Impact of a blood return system on mechanical thrombectomy in treatment of acute pulmonary embolism: a retrospective cohort study comparing 30-day mortality and need for blood transfusion

Background Mechanical thrombectomy (MT) has become an increasingly popular approach in treatment of pulmonary embolism (PE). Blood loss from aspiration is common during this procedure and can potentially limit clot extraction. A blood return system designed to be used during MT was introduced in January 2022; however, there is limited data demonstrating if its use has impacted mortality or need for blood transfusion in patients treated with MT. Purpose The aim of this study is to assess if there is a difference in outcomes amongst patients with acute PE that underwent MT with a blood return system vs. those that underwent MT without one. We hypothesize that MT with a blood return system will reduce mortality and need for post-procedure blood transfusions. Methods A large retrospective, multicentre database was used to identify patients diagnosed with PE that underwent MT. Patients were subsequently divided into two groups: 1) After and including January 2022, which was after the implementation of a blood return system vs. 2) Before January 2022, which was prior to the implementation of a blood return system. Student’s t-test was performed to compare baseline characteristics between the two cohorts. Propensity matching was performed based on relevant comorbidities and severity of PE estimated by PESI score parameters. Kaplan Meier curves were calculated to compare 30-day post-procedure mortality and need for blood transfusion. Results Patients that underwent MT after implementation of a blood return system (n= 2511) and before implementation of a blood return system (n= 2755) were propensity matched yielding 1915 patients per cohort. MT after implementation of a blood return system was associated with a decreased 30-day mortality compared to MT before implementation (6.99% vs 11.77% HR=0.602; 95% CI [0.486, 0.746], log-rank p<0.0001). Additionally, MT after implementation of a blood return system was associated with a decreased need for blood transfusion (7.52% vs 10.38%; HR=0.717; 95% CI [0.572, 0.898], log-rank p=0.0034). Conclusion MT after implementation of a blood return system was associated with a decreased risk of 30-day mortality and a lower likelihood of requiring blood transfusion when compared to MT prior to implementation of a blood return system.