P593Oxygen sensitive cardiac magnetic resonance in demonstrating myocardial ischaemia of the right ventricle in patients with pulmonary artery hypertension

Abstract

Background Progressive right ventricular (RV) dysfunction is a natural progression of pulmonary arterial hypertension (PAH) which is associated with adverse clinical outcomes. The main contributor to progressive RV dysfunction is RV ischemia. Oxygen-sensitive (OS) cardiovascular magnetic resonance (CMR) has been used to determine the in-vivo myocardial oxygenation of the left ventricle (LV). Purpose 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 (NC), age matched controls with no heart disease. The CMR examination involved standard functional imaging and OS-CMR imaging. OS-CMR images were acquired using a T2* sequence at rest and adenosine-induced stress vasodilatation. The RV was divided into 3 segments - RV anterior, RV free-wall and RV inferior. An OS-CMR signal intensity (SI) index (stress/rest signal intensity) was acquired at RV anterior, RV free-wall and RV inferior segments. Results All the PAH patients tolerated and completed the adenosine induced stress OS-CMR without any complications or adverse effects. In NC, reliable OS signal intensity changes was only obtained from the RV inferior segment. As RV dysfunction in PAH is a global process, hence this segment was used in both patients and NC for further comparison. RV OS-CMR signal intensity change between rest and stress in the normal volunteers was 17±4% (mean ± SD). 9 out of twenty (45%) of the PAH patients had a mean BOLD 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 controls was 11±9% vs 17±5% (p-value = 0.045) 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.