Background: In prehospital settings, myocardial infarction (MI) diagnosis relies on symptoms and electrocardiogram (ECG) analysis. The cardiac electrical biomarker (CEB) has been developed to quantify abnormal multipolar electrical activity through a 12-lead ECG, reflecting ischemia-related cellular disruption. This study primarily aimed to assess recruitment capacity and operational feasibility for a future large-scale prospective prehospital study involving CEB measurements. Secondary objectives were to describe successful CEB acquisition and to identify practical barriers to data collection in the prehospital environment.

Methods: This pilot study was a secondary analysis of prospectively collected observational data from the "Ambulance Région de Bienne" service (covering 120,000 inhabitants) between March and September 2023. Adult patients managed for suspected acute coronary syndrome who underwent a prehospital 12-lead ECG with attempted CEB acquisition and were subsequently admitted to the Biel Hospital Centre were eligible. Analyses were descriptive and focused on feasibility-related endpoints.

Results: A total of 70 patients were identified, of whom 60 met eligibility criteria. Regarding recruitment feasibility, a mean enrolment rate of 7.7 patients per month was observed, corresponding to roughly one patient per 70 prehospital missions. Regarding operational experience with CEB acquisition, technical and practical barriers were identified, including telemetry connectivity issues, workflow constraints, and documentation limitations. Successful CEB acquisition was variable; however, the true failure rate could not be reliably determined due to incomplete systematic documentation of all attempted acquisitions.

Conclusions: Recruitment of eligible patients for a future large-scale study appears potentially feasible, with an observed rate of 7.7 patients per month within this single EMS. However, while operational barriers were identified, reliable CEB acquisition could not be assessed due to incomplete capture of failed acquisition attempts. These findings primarily inform study design and implementation strategy for future investigations.