Understanding B-type natriuretic peptide and its role in diagnosing and monitoring congestive heart failure

Soluble ST2 as a Diagnostic and Prognostic Marker for Acute Heart Failure Syndromes

OBJECTIVES: We investigated the association of sST2 with diagnostic and prognostic outcomes and assessed whether it aids B-natriuretic peptide (BNP) in diagnosing and predicting outcomes in emergency department (ED) patients with suspected AHFS. METHODS: We recruited patients who presented to the ED of 3 tertiary hospitals with signs or symptoms of AHFS and met modified Framingham criteria for AHFS. Outcome measures were a final diagnosis of AHFS and 5-and 30-day adverse events. RESULTS: In the 295 subjects with sST2 available, the median sST2 was 0.20 ng/ml (IQR=0.10, 0.34). Although unadjusted analyses indicated sST2 was significantly associated with the diagnosis of AHFS (p=0.02), this was not so in the adjusted analysis (p=0.33). Moderately low diagnostic utility was noted with an AUC of 0.62 (95% CI=0.56, 0.69). Similar sST2 test characteristics were seen when BNP was restricted between 100 and 500 pg/ml. While sST2 was associated with AHFS readmission at 30-days (p=0.04), in the adjusted analyses it was not associated with adverse events. CONCLUSION: In patients with signs or symptoms of AHFS, unadjusted analyses indicated that sST2 was significantly associated with the diagnosis of AHFS and with 30-day AHFS recidivism. However, the associations did not carry over to adjusted analyses, and sST2 did not add significant information with regard to explaining the diagnostic and prognostic variability of BNP.

B-Type Natriuretic Peptide Decreases Gastric Emptying and Absorption

Natriuretic peptides have been shown to decrease contractility of isolated gastric smooth muscle cells. However there is a paucity of research showing whether this effect has functional significance in the whole animal. The objective of this study was to test whether intravenously administered B-type Natriuretic Peptide (BNP) has an effect on gastric emptying and/or absorption in a whole animal mouse model. C57BL/6-Wild-type (WT) and Natriuretic Peptide Receptor type A (NPR-A) knockout (KO) mice were used in these studies. Gastric contractility was examined in anesthetized mice before and after BNP vs. vehicle injection. Gastric emptying of gavage fed 70 Kilo Dalton (kDa) FITC-dextran and absorption of 4 kDa FITC-dextran were compared in BNP vs. vehicle treated conscious WT and KO mice. BNP decreased gastric contractility (measured in change in intragastric pressure) from 2.26 ± 0.29 to 1.44 ± 0.11 mmHg ( P < 0.05), pressure returned to 2.08 ± 0.17 after 5 BNP half-lives ( P < 0.05). There was no significant change in the vehicle or KO. BNP also decreased gastric emptying in WT mice compared to vehicle, 87.8 ± 0.8% vs. 97.3 ± 1.04% ( P < 0.05) and this effect showed a dose-response relationship. In KO mice emptying was 95.8 ± 0.5% (BNP) vs. 91.7 ± 0.7% (Vehicle) ( P > 0.05). The absorption in WT mice was 28.2 ± 7.8 (relative fluorescence units) for BNP vs. 91 ± 25.9 for vehicle ( P < 0.05). For KO mice absorption was 64.3 ± 14.9 for BNP vs. 60.6 ± 17.4 for vehicle ( P > 0.05). The results show that BNP decreases intragastric pressure, emptying and absorption by acting via the NPR-A receptor. We postulate that this effect is aimed at decreasing preload through decreased water and electrolyte absorption from the GI tract and may also be responsible for the symptoms of impaired gastrointestinal function observed in heart failure patients.

N-terminal pro brain natriuretic peptide predicts mortality in patients with end-stage renal disease in hemodialysis

Concentrations of N-terminal pro brain natriuretic peptide (NT-proBNP) increase in patients with heart failure and other cardiovascular (CV) diseases and are strong prognostic markers. In patients with end-stage renal disease (ESRD) in hemodialysis (HD), levels of NT-proBNP are almost always raised. In ESRD patients undergoing HD, we aimed at (i) identifying the factors that affect levels of NT-proBNP, (ii) determining the effect of HD on NT-proBNP, and (iii) determining the prognostic impact of NT-proBNP. A total of 109 patients underwent physical examination, electrocardiogram, and echocardiography. Serum NT-proBNP was measured before and after HD (Elecsys 2010). NT-proBNP levels were markedly elevated (pre-HD 4079 pg/ml, post-HD 2759 pg/ml, P<0.001). There was a strong inverse correlation between NT-proBNP and left ventricular ejection fraction (LVEF) (P=0.043), 24-h urine production (P=0.006), and K(t)/V (efficacy of dialysis) (P=0.016) and a positive correlation with left ventricular hypertrophy (LVH) (P=0.014). Patients with higher concentrations, both pre- and post-HD had an increased mortality rate compared to those with lower concentrations (P=0.007, P=0.002). We found age (P=0.009) and NT-proBNP (pre-HD P=0.007, post-HD P=0.001) predictive of death. Our findings demonstrate that CV disease in terms of LVH and reduced LVEF in addition to 24-h urine production and K(t)/V determine NT-proBNP levels. Post-HD levels of NT-proBNP were lower than pre-HD levels; both predictive of mortality.

Cardiac Troponin T vs Other Biochemical Markers in Patients With Congestive Heart Failure

BACKGROUND

Several pathologic processes can cause myocardial injury, which is followed by cardiac remodeling and congestive heart failure (CHF). Cardiac troponin T (cTnT), a specific and sensitive marker of myocardial injury, has been related to long-term outcome in patients with CHF, so the relationship between cTnT and other biochemical markers associated with the pathophysiology of CHF was investigated in the present study.

METHODS AND RESULTS

Between February 2004 and December 2005, 145 consecutive hospitalized patients (mean left ventricular ejection fraction (LVEF) 31.6+/-0.9%) with CHF were divided into low (<0.01 ng/ml) and high (> or =0.01 ng/ml) serum cTnT groups. Correlations with other prognostic biochemical markers, including brain natriuretic peptide (BNP), type I collagen C-terminal telopeptide (ICTP), procollagen type III peptide (PIIIP), renin, norepinephrine (NOREPI), C-reactive protein (CRP), cholesterol, hemoglobin (Hb), uric acid and HbA1c were examined. cTnT was high in 46 (32%) and low in 99 (68%) patients at baseline. Patients with high cTnT had abnormally high blood concentrations of BNP (p<0.0001), ICTP (p<0.0001), PIIIP (p=0.0006), NOREPI (p=0.0119), CRP (p=0.0003), uric acid (p=0.0026) and HbA1c (p=0.0361). In contrast, concentrations of cholesterol and Hb were significantly lower in patients with high cTnT (p=0.0319 and 0.0005, respectively). Death from or rehospitalization for CHF occurred in 41% in the high vs 9% in the low cTnT group (p=0.0002). Univariate analysis showed that high cTnT (p=0.0005), BNP (p=0.0001), renin (p=0.0158), NOREPI (p=0.0094), old age (p=0.0390), low LVEF (p=0.0231) and high New York Heart Association (NYHA) class (p=0.0006) were predictors of death from or rehospitalization for CHF. By multivariate analysis including BNP, NOREPI, age, LVEF and NYHA class, high cTnT and renin remained as significant predictors.

CONCLUSIONS

Patients with ongoing myocardial injury and high cTnT had associated findings consistent with activation of the sympathetic system, synthesis of cardiac fibrosis, inflammation and metabolic abnormalities. By multivariate analysis, high cTnT and renin remained significant predictors of death or rehospitalization.

Persistently Increased Serum Concentrations of Cardiac Troponin in Patients With Acutely Decompensated Heart Failure are Predictive of Adverse Outcomes

BACKGROUND

Persistently increased serum concentrations of cardiac troponin (cTn) are a prognostic marker in patients suffering from chronic congestive heart failure (CHF), but the significance in acute cardiac decompensation is unclear.

METHODS AND RESULTS

Serial blood samples were collected from 52 patients presenting with acute cardiac decompensation in the absence of an acute coronary event. Serial serum concentrations of cTnI, creatine kinase (CK)-MB, and brain natriuretic peptide (BNP) were measured by rapid assay. BNP and CK-MB steadily decreased from 902+/-529 pg/ml and 2.3+/-1.6 ng/ml at baseline to 453+/-427 pg/ml and 1.2+/-1.6 ng/ml on day 7, respectively, (p<0.0001 for both comparisons). In contrast, cTnI did not decrease significantly and, in 17 patients (35%), increased from 0.063+/-0.047 ng/ml at baseline to 0.167+/-0.181 ng/ml on day 1 (p<0.05). By single variable regression analysis, systolic blood pressure (SBP), use of inotropes or inodilators, vasodilators, and an initially elevated cTnI were predictors of elevated cTnI on day 1. By multiple variable analysis, an elevated SBP (as a mitigating factor) (odds ratios (OR) 0.12; 95% confidence intervals (CI): 0.02-0.76; p=0.0248), and high baseline cTnI (OR 13.85; 95%CI: 1.97-97.54; p=0.0083) were significant predictors of an elevated cTnI on day 1. Patients with elevated cTnI on day 1 had higher rates of worsening CHF and death from CHF than patients without such an increase (p<0.05).

CONCLUSIONS

Persistently increased serum concentrations of cTn in patients with acutely decompensated heart failure are predictive of adverse outcomes.