Risk of Aneurysm Rupture After Thrombolysis in Patients With Acute Ischemic Stroke and Unruptured Intracranial Aneurysms

Unruptured intracranial aneurysms (UIAs) are considered to be a relative contraindication for IV thrombolysis (IVT) in acute ischemic stroke (AIS). Currently, however, data are limited on the risk of UIA rupture after IVT. Our objective was to assess whether IVT for AIS can lead to a UIA rupture and intracranial hemorrhages (ICHs) in patients with unruptured UIAs.This was a prospective cohort study of consecutive patients treated in a comprehensive stroke center between 2005 and 2019. We assessed radiology reports and records at the Finnish Care Register for Health Care to identify patients with UIAs among all patients with AIS treated with IVT at the center. We analyzed patient angiograms for aneurysm characteristics and other brain imaging studies for ICHs after IVT. The main outcome was in-hospital ICHs attributable to a UIA rupture after IVT. Secondary outcomes were in-hospital symptomatic ICHs (European-Australian Cooperative Acute Stroke Study [ECASS-2] criteria, i.e., NIH Stroke Scale score increase ≥4 points) and any in-hospital ICHs.A total of 3,953 patients were treated with IVT during the 15-year study period. One hundred thirty-two (3.3%) of the 3,953 patients with AIS had a total of 155 UIAs (141 saccular and 14 fusiform). The mean diameter of UIAs was 4.7 ± 3.8 mm, with 18.7% being ≥7 mm and 9.7% ≥10 mm in diameter. None of the 141 saccular UIAs ruptured after IVT. Three patients (2.3%, 95% confidence interval [CI] 0.6%-5.8%) with large fusiform basilar artery UIAs had a fatal rupture at 27 hours, 43 hours, and 19 days after IVT. All 3 were administered anticoagulation treatments after IVT, and anticoagulation took effect during the UIA rupture. Any ICHs and symptomatic ICHs were detected in 18.9% (95% CI 12.9%-26.2%) and 8.3% (95% CI 4.4%-13.8%) of all patients with AIS, respectively.IVT appears to be safe in patients with AIS with saccular UIAs, including larges UIAs (≥10 mm). Anticoagulation after AIS in patients with large fusiform posterior circulation UIAs may increase the risk of aneurysm rupture.