Background Patients with acute decompensated heart failure (ADHF) and cardiorenal syndrome (CRS) 1 have poor outcomes. Ultrafiltration (UF) is used to mechanically remove salt and water in ADHF patients with diuretic resistance. However, little is known about the outcomes of ADHF patients on inotropes and/or vasopressors who require continuous renal replacement therapy (CRRT) for both UF and solute clearance in severe acute kidney injury. Methods We retrospectively analyzed 37 consecutive critically ill patients who were admitted for ADHF from 2005-13 and were on inotropes and/or vasopressors at the time of CRRT initiation. The primary outcome was in-hospital mortality. Results In-hospital mortality rate was 62%. Median survival was 15.5 days after CRRT initiation, and 10 months following hospital discharge. When comparing renal and cardiovascular variables for survivors and non-survivors at baseline, admission and CRRT initiation, survivors were less likely to need vasopressors. After controlling for multiple predictors, vasopressor use remained associated with time to death (HR 9.9; 95% CI 2.3-43.3; P = 0.002). Patients with isolated right ventricular dysfunction had an in-hospital mortality of 45% compared with 69% in those with left ventricular dysfunction (P = 0.27). Age of >70 years was associated with 100% in-hospital mortality. Conclusions Rescue therapy using CRRT in refractory CRS1 was associated with high in-hospital mortality, especially when vasopressors were used and when patient age exceeded 70 years. Additionally, survivors had a poor long-term prognosis.