Novel Plasma Biomarkers Associated with Future Peripheral Atherosclerotic Disease and Abdominal Aortic Aneurysm-Insights from Contemporary Prospective Studies from the Malmö Diet and Cancer Study

INTRODUCTION

The potential utility of inflammatory and hemodynamic plasma biomarkers for the prediction of incident lower extremity arterial disease (LEAD), carotid artery stenosis (CAS), isolated atherosclerotic disease without concomitant abdominal aortic aneurysm (AAA), and isolated AAA without concomitant atherosclerotic disease has not yet been integrated in clinical practice. The main objective of this prospective study was to find predictive plasma biomarkers for cardiovascular disease and to evaluate differences in plasma biomarker profiles between asymptomatic and symptomatic CAS, as well as between isolated atherosclerotic disease and isolated AAA.

METHODS

Blood samples collected at baseline from participants in the prospective Malmö Diet and Cancer study (MDCS) cardiovascular cohort (n = 5550 middle-aged individuals; baseline 1991-1994) were used for plasma biomarker analysis. Validation of each incident cardiovascular diagnosis was performed by random sampling. Cox regression analysis was used to calculate hazard ratios (HRs) per one standard deviation increment of each respective log-transformed plasma biomarker with 95% confidence intervals (CI).

RESULTS

Adjusted lipoprotein-associated phospholipase A2 (Lp-PLA2) activity (HR 1.33; CI 1.17-1.52) and mass (HR 1.20; CI 1.05-1.37), C-reactive protein (CRP) (HR 1.55; CI 1.36-1.76), copeptin (HR 1.46; CI 1.19-1.80), N-terminal pro-B-type natriuretic peptide (N-BNP) (HR 1.28; 1.11-1.48), and cystatin C (HR 1.19; 95% 1.10-1.29) were associated with incident symptomatic LEAD. Adjusted N-BNP (HR 1.59; CI 1.20-2.11), mid-regional proadrenomedullin (HR 1.40; CI 1.13-1.73), cystatin C (HR 1.21; CI 1.02-1.43), and CRP (HR 1.53; CI 1.13-1.73) were associated with incident symptomatic but not asymptomatic CAS. Adjusted HR was higher for Lp-PLA2 (mass) for incident isolated AAA compared to for isolated atherosclerotic disease.

CONCLUSIONS

Plasma biomarker profile data support that subclinical vascular inflammation and cardiovascular stress seem to be relevant for the development of atherosclerotic disease and AAA.

Current Prognostic Biomarkers for Abdominal Aortic Aneurysm: A Comprehensive Scoping Review of the Literature

Abdominal aortic aneurysm (AAA) is a progressive dilatation of the aorta that can lead to aortic rupture. The pathophysiology of the disease is not well characterized but is known to be caused by the general breakdown of the extracellular matrix within the aortic wall. In this comprehensive literature review, all current research on proteins that have been investigated for their potential prognostic capabilities in patients with AAA was included. A total of 45 proteins were found to be potential prognostic biomarkers for AAA, predicting incidence of AAA, AAA rupture, AAA growth, endoleak, and post-surgical mortality. The 45 proteins fell into the following seven general categories based on their primary function: (1) cardiovascular health, (2) hemostasis, (3) transport proteins, (4) inflammation and immunity, (5) kidney function, (6) cellular structure, (7) and hormones and growth factors. This is the most up-to-date literature review on current prognostic markers for AAA and their functions. This review outlines the wide pathophysiological processes that are implicated in AAA disease progression.

Ultrasensitive Troponin I and Incident Cardiovascular Disease

BACKGROUND

To examine the association of ultrasensitive cTnI (cardiac troponin I) with incident cardiovascular disease events (CVDs) in the primary prevention setting.

METHODS

cTnI was analyzed in the baseline plasma (2008-2012) of CVD-free volunteers from the Paris Prospective Study III using a novel ultrasensitive immunoassay (Simoa Troponin-I 2.0 Kit, Quanterix, Lexington) with a limit of detection of 0.013 pg/mL. Incident CVD hospitalizations (coronary heart disease, stroke, cardiac arrhythmias, deep venous thrombosis or pulmonary embolism, heart failure, or arterial aneurysm) were validated by critical review of the hospital records. Hazard ratios were estimated per log-transformed SD increase of cTnI in Cox models using age as the time scale.

RESULTS

The study population includes 9503 participants (40% women) aged 59.6 (6.3) years. cTnI was detected in 99.6% of the participants (median value=0.63 pg/mL, interquartile range, 0.39-1.09). After a median follow-up of 8.34 years (interquartile range, 8.0-10.07), 516 participants suffered 612 events. In fully adjusted analysis, higher cTnI (per 1 SD increase of log cTnI) was significantly associated with CVD events combined (hazard ratio, 1.18 [1.08-1.30]). Among all single risk factors, cTnI had the highest discrimination capacity for incident CVD events (C index=0.6349). Adding log cTnI to the SCORE 2 (Systematic Coronary Risk Evaluation) risk improved moderately discriminatory capacity (C index 0.698 versus 0.685; bootstrapped C index difference: 0.0135 [95% CI, 0.0131-0.0138]), and reclassification of the participants (categorical net reclassification index, 0.0628 [95% CI, 0.023-0.102]). Findings were consistent using the US pooled cohort risk equation.

CONCLUSIONS

Ultrasensitive cTnI is an independent marker of CVD events in the primary prevention setting.

Prospective Comparison of Plasma Biomarker and Traditional Risk Factor Profiles for Incident Isolated Atherosclerotic Disease and Incident Isolated Abdominal Aortic Aneurysm

Background: Traditional risk factors for atherosclerotic disease (AD) are well-known, of which some are relevant also for abdominal aortic aneurysms (AAA). The present study compares the importance of plasma biomarkers and traditional risk factor profiles for incident AD without concomitant AAA (isolated AD) and AAA without concomitant AD (isolated AAA) during long-term follow-up.

Methods: In the Malmö Diet and Cancer Study—cardiovascular cohort, 5,381 participants were free from atrial fibrillation or flutter, AD (coronary artery disease, atherothrombotic ischemic stroke, carotid artery disease, or peripheral artery disease), and AAA underwent blood sampling under standardized fasting conditions between 1991 and 1994. Cox proportional hazards regression analysis was used to calculate hazard ratios (HR) with 95% CIs.

Results: During a median follow-up of 23.1 years, 1,152 participants developed isolated AD, and 44 developed isolated AAA. Adjusted HR for lipoprotein-associated phospholipase A2 (mass) (HR 1.53, 95% CI 1.14–2.04 vs. HR 1.05, 95% CI.99–1.12) was higher for incident isolated AAA compared to incident isolated AD, respectively. Mid-regional pro-adrenomedullin (MR-proADM) was associated with incident isolated AD (HR 1.17, 95% CI 1.1–1.25) and incident isolated AAA (HR 1.47, 95% CI 1.15–1.88). MR-proADM was correlated (r = 0.32; p < 0.001) to body mass index (BMI), and BMI was associated with increased risk of incident isolated AAA (HR 1.43, 95% CI 1.02–2). No participant with diabetes mellitus (DM) at baseline developed isolated AAA (0/44), whereas DM was associated with an increased risk of isolated AD (HR 2.57, 95% CI 2.08–3.18). Adjusted HR for male sex (HR 4.8, 95% CI 2.42–9.48, vs. HR 1.76, 95% CI 1.56–1.98) and current smoking (HR 4.79, 95% CI 2.42–9.47 vs. HR 1.97, 95% CI 1.73–2.23) were higher in the incident isolated AAA group compared to the incident isolated AD group, respectively.

Conclusions: The data supports the view that components of vascular inflammation and cardiovascular stress drives AAA development, whereas glycated cross-links in abdominal aortic wall tissue may have a plausible role in reducing AAA risk in individuals with DM.

Therapeutic Assessment of Combination Therapy with a Neprilysin Inhibitor and Angiotensin Type 1 Receptor Antagonist on Angiotensin II-Induced Atherosclerosis, Abdominal Aortic Aneurysms, and Hypertension

Combined neprilysin (NEP) inhibition (sacubitril) and angiotensin type 1 receptor (AT1R) antagonism (valsartan) is used in the treatment of congestive heart failure and is gaining interest for other angiotensin II (AngII)-related cardiovascular diseases. In addition to heart failure, AngII promotes hypertension, atherosclerosis, and abdominal aortic aneurysms (AAAs). Similarly, NEP substrates or products have broad effects on the cardiovascular system. In this study, we examined NEP inhibition (with sacubitril) and AT1R antagonism (with valsartan) alone or in combination on AngII-induced hypertension, atherosclerosis, or AAAs in male low-density lipoprotein receptor-deficient mice. Preliminary studies assessed drug delivery via osmotic minipumps for simultaneous release of sacubitril and/or valsartan with AngII over 28 days. Mice were infused with AngII (1000 ng/kg per minute) in the absence (vehicle) or presence of sacubitril (1, 6, or 9 mg/kg per day), valsartan (0.3, 0.5, 1, 6, or 20 mg/kg per day), or the combination thereof (1 and 0.3, or 9 or 0.5 mg/kg per day of sacubitril and valsartan, respectively). Plasma AngII and renin concentrations increased 4-fold at higher valsartan doses, indicative of removal of AngII negative feedback on renin. Sacubitril doubled plasma AngII concentrations at lower doses (1 mg/kg per day). Valsartan dose-dependently decreased systolic blood pressure, aortic atherosclerosis, and AAAs of AngII-infused mice, whereas sacubitril had no effect on atherosclerosis or AAAs but reduced blood pressure of AngII-infused mice. Combination therapy with sacubitril and valsartan did not provide additive benefits. These results suggest limited effects of combination therapy with NEP inhibition and AT1R antagonism against AngII-induced hypertension, atherosclerosis, or AAAs. SIGNIFICANCE STATEMENT: The combination of valsartan (angiotensin type 1 receptor antagonist) and sacubitril (neprilysin inhibitor) did not provide benefit above valsartan alone on AngII-induced hypertension, atherosclerosis, or abdominal aortic aneurysms in low-density lipoprotein receptor-deficient male mice. These results do not support this drug combination in therapy of these AngII-induced cardiovascular diseases.

Sensitive determination of NT-proBNP for diagnosing abdominal aortic aneurysms incidence on interdigitated electrode sensor

Abdominal aortic aneurysm (AAA) is a vascular disease found to have progressive growth in the area of aorta. Rupturing of aorta causes excessive bleeding that leads to health-related issues, which can be fatal sometimes. Therefore, it becomes important to make early diagnosis of AAA and its condition and start immediate treatment. Blood-based biomarker helps to diagnose AAA and to monitor the condition after AAA surgery. N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a hormone produced in the heart in small quantities and increased when the heart needs to work harder. NT-proBNP was proved to be strongly linked with AAA incidence. Moreover, quantifying the level of NT-proBNP helps to determine the risk factors on cardiovascular system after the surgery. This work is quantifying the NT-proBNP on interdigitated electrode sensor by using NT-proBNP binding aptamer. The detection limit of NT-proBNP was calculated as 1 pg/mL on a linear regression curve [y = 0.2148x + 0.8849; R² = 0.9049]. The linear range with dose-dependent analysis was from 0.01 until 100 ng/mL. Moreover, the control experiment with complementary aptamer sequence did not show the current signal, specifying the detection of NT-proBNP. This research benefits to identify the heart condition of patient after the removal of AAA.

Copeptin, B-type natriuretic peptide and cystatin C are associated with incident symptomatic PAD

Purpose: The aim of this study is to evaluate plasma biomarkers as predictors for peripheral arterial disease (PAD). Materials and methods: Prospective longitudinal cohort study of middle-aged individuals from the cardiovascular cohort of the Malmö Diet and Cancer study (MDCS) (n = 5550; 1991-94). Cystatin C, copeptin, N-terminal pro-B-type natriuretic peptide (N-BNP), midregional proatrial natriuretic peptide (MR-proANP), mid-regional proadrenomedullin (MR-proADM), and conventional risk factors were measured at baseline. The diagnosis of symptomatic PAD was validated in 97% of the cases. Results: Cumulative incidence of PAD during median follow up of 23.4 years was 4.4% (men 5.9%, women 3.3%). Adjusted for age, sex, smoking, body mass index, hypertension, diabetes mellitus and total cholesterol, copeptin (hazard ratio [HR] 1.46; 95% confidence interval [CI] 1.19-1.80), N-BNP (HR 1.28; 95% CI 1.11-1.48), and cystatin C (HR 1.19; 95% CI 1.10-1.29) were independently associated with incident PAD. Subjects with the three biomarkers copeptin, N-BNP, and cystatin C in the highest quartiles, ran a high risk of incident PAD (HR 3.29; 95% CI 1.76-6.17) compared to those with no biomarker in the highest quartile. Conclusion: Copeptin, N-BNP, and cystatin C were associated with incident symptomatic PAD, implying that these biomarkers are sensitive indicators of early subclinical PAD. Clinical significance First prospective longitudinal cohort study evaluating Cystatin C, copeptin, N-terminal pro-B-type natriuretic peptide (N-BNP), midregional proatrial natriuretic peptide (MR-proANP), and mid-regional proadrenomedullin (MR-proADM) as predictors for peripheral arterial disease (PAD). Copeptin, N-BNP, and Cystatin C where independently associated with incident symptomatic PAD after adjustment for conventional risk factors. Copeptin, N-BNP, and Cystatin C seem to be sensitive indicators of early subclinical PAD.

Blood biomarker panel recommended for personalized prediction, prognosis, and prevention of complications associated with abdominal aortic aneurysm

The aim of the study was to evaluate the ability of following biomarkers as diagnostic tools and risk predictors of AAA: C-reactive protein, interleukin-6, pentraxin-3, galectin-3, procollagen type III N-terminal peptide, C-terminal telopeptide of type I collagen, high-sensitive troponin I, and brain natriuretic peptide. Seventy-two patients with an AAA and 100 healthy individuals were enrolled into the study. We assessed individual biomarker performance and correlation between the AAA diameter and biomarker levels, and also, a multivariate logistic regression was used to design a possible predictive model of AAA growth and rupture risk. We identified following four parameters with the highest potential to find a useful place in AAA diagnostics: galectin-3, pentraxin-3, interleukin-6, and C-terminal telopeptide of type I. The best biomarkers in our evaluation (galectin-3 and pentraxin-3) were AAA diameter-independent. With the high AUC and AAA diameter correlation, the high-sensitive troponin I can be used as an independent prognostic biomarker of the upcoming heart complications in AAA patients. Authors recommend to add biomarkers as additional parameters to the current AAA patient management. Main addition value of biomarkers is in the assessment of the AAA with the smaller diameter. Elevated biomarkers can change the treatment decision, which would be done only based on AAA diameter size. The best way how to manage the AAA patients is to create a reliable predictive model of AAA growth and rupture risk. A created multiparameter model gives very promising results with the significantly higher efficiency compared with the use of the individual biomarkers.