Impact of Emergency Medical System Transportation in ST-segment Elevation Myocardial Infarction: A Nationwide Retrospective Study

Prevalence and Predictors of Emergency Medical Service Use in Patients Undergoing Primary Percutaneous Coronary Intervention for ST-Elevation Myocardial Infarction

AIM

We aim to describe prevalence of Emergency Medical Service (EMS) use, investigate factors predictive of EMS use, and determine if EMS use predicts treatment delay and mortality in our ST-elevation myocardial infarction (STEMI) cohort.

METHOD

We prospectively collected data on 5,602 patients presenting with STEMI for primary percutaneous coronary intervention (PCI) transported to PCI-capable hospitals in Victoria, Australia, from 2013-2018 who were entered into the Victorian Cardiac Outcomes Registry (VCOR). We linked this dataset to the Ambulance Victoria and National Death Index (NDI) datasets. We excluded late presentation, thrombolysed, and in-hospital STEMI, as well as patients presenting with cardiogenic shock and out-of-hospital cardiac arrest.

RESULTS

In total, 74% of patients undergoing primary PCI for STEMI used EMS. Older age, female gender, higher socioeconomic status, and a history of prior ischaemic heart disease were independent predictors of using EMS. EMS use was associated with shorter adjusted door-to-balloon (53 vs 72 minutes, p<0.001) and symptom-to-balloon (183 vs 212 minutes, p<0.001) times. Mode of transport was not predictive of 30-day or 12-month mortality.

CONCLUSIONS

EMS use in Victoria is relatively high compared with internationally reported data. EMS use reduces treatment delay. Predictors of EMS use in our cohort are consistent with those prevalent in prior literature. Understanding the patients who are less likely to use EMS might inform more targeted education campaigns in the future.

Association of Symptoms and Mode of Transportation to Emergency Department in Patients With Acute Coronary Syndrome

BACKGROUND

Patients with acute coronary syndrome (ACS) with symptoms matching their expectations of a heart attack are more likely to use emergency medical services (EMS) than not.

OBJECTIVE

To determine whether presenting symptom clusters are associated with EMS use in ACS patients and if EMS use or symptom clusters are associated with prehospital delay.

METHODS

This secondary analysis used data from the PROMOTION trial, a randomized clinical trial that enrolled 3522 subjects with a history of or at risk for ACS from 5 sites in the United States, Australia, and New Zealand. Subjects were randomized to usual care or an educational intervention to reduce prehospital delay. During the 2-year follow-up, subjects admitted for ACS were asked about symptoms, time of symptom onset, and mode of transportation to the hospital. Symptoms were grouped into classic ACS, pain symptoms, and stress symptoms clusters.

RESULTS

Of 3522 subjects enrolled, 331 sought care for ACS during follow-up; 278 had transportation mode documented; 121 (44%) arrived via EMS. Classic ACS plus pain symptoms (adjusted odds ratio [AOR], 2.66; P = .011), classic ACS plus stress symptoms (AOR, 2.61; P = .007), and classic ACS plus both pain and stress symptoms (AOR, 3.90; P = .012) were associated with higher odds of EMS use versus classic ACS symptoms alone. Emergency medical services use resulted in a 68.5-minute shorter median delay (P = .002) versus non-EMS use. Symptom clusters were not predictive of delay time in the adjusted model (P = .952).

DISCUSSION

Although chest symptoms were the most prevalent symptoms for most (85%), the combination of classic ACS symptoms with other symptom clusters was associated with higher EMS use. Further research is needed to determine whether a combination of symptom clusters helps patients correctly interpret ACS symptoms to better understand how symptom clusters influence EMS use.