Abstract Body (Do not enter title and authors here): Introduction: Risk stratification and treatment for pulmonary embolism (PE) have evolved significantly in recent years. It is proposed that patients with intermediate-risk PE, including low and high intermediate-risk categories, may benefit from percutaneous interventions in addition to heparin monotherapy. With the increasing availability of catheter-directed therapy (CDT) and percutaneous mechanical thrombectomy (PMT), more information is needed to optimize these resources.

Methods: We retrospectively analyzed data from an institutional pulmonary embolism response team (PERT) registry (n=591) from 2018 to 2022. Patients were stratified as intermediate-low and intermediate-high risk based on European Society of Cardiology guidelines. Survival time was recorded from the initial PERT consult to the last clinical encounter. Survival events were defined as 1) death within 90 days, or 2) a composite endpoint including death, cardiac arrest, ECMO or vasopressor use, or death within 90 days. Cox proportional hazards and Kaplan-Meier methods estimated the risk of 90-day all-cause mortality and the composite endpoint.

Results: We studied 211 intermediate-risk patients, including intermediate-low (n=112, 53.1%) and intermediate-high risk (n=99, 46.9%). The sample was predominantly female (51.2%) with a mean age of 64.8 years (SD 15.6). Median PESI scores were 103 and 100 for intermediate-low and high risk, respectively. Among patients, 27% had active cancer, and 17% had recent surgery or hospitalization within 30 days prior. A history of PE and DVT was present in 8% and 11% of patients, respectively. Interventions included heparin monotherapy (n=164, 77.7%), CDT (n=27, 12.8%), and PMT (n=20, 9.5%). Within 90 days, 29 patients (13.7%) expired, and 43 patients (20.4%) met the composite endpoint. Active cancer and baseline oxygen requirement were linked to a higher likelihood of meeting the composite endpoint. CDT and PMT were associated with better 90-day survival (log-rank p = 0.024) and a lower probability of meeting the clinical endpoint (log-rank p = 0.052) compared to heparin monotherapy, with no significant difference between CDT and PMT.

Conclusion: In intermediate-risk PE patients, CDT or PMT were associated with better 90-day survival and showed a trend towards a lower likelihood of meeting the composite outcome.