(1127) Mortality and Length of Stay in Massive/Submassive Pulmonary Embolism: Thrombolysis vs Enoxaparin

Introduction: Pulmonary embolism (PE) outcomes vary by severity and treatment. Treatment strategies for PE
include anticoagulation with enoxaparin and thrombolysis with tissue plasminogen activator (tPA). While both
treatments are widely used, the optimal approach for managing sub-massive and massive PE remains
debated. This study aims to compare the mortality and Length of stay (LOS) of patients with sub-massive and
massive PE treated with either enoxaparin or tPA.

Methods: A multicenter retrospective cohort study (n=2909) across HCA hospitals, examining demographics,
clinical characteristics, mortality rates, and LOS. Patients were grouped into sub-massive PE: enoxaparin
(Group 1, n=1,678), sub-massive PE: tPA (Group 2, n=192), massive PE: enoxaparin (Group 3, n=855), massive
PE: tPA (Group 4, n=184). Exclusions included: COVID-19 positivity, age > 89, prior anticoagulation.

Results: Mortality rates were similar for sub-massive and massive PE types (Z = .168, p = .867). tPA increased
mortality versus enoxaparin both in sub-massive (23.43% vs. 3.04%, p < .0001) and massive PE (15.76% vs.
3.33%, p < .0001). Hospital LOS appears not to be impacted by PE type but was shorter for tPA groups; 2 (IRR
= 0.669, Z = -6.662, p < .001) and Group 4 (IRR = 0.824, Z = -3.188, p = .001). Longer LOS was linked to
Nonwhite individuals (IRR = 1.066, Z = 2.061, p = .03), higher Elixhauser Comorbidity Index (ECI) scores (IRR =
1.148, Z = 22.346, p < .001), and ICU admissions (IRR = 1.500, Z = 13.647, p < .001). Massive PE had shorter ICU
stays than sub-massive PE. tPA groups (2 and 4) had shorter ICU stays compared to Group 1. Patients in
Group 1, males, nonwhite individuals, and those with higher ECI scores had more ICU days.

Conclusions: Thrombolysis with tPA in massive and sub-massive PE is linked to higher mortality rates compared
to enoxaparin. Shorter hospital and ICU stays for tPA patients likely reflect higher early mortality. These
findings underscore the need to reassess treatment strategies for massive and sub-massive PE, considering the
risks and benefits of thrombolysis versus anticoagulation with enoxaparin. Current guidelines recommending
tPA as the first-line treatment for massive PE may need reevaluation, highlighting the necessity for further
clinical trials.