Abstract 9675: Right Ventricular and Right Atrial Function in Pulmonary Hypertension Secondary to Heart Failure With Preserved Ejection Fraction: A Comparison With Pulmonary Arterial Hypertension

Introduction: Heart failure with preserved ejection fraction (HFpEF) is a prevalent condition for which no treatment exists. Pulmonary hypertension (PH) and right atrial (RA) and right ventricular (RV) dysfunction are frequently observed. The question remains whether PH and the associated RV/RA dysfunction in HFpEF are treatment targets or a mere reflection of disease severity. Methods: To study the relative contribution of pressure-overload and left-to-right interaction, we compared RA/RV function in three groups: 1. HFpEF (n=13); 2. HFpEF-PH (n=33), and; 3. pulmonary arterial hypertension (PAH) matched to pulmonary artery pressures of HFpEF-PH (n=47). Patients underwent right heart catheterization and cardiac magnetic resonance imaging. Groups were compared using one-way ANOVA, after which post-hoc analysis with unpaired t-test and Bonferroni correction was performed. Results: The right ventricle in HFpEF-PH was less dilated and hypertrophied than in PAH and RV ejection fraction was more preserved (HFpEF-PH: 52±11 vs. PAH: 36±12%). RV filling patterns were altered: vena cava backflow during RA contraction was observed in PAH only. In HFpEF-PH, RA pressure was elevated throughout the cardiac cycle (HFpEF-PH: 10[8-14] vs. PAH: 7[5-10] mmHg), while RA volume was smaller, reflecting excessive RA stiffness (HFpEF-PH: 0.14[0.10-0.17] vs. PAH: 0.08[0.06-0.11]mmHg/mL). RA stiffness was associated with an increased RA eccentricity index (HFpEF-PH: 1.3±0.2 vs PAH: 1.2±0.1) and transmural pressure gradient (9[5-12] vs 2[-2-5] mmHg). Conclusions: Despite similar pressure-overload, RV/RA function was less compromised in HFpEF-PH than in PAH. Increased RA pressure and stiffness in HFpEF-PH were explained by left atrial/RA-interaction. Our results indicate that increased RA pressure is not a sign of overt RV failure, but rather a reflection of HFpEF-severity.