C64-03 Myocardial Perfusion Reserve Reflects Right Ventricular-Pulmonary Arterial Coupling in Patients Evaluated for Pulmonary Hypertension

Rationale Impaired myocardial perfusion may contribute to right ventricular (RV) maladaptation in pulmonary hypertension (PH). Myocardial perfusion reserve (MPR) is an emerging cardiac magnetic resonance (CMR)-based index that compares myocardial blood flow between stress and rest. In this study, we investigated whether MPR in the RV reflects RV-pulmonary arterial (PA) coupling and may serve as a noninvasive marker of RV adaptation in PH. Methods Sixteen patients evaluated for suspected PH between 2008-2023 at Johns Hopkins Hospital underwent same-day right heart catheterization with baseline hemodynamics and multi-beat RV pressure-volume (PV) loop analysis followed by CMR imaging. MPR was calculated as the ratio of RV myocardial perfusion during adenosine stress to perfusion at rest using gadolinium-enhanced first-pass imaging. Gold standard RV-PA coupling measurements were taken by calculating the ratio of end-systolic to arterial elastances (Ees/Ea) using multi-beat PV loops. The association between log-transformed MPR and multi-beat Ees/Ea was assessed with age- and sex-adjusted linear regression. Receiver operating characteristic (ROC) analysis evaluated MPR’s ability to discriminate RV-PA uncoupling, defined as Ees/Ea < 0.78 as previously determined (Rosen et al, ERJ in press). Results Participants had a median age of 59 [42-64]; 75% were female, 69% had PAH, and 60% had systemic sclerosis. Median MPR was 1.5 [1.2-1.9] and median Ees/Ea was 1.0 [0.7-1.9]. Thirty-one percent of patients met criteria for RV-PA uncoupling (Ees/Ea < 0.78). A 10% increase in MPR was associated with a 0.11-unit increase in Ees/Ea (β = 0.11; 95% CI 0.00-0.21; p = 0.047). MPR effectively discriminated RV-PA uncoupling with an AUC = 0.80 (Figure 1). The Youden index of 1.17 corresponded to a sensitivity of 0.91, specificity 0.6, positive likelihood ratio of 2.3, and negative likelihood ratio of 0.15. Conclusions To our knowledge, this is the first demonstration that CMR-derived MPR is significantly associated with multi-beat Ees/Ea. MPR exhibits strong discriminatory performance for identifying RV-PA uncoupling (Ees/Ea < 0.78), which is a strong predictor of mortality in PH. These findings suggest MPR may serve as a promising surrogate marker for RV-PA coupling, facilitating noninvasive assessment of RV adaptation. Further studies are warranted to validate these results and explore MPR’s potential in predicting outcomes. This abstract is funded by: None