Increased right atrial volume measured with cardiac magnetic resonance is associated with worse clinical outcome in patients with pre-capillary pulmonary hypertension

AimsPre-capillary pulmonary hypertension (PHpre-cap) has a poor prognosis, especially when caused by pulmonary arterial hypertension (PAH) associated with systemic sclerosis (SSc-PAH). Whether cardiac magnetic resonance (CMR)-based quantification of atrial volumes in PHpre-cap is beneficial in risk assessment is unknown. The aims were to investigate if (i) atrial volumes using CMR are associated with death or lung transplantation in PHpre-cap, (ii) atrial volumes differ among four unmatched major PHpre-cap subgroups, and (iii) atrial volumes differ between SSc-PAH and idiopathic/familial PAH (IPAH/FPAH) when matched for pulmonary vascular resistance (PVR). Methods and resultsSeventy-five PHpre-cap patients (5719years, 53 female, 43 de novo) with CMR and right heart catheterization were retrospectively included. Short-axis stacks of cine images were analysed, and right and left atrial maximum (RAV(max) and LAV(max)) and minimum volume (RAV(min) and LAV(min)) were indexed for body surface area. Increased (mean+2 SD) and reduced (mean-2SD) volumes were predefined from CMR normal values. Transplantation-free survival was lower in patients with increased RAV(max) than in those with normal [hazard ratio (HR)=2.1, 95% confidence interval (CI) 1.1-4.0] but did not differ between those with reduced LAV(max) and normal (HR 2.0, 95% CI 0.8-5.1). RAV(max) and RAV(min) showed no differences among unmatched or matched groups (P=ns). When matched for PVR, LAV(max), LAV(min), and pulmonary artery wedge pressure were reduced in SSc-PAH compared with IPAH/FPAH (95% CI 0.3-21.4, 95% CI 0.8-19.6, and 95% CI 2-7, respectively). ConclusionsPatients with PHpre-cap and increased right atrial volume measured with CMR had worse clinical outcome. When matched for PVR, left atrial volume was lower in SSc-PAH than in IPAH/FPAH, consistent with left-sided underfilling, indicating a potential differentiator between the groups.