Technical aspects and outcomes of endovascular treatment for vertebrobasilar tandem occlusions as compared to isolated basilar artery occlusion

Background: The optimal treatment approach for posterior circulation tandem occlusion remains unclear. This study aimed to assess the efficacy and safety of treatment strategies for vertebrobasilar tandem occlusions as compared to isolated basilar artery occlusions. This study investigates the challenges of managing these complex cerebrovascular conditions and explores the feasibility of optimizing treatment approaches to improve patient outcomes and safety. Methods: Fifty-nine patients with acute posterior large-vessel occlusion stroke who underwent mechanical thrombectomy between November 2016 and December 2022 were retrospectively analyzed. Patients were categorized as isolated or tandem basilar artery occlusion. The baseline patient characteristics, risk factors, time metrics, recanalization rates, and angiographic characteristics were compared between groups. The study analyzed various interventional strategies, including thrombectomy technique, additional angioplasty, the approach to lesion patterns (ipsilateral to steno-occlusive VA lesion: dirty road or contralateral: clean road), and the sequence of actions during the procedures. The outcome measures were a 90-day modified Rankin scale (mRS) of 4-6, post-thrombectomy recanalization defined as mTICI -2b, 90-day mortality. Results: Out of the 59 patients, 39 (66%) had isolated basilar occlusion(i-BAO), while 20 (33%) presented with tandem occlusions (t-BAO). Patients with i-BAO and t-BAO had mean ages of 59.08±12.53 and 56.30±12.94 years, respectively. Both groups had a median NIHSS score of 22 upon admission. t-BAO group had longer times from symptom onset to hospital admission and recanalization times compared to i-BAO. (median 270 min versus 60min, p=0.015; 384 min versus 240 min, p=0.03). Successful recanalization (modified thrombolysis in cerebral infarction score ≥2b) was obtained in 13 (76.4%) versus 35 (89.7%) patients with t-BAO versus i-BAO, respectively. Thrombectomy performed aspiration with a distal access catheter (CA) was more common in the isolated basilar occlusion group (73.7% vs. 43.8%). In contrast, stent retrievers (SR) were more common in the tandem group (37.5% vs. 18.4). Access was achieved in 17 patients with tandem occlusion. The clean road approach was used in 58.8 % of cases, and the dirty road in 41.2%. t-BAO procedures involved a higher number of intraprocedural passes (median 2.5 vs. 1.5, p=0.047). Third-month mortality rate was significantly higher in the t-BAO group