Abstract 15033: Chronic Thromboembolic Pulmonary Hypertension Patients Have Reduced Bi-Ventricular Myocardial Perfusion Reserve, Which Improves Following Pulmonary Thromboendarterectomy

Introduction: This study seeks to determine whether bi-ventricular myocardial perfusion reserve (MPR) is reduced in patients with chronic thromboembolic pulmonary hypertension (CTEPH) compared to a control group using quantitative myocardial perfusion MRI. Methods: We prospectively enrolled 4 CTEPH patients (55±14 years, 4 males) and performed stress-rest (10 min apart) protocol using our 5-fold accelerated radial perfusion sequence. In one patient, we repeated stress-rest perfusion acquisition following pulmonary thromboendarterectomy (PTE). As a control group, we retrospectively identified 8 subjects (49±12 years, 5 males) with no evidence of vascular late gadolinium enhancement or perfusion defects who underwent a similar stress-rest protocol. The pixel-wise stress-rest myocardial blood flow (MBF) maps and MPR were quantified for both the left ventricular (LV) and right ventricular (RV) free walls. Two sample t-test was used to compare between the CTEPH and control groups. Results: Figure 1a shows representative stress and rest MBF maps and the corresponding MPR values comparing a CTEPH patient and a control subject. Summarizing the results of all patients (Figure 1b), compared to the control group, the CTEPH group had significantly (p < 0.05) lower stress LV MBF (1.56 ± 0.34 vs. 2.66 ± 0.50 ml/g/min), RV MBF (1.48 ± 0.19 vs. 2.56 ± 0.53 ml/g/min), LV MPR (1.65 ± 0.43 vs. 2.32 ± 0.50), and RV MPR (1.59±0.46 vs. 2.50 ± 0.53), but non-significant difference (p > 0.05) in resting LV MBF (0.96 ± 0.12 vs. 1.21 ± 0.43 ml/g/min) and RV MBF (0.96 ± 0.14 vs. 1.07 ± 0.36 ml/g/min). In one patient, PTE improved RV MPR from 1.43 to 2.49 as well as LV MPR from 1.24 to 2.36. Conclusions: This study suggests that both RV and LV MPR are reduced in CTEPH patients compared with controls and that PTE may improve RV as well as LV MPR in CTEPH patients. Future studies include additional enrollment of CTEPH patients, determining the diagnostic and prognostic role of RV and LV MPR in the context of PTE.