Introduction: Fluid challenge during right heart catheterization (RHC) identifies occult left heart diastolic dysfunction (Occ-DD) in 10-20% of patients initially diagnosed with pre-capillary pulmonary hypertension (PH). The prognostic implications of the response to fluid challenge are not known. Abnormal right ventricular (RV) function is a poor prognostic indicator in all forms of PH. Hypothesis: We hypothesized that fluid challenge during RHC identifies patients with worse RV function and survival. Methods: Consecutive patients referred for RHC with fluid challenge from 2009-2016 were studied. Occ-DD was defined by a resting pulmonary arterial wedge pressure (PAWP) < 15 mmHg, and a PAWP > 18 mmHg after 500cc fluid challenge. Resting DD was defined by resting PAWP > 15 mmHg. RV function was assessed by pulmonary artery pulsatility index (PAPi) or RV stroke work index (RVSWI). Statistical analysis was conducted using Kruskal Wallis test. Survival analysis was conducted by log rank test. Results: Of the 310 patients identified, 83% were female with a mean age of 54 + 14 years. The cohort consisted of 204 (66%) patients without DD, 30 (10%) with Occ-DD, and 76 (24%) with resting DD. Patients with Occ-DD were older (59 + 12 vs 51 + 14, p < 0.0001) with greater BMI (31 + 6 vs 28 + 7, p < 0.0001), but had similar prevalence of obesity, hypertension, diabetes mellitus, and coronary disease to all groups. Patients with Occ-DD had lower PAPi (7.8 + 0.4 vs 8.5 + 0.4, p < 0.0001), lower RVSWI (9.9 + 0.8 vs 17.8 + 0.7 mmHg*ml/m2, p < 0.0001) (Figure), and decreased survival (3.7 + 3.5 vs 4.9 + 3.5 years, p < 0.0001) compared to those without DD. After adjustment for RV function, survival was no longer different between groups. Conclusions: Patients with Occ-DD after fluid challenge during RHC have decreased survival due to worse RV function compared to patients without DD. These findings suggest important prognostic implications for fluid challenge in the evaluation of patients with PH.