Background International guidelines for the management of acute coronary syndromes (ACS) recommend use of the prehospital 12-lead electrocardiogram (PHECG). Research conducted before the primary PCI era suggested that PHECG is not always performed for those receiving a hospital diagnosis of ACS, with the patient’s gender and ethnicity speculated as influential.

Aim As part of a mixed methods study investigating the use and impact of the PHECG in the primary PCI era, we explored the factors emergency medical services (EMS) clinicians report as influencing their decision to perform a PHECG.

Methods We conducted a qualitative phenomenological study, in six focus groups with a semi structured topic guide, in three UK regions involving 47 EMS clinicians with experience ranging from nine months to 31 years. We recorded, transcribed and anonymised each focus group; familiarised ourselves with the data including notes and reflections; formed and iterated a coding framework; and constructed themes with the study team, including patient and public representatives.

Results All participants expressed a desire to perform a prehospital ECG in patients suspected with ACS but described a setting characterised by uncertainty and ‘messy’ context. We drew out three themes of influence on the decision to perform an ECG: surface characteristics (age, sex, ethnicity, privacy, presenting condition of the patient); pattern recognition (training, experience of atypical presentations, equipment availability, confidence in interpretation); and tensions/external pressures (distance to PCI, guidelines, organisational pressures). These were interwoven by the concept of clinical autonomy.

Conclusion Factors identified as influencing clinicians’ decision to perform a PHECG ranged from straightforward to complex and were difficult to unpick. Whilst qualitatively clinicians reported performing 12 lead PHECG wherever possible in suspected ACS, the reported multifaceted influences on the decision reinforce the need for the quantitative arm of this study to examine this nationally, alongside its association with patient outcomes.