Increased Right Ventricular Fatty Acid Accumulation in Chronic Thromboembolic Pulmonary Hypertension

In right ventricular hypertrophy associated with severe pulmonary hypertension (PH), a shift of energy metabolism toward glycolysis occurs. There are few investigations regarding fatty acid metabolism in patients with PH and right ventricular hypertrophy.

To assess whether there is fatty acid accumulation in the hypertrophied right ventricle in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and to determine whether this accumulation is related to hemodynamic variables obtained by right heart catheterization.

To assess fatty acid accumulation in the right ventricle, 123I-β-methyl iodophenyl pentadecanoic acid (BMIPP) analog imaging was performed in control subjects (n=16) and patients with CTEPH (n=13) before (n=13) and after (n=8) pulmonary thromboendarterectomy.

There was increased 123I-BMIPP uptake in the right ventricle of subjects with CTEPH before pulmonary endarterectomy. Right ventricular 123I-BMIPP uptake decreased significantly after thromboendarterectomy (P=0.003) in parallel with the change of hemodynamic variables. The right ventricular BMIPP uptake was significantly correlated with the mean pulmonary artery pressure (r=0.51, P=0.0228) but not with pulmonary vascular resistance (r=0.39, P=0.0932).

This is the first study that uses 123I-BMIPP uptake imaging to show that fatty acid accumulates in the right ventricle of patients with CTEPH and that the increased accumulation is reversible after pulmonary thromboendarterectomy. This study suggests that this imaging modality may be useful for monitoring right ventricle metabolic functions in severe PH.