Prehospital ECG shortens ischaemic time in STEMI

Prehospital electrocardiogram (ECG) can shorten ischaemic time for patients with ST-segment elevation MI (STEMI) prior to hospital admission, results of a recent local study have shown.

In this study, patient delay for activation of the emergency response system was significantly reduced with ambulance transport compared with self-arranged transport (median, 46 minutes vs 211 minutes; p<0.001). The median time of patient delay was 90 minutes, with 12 percent of patients experiencing a delay of >12 hours. [Hong Kong Med J 2019;25:356-362]

In terms of system delay, the use of prehospital ECG significantly reduced the time from ambulance on scene to the time of Accident and Emergency Department (AED) registration (median, 25 minutes vs 28 minutes; p=0.021), as well as the time from ambulance on scene to first ECG (6 minutes vs 41 minutes; p<0.001), compared with non-use of prehospital ECG. Prehospital ECG was available 5 minutes earlier if performed upon ambulance on scene compared with that in ambulance compartment. Likewise, prehospital ECG performed at the time of ambulance on scene was available 35 minutes earlier than the first ECG (in the AED) for patients who used self-arranged transport. 

Moreover, prehospital ECG significantly reduced the time AED door-to-triage time (0 minutes vs 2 minutes; p<0.001), AED door-to-first AED ECG time (6 minutes vs 12 minutes; p<0.001), AED door-to-physician consultation time (0 minutes vs 5 minutes; p<0.001) and length of stay in the AED (29 minutes vs 58 minutes; p<0.001). A statistically significant increase in  portion of patients (91 percent vs 57 percent; p<0.001) were correctly triaged as category 1 if they had undergone prehospital ECG.

A  target of response within 17 minutes was reached in 96.7 percent of emergency ambulance calls. In total, 43 patients with STEMI underwent prehospital ECG with known Cardiac Care Unit (CCU) call time, were able to contact the CCU physician on or before patient arrival in AED.  

The retrospective observational study assessed data of 197 chest pain patients from both Queen Mary Hospital CCU and the ‘Prehospital Ambulance 12-lead Electrocardiogram for Chest Pain Patients in Hong Kong West Cluster’ pilot project, which aimed to shorten the total ischaemic time in patients.

The Hong Kong Fire Services Department serves as the primary emergency ambulance provider in Hong Kong and ambulance services are activated upon calls to 999. Patients are transported to the nearest public hospital, based on their geographical location. There is no opportunity for patients to choose the destination hospital, and no primary diversions are used for chest pain/ ST-segment elevation myocardial infarction (STEMI). Though results of the initial phase of the pilot project were positive in reducing door-to-balloon (D2B) time with prehospital 12-lead ECG, myocardial injury would likely to have begun with the onset of symptoms prior to hospital admission.

“Delayed activation of the emergency response system and choice of transportation contributed to patient delay. Prehospital 12-lead ECG, preferably performed on scene, can shorten system delay and total ischaemic time in STEMI management,” concluded authors.