P.045 Prevalence of Right-to-left Shunting in Stroke Occurrence of Patients with Active Cancer

Background: Presence of right-to-left shunt has been proposed as a mechanism of paradoxical embolism in patients with active cancer. Our study thus aims to investigate the role of shunting in stroke occurrence among cancer patients. Methods: This is a retrospective study with our population consisting of patients presenting to the Ottawa Hospital with ischemic stroke between January 01, 2020, and December 31, 2022. Presence of right-to-left shunting is identified in patients with and without cancer diagnosis within one year of ischemic stroke. The prevalence of shunt is assessed using 95% confidence intervals (CI). Results: Among 654 patients, 495 (37% female, median age 53 years) were included in the study, in which 47 (9.5%) had active cancer, with 12 patients (25.5%, 95% CI 14 - 40) diagnosed with a shunt. In contrast, among 448 patients (90.5%) without active cancer, 133 patients (30%, 95% CI 25 - 34) were found to have a shunt. Conclusions: The prevalence of right-to-left shunting tends to be lower in patients with ischemic stroke and active cancer diagnosis. Our results are similar to a recent study indicating a higher rate of shunt among patients without cancer. Our finding does not support the hypothesis that cancer-associated stroke is related to right-to-left shunting.