Plasma atrial natriuretic peptide is elevated in patients with hypertrophic cardiomyopathy

Midregional pro-atrial natriuretic peptide: a novel marker of myocardial fibrosis in patients with hypertrophic cardiomyopathy

We aimed to determine the diagnostic performance of biomarkers in predicting myocardial fibrosis assessed by late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR) in patients with hypertrophic cardiomyopathy (HCM). LGE CMR was performed in 40 consecutive patients with HCM. Left and right ventricular parameters, as well as the extent of LGE were determined and correlated to the plasma levels of midregional pro-atrial natriuretic peptide (MR-proANP), midregional pro-adrenomedullin (MR-proADM), carboxy-terminal pro-endothelin-1 (CT-proET-1), carboxy-terminal pro-vasopressin (CT-proAVP), matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1) and interleukin-8 (IL-8). Myocardial fibrosis was assumed positive, if CMR indicated LGE. LGE was present in 26 of 40 patients with HCM (65%) with variable extent (mean: 14%, range: 1.3-42%). The extent of LGE was positively associated with MR-proANP (r = 0.4; P = 0.01). No correlations were found between LGE and MR-proADM (r = 0.1; P = 0.5), CT-proET-1 (r = 0.07; P = 0.66), CT-proAVP (r = 0.16; P = 0.3), MMP-9 (r = 0.01; P = 0.9), TIMP-1 (r = 0.02; P = 0.85), and IL-8 (r = 0.02; P = 0.89). After adjustment for confounding factors, MR-proANP was the only independent predictor associated with the presence of LGE (P = 0.007) in multivariate analysis. The area under the ROC curve (AUC) indicated good predictive performance (AUC = 0.882) of MR-proANP with respect to LGE. The odds ratio was 1.268 (95% confidence interval 1.066-1.508). The sensitivity of MR-proANP at a cut-off value of 207 pmol/L was 69%, the specificity 94%, the positive predictive value 90% and the negative predictive value 80%. The results imply that MR-proANP serves as a novel marker of myocardial fibrosis assessed by LGE CMR in patients with 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.

Combined effects of low-dose spironolactone and captopril therapy in a rat model of genetic hypertrophic cardiomyopathy

For several years, the severe side effects associated with the use of high doses of the aldosterone antagonist, spironolactone, limited its clinical use. Studies have recently shown efficacy and minimal side effects of low-dose spironolactone combined with standard therapy in the treatment of heart failure and hypertensive patients. The authors evaluated the effects of low-dose spironolactone alone or in combination with angiotensin-converting enzyme (ACE) inhibitors on the progression of left ventricular dysfunction and remodeling in a congenic rat model of hypertrophic cardiomyopathy. The congenic SS-16/Mcwi rats developed severe cardiac hypertrophy despite being normotensive even on high-salt diet. SS-16/Mcwi and SS/Mcwi rats were fed a low-salt (0.4% NaCl) diet and were treated with vehicle (CON), spironolactone (20 mg/kg/d subcutaneously), captopril (100 mg/kg/d drinking water), or both spironolactone and captopril for 4 weeks. Blood pressure, plasma peptides, cardiac fibrosis, and echocardiography measurements were evaluated. Spironolactone at a low dose had no effect on blood pressure, cardiac hypertrophy, and fibrosis in either strain. However, in combination with captopril, spironolactone decreased the cardiac hypertrophy more than captopril treatment alone. In the SS-16/Mcwi rats, the combined therapy significantly preserved the cardiac index when compared with control. These data indicate that the addition of low-dose spironolactone to captopril treatment was more effective in preventing the progression of heart hypertrophy and ventricular dysfunction in the SS-16/Mcwi than captopril alone. This study suggests that combined spironolactone and captopril therapy may be useful in the treatment of hypertrophic cardiomyopathy.

Amount of left ventricular hypertrophy determines the plasma N-terminal pro-brain natriuretic peptide level in patients with hypertrophic cardiomyopathy and normal left ventricular ejection fraction

BACKGROUND

N-terminal pro-brain natriuretic peptide (NT-proBNP) is increased in patients with hypertrophic cardiomyopathy (HCM); however, the determinants of NT-proBNP level have not been clarified in HCM.

HYPOTHESIS

This study was performed to determine the relationship between NT-proBNP levels and various echocardiographic variables of patients with HCM and normal left ventricular ejection fraction (LVEF).

METHODS

We assessed plasma NT-proBNP levels and echocardiographic variables of 36 patients (19 men, 58 +/- 14 years) with HCM and an LVEF of > or = 55%. Echocardiographic variables measured were LV wall thickness, end-diastolic LV internal dimension (LVIDd) and volume (LVEDV), LV mass, and LV mass index (LV mass/body surface area, LVMI). Left ventricular outflow tract pressure gradient, transmitral E and A velocities, deceleration time (DT) of the transmitral E wave, and septal annular E' velocity were measured by Doppler technique. The relationship between echocardiographic variables and plasma NT-proBNP level was analyzed.

RESULTS

The plasma NT-proBNP level was 775.2 +/- 994.2 pg/ml (range 33.1-4729.0 pg/ml). It showed positive correlations with LV end-diastolic septal thickness (r = 0.39, p = 0.010) and LVMI (r = 0.27, p = 0.050), while it revealed negative correlations with LVIDd (r = -0.44, p = 0.004), LVEDV (r = -0.44, p = 0.004) and DT(r = -0.31,p = 0.034). The NT-proBNP level was higher in the patients with than in those without LV diastolic dysfunction (p = 0.033) and was independently related to LVIDd (p = 0.001), LVMI (p = 0.006) and DT (p = 0.031) by multivariate analysis.

CONCLUSION

In patients with HCM and normal LVEF, the amount of LV hypertrophy and LV diastolic dysfunction may exert a significant role in determining plasma NT-proBNP level.

Immunohistochemistry of atrial and brain natriuretic peptides in control cats and cats with hypertrophic cardiomyopathy

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are cardiac hormones involved in electrolyte and fluid homeostasis. Our laboratory has investigated the use of ANP and BNP as diagnostic markers of cardiac disease in cats. We hypothesize that the cardiac distribution of ANP and BNP increases in cats with hypertrophic cardiomyopathy (HCM). Accordingly, we evaluated the immunohistochemical distribution of ANP and BNP in hearts of four cats with naturally occurring HCM relative to five healthy controls. Indirect immunoperoxidase was performed with polyclonal immunoglobulin G against feline ANP (1-28) and proBNP (43-56). In control cats, ANP and BNP immunoreactivity was restricted to the atria. Staining for both peptides was most intense adjacent to the endocardial surface. Auricles stained more diffusely than atria for both peptides. The interstitial capillaries and nerve fibers within the heart were positive only for BNP. Atrial immunoreactivity for ANP and BNP was more diffuse and had a less distinctly layered pattern in HCM than in control cats. Ventricular cardiomyocytes of HCM cats were negative for ANP but stained lightly and diffusely for BNP. The capillaries and nerve fibers remained positive for BNP. We conclude that in cats with HCM, the cardiac distribution of ANP and BNP is more diffuse in the atria and that novel expression of BNP in the ventricular cardiomyocytes occurs.