Evaluation of a prehospital endovascular therapy stroke bypass program.

Introduction: Prehospital stroke endovascular therapy bypass transports patients with suspected large vessel occlusion directly to an endovascular therapy capable center. Our objective was to determine if an endovascular therapy bypass protocol improved access to stroke treatments. Secondary objectives were to determine safety, effectiveness, and rate of subsequent interfacility transfers.

Methods: Endovascular therapy bypass in 2018 was implemented in Eastern Ontario, for patients with a Los-Angeles-Motor-Scale ≥ 4 (positive large vessel occlusion screen) with a 90-min transport time if < 6 h from last seen well. A before-after health record review was conducted from Dec 1, 2017 to Nov 30, 2019. A piloted data form was used to extract demographics, times, primary outcomes (endovascular therapy and intravenous (IV) tissue plasminogen activator (tPA) rate), and secondary outcomes (redirect to closer hospital, airway intervention, and subsequent interfacility transfer). We present descriptive statistics and odds ratios (OR) with 95% confidence intervals (CI) from multivariable logistic regression.

Results: We included 379 stroke patients (165 pre and 214 post-implementation). The endovascular therapy rate between groups was similar (14.1% vs 15.1%). The bypass had an OR of 0.98 (95% CI 0.54-1.78) for receiving endovascular therapy. IV tPA was given to 25.4% of patients pre vs 27.4% post-implementation (OR 1.06, 95% CI 0.65-1.74). No patients became unstable during transport, only one patient had an intubation attempt. The inappropriate bypass (false positive) rate was 12.7% pre vs 12.8% post-implementation (positive predictive value 87%). The bypass protocol had an OR of 1.06 (95% CI 0.58-1.95) for subsequent interfacility transfer with a mean of 2.7 h at the community site before transfer.

Conclusions: Endovascular therapy stroke bypass with 90-min transport radius and Los-Angeles-Motor-Scale ≥ 4 was safe and well executed by paramedics. Our study did not show any difference in endovascular therapy rate from its implementation. The IV tPA rate was similar between groups despite potentially bypassing thrombolysis capable centers.