[Factors that influence the serum of atrial natriuretic peptide and brain natriuretic peptide concentrations--is there a specific marker for senile patients?]

Standardization of plasma brain natriuretic peptide concentrations in older Japanese-relationship to latent renal dysfunction and ischemic heart disease

OBJECTIVES

To determine the contributors to elevating plasma brain natriuretic peptide (BNP) concentrations in older people with normal systolic function. To investigate the relationship between cyclic guanosine monophosphate (cGMP) and BNP in older people with and without ischemic heart disease (IHD).

DESIGN

Observational study.

SETTING

Hospitalized patients in Nagoya University Hospital from November 1997 to May 2000.

PARTICIPANTS

Younger patients (<65) without IHD (n = 31), older patients (> or=65) without IHD (n = 37), and older patients with stable IHD (n = 32). All participants showed 45% or greater of their left ventricular ejection fraction (LVEF).

MEASUREMENTS

LVEF, peak atrial velocity/peak early velocity (A/E) ratio at the mitral valve, and left ventricular mass volume were measured using transthoracic echocardiogram. Plasma BNP level, cGMP, and serum creatinine (Scr) were measured. Creatinine clearance (CLcr) was calculated based on 24-hour urine collection.

RESULTS

Plasma BNP levels in older people with and without IHD were significantly greater than in younger patients (mean +/- standard deviation = 76.4 +/- 96.0 (P <.001), 165.2 +/- 200.6 (P <.001), and 8.1 +/- 7.0, respectively). By simple regression analysis, in the groups without IHD, the logarithm of plasma BNP (Log BNP) concentrations had a significant positive relationship with age (R = 0.657, P <.001), Scr (R = 0.449, P <.001), and A/E ratio (R = 0.326, P =.003) and a significant negative relationship with CLcr (R = -0.663, P <.001). A stepwise multiple regression analysis with Log BNP level as the dependent variable and age, Scr, CLcr, and A/E ratio as independent variables showed that CLcr was a significant independent contributor in groups without IHD (R = -0.766, P <.001). In this analysis, the regression coefficient of the intercept was 2.006, and that of CLcr was -0.010. The cGMP/BNP ratio in older subjects with stable IHD tended to be lower than in those without IHD (P =.063).

CONCLUSIONS

Elevated BNP levels in older patients with normal systolic function may be in part due to latent renal dysfunction, despite normal Scr levels. In healthy older people, it is important to exclude the effects of latent renal function in assessing cardiac function according to BNP level. In older subjects with stable IHD, the cGMP/BNP ratio tended to be lower than in those without IHD. This may be a reflection of a poor response of cGMP to BNP.

Leg edema, ST-T abnormalities, and high BNP values are important signs of heart failure in the elderly

This study was aimed at the mechanism of the circulatory failure characteristic of the elderly through elucidating the cause of leg edema frequently found in patients under treatment in health care facilities for physical or mental handicaps. ECG and measurement of atrial (ANP) and brain (BNP) natriuretic peptides were carried out on 156 patients (mostly females aged 84 years on average) and echocardiographic assessment was done on 44 patients. Non-specific ST-T abnormalities were frequently found in patients with moderate or severe leg edema (61 vs. 37% in those with slight or no edema). BNP levels were markedly increased in patients with either leg edema or ECG abnormalities (Group B) and with both (Group C) compared with those without either (Group A), with averages of 35.5+/-23.9, 91.3+/-80.1, and 184.3+/-139.0 pg/ml, respectively, for Group A, B, and C. UCG examination revealed marked regurgitation of cardiac valves, more frequently in patients with BNP over 50 pg/ml than in those with less (14/24 vs. 2/20), with a difference in extent of 5.7 versus 1.6 on an arbitrary scale. In addition to left ventricular hypertrophy, dilatation of the left atrium and inferior vena cava was frequently observed in patients with higher BNP levels. It is concluded that both cardiac valve regurgitation and myocardial damage represented by ST-T abnormalities on ECG result in heart failure characteristic of the elderly, and that an increase in BNP is an important sign of such heart failure.