Background Discordance between left- and right-sided filling pressures occurs in a subset of patients presenting with acute decompensated heart failure (ADHF). We hypothesized that a disproportionately increased right atrial pressure (RAP) relative to the pulmonary capillary wedge pressure (PCWP) would be associated with both renal dysfunction and mortality in ADHF. Methods A total of 367 patients admitted with ADHF with elevated intracardiac filling pressures were treated with intensive medical therapy guided by invasive hemodynamic monitoring. Baseline characteristics, hemodynamics, and renal function at admission were stratified by RAP/PCWP quartiles. The association of RAP/PCWP quartile with all-cause mortality after a median follow-up of 2.4 years was assessed in univariable and multivariable models, which included adjustment for the RAP. Results The median RAP/PCWP was 0.58 (interquartile range 0.43-0.75). Increasing RAP/PCWP was inversely associated with estimated glomerular filtration rate at baseline and with treatment ( P < .0001) independently of RAP. High RAP/PCWP was associated with increased mortality (quartile 4 vs 1: hazard ratio 95% CI 2.1 1.3-3.5, P = .002). The association of RAP/PCWP with mortality persisted after adjustment for age, gender, mean arterial pressure, RAP, cardiac index, pulmonary vascular resistance, and estimated glomerular filtration rate (hazard ratio 2.4 1.4-3.9, P = .007). Conclusion A disproportionate increase in right to left ventricular filling pressures is associated with renal dysfunction and mortality, independently of the right atrial pressure.