mpaired gas diffusion and RV to pulmonary circulation uncoupling limit exercise performance in heart failure patients

Introduction: In heart failure (HF) patients, an altered gasdiffusing capacity for carbon monoxide (DLCO) is a marker of lung capillary injury that bears relevant clinical and prognostic information. It is unknown whether right heart-pulmonary circulation (RH-PC) uncoupling abnormalities and gas diffusion are linked and may become synergic in causing exercise limitation and ventilation inefficiency. Methods: 17 HF patients (mean age 64±11; male 75%; NYHA II-III; mean left ventricular (LV) ejection fraction 34±9%) underwent DLCO measurements with assessment of membrane component (DM) an capillary blood volume (Vc) and underwent to maximal cardiopulmonary exercise testing (CPET, tilt-ergometer,personalized ramp protocol) combined with Echo-Doppler assessment of right ventricular function by assessing tricuspid annular peak systolic excursion (TAPSE) and pulmonary systolic pressure (PASP). Results: Patients exhibited an abnormal gas diffusion (mean DLCO 17±3.9 ml/min/mmHg) with depressed alveolar-capillary membrane diffusing capacity (DM) component (mean 23.4±6.8 ml/min/mmHg) and elevated capillary volume (mean 111.2±64 ml) along with significant functional limitation (mean peak VO2 12.5±3.7 ml/kg/min) and ventilatory inefficiency(mean VE/VCO2 slope: 34.4±6.9 and mean end-tidal of CO2 mean 32.1±5.2 mmHg). Significant correlations were found between DM, TAPSE/PASP relationship, peak VO2 and VE/VCO2 slope at peak exercise (figure). Conclusions: Our findings show a link between the RV-PC uncoupling with gas diffusion abnormalities suggesting that interventions aimed at targeting the functional performance in HF population have to ideally combine amodulatory effect on both the alveolar-capillary gas diffusion capacity and right heart function.