• The PHANTOM-S Trial: Effect of the use of ambulance-based thrombolysis on time to thrombolysis in acute ischemic stroke

    by Alan Batt. Last modified: 07/05/14




    • Randomized-week, open-label clinical trial
    • 6182 patients analysed
      • 3213 patients during STEMO weeks
      • 2969 during control weeks
    • No significant differences in 7-day in-hospital mortality between treatment groups
    • The use of ambulance-based thrombolysis resulted in decreased time to treatment
    • More patients were treated with tPA due to being shifted into time-frame window
    • More patients were admitted to stroke units further increasing the chances of tPA administration
    • Effect on clinical outcomes still needs to be studied


    • Randomization was based on time frames and not individual patients
    • Single centre trial for the purposes of assessing the STEMO intervention as there was only 1 vehicle used
    • German EMS makes regular use of physicians, and the outcomes of this trial may not be applicable to systems that only utilise Paramedics.
    • Trial was not adequately powered to assess clinical outcomes

    Ebinger M1, Winter B1, Wendt M2, Weber JE2, Waldschmidt C2, Rozanski M1, Kunz A1, Koch P2, Kellner PA3, Gierhake D4, Villringer K4, Fiebach JB4, Grittner U5, Hartmann A6, Mackert BM7, Endres M8, Audebert HJ1; STEMO Consortium. Effect of the use of ambulance-based thrombolysis on time to thrombolysis in acute ischemic stroke: a randomized clinical trial. JAMA. 2014 Apr 23-30;311(16):1622-31. PMID: 24756512.



    To determine if starting thrombolysis in a specialized ambulance reduces delays.

    Design, Setting & Participants

    In the Prehospital Acute Neurological Treatment and Optimization of Medical care in Stroke Study (PHANTOM-S), conducted in Berlin, Germany, we randomly assigned weeks with and without availability of the Stroke Emergency Mobile (STEMO) from May 1, 2011, to January 31, 2013. Berlin has an established stroke care infrastructure with 14 stroke units. We included 6182 adult patients (STEMO weeks: 44.3% male, mean [SD] age, 73.9 [15.0] y; control weeks: 45.2% male, mean [SD] age, 74.3 [14.9] y) for whom a stroke dispatch was activated.


    The intervention comprised an ambulance (STEMO) equipped with a CT scanner, point-of-care laboratory, and telemedicine connection; a stroke identification algorithm at dispatcher level; and a prehospital stroke team. Thrombolysis was started before transport to hospital if ischemic stroke was confirmed and contraindications excluded.

    Main Outcomes and Measurements

    Primary outcome was alarm-to-thrombolysis time. Secondary outcomes included thrombolysis rate, secondary intracerebral hemorrhage after thrombolysis, and 7-day mortality.


    Time reduction was assessed in all patients with a stroke dispatch from the entire catchment area in STEMO weeks (3213 patients) vs control weeks (2969 patients) and in patients in whom STEMO was available and deployed (1804 patients) vs control weeks (2969 patients). Compared with thrombolysis during control weeks, there was a reduction of 15 minutes (95% CI, 11-19) in alarm-to-treatment times in the catchment area during STEMO weeks (76.3 min; 95% CI, 73.2-79.3 vs 61.4 min; 95% CI, 58.7-64.0; P < .001). Among patients for whom STEMO was deployed, mean alarm-to-treatment time (51.8 min; 95% CI, 49.0-54.6) was shorter by 25 minutes (95% CI, 20-29; P < .001) than during control weeks. Thrombolysis rates in ischemic stroke were 29% (310/1070) during STEMO weeks and 33% (200/614) after STEMO deployment vs 21% (220/1041) during control weeks (differences, 8%; 95% CI, 4%-12%; P < .001, and 12%, 95% CI, 7%-16%; P < .001, respectively). STEMO deployment incurred no increased risk for intracerebral hemorrhage (STEMO deployment: 7/200; conventional care: 22/323; adjusted odds ratio [OR], 0.42, 95% CI, 0.18-1.03; P = .06) or 7-day mortality (9/199 vs 15/323; adjusted OR, 0.76; 95% CI, 0.31-1.82; P = .53).

    Conclusions & Relevance

    Compared with usual care, the use of ambulance-based thrombolysis resulted in decreased time to treatment without an increase in adverse events. Further studies are needed to assess the effects on clinical outcomes.

    Trial Registration

    clinicaltrials.gov Identifier: NCT01382862.

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    Alan Batt

    Alan Batt

    Paramedic, educator, researcher
    Alan is a critical care paramedic, paramedic educator and prehospital researcher, currently working around the world as an educator and researcher. He has previously worked and studied across Europe, North America and the Middle East. He holds a Graduate Certificate in Intensive Care Paramedic Studies, and an MSc in Critical Care. His main interests are in care of the elderly, end-of-life care, patient safety, professionalism (including role and identity), and paramedic education.

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