Prehospital Triage of Acute Ischemic Stroke Patients to an Intravenous tPA-Ready versus Endovascular-Ready Hospital: A Decision Analysis.

BACKGROUND: American Stroke Association guidelines for prehospital acute ischemic stroke recommend against bypassing an intravenous tPA-ready hospital (IRH), if additional transportation time to an endovascular-ready hospital (ERH) exceeds 15-20 min. However, it is unknown when the benefit of potential endovascular therapy at an ERH outweighs the harm from delaying intravenous therapy at a closer IRH, especially since large vessel occlusion (LVO) status is initially unknown. We hypothesized that current time recommendations for IRH bypass are too short to achieve optimal outcomes for certain patient populations. METHODS: A decision analysis model was constructed using population-based databases, a detailed literature review, and interventional trial data containing time-dependent modified Rankin Scale distributions. The base case was triaged by Emergency Medical Services (EMS) 110 min after stroke onset and had a 23.6% LVO rate. Base case triage choices were (1) transport to the closest IRH (12 min), (2) transport to the ERH (60 min) bypassing the IRH, or (3) apply the Cincinnati Stroke Triage Assessment Tool and transport to the ERH if positive for LVO. Outcomes were assessed using quality-adjusted life years (QALYs). Sensitivity analyses were performed for all major variables, and alternative prehospital stroke scales were assessed. RESULTS: In the base case, transport to the IRH was the optimal choice with an expected outcome of 8.47 QALYs. Sensitivity analyses demonstrated that transport to the ERH was superior until bypass time exceeded 44 additional minutes, or when the onset to EMS triage interval exceeded 99 min. As the probability of LVO increased, ERH transport was optimal at longer onset to EMS triage intervals. The optimal triage strategy was highly dependent on specific interactions between the IRH transportation time, ERH transportation time, and onset to EMS triage interval. CONCLUSIONS: No single time difference between IRH and ERH transportation optimizes triage for all patients. Allowable IRH bypass time should be increased and acute ischemic stroke guidelines should incorporate the onset to EMS triage interval, IRH transportation time, and ERH transportation time.

Assessment of thrombus length in acute ischemic stroke by post-contrast magnetic resonance angiography.

OBJECTIVES: Post-contrast magnetic resonance angiography (PC-MRA) enables visualization of vessel segments distal to an intra-arterial thrombus in acute ischemic stroke. We hypothesized that PC-MRA also allows clot length measurement in different intracranial vessels. METHODS: Patients with MRI-confirmed ischemic stroke and intracranial artery occlusion within 24 hours of symptom onset were prospectively evaluated. PC-MRA was added to a standard stroke MRI protocol. Thrombus length was measured on thick slab maximum intensity projection images. Clinical outcome at hospital discharge was assessed by modified Rankin Scale (mRS). RESULTS: Thirty-four patients (median age 72 years) presenting with a median National Institutes of Health Stroke Scale score of 11 and a median onset to imaging time of 116 min were included. PC-MRA enabled precise depiction of proximal and distal terminus of the thrombus in 31 patients (91%), whereas in three patients (9%) PC-MRA presented a partial occlusion. Median thrombus length in patients with complete occlusion was 9.9 mm. In patients with poor outcome (mRS ≥3) median thrombus length was significantly longer than in those with good outcome (mRS ≤2;P=0.011). CONCLUSIONS: PC-MRA demonstrates intra-arterial thrombus length at different vessel occlusion sites. Longer thrombus length is associated with poor clinical outcome. CLINICAL TRIAL REGISTRATION: NCT02077582; Results.