤ 177.5 ms (OR 9.31; 95% CI, 2.06–41.14; p = 0.001), LA volume > 100 mL (OR 9.70; 95% CI, 1.92–49.03; p = 0.002)) and biomarkers (NT-proBNP > 4060 ng/L (OR 12.54; 95% CI, 2.80–55.99; p < 0.001) and GDF-15 > 3393 pg/mL (OR 18.33; 95% CI, 2.39–140.39; p = 0.001)) were significantly associated with elevated PSP in severe AS. Conclusions: Left ventricular diastolic dysfunction and elevated biomarkers levels could predict the development of pulmonary hypertension in patients with severe aortic stenosis. Elevation of biomarkers paired with worsening of LV diastolic dysfunction could help to stratify patients for earlier surgical treatment before the development of pulmonary hypertension.

Proteomic Biomarkers for Incident Aortic Stenosis Requiring Valvular Replacement

Background:

Aortic valve stenosis (AS) is the most common indication for cardiac valve surgery; untreated AS is linked to high mortality. The etiological background of AS is unknown. Previous human studies were typically based on case-control studies. Biomarkers identified in prospective studies could lead to novel mechanistic insights.

Methods:

Within a large population survey with blood samples obtained at baseline, 334 patients were identified who later underwent surgery for AS (median age [interquartile range], 59.9 [10.4] years at survey and 68.3 [12.7] at surgery; 48% female). For each case, 2 matched referents were allocated. Plasma was analyzed with the multiplex proximity extension assay for screening of 92 cardiovascular candidate proteins. Conditional logistic regression models were used to assess associations between each protein and AS, with correction for multiple testing. A separate set of 106 additional cases with 212 matched referents was used in a validation study.

Results:

Six proteins (growth differentiation factor 15, galectin-4, von Willebrand factor, interleukin 17 receptor A, transferrin receptor protein 1, and proprotein convertase subtilisin/kexin type 9) were associated with case status in the discovery cohort; odds ratios ranged from 1.25 to 1.37 per SD increase in the protein signal. Adjusting the multivariable models for classical cardiovascular risk factors at baseline yielded similar results. Subanalyses of case-referent triplets (n=133) who showed no visible coronary artery disease at the time of surgery in the index person supported associations between AS and growth differentiation factor 15 (odds ratio, 1.40; 95% confidence interval, 1.10-1.78) and galectin-4 (odds ratio, 1.27; 95% confidence interval, 1.02-1.59), but these associations were attenuated after excluding individuals who donated blood samples within 5 years before surgery. In triplets (n=201), which included index individuals with concurrent coronary artery disease at the time of surgery, all 6 proteins were robustly associated with case status in all sensitivity analyses. In the validation study, the association of all but 1 (interleukin 17 receptor A) of these proteins were replicated in patients with AS with concurrent coronary artery disease but not in patients with AS without coronary artery disease.

Conclusions:

We provide evidence that 5 proteins were altered years before AS surgery and that the associations seem to be driven by concurrent atherosclerotic disease.