Impact of Prehospital Electrocardiogram on Outcome in Patients With Suspected Acute Coronary Syndrome in Helicopter Emergency Medical Service: A Retrospective Analysis Using JSAS-R

OBJECTIVE: Current guidelines recommend achieving a first medical contact-to-percutaneous coronary intervention time of ≤ 120 minutes and a door-to-balloon (D2B) time of ≤ 90 minutes in patients with acute coronary syndrome (ACS) requiring urgent reperfusion. Although prehospital electrocardiography (ECG) in ambulances has been shown to reduce mortality and D2B time in patients with ACS, its effectiveness in helicopter emergency medical service (HEMS) remains unclear. This study aimed to assess the impact of prehospital ECG on time to cardiac catheterization, mortality, and prehospital treatment by flight physicians in patients with ACS transported via HEMS. METHODS: Using data from the Japan Society for Aviation Medicine Doctor Helicopter National Case Registry System, we retrospectively analyzed patients transported by physician-crewed HEMS between April 2020 and March 2023, who were suspected of ACS and underwent coronary angiography. RESULTS: Of 499 eligible patients, 204 (41%) were in the non-ECG group and 295 (59%) were in the prehospital ECG group. Prehospital ECG was significantly associated with a shorter time from hospital arrival to cardiac catheterization (risk difference, -9.1 minutes; 95% confidence interval [CI], -17.5 to -0.8 minutes), despite a slightly longer time at the scene (risk difference, 1.09 minutes; 95% CI, 0.11-2.09). Nitrate administration was more frequent in the prehospital ECG group (odds ratio, 2.70; 1.40-5.10), whereas all-cause mortality did not differ significantly. CONCLUSION: Prehospital ECG in HEMS was associated with a shorter time to cardiac catheterization, potentially improving ACS management.