B-type Natriuretic Peptide in the Diagnosis of Heart Failure Related Ascites

The serum albumin ascites gradient (SAAG) is a recommended tool for ascites diagnosis since values ≥1.1 g/dl are found in nearly 97% of patients with portal hypertension. However, it mislabels chronic liver disease and heart failure as the cause of ascites. Because type-B Natriuretic Peptide (BNP) is increased in several body fluids of patients with both systolic and diastolic dysfunction, it was found to be a useful marker for diagnosing heart failure and pleural effusion due to heart failure. Nevertheless, to date, the performance of BNP testing for assessing the etiology of ascites has not been examined. The current prospective study is aimed at comparing the following strategies for diagnosing heart failure as the cause of ascites: 1) SAAG plus total protein concentration in ascitic fluid (gold standard); 2) SAAG plus BNP concentration in ascitic fluid; 3) SAAG plus BNP concentration in serum; 4) serum BNP concentrations. SAAG, ascitic fluid protein concentration, serum and ascites type-B Natriuretic Peptide and echocardiography will be performed in all patients. The final diagnosis of the cause of ascites will be adjudicated by independent physicians, blinded for the results of ascitic fluid biochemistry and BNP. Patients will be divided into four groups: Heart failure, Liver cirrhosis, concurrent heart failure and liver cirrhosis (mixed) and other causes of ascites.