Biomarkers as surrogate end points in heart failure trials

Patients with cardiorenal syndrome revealed increased neurohormonal activity, tubular and myocardial damage compared to heart failure patients with preserved renal function

BACKGROUND

Cardiorenal syndrome (CRS) is associated with increased cardiovascular morbidity and mortality; still, its biomarker pattern has been poorly evaluated so far. The aim of this study was to measure the inflammatory activation, neurohormonal status and kidney and myocardial damage in patients with CRS compared to patients with heart failure (HF) without renal impairment (RI).

METHODS

We analyzed 246 patients on the basis of renal function (group 1: 120 HF patients without RI; group 2: 126 CRS patients). In each group, interleukin-6, tumor necrosis factor-α, B-type natriuretic peptide (BNP), neutrophil gelatinase-associated lipocalin (NGAL), troponin T (TnT), osteoprotegerin and blood urea nitrogen (BUN) were measured. The diagnostic power of all laboratory parameters to detect CRS was evaluated by the receiver operating characteristic (ROC) curve and logistic regression analysis.

RESULTS

A significant increase in BNP [626.4 pg/ml, confidence interval (CI) 518-749 vs. 487.8 pg/ml, CI 411-578; p < 0.05], NGAL (156 ng/ml, CI 129-186 vs. 89.1 ng/ml, CI 72-109; p < 0.0001), BUN (108.9 mg/dl, CI 98-120 vs. 51 mg/dl, CI 46-55; p < 0,0001) and TnT (0.62 ng/ml, CI 0.51-0.75 vs. 0.21 ng/ml, CI 0.15-0.28; p < 0.001) was seen in CRS patients compared to HF patients without RI. ROC curve analysis showed that only NGAL, BUN, BUN/creatinine ratio and TnT can discriminate patients with CRS from patients without RI.

CONCLUSIONS

In CRS patients, renal tubular damage and neurohormonal and cardiac injury activation are increased compared to patients without RI. The current biomarker pattern could be used for an early diagnosis of RI in acute and chronic HF.

Clinical relevance of biomarkers in heart failure and cardiorenal syndrome: the role of natriuretic peptides and troponin

In recent years, numerous biomarkers have been studied in heart failure to improve diagnostic accuracy and identify patients at higher risk. The overall outcome remains fairish despite improvements in therapy, with mean survival after first hospitalization, around 5 years. We therefore need surrogate end points to better understand the pathogenetic mechanisms of the disease, including interplays with other organs. The kidney plays an important role in the initiation and progression of HF, and around one-third of patients with HF show some degree of renal dysfunction. In addition, treatment for HF often worsens renal function, consequently to hemodynamic and clinical improvement do not correspond an effective improvement in HF prognosis. Association between HF and renal impairment (RI) is now classified as cardiorenal syndrome (CRS) pointing out the bidirectional nature of this vicious circle leading to a mutual and progressive damage of both organs. The clinicians can rely on circulating biomarkers that give insights into the underlying pathogenetic mechanisms and help in risk stratification. Recently, a multimarker strategy including biomarker tool to traditional risk scores has been purposed and applied: Although each biomarker provided incremental outcome benefit, the combination of multiple biomarkers should offer the greatest improvement in risk prediction. Natriuretic peptides (NP) and cardiac troponins (TN) are the two biomarkers most studied in this setting, probably because of their organ-specific nature. However, both NP and TN cutoffs in presence of renal dysfunction need to be revised and discussed in relation to age, gender and stage of RI. In this context, the biomarkers are a unique opportunity to elucidate pathophysiological mechanisms, tailor clinical management to the single patient and improve outcomes. Specific studies about the exact role of biomarkers as in HF as in CRS should be planned and considered for future trials.

The Value of N-Terminal Pro–B-Type Natriuretic Peptide in Determining Antihypertensive Benefit

We investigated 3 hypotheses: (1) N-terminal pro–B-type natriuretic peptide (NT-proBNP) predicts cardiovascular disease events in patients with hypertension, (2) NT-proBNP is associated with blood pressure variability, and (3) NT-proBNP predicts benefit from antihypertensive regimens. The Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) randomized a subset of 6549 patients at risk with no history of coronary heart disease to either atenolol-based or amlodipine-based blood pressure–lowering treatment. During 5.5 years of follow-up, 485 cardiovascular disease cases accrued and were matched with 1367 controls. Baseline and 6-month in-trial NT-proBNP were measured. The results show that NT-proBNP improves cardiovascular disease risk prediction beyond established predictors, continuous net reclassification improvement of 22.3% ( P <0.0001). Furthermore, a 1-mm Hg increase in the SD of systolic blood pressure was associated with 2% higher baseline NT-proBNP in a multivariable regression analysis ( P <0.0001). However, NT-proBNP predicted cardiovascular disease risk independently of blood pressure variation (odds ratio per SD increase in log NT-proBNP 1.24; 95% confidence interval, 1.06–1.45; P =0.007). Atenolol-based treatment led to a 69.6% increase in NT-proBNP at 6 months ( P <0.0001). In contrast, amlodipine-based treatment reduced NT-proBNP by 36.5% ( P <0.0001). Amlodipine recipients who achieved a 6-month NT-proBNP below the median (61 pg/mL) were at lower risk of cardiovascular disease when compared with those who did not (odds ratio, 0.58; 95% confidence interval, 0.37–0.91) after adjustment for confounders inclusive of baseline NT-proBNP and achieved blood pressure. If confirmed, these novel results suggest that NT-proBNP, as well as aiding cardiovascular disease risk assessment, may also help assess the efficacy of specific antihypertensive regimens. Further relevant studies seem warranted.

Novel biomarkers in chronic heart failure

Understanding of chronic heart failure (HF) has progressed from a syndrome of disordered hemodynamics caused by alterations in the structure of the heart to one that involves intertwined molecular pathways in disarray. Accordingly, the assessment and treatment of patients with chronic HF has shifted from a focus on hemodynamics to modification of maladaptive molecular processes. Accumulating evidence shows that molecular biomarkers of disease could provide a unique window into the pathophysiology of chronic HF, potentially improving our ability to predict adverse outcomes, provide novel drug targets, and even help gauge therapeutic efficacy. The more 'traditional' biomarkers such as cardiac troponin, natriuretic peptides, and C-reactive protein have been studied in large cohorts of patients with chronic HF and have relatively established clinical applications. In this Review, we summarize the properties, clinical data, and potential applications of some emerging biomarkers that could uniquely indicate the level of biomechanical stretch, inflammation, ventricular remodeling, myocardial injury, and renal dysfunction that occurs in chronic HF. We will also discuss the potential role for these biomarkers within a multimarker-based strategy that could, in the future, lead to better care for these patients.