Novel CMR-imaging biomarkers to track response to treatment including Sotatercept in a patient with idiopathic pulmonary arterial hypertension: a case report

Abstract Background Pulmonary arterial hypertension (PAH) causes progressive right ventricular (RV) pressure overload and left ventricular (LV) underfilling. Sotatercept is an activin-signal inhibitor, approved by FDA in 2024 and EMA in 2025, as an add-on treatment in adult patients with PAH. Cardiovascular magnetic resonance (CMR) derived atrioventricular plane displacement (AVPD) and left ventricular pressure-volume (PV) loops may represent non-invasive markers of treatment response, particularly important as novel therapies addressing remodelling emerge. Case summary A 30-year-old woman was diagnosed with idiopathic PAH (IPAH), after presenting with dyspnoea and peripheral oedema. Baseline CMR showed severe RV dilation, reduced RV ejection fraction, and low indexed LV stroke volume, with reduced bilateral AVPD and markedly impaired LV PV-loop indices, with low stroke work, low mean external power, and high ventriculo-arterial coupling. Initial dual PAH therapy, with an endothelin receptor antagonist (ERA) and a phosphodiesterase five inhibitor (PDE5i) initially improved symptoms, pulmonary vascular resistance, as well as AVPD and PV-loop derived indices, whereas conventional CMR indices showed only minimal change. One year later, despite triple therapy, including prostacyclin analogue, the patient deteriorated clinically and CMR showed worsening of AVPD and PV-loop indices. Treatment escalation with Sotatercept immediately improved clinical status, haemodynamic, AVPD, and PV-loop indices despite persistent RV remodelling. Discussion Serial CMR-derived AVPD and LV PV-loops may provide clinically useful additional information during longitudinal follow-up of PAH patients, especially in those approaching maximal available medical therapies. In the present case, both AVPD and LV PV-loops reflected treatment response, and showed significant improvement after initiation of Sotatercept.