Pre-hospital ECG in Acute Coronary Syndromes

This mixed methods design study consists of four work packages:

WP1 - Population-based, linked cohort study using MINAP data from 2010-2016

This work package will entail analysis of data from around 420,000 pseudonymised patient records from the MINAP database, linking to the Office for National Statistics (ONS) in order to determine mortality/vital status. No patients will be contacted to obtain consent for inclusion of their records in the study as NICOR (custodian of MINAP data) hold section 251 exemption to hold and process patient data for clinical audit purposes without their explicit consent. The data will be released to the research team, using established processes, in pseudonymised format.

The study statisticians will analyse the data provided from MINAP to determine how many heart attack patients who came by ambulance survive to 30 days, estimate time to death, and will estimate from the data whether more people who had an ambulance ECG survive compared to those who did not have the test.

The aim of the study is also to determine from the data whether patients who have an ambulance ECG receive treatment in hospital faster than those who did not.

WP2 - Retrospective chart review of ambulance records

The study statisticians will generate from the larger sample discussed above, a smaller sample (approximately 1800 patients in total) specific to three National Health Service (NHS) ambulance services (Welsh, West Midlands and South West). The investigators will then work with those ambulance services to review the records held by the ambulance service, to see what other information over and above that is collected in the national MINAP audit (e.g. presenting symptoms, severity of any chest pain, public place or home, patient preferences including declining to have the test, ambulance clinician grade and gender). The investigators have worked with a 'task and finish group' of paramedics and cardiology experts to agree which data might be helpful and devised specific forms to collect these data. Data collection from ambulance records will be undertaken by NHS paramedics in the three ambulance services, seconded to work on this project. These paramedics will receive specific training in study procedures to ensure accuracy and data quality. Anonymised data collected by these 'research paramedics' will be sent to the research team by secure electronic database.

WP3 - Ambulance clinician self-report on PHECG recording

In this work package, clinical staff from the three participating ambulance Trusts (48 in total) will be invited to participate in focus group discussions led by an experienced researcher. A semi-structured topic guide (developed beforehand with the help and advice of a small group of paramedics and cardiac experts, and our knowledge of previous literature on paramedic decision making) will be used to explore the view of consenting ambulance clinicians about their perceptions of the role of the PHECG, their experiences of assessing patients with suspected heart attack, and factors which might influence the decision to record (or not) an ECG when assessing and treating a patient.

Focus group discussions will be audio-recorded and transcribed. A method called framework analysis will be used to analyse the transcribed records of the focus group discussions to see whether any particular themes arise, including consensus or disagreement of ambulance staff views on recording an ECG, and consider them against any differences in the characteristics of focus group participants (e.g. grade of clinician, employing ambulance service's local practice).

WP4 - Synthesis of the findings

The investigators will bring together ambulance staff, patient representatives, cardiac experts and researchers to consider the findings from the three work packages described above, with aim to synthesise the study findings and present evidence addressing the study research questions. This will be done with consideration of the investigators' work as forming the 'development phase' for the design of a complex intervention for further testing in a later study.

The project has been designed with input from patient and public representatives especially around the importance of the research question(s), potential impact of the findings for patients and the public. The study team includes three paramedics who have been instrumental in the design of the study as well as supporting documentation particularly for WP3.

Inclusion criteria

• Patients > 18 years of age
• Patients with ACS
• Patients who have been brought to hospital by Emergency Medical Service (EMS)
• Patients included in the MINAP registry
• First episode of ACS
• Patients with confirmed STEMI and NSTEMI
• EMS personnel trained in performing an ECG in the pre-hospital setting
• EMS personnel involved in care of patients with a suspected heart attack

Exclusion criteria

• patients < 18 years of age
• patients who self-presented at hospitals with suspected ACS
• patients who developed ACS whilst in hospital