Rest ETCO2 and VE/VCO2 are Superior to Exercise Gas Exchange Parameters with Invasive Cardiopulmonary Exercise Testing to Predict Pulmonary Vascular Disease in Patients with Dyspnea of Unclear Etiology

Abstract

Purpose We sought to predict exercise-induced pulmonary hypertension (PH) and behavior of resting PH with exercise with gas exchange parameters. Methods We reviewed clinical, echocardiographic and invasive cardiopulmonary exercise testing data for 75 consecutive patients with unexplained dyspnea . Results Among the overall cohort, mean age (± SD) was 58.9±14.5 years. Based on the final diagnosis and physiological phenotype, we divided the overall cohort into three groups: pulmonary vascular disease (PVD) - combination of WHO group I/III/IV (n=23, 30%), pulmonary venous hypertension - WHO group II (n=38, 52%) and the control group with no PH (n=14, 19%). Echocardiographic parameters among PVD vs PVH vs Control group: right ventricle (RV): left ventricle ratio 0.9±0.2 vs 0.9±.02 vs 0.8±0.2, tricuspid annular pan-systolic excursion 17±5 vs 20±5 vs 21±3 mm, RV outflow tract acceleration time 98±17 vs 107±23 vs 124±23 m.sec, while other rest -> exercise parameters are in Figure 1. Among different gas exchange parameters, rest ETCO 2 and VE/VCO2 had the highest predictive ability on ROC analysis to identify both rest and exercise PVR > 3 WU, and PVD (vs non-PVD diagnosis) with AUC: 0.81-0.82 range. Based on these findings, we created a simple easy-to-use gas exchange scoring system with rest ETCO2 and VE/VCO2 that can help identify patients with pulmonary vascular disease (Figure 2). Conclusion In dyspnea of unclear etiology, rest gas exchange parameters (ETCO2 and VE/VCO2) can identify pulmonary vascular disease as the cause.