Cardiac MRI in the assessment of chronic thromboembolic pulmonary hypertension and response to treatment

Chronic thromboembolic pulmonary hypertension affects patients with previous pulmonary thromboembolism who develop pulmonary hypertension and right heart failure. Pulmonary endarterectomy surgery revolutionised its management by offering potential cure to patients with otherwise very poor prognosis. Haemodynamic assessment using right heart catheterisation is a well validated means of evaluating success of surgery and prognostication. However, it does not allow comprehensive assessment of the right ventricle, furthermore it requires repeated invasive procedures. Cardiac MR is emerging as the gold standard for the assessment of the right ventricle. Its versatility allows assessment of mass, volumes, function, myocardial strain, right ventricular-pulmonary artery coupling, lung parenchymal perfusion and it can be combined with simultaneous exercise testing. It is non-invasive and does not use radiation. The existing literature on cardiac MRI in chronic thromboembolic pulmonary hypertension focuses on evaluation of response to surgery with studies consistently showing significant improvement in right ventricular mass, volume and function. Moreover, reduced right ventricular myocardial strain, improvement in right ventricle-pulmonary artery coupling and restoration of gravity-dependent pulmonary flow pattern are seen. Dynamic testing unmasks abnormal response to exercise in the context of normal resting indices. Cardiac MR is a promising tool in the evaluation of patients undergoing pulmonary endarterectomy. There is a clear need for larger studies with longer follow up focusing on evaluation of strong clinical endpoints.