Abstract 13772: Percent Predicted Peak Oxygen Pulse Predicts Vascular Responses to Exercise in HFpEF

Introduction: Cardiopulmonary exercise testing (CPET) can help identify early stages of heart failure with preserved ejection fraction (HFpEF). We sought to determine if percent predicted peak oxygen pulse (%PredO 2 P, as defined by peak oxygen uptake/heart rate), a noninvasive measure combining stroke volume and peripheral oxygen extraction, could serve as a marker of the hemodynamic response to exercise in HFpEF patients. Methods: 154 consecutive patients who underwent maximal CPET (RER>1.05) and were diagnosed with HFpEF (defined as LVEF>50% and PCWP/CO >2 mmHg*min/L or supine resting PCWP >15 mmHg) were included. Exclusion criteria included patients who were taking AV nodal agents, were paced, or had atrial fibrillation. Peak O 2 P and percent predicted were calculated using the Wasserman equation for peak VO2 in conjunction with peak predicted heart rate (220-age). Results: Tertiles of %PredO 2 P were determined with first tertile at 42.1-76.2%, second tertile at 76.2-94.4%, and third tertile at 94.4-139.2%. Baseline parameters differed across %PredO 2 P tertiles ( Table 1 ) with BMI increasing (trend p=0.014). Peak cardiac output (1 st : 10.0±3.0 L/min, 2 nd : 11.1±2.4, 3 rd : 11.5±3.5; p=0.038) and peak stroke volume (1 st : 70.6±20.1 mL, 2 nd : 83.0±16.6, 3 rd : 92.7±20.1; pst : 143±23 bpm, 2 nd : 135±25, 3 rd : 123±26; pst : 959±304 dynes*s/cm 5 , 2 nd : 831±187, 3 rd : 810±321; p=0.009) were lower. Exercise PAP/CO slope (1 st : 4.5±2.1 mmHg*min/L, 2 nd : 3.6±1.6, 3 rd : 3.3±1.7; p=0.003) and PCWP/CO slope (1 st : 3.4±1.8 mmHg*min/L, 2 nd : 2.9±1.4, 3 rd : 2.8±2.0; p=0.015) were lower across tertiles of %PredO 2 P. Conclusions: %PredO 2 P is a noninvasive variable that associates with vascular responses to exercise in HFpEF patients. Higher %PredO 2 P was associated with improved vascular responses to exercise with lower SVR, PAP/CO and PCWP/CO slopes.