Retrospective cross-sectional review of outcomes from a nurse delivered pre-hospital diagnostic support service for suspected acute coronary syndrome: the computer is still poor at detecting STEMI

Introduction Acute coronary syndromes (ACS) are associated with high mortality. ST elevation Myocardial Infarction (STEMI) is the highest risk ACS, requiring timely diagnosis and management. A pre-hospital ECG has been shown to improve door to balloon time and therefore improve STEMI outcomes. However, ECG interpretation can be difficult, especially in the pre-hospital ?environment due to issues with experience and training. There are risks associated with under and over diagnoses. To help improve diagnostic accuracy and triage decisions, NHS Highland operates an ECG interpretation service whereupon all ECGs in suspected ACS patients are emailed from the community by the paramedic or primary care practitioner to Coronary Care Unit (CCU). At the CCU either a specialist cardiac nurse or consultant cardiologist provides ECG interpretation and advice to the pre-hospital team. This study reports outcomes from a consecutive cohort of patients. Methodology Consecutive suspected ACS patients referred to the pre-hospital ECG support service in May to July 2017 were included. Data collected included demographics, triage location, final diagnosis, troponin and 1 year outcome. Data were analysed to compare outcomes with provisional pre-hospital diagnosis and triage. Chi-squared test was used to determine if differences between groups were statistically significant (alpha=0.05). Results 428 ECGs were emailed to CCU over a 3 month time period, of which 337 were suitable for further analysis (91 excluded as duplicates or missing patient data). 27 patients from the transmitted ECGs had an ACS, of which 30% were STEMI and 70% were NSTEMI. The majority of patients with ACS (96.3%) had their ECG transmitted by ambulance staff. The ECG computerised diagnosis correctly identified only 30% of the ACS patients. Chest pain was the most common presenting complaint but 19% of ACS had a non chest pain symptom (breathless/collapse). 100% of ACS were admitted with 70% going to A&E (no free bed in cardiology) and 4% going directly to the cardiac catheterisation laboratory. Death rate was high, with 22% mortality during the index admission and 37% 1 year mortality. Conclusions The pre-hospital ECG transmission to CCU provides an additional support and clinical tool to optimise pre-hospital ACS care. However, the computer diagnosis alone misdiagnosed most ACS patients. Implementation of a clinical decision support system with integration of ECG, patient symptoms and clinical signs could improve pre-hospital ACS management.