Chronic obstructive pulmonary disease (COPD) augments the likelihood of having left ventricular diastolic dysfunction (LVDD)-precursor of heart failure with preserved ejection fraction (HFpEF). LVDD shares overlapping symptomatology (cough and dyspnea) with COPD. Stress induced LVDD is indicative of masked HFpEF. Our aim was to evaluate the predictive value of inflammatory, oxidative stress, cardio-pulmonary and echocardiographic parameters at rest for the diagnosis of stress LVDD in non-severe COPD patients, who complain of exertional dyspnea and are free of overt cardiovascular diseases. A total of 104 COPD patients (26 patients with mild and 78 with moderate COPD) underwent echocardiography before cardio-pulmonary exercise testing (CPET) and 1-2 minutes after peak exercise. Patients were divided into two groups based on peak average E/e': patients with stress induced left ventricular diastolic dysfunction (LVDD)-E/e' > 15 masked HFpEF and patients without LVDD-without masked HFpEF. CPET and echocardiographic parameters at rest were measured and their predictive value for stress E/e' was analysed. Markers for inflammation (resistin, prostaglandine E2) and oxidative stress (8-isoprostanes) were also determined. Stress induced LVDD occurred in 67/104 patients (64%). Those patients showed higher VE/VCO2 slope. None of the CPET parameters was an independent predictor for stress LVDD.Except for prostglandine E2, none of the inflammatory or oxidative stress markers correlated to stress E/e'. The best independent predictors for stress LVDD (masked HFpEF) were RAVI, right ventricular parasternal diameter and RV E/A >0.75. Their combination predicted stress LVDD with the accuracy of 91.2%. There is a high prevalence of masked HFpEF in non-severe COPD with exertional dyspnea, free of overt cardiovascular disease. RAVI, right ventricular parasternal diameter and RV E/A >0.75 were the only independent clinical predictors of masked HFpEF. 288.