Association between right heart size and right ventricular output reserve in patients with pulmonary arterial hypertension

<bold>Objectives:</bold> Right ventricular (RV) output reserve, defined as increase of cardiac output during exercise, is reduced in patients with pulmonary arterial hypertension (PAH). Aim of this study was to evaluate the association of right heart size and invasively measured RV function at rest and during exercise in PAH patients. <bold>Methods:</bold> PAH-patients who received routine hemodynamic assessment at rest and during exercise with echocardiographic measurement of right heart size (right atrial (RA) and RV area) were included. Clinical, echocardiographic, laboratory, exercise and hemodynamic parameters were retrospectively analysed. The primary endpoint was to assess the association between right heart size and right ventricular function. <bold>Results:</bold> Data from 215 PAH patients (age 58.9 ± 15.9 years, 63.3% female, 62.2% double or triple combination treatment) was analysed in this cross-sectional study. Cardiac index was significantly lower for patients with enlarged RA-area >18 cm2 at rest, 25 and 50 Watts (all p<0.001) and for patients with enlarged RV area >20 cm2 at rest, 25, 50 and 75 Watts (all p<0.001; Figure 1). Furthermore, pulmonary arterial compliance (all p<0.05) and mPAP/CO slope (all p<0.001) significantly differed between groups for both RA and RV area. RA and RV area correlated with TAPSE/sPAP (both p<0.001, R -0.570 and -0.530). Patients with RA-area >18 cm2 or RV area >20 cm2 had a significantly greater pulmonary vascular resistance (both p<0.001) than patients with normal right heart size. <bold>Conclusion:</bold> This study could underline that an enlargement of RA- and RV-area is associated with an impaired RV function at rest and during exercise in PAH-patients.