Abstract 16688: CZT Equilibrium Radionuclide Angiography (ERNA) Detects Improvements in Right Ventricle Size and Function for Pulmonary Arterial Hypertension Participants Intensifying Therapy

Abstract

Introduction: Pulmonary Arterial Hypertension (PAH) is associated with pruning and vasconstriction of the pulmonary arteries, resulting in right ventricular (RV) failure and death. RV size and function are among the most powerful prognostic predictors for disease outcomes and can change in response to therapy. However, obtaining quantitative RV information remains challenging with echocardiography, while cardiac MRI remains expensive, claustrophobic, and relatively less accessible. Hypothesis: CZT ERNA is a simple and readily available cardiac imaging technique that will measure changes in RV size and function for PAH participants intensifying therapy (RVEF, RVEDV, RVESV). Methods: D-SPECT (Spectrum Dynamics) CZT-ERNA was performed on 24 participants using low dose (approximately 10 mCi Tc-99m TCO4 - ; ~2.5 mSv), 10 minute imaging protocol: 12 were imaged just prior to starting or intensifying therapy and again 6 months later (Active), and 12 age- and sex-matched controls on stable therapy were imaged twice within a 3 week period. Additionally, 6 minute walk distance, laboratories (including NTproBNP) and WHO functional class were assessed at the time of each scan. All scans were processed using Cedars Sinai QBS automatic software; we did manual re-processing when chamber separation was poor or extra-cardiac activity was substantial (n=22/40 scans). Results: All 24 participants completed two scans; four (2 Active, 2 control) were excluded from paired analysis due to low intensity images on one scan (of a pair), and one Active participant was excluded due to clinical worsening requiring hospitalization. There were no adverse events related to imaging. RVEF (45% ± 3.5 vs 55% ± 4.2; p=0.008) and RV stroke volume (89mL ± 10.3 vs 108mL ± 12.3; p=0.03) improved in the active group but were stable in the control group (RVEF= 58% ± 3.7 vs 56% ± 5.0; RVSV=108mL ± 12.9 vs 116mL ± 16.6). A participant with particularly striking improvement is illustrated below. Scan times were 10 minutes with total testing time between 60-90 min. Conclusions: CZT-ERNA is quick, easy and seems effective for obtaining quantitative measures of the RV in PAH.