[Preclinical loading in patients with acute chest pain and acute coronary syndrome - PRELOAD survey].

Background: Guidelines on myocardial infarction (MI) recommend antithrombotic and anticoagulatory treatment at time of diagnosis. MI with ST segment elevation (STEMI) is mostly a certain diagnosis. Acute coronary syndrome without ST segment elevation (NSTE-ACS) has diagnostic uncertainty and remains a working diagnosis in the prehospital setting.

Objective: Assessment of prehospital loading with aspirin and heparin depending on ACS subtype and pretreatment with oral anticoagulants.

Methods: The PRELOAD survey was a nationwide German study. STEMI/NSTE-ACS scenarios were designed and varied in pretreatment: I) no pretreatment, II) new oral anticoagulants (NOAC), III) vitamin K antagonist (VKA). Loading strategy was assessed and included: a) aspirin (ASA), b) unfractionated heparin (UFH), c) ASA + UFH, d) no loading.

Results: A total of 708 emergency physicians were included. In NSTE-ACS without pretreatment, 79% chose loading (p < 0.001). ASA + UFH (71.4%) was the preferred option. In corresponding STEMI scenario, 100% chose loading and 98.6% preferred ASA + UFH (p < 0.001). In NSTE-ACS with NOAC pretreatment, 69.8% favored loading (p < 0.001); in VKA pretreatment the corresponding rate was 72.3% (p < 0.001). In each scenario, ASA was the preferred option. In STEMI with NOAC pretreatment, 97.5% chose loading (p < 0.001); analogous rate was 96.8% in STEMI with VKA pretreatment (p < 0.001). ASA was the preferred option again.

Conclusions: Prehospital loading was the preferred treatment strategy despite the diagnostic uncertainty in NSTE-ACS and guidelines recommending loading at time of diagnosis. Pretreatment with oral anticoagulants resulted in a strategy shift to loading with only aspirin. In STEMI patients, this indicates potential undertreatment.