B54-45 Obesity Paradox Has Limits in Pulmonary Embolism Outcomes

Introduction The “obesity paradox” describes improved survival among patients with obesity across several cardiovascular conditions, including pulmonary embolisms (PE). Prior retrospective studies showed lower mortality and complications in patients with BMI 30-39.9 and >40 kg/m² compared with normal BMI. This study evaluates outcomes after PE in patients with super-morbid obesity (SMO; BMI ≥50kg/m2). Methods We performed a retrospective cohort study using TriNetX US Collaborative Network to compare 30-day all-cause mortality following acute PE among the following BMI groups: 18.5-30, 30-40, and 40-50 kg/m² against patients with SMO. Propensity matching was performed for sex, age, diabetes, obstructive sleep apnea, neoplasm, coagulopathies (Group 1), and an additional model including mechanical thrombectomies, systemic thrombolysis, and emergent intubation (Group 2). Results SMO vs BMI 18.5-30 SMO was associated with significantly lower mortality (Group 1 HR 0.706, 95% CI I 0.64-0.78; Group 2 HR 0.72, 95% CI 0.652-0.795; both p < 0.0001). The proportional hazards assumption (PHA) was violated in both groups, suggesting time-dependent risk relationships. SMO vs BMI 30-40 Compared with BMI 30-40, SMO trended toward higher mortality in Group 1 (HR 1.11, 95% CI 0.998-1.238; p = 0.055). After adjusting for interventions (Group 2), SMO demonstrated a significant increase in mortality risk (HR1.141, 95% CI 1.024-1.272; p = 0.017), with PHA maintained. SMO vs BMI 40-50 SMO consistently demonstrated higher mortality risk compared with BMI 40-50 (Group 1 HR 1.182, 95% CI 1.059-1.319; p = 0.0028; Group 2 HR 1.228, 95% CI 1.099-1.372; p = 0.0003), with PHA met. Discussion This study provides further insight into the obesity paradox in acute PE by demonstrating variable mortality patterns across higher BMI strata. SMO patients exhibited significantly lower mortality than normal-BMI patients, although PHA violations suggest dynamic risk variation. However, mortality advantages diminished and ultimately reversed when compared to moderate and severe obesity. This trend suggests that above a certain threshold, the physiological stressors associated with extreme obesity may outweigh any protective effects. SMO may face delayed diagnosis and limited treatment options due to imaging constraints (poor TTE windows, CT weight/bore limits) and reduced feasibility of catheter-based therapies, ECMO, and thrombolysis. Overall, these findings suggest that the obesity paradox has an upper limit in acute PE, and that BMI stratification may refine risk assessment and clinical decision-making for this population.