Allababidi, Adel Kabbara

Introduction: Obesity is rising in prevalence worldwide and co-exists in patients with group 1 pulmonary hypertension (PH). Clinical and hemodynamic implications of having obesity in group 1 PH remain unknown. Hypothesis . We hypothesized that obese patients with group 1 PH would exhibit worse hemodynamic parameters including higher right atrial pressure (RAP) and pulmonary capillary wedge pressure (PCWP) compared to non-obese patients. Aims: To compare hemodynamic parameters obtained from right heart catheterization (RHC) and echo among group 1 PH with and without obesity. Methods: We evaluated a cohort of patients with group 1 PH who underwent RHC at Mayo Clinic Rochester between 2002 to 2021 with diagnosis adjudicated by detailed chart review and initiation of pulmonary vasodilator therapy. Patients with a mean pulmonary artery pressure (mPAP) ≥ 25 mm who were clinically diagnosed with WHO Group 1 PH and recommended pulmonary vasodilator therapy initiation were included. Results: Of 822 participants with group 1 PH, obesity was common, present in 325 patients (40%). There was no difference in survival among patients with and without obesity (HR 1.15; 95% CI 0.95-1.38; p=.15). Obese patients had higher RAP (12.8 ± 6.8 vs 10.4 ± 6.5 mm of Hg, p<.0001) and cardiac output (5.2 ± 2.2 vs 4.5 ± 1.8 L/min, p<.0001) compared to non-obese group (Table 1). Despite having group 1 PH, pulmonary capillary wedge pressure (PCWP) was higher with obesity (13.8 ± 6.3 vs 12.2 ± 6.5 mm of Hg, p=.001) compared to those without obesity. Along with higher PCWP, there was less pulmonary vascular disease severity with obese group 1 PH, with higher pulmonary artery compliance (PAC, 1.65 ± 1.06 vs 1.38 ± 0.84 mL/mm of Hg, p=.0002) and lower pulmonary vascular resistance (PVR, 7.9 ± 5.2 vs 9.4 ± 7.7 Wood Units, p=.0007). After accounting for age, gender, diabetes mellitus and systemic hypertension, the RAP, cardiac output, PAC and PCWP remained significantly higher, and PVR remained lower in obese patients (p<0.05 for all). Conclusions: Comorbid obesity is associated with higher biventricular filling pressures, higher cardiac output and lower pulmonary vascular disease severity in otherwise clinically diagnosed group 1 PH. These findings call for further study of whether targeting obesity with novel weight loss drugs such as glucagon like peptide 1 receptor agonists or other drugs can lower biventricular filling pressures and associated pulmonary hypertension in group 1 PH with obesity.