Determinants of Elevated NT-proBNP Levels in Patients With Hypertrophic Cardiomyopathy: An Echocardiographic Study

Association of NT-proBNP and hs-cTnT with Imaging Markers of Diastolic Dysfunction and Focal Myocardial Fibrosis in Hypertrophic Cardiomyopathy

Serum biomarkers such as N-terminal prohormone of the brain natriuretic peptide (NT-proBNP) and cardiac troponins are elevated in patients with hypertrophic cardiomyopathy (HCM). At present, it is not clear if these markers are associated with distinct clinical alterations in HCM, such as left ventricular hypertrophy, outflow tract obstruction, myocardial fibrosis and/or diastolic dysfunction (DD), which are associated with adverse cardiovascular outcome. Here we evaluate the association of NT-proBNP and high sensitivity cardiac troponin T (hs-cTnT) to a variety of cardiac imaging parameters in HCM patients in a multivariable regression analysis. This retrospective cross-sectional study included 366 HCM patients who underwent transthoracic echocardiography (TTE), 218 of whom also obtained cardiovascular magnetic resonance (CMR) to assess focal myocardial fibrosis by LGE. Multivariable regression analyses revealed the strongest association of the DD parameters E/E′ mean and E/E′ septal with NT-proBNP (b = 0.06, 95%-CI [0.05−0.07], p < 0.001, R2 = 0.28; b = 0.08, 95%-CI [0.06−0.1], p < 0.001, R2 = 0.25) and LGE size showed the strongest association with hs-cTnT (b = 0.20, 95%-CI [0.15−0.24], p < 0.001, R2 = 0.28). This study indicates that NT-proBNP and hs-cTnT are associated with structural and functional alterations in HCM. NT-proBNP is a stronger predictor for DD, while hs-cTnT is associated with the extent of focal myocardial fibrosis. Both biomarkers might be useful in the diagnostic procedure in addition to imaging parameters.

Molecular mechanisms of sacubitril/valsartan in cardiac remodeling

Cardiovascular diseases have become a major clinical burden globally. Heart failure is one of the diseases that commonly emanates from progressive uncontrolled hypertension. This gives rise to the need for a new treatment for the disease. Sacubitril/valsartan is a new drug combination that has been approved for patients with heart failure. This review aims to detail the mechanism of action for sacubitril/valsartan in cardiac remodeling, a cellular and molecular process that occurs during the development of heart failure. Accumulating evidence has unveiled the cardioprotective effects of sacubitril/valsartan on cellular and molecular modulation in cardiac remodeling, with recent large-scale randomized clinical trials confirming its supremacy over other traditional heart failure treatments. However, its molecular mechanism of action in cardiac remodeling remains obscure. Therefore, comprehending the molecular mechanism of action of sacubitril/valsartan could help future research to study the drug’s potential therapy to reduce the severity of heart failure.

Identifying Cardiac Diseases using Cardiac Biomarkers in Rhesus Macaques (Macaca mulatta)

Cardiac biomarkers are an important tool for diagnosing cardiac diseases in both human and veterinary patients. Serum concentrations of N-terminal probrain natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI) have been used to indicate the presence of various cardiac diseases including hypertrophic cardiomyopathy (HCM) in various species including humans. However, these cardiac biomarkers have not been established as a diagnostic tool for detecting cardiac disease in rhesus macaques. In the rhesus macaque colony at the California National Primate Research Center, naturally occurring HCM and various other cardiac diseases have been identified. In this study, commercially available assays were used to measure serum cTnI and NT-proBNP concentrations to evaluate their utility as a diagnostic screening tool for cardiac diseases in rhesus macaques. This study revealed that the serum cTnI concentration was significantly higher in animals with echocardiographically apparent cardiac disease as compared with the animals that had no cardiac structural and functional changes (the control group). However, no significant differences were detected between animals with HCM and non-HCM cardiac disease. Because the area under the receiver operating characteristic curve was 0.81 when the serum cTnI was compared between the control and cardiac disease groups, serum cTnI was considered a moderately accurate test to predict the presence of cardiac disease. The optimal cut-off value of serum cTnI concentration for diagnosis of cardiac disease was 0.0085 ng/mL, with a sensitivity of 0.68 and specificity of 0.94. Significant but weak correlations were noted between the serum cTnI concentration and several echocardiographic parameters. Conversely, no significant differences in NT-proBNP concentrations were detected between animals with and without cardiac diseases. In conclusion, measurement of serum cTnI can be used to aid in diagnosing cardiac diseases in rhesus macaques. However, cTnI measurement does not replace echocardiographic evaluation to diagnose cardiac diseases in rhesus macaques due to the poor sensitivity of the assay and the weak correlation to with more established echocardiographic markers for cardiac disease.

Evaluation of N-terminal prohormone of brain natriuretic peptide and cardiac troponin-I levels in cats with systolic anterior motion of the mitral valve in the absence of left ventricular hypertrophy

OBJECTIVES

To identify the prevalence of systolic anterior motion of the mitral valve (SAM) in apparently healthy cats in the absence of left ventricular hypertrophy (LVH) and examine the relationship between specific cardiac biomarker concentrations and echocardiographic parameters in these individuals.

ANIMALS

eighty client-owned cats.

MATERIALS AND METHODS

retrospective study; inclusion criteria were the presence of SAM on conscious echocardiography and concurrent measurement of plasma N-terminal prohormone of brain natriuretic peptide (NT-proBNP) and serum cardiac troponin-I (cTnI). Cats were excluded if they had LVH, left atrial enlargement or systemic disease. The percentages of cats with NT-proBNP and cTnI concentrations above the normal reference range were calculated. The correlation between each biomarker concentration and left ventricular myocardial wall thickness, left atrial size and maximum left ventricular outflow tract velocity was evaluated.

RESULTS

Thirty-four of 80 patients with SAM showed no evidence of cardiac remodelling (LVH or left atrial enlargement). Of these patients, 30 of 34 had elevated NT-proBNP, and cTnI was elevated in 13 of 27 (48.1%) cats where this biomarker was measured in association with the NT-proBNP assay. A positive correlation was observed between concentration of plasma NT-proBNP and maximum left ventricular outflow tract velocity (rs = 0.67, p<0.0001). No significant correlations were found between the concentration of biomarkers and the remaining echocardiographic parameters.

CONCLUSIONS

SAM is frequently observed in cats even in the absence of cardiac remodelling, and these individuals often demonstrate elevated plasma NT-proBNP and serum cTnI concentrations. Plasma NT-proBNP elevation is correlated with the severity of the left ventricular outflow obstruction caused by SAM.

Undetermined stroke genesis and hidden cardiomyopathies determined by cardiac magnetic resonance

OBJECTIVE

To determine whether cardiac magnetic resonance imaging (CMR) could be useful in identifying previously undiagnosed cardiomyopathies in a cohort of patients with ischemic stroke who underwent standard etiologic investigation and to describe the type and frequency of these cardiomyopathies.

METHODS

We performed a subanalysis of a previously collected prospective cohort of patients with ischemic stroke. Patients with structural changes on echocardiography that are considered causal for stroke in the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification were excluded. A 3T CMR was performed. We compared the frequency of the cardiomyopathies that we found with reference values for the general population.

RESULTS

One hundred thirty-two patients with a mean age of 68.4 years were included. In 7 patients (5.3%, 95% confidence interval 2.59%-10.54%) CMR identified cardiomyopathy. Four patients had hypertrophic cardiomyopathy, 2 had restrictive cardiomyopathy, and 1 had noncompaction cardiomyopathy. Six of these patients had been classified after standard evaluation as having undetermined stroke and 1 patient as having cardioembolic stroke (atrial fibrillation). We found a higher frequency of hypertrophic cardiomyopathy in the entire cohort and in the undetermined cause group compared to the general population (3.03% and 5.81% vs 0.2%, respectively, p = 0.001 and p < 0.001). The frequency of noncompaction cardiomyopathy was also higher in our cohort (0.76% vs 0.05%, respectively, p < 0.001).

CONCLUSIONS

Although rare, cardiomyopathies should be considered as a possible cause of ischemic stroke classified as of undetermined etiology after standard evaluation.

Hypertrophic Cardiomyopathy: The Time-Synchronized Relationship between Ischemia and Left Ventricular Dysfunction Assessed by Highly Sensitive Troponin I and NT-proBNP

The aim of this study was to compare NT-proBNP using the absolute values and NT-proBNP/ULN values that were standardized by age and gender between three subgroups: those without ischemia (negative hs-troponin I and no anginal pain (hsTnI-/AP-)), those with painless ischemia (hsTnI+/AP-), and those with painful ischemia (hsTnI+/AP+). Additionally, echocardiographic parameters were compared in these three subgroups. The absolute value of NT-proBNP was significantly higher in the painful ischemia subgroup (hsTnI-/AP- vs. hsTnI+/AP- vs. hsTnI+/AP+: 502 (174-833) vs. 969 (363-1346) vs. 2053 (323-3283) pg/ml; p = 0.018 for the whole-model analysis). The standardized value of NT-proBNP/ULN was gradually increased (hsTnI-/AP- vs. hsTnI+/AP- vs. hsTnI+/AP+: 3.61 + 0.63 vs. 6.90 + 1.31 vs. 9.35 + 1.87; p = 0.001 for the whole-model analysis). In the comparison between subgroups (hsTnI-/AP- vs. hsTnI+/AP- vs. hsTnI+/AP+), two echocardiographic parameters increased significantly. The left ventricular maximum wall thickness (LVMWT) at diastole was 1.99 ± 0.08 cm vs. 2.28 ± 0.13 cm vs. 2.49 ± 0.15 cm (p = 0.004 for the whole-model analysis). The maximal gradient of the provoked left ventricular outflow tract (LVOT) gradient increased significantly in only the painful-ischemia subgroup (11 (7-30) mmHg vs. 12 (9.35-31.5) mmHg vs. 100 (43-120) mmHg). In conclusion, both painless ischemia and painful ischemia are associated with a gradual, significant increase in NT-proBNP/ULN in comparison to the double-negative hsTnI/AP subgroup. In contrast, NT-proBNP is significantly higher in only the subgroup with painful ischemia.

N-terminal pro-brain natriuretic peptide is related with coronary flow velocity reserve and diastolic dysfunction in patients with asymmetric hypertrophic cardiomyopathy

BACKGROUND

The relations of elevated N-terminal pro-brain natriuretic peptide (NT-pro-BNP) and cardiac ischemia in hypertrophic cardiomyopathy (HCM) patients is uncertain. Therefore we designed the study with the following aims: (1) to analyze plasma concentrations of NT-pro-BNP in various subsets of HCM patients; (2) to reveal the correlations of NT-pro-BNP, myocardial ischemia, and diastolic dysfunction; (3) to assess predictors of the elevated plasma levels of NT-pro-BNP.

METHODS AND RESULTS

In 61 patients (mean age 48.9±16.3 years; 26 male) with asymmetric HCM plasma levels of NT-pro-BNP were obtained. Standard transthoracic examination, tissue Doppler echocardiography with measurement of transthoracic coronary flow velocity reserve (CFVR) in left anterior descending artery (LAD) was done. Mean natural logarithm value of NT-pro-BNP was 7.11±0.95pg/ml [median value 1133 (interquartile range 561-2442)pg/ml]. NT-pro-BNP was significantly higher in patients with higher NYHA class, in obstructive HCM, more severe mitral regurgitation, increased left atrial volume index (LAVI), presence of calcified mitral annulus, elevated left ventricular (LV) filling pressure and in decreased CFVR. Levels of NT-pro-BNP significantly correlated with the ratio of E/e' (r=0.534, p<0.001), LV outflow tract gradient (r=0.503, p=0.024), LAVI (r=0.443, p<0.001), while inversely correlated with CFVR LAD (r=-0.569, p<0.001). When multivariate analysis was done only CFVR LAD and E/e' emerged as independent predictors of NT-pro-BNP.

CONCLUSION

Plasma levels of NT-pro-BNP were significantly higher in HCM patients with more advanced disease. Elevated NT-pro-BNP not only reflects the diastolic impairment of the LV, but it might also be the result of cardiac ischemia in patients with HCM.

Interrelationship between the Myocardial Mass, Fibrosis, BNP, and Clinical Outcomes in Hypertrophic Cardiomyopathy

Objective Increased left ventricular mass (LVM) and LV fibrosis mass (LVFM) are characteristics of hypertrophic cardiomyopathy (HCM). Additionally, a substantial increase in the plasma B-type natriuretic peptide (BNP) level is observed. Therefore, we investigated the interrelationship and clinical significances of these parameters in a HCM cohort that underwent cardiac MRI (CMR). Methods Patients with HCM (n=109) receiving regular outpatient treatment underwent CMR and follow-up through 2015 from CMR examinations. The clinical outcome measures were all-cause mortality, admission for worsening heart failure, and ventricular tachycardia/fibrillation. Results The baseline body mass index (BMI), LV outflow tract (LVOT) obstruction, New York Heart Association (NYHA) class, and increased left atrial dimension (LAD) index were associated with the plasma BNP level. In the CMR analysis, LVM and LVFM indices significantly correlated with the BNP level (r=0.422 and 0.368, respectively), which were independent determinants according to a multivariate analysis (p=0.009 and 0.023, respectively). A Kaplan-Meier analysis during a median follow-up of 19.4 months showed that the baseline LVM or LVFM index was not associated with the clinical outcomes. However, the baseline BNP level was significantly associated with them (p<0.001). In addition, a multivariate Cox proportional hazard analysis showed that plasma BNP was an independent predictor for the clinical outcomes after adjusting for age, sex, LVM, and LVFM. Conclusion The LVM and LVFM are determinants of the BNP level independent of the BMI, LVOT obstruction, LAD, and NYHA class in patients with HCM. However, plasma BNP may be a more sensitive integrated-marker for the clinical outcomes than LVM or LVFM.

Growth differentiation factor-15, a novel biomarker related with disease severity in patients with hypertrophic cardiomyopathy

BACKGROUND

The growth differentiation factor 15 (GDF-15) has been shown up-regulated in stress conditions and to have regulatory actions in myocyte hypertrophy. We hypothesized that GDF-15 could be related to disease severity and functional status in patients with hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

We performed a study which includes 102 consecutive outpatient HCM subjects, 73% males, aged 47.1±14.6 years. A complete history and clinical examination was performed, including 12-lead electrocardiogram, echocardiography, symptom-limited treadmill exercise, 24-hour ECG-Holter monitoring, and magnetic resonance with Gadolinium. Several biomarkers, associated with myocardial remodeling and damage, were compared to GDF-15 levels. The assays were performed with commercial ELISAs or standardized methods when available. There was a significant association between GDF-15 levels and comorbidities, being higher in hypertension (p=0.001), diabetes (p=0.030), atrial fibrillation (p=0.012), dyspnea (p=0.020) and NYHA≥II functional class (p=0.037). GDF-15 levels were positively correlated with clinical variables (age, worse exercise capacity and mild renal dysfunction) and biomarkers of interstitial remodeling, such as metalloproteinase-2 (r: 0.40; p=0.009), N-terminal pro-B-type natriuretic peptide (r: 0.28; p=0.049), high-sensitivity troponin T (r: 0.30; p=0.003) and von Willebrand factor (r: 0.33; p=0.001). Multivariate analysis was assessed to estimate the involvement of these different factors in the GDF-15 levels, confirming the independent implication of severe dyspnea and functional status.

CONCLUSIONS

The present results show that higher levels of GDF-15 are associated to conditions of severe disease in HCM. Hence, GDF-15 is suggested as a novel marker related to the severity and could represent a further useful tool in monitoring functional capacity of HCM patients.