346: Anticoagulant Choice and Outcomes of Intermediate-Risk Pulmonary Emboli in Patients With Cancer

Introduction: Pulmonary embolism (PE) is common in patients with cancer. Intermediate-risk PE is classified by acute right ventricular failure without hypotension and carries an associated elevated risk of 30-day mortality. Without high-quality comparative data, there remains clinical equipoise for the optimal initial anticoagulation strategy in this population, and clinicians are using both unfractionated heparin (UFH) and low molecular weight heparin (LMWH). Our study aims to evaluate the association between choice of initial anticoagulation and clinical outcomes in patients with cancer presenting with intermediate-risk PE. We hypothesize LMWH, compared to UFH, is associated with improved clinical outcomes in this population. Methods: We conducted a retrospective analysis of consecutive adult patients with cancer who presented to a single tertiary care center with intermediate-risk PE, using data from the institutional Pulmonary Embolism Response Team registry. Data on demographics, initial anticoagulant choice, and clinical outcomes were collected. Primary outcome was hospital-free days (HFD). Continuous variables were compared using t-tests. Multivariable regression models were used to adjust for potential confounders and assess the association between anticoagulant choice and outcomes. Results: Of the 223 patients meeting inclusion criteria, 64 (27%) had cancer. The cohort was 73% White, 63% female, with a mean age of 67±12 years. The most common cancer types were breast, gastrointestinal, and genitourinary cancers (each 20%). Among cancer patients, 42 (66%) received UFH and 22 (34%) received LMWH. Time to therapeutic anticoagulation with UFH averaged 14.8 ±10.1 hours. Patients receiving LMWH had 3.9 more HFDs (23.1 vs. 19.2, p=0.05) than those receiving UFH. Overall hospital mortality was 6%. Those receiving LMWH had a lower risk of mortality, compared to those receiving UFH (3% v. 8%, OR 11.68, CI 1.27—107.8; p=0.02). Conclusions: In patients with cancer and intermediate-risk PE, initial anticoagulation with LMWH is associated with more HFD and lower risk of in-hospital mortality compared to UFH. These findings suggest a potential benefit of LMWH in this population; however, prospective studies are warranted to confirm these findings.