Outcomes of mechanical thrombectomy in orally anticoagulated patients with anterior circulation large vessel occlusion: a propensity-matched analysis of the Imperial College Thrombectomy Registry

Background: Mechanical thrombectomy (MT) remains an effective treatment for patients with acute ischemic stroke receiving oral anticoagulation (OAC) and large vessel occlusion (LVO). However, to date, it remains unclear whether MT is safe in patients on treatment with OAC.

Aims: In our study, we performed a propensity-matched analysis to investigate the safety and efficacy of MT in patients with acute ischemic stroke receiving anticoagulants. A propensity score method was used to target the causal inference of the observational study design.

Methods: This observational, prospective, single-centre study included consecutive patients with acute LVO ischemic stroke of the anterior circulation. Demographic, neuro-imaging and clinical data were collected and compared according to the anticoagulation status at baseline, patients on OAC vs those not on OAC. The primary study outcomes were the occurrence of any intracerebral haemorrhage (ICH) and symptomatic ICH. The secondary study outcomes were functional independence at 90 days after stroke (defined as modified Rankin Scale (mRS) scores of 0 through 2), mortality at 3 months and successful reperfusion rate according to the modified treatment in cerebral infarction (mTICI) score.

Results: Overall, our cohort included 573 patients with acute ischemic stroke and LVO treated with MT. After propensity score matching, 495 patients were matched (99 OAC group vs 396 no OAC group). There were no differences in terms of clinical characteristics between the two groups, except for the rate of intravenous thrombolysis less frequently given in the OAC group. There was no significant difference in terms of the rate of any ICH and symptomatic ICH between the two groups. With regards to the secondary study outcome, there was no significant difference in terms of the rate of successful recanalization post-procedure and functional independence at 3 months between the two groups. Patients in the OAC group showed a reduced mortality rate at 90 days compared to the patients with no previous use of anticoagulation (20.2% vs 21.2%, p = 0.031). Logistic regression analysis did not reveal a statistically significant influence of the anticoagulation status on the likelihood of any ICH (OR = 0.95, 95% CI = 0.46-1.97, p = 0.900) and symptomatic ICH (OR = 4.87, 95% CI = 0.64-37.1, p = 0.127). Our analysis showed also that pre-admission anticoagulant use was not associated with functional independence at 90 days after stroke (OR = 0.76, 95% CI = 0.39-1.48, p = 0.422) and rate of successful reperfusion (OR = 0.81, 95% CI = 0.38-1.72, p = 0.582).

Conclusion: According to our findings anticoagulation status at baseline did not raise any suggestion of safety and efficacy concerns when MT treatment is provided according to the standard guidelines. Confirmation of these results in larger controlled prospective cohorts is necessary.