Amino-terminal pro-brain natriuretic peptide for the diagnosis of acute heart failure in patients with previous obstructive airway disease.

STUDY OBJECTIVE: We evaluate results from amino-terminal pro-brain natriuretic peptide (NT-proBNP) testing with or without those of clinical judgment for the evaluation of dyspneic patients with previous chronic obstructive pulmonary disease or asthma. METHODS: As a secondary analysis of previously collected observational data from a convenience sample of 599 breathless patients, 216 patients with previous chronic obstructive pulmonary disease or asthma who presented to the emergency department were analyzed according to results of NT-proBNP, clinical impression, and their final diagnosis. Test performance of NT-proBNP in these patients with chronic obstructive pulmonary disease or asthma was examined for the group as a whole, as well as in patients with and without previous heart failure. NT-proBNP results were compared to clinician-estimated likelihood for heart failure using receiver operating curves and as a function of NT-proBNP plus clinical evaluation. The final diagnosis was determined by 2 independent cardiologists blinded to NT-proBNP using all available data from the 60-day follow-up period. RESULTS: Overall, 55 patients (25%) had acute heart failure; the median value of NT-proBNP was higher in these patients compared with those without acute heart failure (2,238 vs 178 pg/mL); use of cut points of 450 pg/mL for patients younger than 50 years and 900 pg/mL for patients 50 years or older yielded a sensitivity of 87% (95% confidence interval [CI] 72% to 93%) and a specificity of 84% (95% CI 76% to 88%). In patients without previous heart failure (n=164), median NT-proBNP levels were also higher in patients with heart failure of new onset compared with those with chronic obstructive pulmonary disease or asthma exacerbation (1561 versus 168 pg/mL). High clinical suspicion for acute heart failure (probability >80%) detected only 23% of patients with new-onset heart failure, whereas 82% of these patients had elevated NT-proBNP levels. In patients who had both previous acute heart failure and chronic obstructive pulmonary disease or asthma (n=52), median NT-proBNP levels were significantly higher in those with acute heart failure (4,435 pg/mL) than patients with chronic obstructive pulmonary disease or asthma exacerbation (536 pg/mL). In patients with acute-on-chronic heart failure, NT-proBNP levels were elevated in 91%, whereas clinical impression considered only 39% of cases as high likelihood for acute heart failure. CONCLUSION: NT-proBNP may be a useful adjunct to standard clinical evaluation of dyspneic patients with previous obstructive airway disease.

Utility of B-type natriuretic peptide for the evaluation of intensive care unit shock.

OBJECTIVES: Among patients with congestive heart failure, B-type natriuretic peptide measurement is useful to estimate filling pressures and to prognosticate adverse outcome. However, among critically ill intensive care unit patients with shock, the utility of B-type natriuretic peptide to assess cardiac hemodynamics or prognosis has not been explored. DESIGN: Clinical investigation. SETTING: Hospital. PATIENTS: Forty-nine patients with shock and indication for pulmonary artery catheterization. INTERVENTIONS: Analysis for B-type natriuretic peptide was performed on blood obtained at the time of catheter placement. MEASUREMENTS AND MAIN RESULTS: Correlations between B-type natriuretic peptide and pulmonary artery occlusion pressure as well as cardiac index were calculated using Spearman analysis. Mortality at the time of study completion was correlated with B-type natriuretic peptide values and Acute Physiology and Chronic Health Evaluation II scores, and logistic regression identified independent predictors of mortality. A wide range of B-type natriuretic peptide concentrations was seen in intensive care unit patients (<5 to >5000 pg/mL); only eight patients (16%) had normal B-type natriuretic peptide concentrations. Log-transformed B-type natriuretic peptide concentrations did not correlate with interpatient cardiac index or pulmonary artery occlusion pressure (all p = not significant); however, a B-type natriuretic peptide <350 pg/mL had a negative predictive value of 95% for the diagnosis of cardiogenic shock. Median B-type natriuretic peptide concentrations were higher in those who died than those who survived (943 pg/mL vs. 378 pg/mL, p <.001). In multivariable analysis, a B-type natriuretic peptide concentration in the highest log-quartile was the strongest predictor of mortality (odds ratio = 4.50, 95% confidence interval = 1.87-99.0, p <.001). CONCLUSION: B-type natriuretic peptide concentrations are frequently elevated among critically ill patients in the intensive care unit and cannot be used as a surrogate for pulmonary artery catheterization. B-type natriuretic peptide concentrations in intensive care unit shock may provide powerful information for use in mortality prediction.