Endovascular thrombectomy in patients with acute ischaemic stroke and atrial fibrillation: a MR CLEAN subgroup analysis

Aims: Endovascular thrombectomy (EVT) improves outcome after acute ischaemic stroke (AIS) caused by an intracranial occlusion. The aim of the present study was to determine whether atrial fibrillation (AF) modifies the effect of EVT. Methods and results: MR CLEAN was a randomised clinical trial of EVT plus usual care vs. usual care alone for patients with an intracranial occlusion. The primary outcome was the modified Rankin scale (mRS) score at 90 days. The primary effect parameter was the adjusted common odds ratio (acOR), estimated with ordinal logistic regression and adjusted for age and stroke severity at baseline. Treatment effect modification by AF was assessed using a multiplicative interaction variable. We included all 500 patients. In total, 135 (27%) had AF. These patients were older, had a worse pre-stroke mRS score and were less often treated with IV alteplase. In patients without AF, the estimated treatment effect was similar to the overall treatment effect (acOR 1.9, 95% CI: 1.3 to 2.7). In patients with AF, the treatment effect appeared lower (acOR 1.0, 95% CI: 0.6 to 1.9). The interaction of treatment effect and AF was not significant (p=0.09, after adjustment p=0.12). Conclusions: This study did not show significant difference in the EVT effect between acute stroke patients with and those without AF.