Introduction: Reduced left ventricular (LV) myocardial efficiency (myocardial work per O2 (MVO2)) and increased sympathetic nervous (SN) activity have been associated with the failing LV. Less is known regarding the right heart. We hypothesized that patients (pts) with RV dysfunction demonstrate increased MVO2 suggesting altered RV energetics and increased SN activity which relate to patient outcomes.Methods: 31 pts with LV systolic dysfunction and NYHA class II or III previously studied to measure LV parameters, were assessed for RV function and size using echocardiography. PET imaging was used to measure RV oxidative metabolism (C-acetate clearance rate (kmono)) and SN function (C-Hydroxyephedrine (HED) standard uptake values (SUVs) where decreased HED indicates increased SN activity). MVO2 was extrapolated from the linear relationship of MVO2 to kmono for the LV. Time to first cardiac event (FCE) (hospitalization for heart failure, worsening functional class, arrhythmia, heart transplantation and cardiac death) was determined.Results: Pts with (n=10) or without (n=21) RV dysfunction were comparable in terms of gender (male: 76 vs 70%), LV ejection fraction (38±9 vs 39±9%) and systemic hypertension (76 vs 70%). Pts with RV dysfunction were older (70±13 vs 60±11 yrs; p=0.03), had a greater prevalence of pulmonary hypertension (60% vs 14%; p=0.01), higher RV systolic pressure (47±15 vs 35±7 mmHg; p=0.03), higher RV MVO2 (0.10±0.04 vs 0.06±0.02 mL/min/g; p=0.002) and lower HED SUV (6.0±0.5 vs 7.1±1.1; p=0.007). RV dilatation was also associated with increased RV MVO2 (0.12±0.02 vs 0.07±0.03 mL/min/g; p=0.01) and decreased RV HED SUV (5.8±0.5 vs 6.9±0.2; p=0.05). There was a trend for a negative correlation between RV MVO2 and time to FCE (ρ=-0.43; p=0.13). The Kaplan-Meier survival analysis indicated a trend for shorter event-free survival in pts with higher than median RV MVO2 (508±213 vs 1098±245 days; p=0.07). No significant correlation was detected between time to FCE and RV HED uptake.Conclusions: RV dysfunction and dilatation were associated with increased RV MVO2 suggesting altered RV energetics and reduced RV HED uptake indicating high SN activity. Measurement of RV MVO2 may be useful as a predictor of cardiac morbidity in RV failure pts.