The impact of outpatient emergency medical system in STEMI patients undergoing primary angioplasty: a single-centre experience
Authors: Mane FG , Flores R , Conde I , Silva R , Medeiros P , Rodrigues C , Oliveira C , Ferreira AS , Costa J , Quina C , Braga C , Marques J 
Published: May 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
In ST-segment elevation myocardial infarction (STEMI), emergency medical system delays importantly affect outcomes. The place of first medical contact may affect the time to reperfusion and consequently affect outcomes, as the most direct transfer to the catheterization laboratory is warranted.

Purpose
The authors aimed to retrospectively describe the association between place of first medical contact and STEMI patient’s care standards and outcomes.

Methods
Characteristics and outcomes of 1205 consecutive STEMI patients treated in a PCI-centre were collected. Outpatient emergency medical system (EMS) was provided by different vehicles of the Portuguese National Institute of Medical Emergency. Other patients were first observed in primary care centres or in hospitals (PCC/H). Time delays, in-hospital and one-year all-cause mortality were assessed.

Results
A total of 281 patients (23%) were first observed by the EMS and 924 patients (77%) were first observed in PCC/H. Of those first observed in PCC/H, 258 patients (28%) were admitted in the PCI reference centre. Baseline characteristics were well-balanced between groups, including the percentage of patients that presented in cardiogenic shock (EMS: 6% vs PCC/H: 5%; p=0.43).
Median total ischaemic time was significantly lower in patients first observed by EMS when compared to patients admitted in PCC/H (182 min vs. 246 min, respectively. p &lt;0.01). Median emergency system dependent time to reperfusion (i.e. first-medical contact to reperfusion) was significantly lower after first contact with EMS instead of direct PCC/H contact (105 min vs. 130 min, respectively. p&lt;0.01).
In patients admitted directly in the PCI-centre, median time from first-medical contact to reperfusion was significantly lower than in those first contacted by the EMS (76 min vs. 105 min; respectively. p&lt;0.01). However, the total ischaemic time did not differ between the two groups (EMS 182 min vs. PCC/H: 195 min ; p=0.64).
First medical contact in a hospital without catheterization laboratory was a strong predictor of time of first-medical contact to artery opening of &gt;120 min (odds ratio 6.09 CI95% [4.74-7.82]; p&lt;0.001).
The authors observed no association between place of first medical contact and in-hospital mortality (EMS: 5% vs. PCC/H 5%, p = 0.94) or 1-year mortality (EMS: 9% vs. PCC/H 10%, p=0.50).
Nonetheless, the observed time intervals for nonsurvivors were significantly longer than in survivors (table 1) and time of first-medical contact to artery opening of &gt;120 min was a strong predictor of in-hospital (odds ratio 2.51 CI95%[1.42-4.46]; p &lt; 0.01) and 1 year mortality (odds ratio 2.31 CI95%[1.55-3.44]; p &lt; 0.01).

Conclusion
In a contemporary well-organized emergency network, STEMI patients should be first observed by the EMS as it leads to shorter delays treatment. However, less than one-third of the patients with STEMI is first contacted by the EMS.