Endovascular Thrombectomy in Acute Ischemic Stroke: Outcome in Referred Versus Directly Admitted Patients

Endovascular mechanical thrombectomy (mTE) in acute ischemic stroke due to large cerebral artery occlusion is effective and safe. The procedure is currently offered by specialized hospitals. Physicians from smaller hospitals need to refer patients to stroke centers. Secondary referrals involve delays for transportation. Little is known about effects of distant referrals on outcome and complications as compared to direct admittance.

To evaluate the effects of referral patterns on outcome and safety, we analyzed 941 patients with anterior circulation stroke receiving mTE between January 2010 and December 2015. Patients were divided into three groups: directly admitted patients (DAP), inner-city transfers (ICT) and long-distance referrals (LDR). We assessed (1) procedural parameters (2) frequency of good functional outcome (mRS ≤2 at 3 months) and (3) mortality rates.

Referrals had a significantly longer imaging-to-groin time compared to DAP (median 150 min vs. 85 min, p <0.001), the same was true for LDR vs. ICT (median 157 min vs. 133.5 min, p <0.001). Time to recanalization was significantly longer for referrals compared to DAP (median 348 min vs. 260 min, p <0.001). There was no significant difference in the frequency of good functional outcome (DAP 39.5%, ICT 35.1%, LDR 37.0%; p =0.709), all-cause mortality at day 90 (DAP 31.5%, ICT 23.0%, LDR 27.0%; p =0.212) and the rate of symptomatic intracranial hemorrhage (p =0.834).

Timing remains a critical factor in acute ischemic stroke treatment by endovascular means. Long distance referral to specialized neurovascular centers with high recanalization rates, however, does allow for a good functional outcome in a significant number of patients.