Abstract 4138187: Right Atrial Pressure/Pulmonary Artery Wedge Pressure Ratio Correlates With Early Outcomes After Pulmonary Thromboendarterectomy

Background: Elevated right atrial pressure/pulmonary artery wedge pressure (RAP/PAWP) ratio has been associated with poor outcomes in pulmonary arterial hypertension (PAH). However, the current risk assessment tools in PAH focus on absolute RAP values and cut-offs over the measured RAP in context of PAWP. This ratio has not been investigated in chronic thromboembolic pulmonary hypertension (CTEPH). The ratio of RAP to PAWP may help with risk assessment prior to pulmonary thromboendarterectomy (PTE). Method: We retrospectively reviewed patients with CTEPH who underwent PTE at the University of California San Diego between January 2021 and December 2023. Baseline characteristics including invasive pulmonary hemodynamics and post-operative outcomes were analyzed. Mean computer generated values were used for both RAP and PAWP. Post-operative outcomes of interest were reperfusion pulmonary edema (RPE), ventilator days, re-intubation, intensive care unit (ICU) length of stay (LOS), hospital LOS, and 30-day mortality. Results: Of 532 CTEPH patients undergoing PTE during this time period, total of 496 patients with baseline hemodynamics meeting analysis criteria were categorized into 2 groups: RAP/PAWP ratio ≥1 ( inverse group, n=133, 26.8%) and RAP/PAWP ratio <1 (control group, n=363, 73.2%). There were no differences in sex, age, body mass index and comorbidities. However, patients in the inverse group had a higher incidence of hemoptysis, worse baseline functional class, worse baseline hemodynamics including lower cardiac index, and higher median N-terminal pro-brain natriuretic peptide. Post PTE, rates of RPE and re-intubation were higher in the inverse group (14% vs. 6%, p =0.005 and 5% vs. 1%, p =0.036, respectively). Ventilator days (3.1±5.1 days vs. 1.9±2.7 days, p =0.009), ICU and hospital LOS (5.7±5.5 vs. 4.2±3.8 days, p = 0.005 and 15.0±7.2 vs. 12.4±7.0 days, p =0.001, respectively) were longer in the inverse group. Additionally, 30-day mortality was higher in the inverse group (4% vs. 1%, p =0.019). Overall 30-day post PTE mortality during this period was 1.6%. Conclusion: CTEPH patients with mean RAP equal or higher than the mean PAWP have higher rates of early complications following PTE surgery. Additional analysis is needed to evaluate if this ratio is an independent risk factor prior to CTEPH intervention.