Feasibility of Oxygen Sensitive Cardiac Magnetic Resonance in Demonstrating Right Ventricular Myocardial Ischaemia in Patients with Pulmonary Arterial Hypertension

Abstract

Background: Progressive right ventricular (RV) dysfunction in pulmonary arterial hypertension (PAH) which is contributed by RV ischaemia leads to adverse clinical outcomes. Oxygen-sensitive (OS) cardiovascular magnetic resonance (CMR) has been used to determine the in-vivo myocardial oxygenation of the left ventricle (LV). The aim of the present study was to (1) Determine the feasibility of RV targeted rest/stress OS-CMR imaging in PAH patients and normal volunteers; (2) To define the presence and extent of RV myocardial ischaemia in patients with known PAH. Methods: We prospectively recruited 20 patients with right heart catheter proven PAH and 9 normal healthy volunteers (NV). The CMR examination involved standard functional imaging and OS-CMR Imaging. An OS-CMR signal intensity (SI) index (stress/rest signal intensity) was acquired at RV anterior, RV free-wall and RV inferior segments. Results: Reliable OS signal intensity changes were only obtained from the RV inferior segment. As RV dysfunction in PAH is a global process, this segment was used in both patients and NV for further comparison. RV OS SI change between rest and stress in the NV was 17 ± 4% (mean ± SD). 9/20 (45%) of the PAH patients had a mean OS-CMR signal intensity change of less than 9% (or 2SD different from the mean values in normal volunteers). Overall, RV OS SI index between the PAH patients and NV was 11 ± 9% vs 17 ± 5% (p-value = 0.04) in RV inferior segment. Conclusion: Pharmacological induced OS-CMR is a feasible and safe technique to identify and study myocardial oxygenation in the RV of PAH patients.