B-type natriuretic peptide level in a patient with constrictive pericarditis

Disproportionately low BNP levels in patients of acute heart failure with preserved vs. reduced ejection fraction

BACKGROUND

B-type natriuretic peptide (BNP) has been widely used for the diagnosis of heart failure, its severity, and prognosis. However, little is known about factors related to disproportionately low BNP levels even during acute heart failure conditions.

METHODS AND RESULTS

Among 424 patients hospitalized for acute heart failure, we categorized the patients into the HFpEF (LVEF > 50%) or HFrEF (LVEF ≤ 50%) group and subdivided them into disproportionately low BNP (LB) group and high BNP (HB) group using a cut-off BNP level of 200 pg/mL at admission. The proportion of patients with LB was higher in the HFpEF group (22.2%) than in the HFrEF group (10.9%, p = 0.002). Patients with LB had a high BMI, lower blood pressure, and history of previous cardiovascular surgery in the HFpEF group, while patients in the HFrEF group had a high BMI and smaller left ventricular end-diastolic volume index. Furthermore, presence of LB in the HFrEF group was related to good prognosis, but LB in the HFpEF group was an indicator of poor prognosis as HB group.

CONCLUSIONS

The factors associated with LB were different between the HFpEF and HFrEF groups. LB was related to good prognosis in HFrEF, but not in HFpEF.

Cardiac tamponade as an independent condition affecting the relationship between the plasma B-type natriuretic peptide levels and cardiac function

Plasma B-type natriuretic peptide (BNP) is finely regulated by the cardiac function and several extracardiac factors. Therefore, the relationship between the plasma BNP levels and the severity of heart failure sometimes seems inconsistent. The purpose of the present study was to investigate the plasma BNP levels in patients with cardiac tamponade and their changes after pericardial drainage. This study included 14 patients with cardiac tamponade who underwent pericardiocentesis. The cardiac tamponade was due to malignant diseases in 13 patients and uremia in 1 patient. The plasma BNP levels were measured before and 24-48 h after drainage. Although the patients reported severe symptoms of heart failure, their plasma BNP levels were only 71.2 ± 11.1 pg/ml before drainage. After appropriate drainage, the plasma BNP levels increased to 186.0 ± 22.5 pg/ml, which was significantly higher than that before drainage (P = 0.0002). In patients with cardiac tamponade, the plasma BNP levels were low, probably because of impaired ventricular stretching, and the levels significantly increased in response to the primary condition after drainage. This study demonstrates an additional condition that affects the relationship between the plasma BNP levels and cardiac function. If inconsistency is seen in the relationship between the plasma BNP levels and clinical signs of heart failure, the presence of cardiac tamponade should therefore be considered.

Characteristics of acute congestive heart failure with normal ejection fraction and less elevated B-type natriuretic peptide

BACKGROUND

Heterogeneity in B-type natriuretic peptide (BNP) levels, especially among individuals with acute heart failure with normal left ventricular ejection fraction (HFNEF), can cause confusion in interpreting results. We investigated the characteristics of cases of acute HFNEF with only modestly elevated BNP.

METHODS

One hundred forty-two patients with acute or acute exacerbation of chronic HFNEF were divided into two groups by BNP level: BNP < 100 pg/ml (NB group, n = 45) and BNP > or = 100 pg/ml (B group, n = 97). We compared clinical findings, echocardiography results, and neurohormonal factors between these two groups.

RESULTS

In the NB group, a history of open-heart surgery (OHS) was more frequent (71% vs. 22%, p < 0.0001) and hypertension was less frequent (p = 0.0005). Left atrial diameter (LAd) was higher (p = 0.0026), while interventricular septal thickness, posterior wall thickness, relative wall thickness, left ventricular mass index were lower (p = 0.0005, p = 0.0225, p = 0.0114, p = 0.0051, respectively) in the NB group. In patients with HFNEF, a history of OHS remained an independent predictor of BNP level (< 100 pg/ml) after adjustment for hypertension, age, LAd, and interventricular septal thickness (odds ratio 3.6, p = 0.0252).

CONCLUSION

We found associations between acute HFNEF with less elevated BNP and a history of OHS. In a patient suspected of HFNEF, a history of OHS is considered diagnostic evidence of presence of diastolic heart failure when plasma levels of BNP are less elevated.

Natriuretic peptides and filling pressure at rest and stress

The natriuretic peptides are a family of compounds secreted from the atria and ventricles in response to a variety of stimuli, including increased wall stress, tachycardia, and myocardial ischemia. Increases in the levels of these compounds correlate with increased left-ventricular filling pressure in patients with systolic dysfunction, although the production of the compounds from severely impaired ventricles may be reduced, leading to lower than anticipated levels in severe heart failure. The association of increased natriuretic peptides with diastolic dysfunction has been variable, with no elevation reported in many patients with mild dysfunction. These patients with mild diastolic dysfunction become symptomatic with exercise, in association with increased filling pressure with stress, which may be documented using echocardiography or possibly the natriuretic peptide response. However, the variability of peptide levels within individuals may pose a problem to the interpretation of sequential data in response to exercise or therapies.