Change of myocardial fluorodeoxyglucose uptake distribution after specific therapy of pulmonary arterial hypertension patients

Abstract

Abstract Background Right ventricular (RV) function is a major determinant of survival in patients with pulmonary arterial hypertension (PAH). In our previous study, we confirmed that increased RV fluorodeoxyglucose (FDG) uptake in positron emission tomography (PET) (presented as higher ratio of FDG uptake of RV to LV) was associated with progressive RV dysfunction and preceded hemodynamic and clinical deterioration in PAH patients. Now, we obtained second PET/MRI assessments of the study group after 2-years of PAH-targeted treatment. Aim The aim of the study was to obtain change of cardiac FDG uptake in PAH patients after follow-up period and to indicate factors mainly affecting this change. Methods Twenty-eight PAH patients (51.32±15.91 years) had simultaneous PET/MRI scans performed during baseline visit. FDG was used and its uptake was quantified as mean standardized uptake value (SUV) for both left (LV) and RV. Second PET/MRI assessments were done after 2 years in the group of twenty patients (four deaths, four patients did not agree to perform additional scans). Results After follow-up period, we observed significant change of MRI-derived RV ejection fraction (45±10% to 51.2±12.7%, p=0.03), and improvement in hemodynamic parameters obtained from right heart catheterization (RHC) e.g. mean pulmonary artery pressure, mPAP (48.5±17.2 to 41.8±17.1 mmHg, p=0.01) and pulmonary vascular resistance, PVR (8.7±5.3 to 7.0±4.2 WU, p=0.04). Follow-up SUVRV/SUVLV ratio significantly correlated with follow-up RV hemodynamic parameters confirming relationship between RV function and cardiac metabolic alterations (Table 1). Interestingly, patients who had improvement in SUVRV/SUVLV (lower follow-up value than baseline, n=11) had significantly higher mPAP at baseline visit (58.9±18.7 vs 40.3±11.8 mmHg, p=0.02), suggesting that RV FDG accumulation in advanced PAH may decrease after the PAH-specific treatment in accordance with the degree of reduction in the pulmonary vascular resistance. Conclusion Impaired RV function is associated with increased glucose uptake of RV myocytes estimated by FDG PET in PAH patients. Targeted treatment may improve RV function and thus affect previously altered cardiac glucose uptake. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Polish National Science Centre