Cardiovascular magnetic imaging is a noninvasive, three dimensional tomographic technique that allows for a detailed morphology of the cardiac chambers, the accurate quantification of right ventricle volumes, myocardial mass, and transvalvular flow. It can also determine whether right ventricular diastolic function is impaired through pulmonary hypertension. The aim of this article is to review the main kinetic, morphological and functional changes of the right ventricle that can occur in patients affected by pulmonary arterial hypertension (PAH) and to assess how the MRI findings can influence the prognosis, and guide the decision-making strategy. In those cases in which MRI shows a significant cardiac diastolic dysfunction, the prognosis is predictive of pharmacological treatment failure, and mortality. This leaves double lung-heart transplantation as the only therapeutic option. The coexistence of PAH and left ventricle impairment causes worse right ventricle function, leads to a poor prognosis, and may change the therapeutic strategies (for example, PAH associated with left ventricle dysfunction may require a double lung-heart transplant).