Number of passes in mechanical thrombectomy: where is your limit?

Abstract

Background and aims. Stent retriever based thrombectomy is the mainstay of treatment of acute ischemic stroke caused by large vessel occlusion. However, recanalization is sometimes not achieved even after multiple passes of the thrombectomy device. Whether revascularization becomes futile or harmful with an increasing number of passes as well as criteria for when to halt attempting recanalization remain unknown. The purpose of our work is to analyze literature data on this issue. Materials and methods. We performed a short review of the literature and summarized evidence on the impact of repeated stentriever attempts on outcome.Results. Despite some controversies, the published data indicate that up to 30 % of patients still reach favorable outcome even when ≥5 stentriever passes are performed. Probability of obtaining functional independence after multiple stentriever attempts is even higher in patients with lower baseline NIHSS score. Patients who achieve successful reperfusion after ≥5 passes have significantly higher rates of functional independence and significantly lower rates of hemorrhagic transformation compared with those who do not achieve reperfusion. Rate of target recanalization after ≥4 passes may reach 19 %. Number of passes alone is not an independent negative predictor of functional independence. The impact of multiple stentriever attempts on hemorrhagic transformation has not been well-established.Conclusions. Target vessel recanalization is an essential goal of mechanical thrombectomy, which should be pursued despite the additional number of passes and procedural time required. Number of stentriver attempts is not a game- changing factor in the decision to abort the procedure for technical futility. Treatment decisions need to be individualized for each patient based on operator’s experience and preferences, patient and clot-specific characteristics.