Association between M1 tortuosity and intracranial hemorrhage after mechanical thrombectomy using a stent retriever for M2 occlusions

BackgroundMechanical thrombectomy (MT) is an important treatment for middle cerebral artery (MCA) M2 occlusions. However, it carries a risk of intracranial hemorrhage (ICH), especially with a stent retriever. We investigated the correlation between MCA M1 tortuosity and ICH after MT using a stent retriever for M2 occlusions, along with other clinical outcomes.MethodsThis single-center, retrospective study included patients with isolated MCA M2 occlusions treated using a stent retriever. M1 tortuosity was assessed using pre-MT imaging, with patients classified into tortuous (≥ 2 angulations) and non-tortuous (≤ 1 angulation) groups. The primary outcome was any ICH. Secondary outcomes included symptomatic ICH (sICH), procedural outcomes, and functional outcomes.ResultsAmong 153 patients (median age: 78 years, 48% female), 55 (36%) had tortuous M1 segments. The tortuous group showed higher NIHSS scores (median score 19 vs. 14, <i>p</i> = 0.045) and a higher prevalence of chronic renal failure at baseline (15% vs. 4%, <i>p</i> = 0.029). Any ICH occurred in 69 patients (45%) and was more frequent in the tortuous group (64% vs. 35%, <i>p</i> = 0.003; adjusted odds ratio [aOR], 3.09; 95% confidence interval [CI], 1.48-6.42). Among the ICH subtypes, subarachnoid hemorrhage (SAH) was more common in the tortuous group (49% vs. 27%, <i>p</i> = 0.01; aOR, 2.61; 95% CI, 1.26-5.41). However, the incidence of sICH (5.5% vs. 4.1%, <i>p</i> = 0.70) and good neurological outcome at 90 days after MT (45% vs. 50%, <i>p</i> = 0.62) were comparable.ConclusionMCA M1 tortuosity was associated with a higher incidence of any ICH, particularly SAH, after MT using a stent retriever for M2 occlusions.