Prevalence of Right-to-Left Shunting on Echocardiography in Patients with Cancer and Stroke

The presence of right-to-left shunt has been proposed as a prominent mechanism of paradoxical embolism in patients with active cancer. We conducted a retrospective observational study including patients presenting to the Ottawa Hospital between January 2020 and December 2022 with ischemic stroke with and without active cancer. Among 491 patients (36.9% female, median age 53), 43 (8.8%) had active cancer, with 12 (27.9%, 95% CI 15-44) having a shunt. Of 448 patients without cancer, 133 (29.7%, 95% CI 25-34) had a shunt. Overall, our finding does not support the hypothesis that cancer-associated stroke is related to right-to-left shunting.