Is first-pass effect a meaningful metric to evaluate thrombectomy technologies?

Background: Good clinical outcomes following stroke thrombectomy have been associated with successful reperfusion following a single pass, often referred to as the first pass effect (FPE). Inherent in FPE is a potential association with rapid recanalization. It remains unclear if the benefit associated with FPE is an epiphenomenon rather than a meaningful metric to evaluate thrombectomy. We retrospectively analyzed a high-volume single-practice database to evaluate the association of FPE with good clinical outcome. Methods: A database of 1047 consecutive thrombectomies from 2011 to 2020 was retrospectively queried. Demographics and presentation/procedural metrics were correlated with clinical outcome (3-month modified Rankin Scale (mRS)); patients aged 18 years and older with 3-month clinical follow-ups were included. Univariate analysis was performed to evaluate for an association with good clinical outcome (mRS 0-2) at 90 days. Variables meeting a univariate analysis P-value of 0.05 were included in multivariate analyses. Variables included time of onset to recanalization (OTR), onset to puncture (OTP), and puncture to recanalization (PTR), as well as the number of passes. Results: A total of 685 patients met the criteria for inclusion. Univariate analysis identified nine variables associated with good clinical outcome at 90 days. Multivariate analysis found OTP, patient age, and successful reperfusion (mTICI ≥ 2B) were associated with good clinical outcome. We built a multivariate model across a range of ratios of PTR to OTR. PTR became significantly associated with good clinical outcome (P = 0.044) when PTR/OTR ≥ 3%. Further subset analyses were performed using a conventional definition of FPE. All multivariate analyses revealed time metrics were significantly associated with good clinical outcome while one versus multiple passes was not. Conclusions: This study demonstrates that time, age, and degree of recanalization are highly associated with good clinical outcome following thrombectomy, whereas the number of passes is not.