Rudolph M.I.Borngaesser F.Zmily O.M.Mpody C.Wongtangman K.Wachtendorf L.J.Khandaker R.Suleiman A.Binda D.D.Ramishvili T.Schaefer M.S.Di Biase L.Garcia M.J.Nafiu O.O.Devereaux P.J.Bhatt D.L.Eikermann M.Karaye I.M.Mahidol University2026-06-202026-06-202026-01-01British Journal of Anaesthesia (2026)00070912https://repository.li.mahidol.ac.th/handle/123456789/117425Background: A previous large clinical trial demonstrated an increased risk of perioperative stroke with beta blockers initiated just before surgery. This study evaluated the association between long-term beta blocker prescription and ischaemic stroke after noncardiac surgery. Methods: We conducted a multicentre retrospective study of male and female adults undergoing noncardiac surgery between 2005 and 2021 at two academic healthcare networks in the USA. The primary exposure was long-term beta blocker prescription within 1 yr before surgery. We assessed postoperative ischaemic stroke risk at 30 and 365 days using modified Poisson regression with robust error variances, and conducted effect modification analyses. Results: Long-term beta blocker prescription was associated with an increased risk of postoperative stroke at 30 days (adjusted relative risk [RRadj] 1.26, 95% confidence interval [CI] 1.17–1.36, P<0.001) and 365 days (RRadj 1.22, 95% CI 1.16–1.28, P<0.001). For stroke within 365 days of surgery, this association was amplified in patients with ASA physical status of 1–2 (RRadj 1.96, 95% CI 1.56–2.45, P<0.001) compared with that in patients with ASA physical status of 3–4 (RRadj 1.20, 95% CI 1.15–1.26, P<0.001; P for interaction <0.001). No significant association was observed in patients with severe heart failure. Conclusions: Long-term beta blocker prescription was associated with increased risk of ischaemic stroke within 30 days and up to 365 days after surgery. No association of beta blocker use and ischaemic stroke risk was observed in patients with severe heart failure, or a history of stroke.MedicineArticleSCOPUS10.1016/j.bja.2025.11.0272-s2.0-1050417091741471677141506973