Safety and Outcomes of Intravenous Thrombolysis in Posterior Versus Anterior Circulation Stroke

Abstract

Background and Purpose— Posterior circulation stroke (PCS) accounts for 5% to 19% of patients with acute stroke receiving intravenous thrombolysis. We aimed to compare safety and outcomes following intravenous thrombolysis between patients with PCS and anterior circulation stroke (ACS) and incorporate the results in a meta-analysis. Methods— We included patients in the Safe Implementation of Treatments in Stroke Thrombolysis Registry 2013 to 2017 with computed tomography/magnetic resonance angiographic occlusion data. Outcomes were parenchymal hematoma, symptomatic intracerebral hemorrhage (SICH) per SITS-MOST (Safe Implementation of Thrombolysis in Stroke Monitoring Study), ECASS II (Second European Co-operative Stroke Study) and NINDS (Neurological Disorders and Stroke definition), 3-month modified Rankin Scale score, and death. Adjustment for SICH risk factors (age, sex, National Institutes of Health Stroke Scale, blood pressure, glucose, and atrial fibrillation) and center was done using inverse probability treatment weighting, after which an average treatment effect (ATE) was calculated. Meta-analysis of 13 studies comparing outcomes in PCS versus ACS after intravenous thrombolysis was conducted. Results— Of 5146 patients, 753 had PCS (14.6%). Patients with PCS had lower median National Institutes of Health Stroke Scale: 7 (interquartile range, 4–13) versus 13 (7–18), P <0.001 and fewer cerebrovascular risk factors. In patients with PCS versus ACS, parenchymal hematoma occurred in 3.2% versus 7.9%, ATE (95% CI): −4.7% (−6.3% to 3.0%); SICH SITS-MOST in 0.6% versus 1.9%, ATE: −1.4% (−2.2% to −0.7%); SICH NINDS in 3.1% versus 7.8%, ATE: −3.0% (−6.3% to 0.3%); SICH ECASS II in 1.8% versus 5.4%, ATE: −2.3% (−5.3% to 0.7%). In PCS versus ACS, 3-month outcomes (70% data availability) were death 18.5% versus 20.5%, ATE: 6.0% (0.7%–11.4%); modified Rankin Scale score 0–1, 45.2% versus 37.5%, ATE: 1.7% (−6.6% to 3.2%); modified Rankin Scale score 0–2, 61.3% versus 49.4%, ATE: 2.4% (3.1%–7.9%). Meta-analysis showed relative risk for SICH in PCS versus ACS being 0.49 (95% CI, 0.32–0.75). Conclusions— The risk of bleeding complications after intravenous thrombolysis in PCS was half that of ACS, with similar functional outcomes and higher risk of death, acknowledging limitations of the National Institutes of Health Stroke Scale for stroke severity or infarct size adjustment.

Predictors for affected stroke territory and outcome of acute stroke treatments are different for posterior versus anterior circulation stroke

“…Atrial fibrillation was previously found more frequently in patients with ACS 5 , 8 , 9 , 15 . On the other hand, the lower incidence of diabetes in PCS contrasts with previous observations which indicated an equal prevalence of diabetes in PCS and ACS 5 , 13 , 15 , 21 , 22 , 26 , 27 or even a higher prevalence in PCS patients 7 – 9 , 29 . While we did not find any differences between PCS and ACS patients concerning pre-stroke medication, other studies suggest a greater use of antihypertensives 5 and platelet inhibitors in ACS 10 , 22 .…”

“…Moreover, we observed a better three months functional outcome after acute stroke therapy in PCS. Our findings are in line with a recent data analysis from the SITS-MOST (Safe Implementation of Thrombolysis in Stroke Monitoring Study) registry, which had intracerebral haemorrhage (ICH) after intravenous thrombolysis as primary outcome, and found less ICH in patients with PCS strokes, along with a higher proportion of patients reaching functional independence (mRS 0–2) at 3 months 16 .…”

“…We could not confirm the observation of PCS patients being younger than ACS patients 8 , 13 , 15 , 26 . Similar to others, we found more men among patients suffering a PCS 5 , 8 , 9 , 15 , 26 , 27 . The reason for this sex discrepancy is unclear.…”

“…Acute ischaemic stroke can be treated with thrombolysis and thrombectomy to restore perfusion of the brain. Both methods are safe and effective in ACS 12 as well as in PCS 13 – 16 . However, the success of both treatments depends on patient factors, stroke severity as well as time since symptom onset 17 .…”

Intracranial Hemorrhage After Reperfusion Therapies in Acute Ischemic Stroke Patients

“…This finding is likely explained by "ceiling effects" of the NIHSS, particularly for basilar artery occlusion, which may be associated with severe disturbance of consciousness and high NIHSS score while causing ischemia in a tissue volume less than that of a complete middle cerebral artery territory (52). Recently, the risk of sICH after IV tPA in posterior circulation strokes was found to be half of that of anterior circulation strokes, albeit with higher risk of death, which illustrates the limitations of the NIHSS score for stroke severity assessment (53).…”