García-Tornel A, Requena M, Rubiera M, Muchada M, Pagola J, Rodriguez-Luna D, et al. When to Stop: Detrimental Effect of Device Passes in Acute Ischemic Stroke Secondary to Large Vessel Occlusion. Stroke. 2019;50:1781–1788
The achievement of mTICI 3 after one pass, known as first pass effect, is clearly associated with better functional outcome, as compared with those patients with more passes needed to obtain full recanalization. But how many passes should we attempt before stop procedure? Or maybe we should pursue a good (TICI 2B) but not perfect recanalization, instead of seeking TICI 3, because such recanalization is more than enough for patient outcome?
These are some of the aims of this study, in addition to finding the relation between number of passes and recanalization degree and clinical outcome.
García-Tornel et al. performed a retrospective analysis of a prospectively database that includes all patients with acute ischemic stroke secondary to an occlusion of terminal intracranial carotid artery or M1 and M2 portions undergoing EVT at a tertiary stroke center since 2012. Primary end points of the study were the association of degree of recanalization (mTICI 2B or 3), number of passes and its interaction with dramatical clinical recovery (DCR,defined as NIHSS score ≤2 or decrease in 8 NIHSS points in 24 hours), good functional outcome (defined modified Rankin Scale score ≤2 at 90 days), and mortality. Variables associated with first pass recanalization (FPR) and degree of recanalization were also studied.
Among 459 (84,5%) patients who achieved a recanalization grade mTICI ≥2b, 213 (39%) obtained such recanalization after first device pass. In the multivariate analysis, first-pass recanalization and mTICI 3 were independent predictors of good functional outcome (odds ratio: 2.5 and odds ratio: 2.6, respectively) and dramatical clinical recovery (odds ratio, 1.8; and odds ratio, 2.9, respectively). Rate of recanalization declined after each pass 39%, 35%, 33%, and 24% for passes 1 to 4, respectively, and 28% for every attempt above 4 passes (P<0.001). In patients who achieved recanalization, a linear association between number of passes and good functional outcome was observed: 1 pass (58.6%), 2 passes (50.5%), 3 passes (48.4%), 4 passes (38.5%), or 5 or more passes (25.6%; P<0.001) as compared with patients who did not achieve recanalization (16.9%).
Obtaining a good recanalization degree, at least TICI 2b, is essential to aspire to a clinical improvement of the patient sufficient for their functional independence. However, it is important to know how many passes we should perform to maintain the benefit of thrombectomy. Is it always beneficial to obtain a TICI 3, even if it prolongs the procedure and involves an undetermined number of passes? Does endothelial damage increase from a certain number of passes favoring aggregation phenomena that complicate the procedure? As discussed in this paper, it seems that the theoretical benefit of a complete recanalization could be neutralized by the detrimental effect of multiple passes. It seems that 4 is the limit number of passes in which if we achieve a recanalization of TICI 2B, we would achieve the balance between the benefit of the procedure and its damage. Obviously, each case is different and there will be patients who need 5 passes to obtain a good degree of recanalization and their clinical improvement compensates for the fifth pass, but we could begin to consider that less is more in thrombectomy and what we do not get with 4 passes, we may not get it with 6.