In individuals with pulmonary arterial hypertension (PAH), mild changes in right ventricular (RV) glucose metabolism may be associated with patient prognosis, according to findings from a positron emission tomography/magnetic resonance imaging (PET/MRI) hybrid imaging follow-up study published in EJNMMI Research.
Among those with undiagnosed or poorly managed PAH, progressive increases in RV afterload that result in RV failure are inevitable. Specific challenges are presented regarding the appropriate characterization of RV function, particularly prior to patients’ initial clinical deterioration.
The researchers hypothesized that adequate escalation of PAH treatment may be associated with the reversal of unfavorable increased RV glucose uptake, which is linked to improved patient prognosis. The current analysis is a follow-up of the observational patient registry study.
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All participants were followed on a regular 3-month basis, with the initial structured follow-up visit conducted 24 months from the baseline visits. At this time, PET/MRI scans, echocardiography, 6-minute walk test, and biochemical analysis were performed.
Read more about PAH epidemiology
The occurrence of a clinical endpoint was verified between baseline visits and follow-up visit 1. A clinical endpoint was defined as “death or [World Health Organization] class worsening and/or hospitalization due to pulmonary hypertension progression or right heart failure…” After all follow-up 1 visits took place, the investigators observed the study group for the next 24 months for the occurrence of a clinical endpoint, which ended in the second follow-up visit.
In the current study, therapy escalation was defined as “initiation of prostacyclin (PGI) treatment (parenteral or oral) or adding second-line oral therapy according to [European Society of Cardiology] guidelines.” Right heart catheterization was performed at the first and second visits.
Among 26 patients with PAH who were initially considered clinically stable and had baseline PET/MRI scans, 20 underwent a second PET/MRI scan after 24 months. Standard uptake value of the right ventricle to the left ventricle (SUVRV/SUVLV) ratio was used to estimate and compare cardiac glucose uptake.
In the initial 24 months of observation, 16 patients experienced a clinical endpoint and required escalation of PAH therapy (ie, 4 deaths and 12 individuals with symptoms of PAH progression). At follow-up 1, a significant change in MRI-derived RV ejection fraction (45.1%±9.6%-52.4%±12.9%; P =.01) and improvement in mean pulmonary arterial pressure (50.5±18.3-42.8±18.6 mm Hg; P =.03) were observed.
Read more about PAH treatment
The SUVRV/SUVLV ratio demonstrated a tendency to decrease (mean change, –0.20±0.74). Patients who had a baseline SUVRV/SUVLV ratio higher than 0.54 experienced a worse prognosis after 48 months of observation (log-rank test,
P =.0007). A follow-up SUVRV/SUVLV ratio of more than 1 was predictive of a clinical endpoint in the 24 months that followed, regardless of the use of prior escalated therapy.
“Statistically significant correlations between PET/MRI parameters and hemodynamic measurements observed at both follow-up visits suggests that there is a strong relationship between affected pulmonary arteries and RV cardiomyocytes,” the researchers stated. “The study underlines [the] emerging role of further research in the field of possible metabolic modulations therapies in PAH,” they concluded.
Reference
Kazimierczyk R, Szumowski P, Nekolla SG, et al. The impact of specific pulmonary arterial hypertension therapy on cardiac fluorodeoxyglucose distribution in PET/MRI hybrid imaging-follow-up study. EJNMMI Research. Published online March 9, 2023. doi:10.1186/s13550-023-00971-w
