Plasma amino-terminal pro-B-type natriuretic peptide quantification in hypertrophic cardiomyopathy

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.

Implications of the ACC/AHA risk score for prediction of heart failure: the Rotterdam Study

BACKGROUND

Despite the growing burden of heart failure (HF), there have been no recommendations for use of any of the primary prevention models in the existing guidelines. HF was also not included as an outcome in the American College of Cardiology/American Heart Association (ACC/AHA) risk score.

METHODS

Among 2743 men and 3646 women aged ≥ 55 years, free of HF, from the population-based Rotterdam Study cohort, 4 Cox models were fitted using the predictors of the ACC/AHA, ARIC and Health-ABC risk scores. Performance of the models for 10-year HF prediction was evaluated. Afterwards, performance and net reclassification improvement (NRI) for adding NT-proBNP to the ACC/AHA model were assessed.

RESULTS

During a median follow-up of 13 years, 429 men and 489 women developed HF. The ARIC model had the highest performance [c-statistic (95% confidence interval [CI]): 0.80 (0.78; 0.83) and 0.80 (0.78; 0.83) in men and women, respectively]. The c-statistic for the ACC/AHA model was 0.76 (0.74; 0.78) in men and 0.77 (0.75; 0.80) in women. Adding NT-proBNP to the ACC/AHA model increased the c-statistic to 0.80 (0.78 to 0.83) in men and 0.81 (0.79 to 0.84) in women. Sensitivity and specificity of the ACC/AHA model did not drastically change after addition of NT-proBNP. NRI(95%CI) was - 23.8% (- 19.2%; - 28.4%) in men and - 27.6% (- 30.7%; - 24.5%) in women for events and 57.9% (54.8%; 61.0%) in men and 52.8% (50.3%; 55.5%) in women for non-events.

CONCLUSIONS

Acceptable performance of the model based on risk factors included in the ACC/AHA model advocates use of this model for prediction of HF risk in primary prevention setting. Addition of NT-proBNP modestly improved the model performance but did not lead to relevant discrimination improvement in clinical risk reclassification.

Correlations between cardiac troponin I and nonsustained ventricular tachycardia in hypertrophic obstructive cardiomyopathy

BACKGROUND

Nonsustained ventricular tachycardia (NSVT) is an independent risk factor for sudden cardiac death (SCD) in patients with hypertrophic obstructive cardiomyopathy (HOCM). However, data concerning the correlations of cardiac biomarkers and NSVT in HOCM are rather limited.

HYPOTHESIS

Our study aimed to investigate the associations between the occurrence of NSVT and circulating biomarkers representing myocardial injury (cardiac troponin I, cTnI), cardiac function (N-terminal pro-brain natriuretic peptide, NT-pro BNP), and inflammation (high-sensitivity C-reactive protein) in a large Chinese HOCM cohort.

METHODS

A total of 755 consecutive HOCM patients were recruited. Systematic cardiac evaluations and circulating biomarkers were examined routinely in all subjects under the clinically stable status. According to the results of 24-hour Holter monitoring, patients were divided into the NSVT group (n = 138) and the nonventricular tachycardia (non-VT) group (n = 617).

RESULTS

Compared with the non-VT group, circulating levels of both cTnI and NT-pro BNP elevated significantly in patients with positive NSVT episodes (P < .001). Multivariable analyses demonstrated that cTnI was independently associated with the presence of NSVT (OR = 1.675, 95% CI: 1.406-1.994, P < .001). Concentrations of cTnI increased progressively not only with the aggravation of ventricular arrhythmic events (P < .001), but also with the growing risk of SCD in HOCM patients (P < .001). Serum cTnI ≥ 0.0265 ng/mL indicated predictive value for the occurrence of NSVT in the HOCM cohort (area under the curve = 0.707, 95% CI: 0.660-0.754, P < .001).

CONCLUSIONS

Elevated cTnI was an independent determinant of NSVT, and it seemed to be valuable for assessing the clinical status of ventricular arrhythmias and the risk of SCD in patients with HOCM.

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.

Sex-Related Differences in the Impact of Systemic Hypertension on Left Ventricular Remodeling in Patients with Hypertrophic Obstructive Cardiomyopathy

BACKGROUND

The clinical condition of hypertrophic obstructive cardiomyopathy (HOCM) and concomitant systemic hypertension is growing more and more prevalent, and it brings about a challenging diagnostic and therapeutic dilemma. However, whether systemic hypertension has an impact on HOCM, and whether sex-related differences exist in this impact, remains unclear.

METHODS

A total of 453 HOCM patients (age 48.7 ± 12.8 years, 252 [55.6%] males) were recruited in this study. There were 150 patients (33.1%, 81 males and 69 females) with a history of controlled systemic hypertension. Cardiac magnetic resonance (CMR) imaging was performed in all patients. Left ventricular (LV) remodeling index (LVRI) was determined by CMR. LVRI >1.3 g/mL was defined as pathological LV remodeling.

RESULTS

Men had significantly greater LVRI (1.40 ± 0.54 vs. 1.15 ± 0.38 g/mL, p < 0.001) and LVRI >1.3 g/mL (p = 0.002), compared with women. The incidence of syncope and 5-year sudden cardiac death risk score were significantly lower in HOCM with hypertension than those without hypertension. LVRI (p = 0.003) and LVRI >1.3 g/mL (p = 0.007) were significantly smaller in males with hypertension, but not in females with hypertension. However, log cardiac troponin I and log N-terminal pro-B-type natriuretic peptide were positively correlated with LVRI in men and women. On multivariable logistic analysis, hypertension (OR 0.172, 95% CI 0.056-0.528, p = 0.002) remained an independent determinant of pathological LV remodeling in males, whereas not in females.

CONCLUSIONS

There were significant sex differences in the impact of systemic hypertension on LV remodeling in patients with HOCM. Controlled systemic hypertension may contribute to improving LV remodeling in male patients with HOCM, but not in females.

Prognostic Implications of Point-of-Care and Serial B-type Natriuretic Peptide Levels in Patients With Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HC) is a heterogenous disease with a variable clinical course. Predictors of long-term adverse cardiovascular events are needed. Our objectives were to determine the long-term prognostic value of a single and serial point of care (POC) B-type natriuretic-peptide (BNP) measurements in HC. One hundred and eleven ambulatory patients with HC (mean age 53 ± 16 years) were prospectively recruited over a 2-year period (2004 to 2006). A clinical assessment, comprehensive echocardiogram, and a POC BNP level was obtained at baseline and at a 1- to 2-year follow-up. They were subsequently followed for the occurrence of major adverse cardiac events (MACE). The median baseline BNP concentration was 114 pg/ml (range 5.3 to 1550 pg/ml). During a mean follow-up of 6.2 ± 3.4 years, 42 patients (38%) had a MACE. In a multivariable Cox model including clinical and echocardiographic predictors, logBNP (HR 4.30; 95% confidence interval 1.97 to 9.37, p <0.001) and left ventricualr ejection fraction (LVEF) (HR 0.96; 95% confidence interval 0.94 to 0.99, p = 0.011) remained significant predictors of MACE. Nested models demonstrated incremental prognostic value of logBNP for MACE (chi-square increased from 4.3 to 22.8, p <0.01) over clinical and echocardiographic factors. Patients with persistently elevated BNP (>100 pg/ml) at baseline and at the second visit were at a higher risk of developing MACE during follow-up (5-year MACE-free survival of 0.91 (SE 0.06) vs 0.45 (SE 0.09), p <0.001). In conclusion, POC BNP levels in patients with HC were predictive of long-term MACE and had independent and incremental value. Patients with persistently elevated BNP levels were at a higher risk of MACE.

Prognostic significance of repeated brain natriuretic peptide measurements after percutaneous transluminal septal myocardial ablation in patients with drug-refractory hypertrophic obstructive cardiomyopathy

Objectives

To evaluate whether repeated brain natriuretic peptide (BNP) measurements after percutaneous transluminal septal myocardial ablation (PTSMA) provide prognostic information regarding the response to PTSMA in patients with drug-refractory hypertrophic obstructive cardiomyopathy (HOCM).

Background

Plasma BNP levels are associated with clinical outcomes in patients with HOCM. However, the prognostic value of plasma BNP level changes before and after PTSMA remains unclear.

Methods

We measured the plasma BNP levels serially before and after PTSMA, and evaluated the relationship between the changes in plasma BNP levels and clinical improvement in 47 patients. The patients were assigned to two groups based on the reduction in the New York Heart Association class ≥1 (good responder) or <1 (poor responder) before and after PTSMA. The Kansas City Cardiomyopathy Questionnaire (KCCQ) was used to measure health status.

Results

The plasma BNP levels gradually decreased after PTSMA, although the levels plateaued 3 months until 12 months after PTSMA. Although the plasma BNP levels and resting left ventricular outflow tract peak pressure gradient before PTSMA were comparable between the groups, the ratio of the BNP levels before and after PTSMA in the good responder group was significantly lower than that in the poor responder group (0.43 (range, 0.24–0.68) vs 0.78 (range, 0.62–0.93), p=0.002). The KCCQ score changes in the good responder group were significantly higher than those in the poor responder group.

Conclusions

The plasma BNP level ratio was associated with long-term clinical improvement of heart failure after PTSMA for drug-refractory HOCM.

Platelet Function Analyzer 100 and Brain Natriuretic Peptide as Biomarkers in Obstructive Hypertrophic Cardiomyopathy

To test dual blood biomarkers compared with electrocardiogram (ECG) for hypertrophic cardiomyopathy (HC) screening, we performed 3 analyses and cut-point assessments. First, we measured platelet function analyzer (PFA)-100 (n = 99) and normalized B-type natriuretic peptide (BNP) or NT-proBNP (BNP/upper limit of normal [ULN], n = 92) in 64 patients with HC and 29 normal controls (NCs). Second, from the regression equation between PFA and gradient (r = 0.77), we derived estimated PFA in a population of 189 patients with functional class I HC in whom measured BNP/ULN and ECG were available, and calculated single and dual biomarker sensitivity and specificity compared with ECG. Finally, we compared BNP/ULN in class I patients based on mutation and familial history status. In 42 patients with obstructive HC versus NCs, there was a slight overlap of PFA and BNP/ULN, but for the product of PFA × BNP/ULN, there was near-complete separation of values. Among patients with class I obstructive HC, estimated PFA × BNP/ULN had a sensitivity of 93% and a specificity of 100%; in latent and nonobstructive HC, sensitivity dropped to 61% and 72%; for ECG in obstructive, latent, and nonobstructive HC, sensitivity was 71%, 34%, and 67%. Functional class I patients with positive (n = 28) and negative (n = 36) sarcomere mutations and a positive (n = 71) or a negative (n = 109) family history had significant elevations of BNP/ULN versus NC, with no between-group differences. In conclusion, PFA and BNP were highly associated with obstructive HC and could potentially be used for screening; BNP was not uniquely elevated in patients with familial versus nonfamilial or mutation-positive versus mutation-negative HC.

Higher copeptin levels are associated with worse outcome in patients with hypertrophic cardiomyopathy

BACKGROUND

Correlation of increased copeptin levels with various cardiovascular diseases has been described. The clinical use of copeptin levels in patients with hypertrophic cardiomyopathy (HCM) has not been investigated before.

HYPOTHESIS

In this study, we aimed to investigate the prognostic value of copeptin levels in patients with hypertrophic cardiomyopathy (HCM).

METHODS

HCM was defined as presence of left ventricular wall thickness ≥15 mm in a subject without any concomitant disease that may cause left ventricular hypertrophy. Levels of copeptin and plasma N-terminal probrain natriuretic peptide (NT-proBNP) were evaluated prospectively in 24 obstructive HCM patients, 36 nonobstructive HCM patients, and 36 age- and sex-matched control subjects. Blood samples were collected in the morning between 7 and 9 am after overnight fasting. Patients were followed for 24 months. Hospitalization with diagnosis of heart failure/arrhythmia, implantable cardioverter-defibrillator implantation, and cardiac mortality were accepted as adverse cardiac events.

RESULTS

Copeptin and NT-proBNP levels were higher in the HCM group compared with controls (14.1 vs 8.4 pmol/L, P < 0.01; and 383 vs 44 pg/mL, P < 0.01, respectively). Copeptin and NT-proBNP levels were higher in the obstructive HCM subgroup compared with the nonobstructive HCM subgroup (18.3 vs 13.1 pmol/L, P < 0.01; and 717 vs 223 pg/mL, P < 0.01, respectively). In multivariable logistic regression analysis, copeptin and NT-proBNP levels remained as independent predictors of heart failure (P < 0.01 for both) and adverse cardiac events (P < 0.01 for both).

CONCLUSIONS

Copeptin and NT-proBNP levels were significantly higher in patients with obstructive HCM, and higher levels were associated with worse outcome.

High-Sensitivity Troponin: A Clinical Blood Biomarker for Staging Cardiomyopathy in Fabry Disease

BACKGROUND

High-sensitivity troponin (hs-TNT), a biomarker of myocardial damage, might be useful for assessing fibrosis in Fabry cardiomyopathy. We performed a prospective analysis of hs-TNT as a biomarker for myocardial changes in Fabry patients and a retrospective longitudinal follow-up study to assess longitudinal hs-TNT changes relative to fibrosis and cardiomyopathy progression.

METHODS AND RESULTS

For the prospective analysis, hs-TNT from 75 consecutive patients with genetically confirmed Fabry disease was analyzed relative to typical Fabry-associated echocardiographic findings and total myocardial fibrosis as measured by late gadolinium enhancement (LE) on magnetic resonance imaging. Longitudinal data (3.9±2.0 years), including hs-TNT, LE, and echocardiographic findings from 58 Fabry patients, were retrospectively collected. Hs-TNT level positively correlated with LE (linear correlation coefficient, 0.72; odds ratio, 32.81 [95% CI, 3.56-302.59]; P=0.002); patients with elevated baseline hs-TNT (>14 ng/L) showed significantly increased LE (median: baseline, 1.9 [1.1-3.3] %; follow-up, 3.2 [2.3-4.9] %; P<0.001) and slightly elevated hs-TNT (baseline, 44.7 [30.1-65.3] ng/L; follow-up, 49.1 [27.6-69.5] ng/L; P=0.116) during follow-up. Left ventricular wall thickness and EF of patients with elevated hs-TNT were decreased during follow-up, indicating potential cardiomyopathy progression.

CONCLUSIONS

hs-TNT is an accurate, easily accessible clinical blood biomarker for detecting replacement fibrosis in patients with Fabry disease and a qualified predictor of cardiomyopathy progression. Thus, hs-TNT could be helpful for staging and follow-up of Fabry patients.

Clinical utility of natriuretic peptides and troponins in hypertrophic cardiomyopathy

The diagnosis of hypertrophic cardiomyopathy (HCM) is based on clinical, echocardiographic and in some cases genetic findings. However, prognostication remains limited except in the subset of patients with high-risk indicators for sudden cardiac death. Additional methods are needed for risk stratification and to guide clinical management in HCM. We reviewed the available data regarding natriuretic peptides and troponins in HCM. Plasma levels of natriuretic peptides, and to a lesser extent serum levels of troponins, correlate with established disease markers, including left ventricular thickness, symptom status, and left ventricular hemodynamics by Doppler measurements. As a reflection of left ventricular filling pressure, natriuretic peptides may provide an objective measure of the efficacy of a specific therapy. Both natriuretic peptides and troponins predict clinical risk in HCM independently of established risk factors, and their prognostic power is additive. Routine measurement of biomarker levels therefore may be useful in the clinical evaluation and management of patients with HCM.

Predictive Values of N-Terminal Pro-B-Type Natriuretic Peptide and Cardiac Troponin I for Myocardial Fibrosis in Hypertrophic Obstructive Cardiomyopathy

Background

Both high-sensitivity cardiac troponin T and B-type natriuretic peptide are useful in detecting myocardial fibrosis, as determined by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR), in patients with non-obstructive hypertrophic cardiomyopathy. However, their values to predict myocardial fibrosis in hypertrophic obstructive cardiomyopathy (HOCM) remain unclear. We investigated the role of N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP) and cardiac troponin I (cTnI) to identify LGE-CMR in patients with HOCM.

Methods

Peripheral concentrations of NT-proBNP and cTnI were determined in patients with HOCM (n = 163; age = 47.2 ± 10.8 years; 38.7% females). Contrast-enhanced CMR was performed to identify and quantify myocardial fibrosis.

Results

LGE was detected in 120 of 163 patients (73.6%). Patients with LGE had significantly higher levels of NT-proBNP and cTnI than those without LGE (1386.2 [904.6–2340.8] vs. 866.6 [707.2–1875.2] pmol/L, P = 0.003; 0.024 [0.010–0.049] vs. 0.010 [0.005–0.021] ng/ml, P <0.001, respectively). The extent of LGE was positively correlated with log cTnI (r = 0.371, P <0.001) and log NT-proBNP (r = 0.211, P = 0.007). On multivariable analysis, both log cTnI and maximum wall thickness (MWT) were independent predictors of the presence of LGE (OR = 3.193, P = 0.033; OR = 1.410, P < 0.001, respectively), whereas log NT-proBNP was not. According to the ROC curve analysis, combined measurements of MWT ≥21 mm and/or cTnI ≥0.025ng/ml indicated good diagnostic performance for the presence of LGE, with specificity of 95% or sensitivity of 88%.

Conclusions

Serum cTnI is an independent predictor useful for identifying myocardial fibrosis, while plasma NT-proBNP is only associated with myocardial fibrosis on univariate analysis. Combined measurements of serum cTnI with MWT further improve its value in detecting myocardial fibrosis in patients with HOCM.

Detection by ELISA of C-terminal proBNP in plasma from cats with cardiomyopathy

The B-type natriuretic peptide prohormone (proBNP) is enzymatically cleaved into an inactive N-terminal peptide and a biologically active C-terminal peptide with many beneficial cardiorenal effects. The purpose of this study was to develop and test in cats with cardiomyopathy an immunoassay to quantify the concentrations of C-terminal proBNP in feline plasma. An anti-canine proBNP monoclonal antibody (UI-1021) was shown to have adequate binding affinity to proBNP 80-106 for use in a solid-phase immunoassay, and by epitope mapping to bind within positions 84-87 of feline proBNP. UI-1021 was paired with an affinity-purified rabbit polyclonal detection antibody to feline proBNP 100-106, in a sandwich ELISA with feline proBNP 80-106 standard. The linearity and analytical range and sensitivity of the assay were confirmed from 1.4 to 85 pmol/L. Spike recovery averaged 106.5% (95% confidence interval 78-135%). Within run and intra-assay coefficients of variation were <12%. A protease inhibitor mixture preserved proBNP 80-106 immunoreactivity for at least 5 days in plasma. Clinical verification of the ELISA was done using plasma from 13 cats with cardiomyopathy, whose C-terminal proBNP concentrations ranged from 1.7 to 78.8 pmol/L vs. <1.4-1.8 pmol/L in plasma from 18 healthy cats. Concentrations were found to be substantially lower than reported N-terminal proBNP concentrations, and similar to those of human heart failure patients where relative C-terminal BNP deficiencies have been proposed as contributory to the progression of the disease.

B-type natriuretic peptide and survival in hypertrophic cardiomyopathy

OBJECTIVES

The aim of this study was to determine the relationship between B-type natriuretic peptide (BNP) and survival in patients with hypertrophic cardiomyopathy.

BACKGROUND

Natriuretic peptides are released in response to neurohormonal activation, myocardial stretch, and wall tension and therefore reflect hemodynamic derangements.

METHODS

A total of 772 patients with hypertrophic cardiomyopathy had BNP obtained in conjunction with echocardiography and clinical evaluation, inclusive of cardiopulmonary exercise evaluation in 429 patients (56%).

RESULTS

Survival free of all-cause mortality was lower across increasing levels of BNP (log-rank test, p = 0.002). Three-year survival by tertile was 99.2% (95% confidence interval: 94.3% to 99.9%; BNP level ≤98 pg/ml), 94.8% (95% confidence interval: 88.2% to 97.8%; BNP level, >98 to <298 pg/ml), and 89.9% (95% confidence interval: 82.0% to 94.5%; BNP level ≥298 pg/ml). Compared with patients in the first tertile, the hazard ratios for death in the second and third tertiles were 4.88 (p = 0.006) and 6.98 (p = 0.0003), respectively. This relationship persisted in patients without resting obstructive physiology (n = 497, p = 0.01). BNP levels were related to New York Heart Association functional status (p < 0.0001) and the subsequent need for septal reduction therapy in follow-up (p = 0.04).

CONCLUSIONS

In this large cohort of patients with hypertrophic cardiomyopathy, BNP was an independent predictor of morbidity and mortality.

Degree and distribution of left ventricular hypertrophy as a determining factor for elevated natriuretic peptide levels in patients with hypertrophic cardiomyopathy: insights from cardiac magnetic resonance imaging

Whether the left ventricular (LV) mass index (LVMI) and LV volumetric parameters are associated independently with natriuretic peptide levels is unclear in hypertrophic cardiomyopathy (HCM). Therefore, we investigated which parameters have an independent relationship with N-terminal pro-B type natriuretic peptide (NT-proBNP) levels in HCM patients using echocardiography and cardiac magnetic resonance imaging (CMR). A total of 103 patients with HCM (82 men, age 53 ± 12 years) were evaluated. Echocardiographic evaluations included left atrial volume index (LAVI) and early diastolic mitral inflow E velocity to early annular Ea velocity ratio (E/Ea). LVMI, maximal wall thickness and LV volumetric parameters were measured using CMR. The median value of NT-proBNP level was 387.0 pg/ml. The mean NT-proBNP level in patients with non-apical HCM (n = 69; 36 patients with asymmetric septal hypertrophy, 11 with diffuse, and 22 with mixed type) was significantly higher than in those with apical HCM (n = 34, P < 0.001). NT-proBNP level was negatively correlated with LV end-diastolic volume (LVEDV) (r = -0.263, P = 0.007) and positively with LVMI (r = 0.225, P = 0.022) and maximal wall thickness (r = 0.495, P < 0.001). Among the echocardiographic variables, LAVI (r = 0.492, P < 0.001) and E/Ea (r = 0.432, P < 0.001) were correlated with NT-proBNP. On multivariable analysis, non-apical HCM, increased maximal wall thickness and LAVI were independently related with NT-proBNP. Severity of LV hypertrophy and diastolic parameters might be important in the elevation of NT-proBNP level in HCM. Therefore, further evaluation of these parameters in HCM might be warranted.

The diagnostic significance of the plasma N-terminal pro-B-type natriuretic Peptide concentration in asymptomatic cats with cardiac enlargement

We evaluated the diagnostic significance of the N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration in asymptomatic cats with cardiac enlargement. The plasma NT-proBNP concentration was measured in 21 clinically healthy control cats, and 67 asymptomatic cats with cardiac enlargement defined as end-diastolic interventricular septum thickness (IVSd) and/or diastolic left ventricular posterior wall thickness (LVPWd) >0.6 cm, vertebla heart scale (VHS) >7.8, and/or left atria/aorta ratio (LA/Ao) >1.5. The plasma NT-proBNP concentration in the asymptomatic cats with cardiac enlargement (median: 662.0, range: 24.0-2,449.0 pmol/l) was significantly higher than that in the controls (24.0, 24.0-95.0 pmol/l, P<0.001). The plasma NT-proBNP concentration was significantly correlated with the VHS, LA/Ao, IVSd and LVPWd (r=0.578, P<0.001; r=0.462, P<0.001; r=0.563, P<0.001; and r=0.764, P<0.001, respectively). Receiver operating characteristic analysis showed a cut-off value of 95.0 pmol/l for the detection of asymptomatic cats with cardiac enlargement, sensitivity and specificity of 88.1 and 100%, respectively, and an area under the curve of 0.971. These results suggest that the determination of the plasma NT-proBNP concentration can be a useful screening test for asymptomatic cats with cardiac enlargement.

NT-proBNP measurement fails to reliably identify subclinical hypertrophic cardiomyopathy in Maine Coon cats

The purpose of this study was to evaluate the value of measuring plasma NT-proBNP concentration as a screening tool in cats with varying severity of subclinical hypertrophic cardiomyopathy (HCM). Plasma NT-proBNP concentration was measured in 35 cats that had previously been classified as normal, equivocal, moderate HCM or severe HCM via echocardiography. No cat had ever been in congestive heart failure. Cats with severe HCM had a significantly higher NT-proBNP concentration compared to the other groups (P<0.0003), however, the sensitivity of NT-proBNP for diagnosing cats with severe disease was only 44% (cutoff≤100pmol/l) to 55% (cutoff≤40pmol/l). There was no significant difference in NT-proBNP concentration between normal, equivocal and moderate categories (sensitivity for detecting moderate HCM was 0%). Based on the results of this study, NT-proBNP concentration is not considered adequate as a screening test for detecting mild to moderate HCM in Maine Coon cats and it appears that it may miss many cats with severe HCM.

Natriuretic peptides: the feline experience

In feline medicine natriuretic peptides (NP), particularly NT-proBNP, have emerged as biomarkers with significant potential. Since the introduction of the commercial ELISA that enabled the convenient and accurate measurement of circulating N terminal ANP and BNP fragments research examining the utility of these peptides as an aid to the diagnosis of feline cardiovascular disease has accelerated. This article describes the results of these studies and tries to put them in the context of clinical practice by exploring the areas of agreement and controversy and explaining the influence of confounding factors on the interpretation of NP concentrations. Considerable further work is needed to fully evaluate the clinical utility of NP regarding their potential for diagnosis, prognosis, and guidance of treatment.

Brain natriuretic peptide and the athlete's heart: a pilot study

BACKGROUND

The role of brain natriuretic peptide (BNP) in differentiating the athlete's heart from maladaptive cardiac hypertrophy is unclear.

METHODS

To address this issue, an integrated M mode, two-dimensional B mode and Doppler echocardiographical study were performed and plasma BNP levels were measured in 25 strength athletes, 25 patients with established hypertrophic cardiomyopathy (HCM) and 25 healthy volunteers.

RESULTS

Among athletes, BNP levels correlated negatively with the total training time (r = -0.79, p = 0.002) and positively with ejection fraction (r = 0.58, p = 0.049) and fractional shortening (r = 0.57, p = 0.049). A BNP cut-off value of 11.8 pg/ml had 88% specificity and 74% negative predictive value for the exclusion of HCM.

CONCLUSIONS

Brain natriuretic peptide might be useful as a preparticipation screening test in athletes.

Investigation into the use of plasma NT-proBNP concentration to screen for feline hypertrophic cardiomyopathy

OBJECTIVE

To evaluate the utility of feline NT-proBNP plasma concentration [NT-proBNP] as a screening tool for cats with subclinical hypertrophic cardiomyopathy (HCM).

ANIMALS, MATERIALS AND METHODS

Forty adult Maine Coon or Maine Coon crossbred cats from the feline HCM research colony at the University of California, Davis were studied. All cats had previously been genotyped as heterozygous or negative for the A31P myosin binding protein C (MYBPC) mutation. Echocardiograms were performed to assess the severity of HCM in each cat. Blood samples were collected for evaluation of [NT-proBNP].

RESULTS

In these cats with severe HCM, [NT-proBNP] was significantly elevated (P<0.0001) when compared to all other groups of cats and an [NT-proBNP]>44pmol/L accurately predicted the presence of severe HCM. However, [NT-proBNP] was not increased in cats with moderate or equivocal HCM when compared to normal cats. Cats heterozygous for the MYBPC mutation had a significantly elevated [NT-proBNP] when compared to cats without the A31P mutation (P=0.028).

CONCLUSIONS

Measurement of [NT-proBNP] has a high sensitivity and specificity as a means of detecting severe HCM in cats, but it is not sensitive for the identification of moderate HCM as judged by the evaluation of Maine Coon and Maine Coon cross cats in our colony. Consequently, we conclude that this test cannot be used to screen cats for the presence of mild to moderate HCM.

Biomarkers of pathophysiology in hypertrophic cardiomyopathy: implications for clinical management and prognosis

The study of biomarkers and their signalling pathways has allowed the development of new therapeutic strategies in a range of disorders. The aim of the present systematic review is to provide an overview of different biomarkers in patients with hypertrophic cardiomyopathy that could give some insight into the pathophysiologic mechanism(s) underlying the typical clinical and histological manifestations of the disease. Several pathophysiological models are presented and discussed, including studies that have investigated these biomarkers for diagnostic and prognostic reasons, in relation to disease progression and/or mortality.

Significance of plasma levels of N-terminal Pro-B-type natriuretic peptide on left ventricular remodeling in non-obstructive hypertrophic cardiomyopathy attributable to the Asp175Asn mutation in the alpha-tropomyosin gene

Hypertrophic cardiomyopathy (HC) is an inherited heart disease characterized by left ventricular (LV) remodeling. The present study was conducted to investigate the association of N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) levels with LV remodeling on magnetic resonance imaging and procollagen formation in 17 healthy controls and 24 patients with nonobstructive HC attributable to an identical Asp175Asn (aspartic acid to asparagine at codon 175) mutation in the alpha-tropomyosin gene. None of the patients had history of decompensated heart failure, and all patients had normal LV ejection fraction. Patients with HC had higher NT-pro-BNP levels compared with controls (median 60 pmol/L, range <40 to 359, vs <40 pmol/L; p <0.001), but 9 patients with HC had normal NT-pro-BNP levels (<40 pmol/L). In patients with HC, levels of NT-pro-BNP were correlated significantly with LV end-systolic volume index (r = 0.50, p <0.05), LV mass index (r = 0.47, p <0.05), proportion of hypokinetic segments (r = 0.50, p <0.05), and levels of serum aminoterminal propeptide of type III procollagen (r = 0.52, p <0.01). When patients with HC were divided into 3 groups on the basis of their NT-pro-BNP levels, there were statistically significant linear associations of LV end-systolic volume (test for linearity p = 0.034), LV mass index (p = 0.009), proportion of hypokinetic segments (p = 0.016), and levels of serum aminoterminal propeptide of type III procollagen (p = 0.020) with NT-pro-BNP levels over the 3 groups, suggesting a tight relation between LV remodeling and levels of NT-pro-BNP. In conclusion, in patients with nonobstructive HC attributable to an Asp175Asn mutation in the alpha-tropomyosin gene, elevated NT-pro-BNP levels are associated with incipient LV remodeling, suggesting that NT-pro-BNP could be used to diagnose insidious unfavorable LV remodeling in HC.

Effects of cigarette smoking on heart rate variability and plasma N-terminal pro-B-type natriuretic peptide in healthy subjects: is there the relationship between both markers?

BACKGROUND

Cigarette smoking increased the risk of acute cardiac events related with endothelial dysfunction and increased sympathetic activity. Impaired autonomic nervous activity is recognized as a considerable symptom of cardiac dysfunction and is strongly associated with increased risk overall mortality.

METHODS

A total of 75 healthy habitual smokers (40 female, 35 male, mean age 36.5 +/- 8.5 years), and 73 non-smokers subjects (45 female, 28 male, mean age 34.6 +/- 7.2 years) were studied. LF and LF/HF ratio were significantly higher in smokers than in non-smokers. On the contrary, SDNN, SDANN, RMSSD, and HF values were lower in smokers compared to those in non-smokers. Not the duration of smoking but the number of cigarettes smoked per day was correlated with the HRV parameters and NT-pro BNP. Furthermore, the average levels of NT-pro BNP were found to be positively correlated with LF, LF/HF and inversely correlated with SDNN, SDANN, RMSSD and HF.

RESULTS

As a result, smoking impaires sympathovagal balance and decreases the heart rate variability in healthy subjects. And even a one cigarette smoking leads to overt sympathetic excitation. Furthermore, smoking results in an increase in NT-proBNP levels and the changes in adrenergic nervous system and NT-proBNP levels are well correlated.

CONCLUSION

These findings could contribute to the higher rate of cardiovascular events in smokers.

The differential diagnosis of an elevated amino-terminal pro-B-type natriuretic peptide level

Although amino-terminal pro-B-type natriuretic peptides (NT-proBNP) are useful for the diagnosis or exclusion of heart failure (HF), this marker may identify a wide range of disease processes other than HF. Indeed, elevation of NT-proBNP may occur in a number of heart diseases (including heart muscle disease, valve disease, rhythm abnormalities, pulmonary hypertension, and cytotoxic injury to the heart) and in disease processes other than primary cardiac illnesses, including gram-negative sepsis. Importantly, although NT-proBNP may increase in settings other than HF, the presence and severity of such NT-proBNP release is often significantly associated with risk for adverse outcome. Accordingly, elevation of NT-proBNP in the context of non-HF situations should not be regarded as a "false-positive" finding, and elevated NT-proBNP values should not be discarded without consideration of the serious adverse outcomes associated with the elevation. Future studies will be necessary to further understand the utility of NT-proBNP testing in states other than cardiovascular disease.

Clinical significance of N-terminal-probrain natriuretic peptide in hypertrophic cardiomyopathy

N-Terminal-probrain natriuretic peptide (NT-proBNP) plasma levels are elevated in patients with congestive heart failure. Published data concerning the utility of NT-proBNP in hypertrophic cardiomyopathy (HCM) are lacking. Our aim was to evaluate the clinical significance of NT-proBNP in patients with HCM. A blood sample was collected for plasma NT-proBNP measurement from 43 consecutive patients with documented HCM. NT-proBNP was measured using a chemiluminescent immunoassay kit (Roche Diagnostics) on an Elecsys 2010 analyzer. Median value of NT-proBNP was 219 pg/ml (range 8-3 045 pg/ml) in NYHA class I patients, 698 pg/ml (125-2 463 pg/ml) in NYHA class II patients, and 2 683 pg/ml (131-11 542 pg/ml) in NYHA class III and IV patients. NT-proBNP plasma levels were significantly higher across the severity of functional limitation (i.e., NYHA class classification) (P = 0.002). NT-proBNP levels were significantly higher in female than male (P = 0.034), in referral vs nonreferral patients (P = 0.004), in symptomatic vs asymptomatic patients (P = 0.020), in patients with basal subaortic gradient >or=30 mmHg (P = 0.001) and in the patients who were on cardioactive medication (P = 0.010). In univariate analysis NT-proBNP was significantly correlated with age (P < 0.001), left ventricular maximum wall thickness (P = 0.001), left atrial size (P = 0.019), and subaortic gradient >or=30 mmHg (P < 0.001). In multivariate regression analysis, age (P < 0.001), maximum wall thickness (P = 0.007), and gradient >or=30 mmHg (P = 0.027) were independently associated with NT-proBNP levels. Our data support the idea that measurement of plasma NT-proBNP levels in HCM patients is useful to assess their clinical status, especially the severity of hypertrophy and the presence of obstruction, although age must be taken into account.

Interpretation of B-type natriuretic peptide in cardiac disease and other comorbid conditions

B-Type natriuretic peptide (BNP) is elevated in states of increased ventricular wall stress. BNP is most commonly used to rule out congestive heart failure (CHF) in dyspneic patients. BNP levels are influenced by age, gender and, to a surprisingly large extent, by body mass index (BMI). In addition, it can be elevated in a wide variety of clinical settings with or without CHF. BNP is elevated in other cardiac disease states such as the acute coronary syndromes, diastolic dysfunction, atrial fibrillation (AF), amyloidosis, restrictive cardiomyopathy (RCM), and valvular heart disease. BNP is elevated in non-cardiac diseases such as pulmonary hypertension, chronic obstructive pulmonary disease, pulmonary embolism, and renal failure. BNP is also elevated in the setting of critical illness such as in acute decompensated CHF (ADHF) and sepsis. This variation across clinical settings has significant implications given the increasing frequency with which BNP testing is being performed. It is important for clinicians to understand how to appropriately interpret BNP in light of the comorbidities of individual patients to maximize its clinical utility. We will review the molecular biology and physiology of natriuretic peptides as well as the relevant literature on the utilization of BNP in CHF as well as in other important clinical situations, conditions that are commonly associated with CHF and or dyspnea.