Symptom presentation of acute myocardial infarction – can we correctly identify patients with atypical symptoms of myocardial infarctions over the phone?
Authors: Moeller A.L , Mills E.H.A , Gnesin F , Zylyftari N , Folke F , Lippert F.K , Torp-Pedersen C 
Published: November 2020

Abstract

Introduction
Acute myocardial infarction (AMI) can manifest itself with a variety of symptoms which can hinder early recognition of the disease, particularly when diagnosis is performed over the phone. It is currently unknown to what extent AMI patients are correctly recognized and quickly referred to treatment when calling for help at the emergency medical services (EMS) and out-of-hours service (OOHS). Therefore, we investigated how the symptom presentation of AMI patients affected their chances of being recognized.

Purpose
This study aimed to describe the symptoms reported by AMI patients when calling the EMS and OOHS and investigate to what extent these patients were correctly recognized and lastly, how the symptom presentation affected the survival.

Methods
All calls to the EMS and OOHS in the Capital Region of Denmark from 1st January 2014 to 31st December 2017 are included in this study resulting in 4,905,318 calls made by 1,313,980 people. A total of 5,526 people were identified with either a hospital admission with an AMI or an AMI as cause of death maximum 72 hours after a call to the EMS or OOHS. The main symptoms were registered by the EMS and OOHS personnel and we grouped the symptoms into symptom categories. Finally, a patient was defined as recognized if an emergency ambulance were dispatched. The unrecognized patients were separated into one group which were not referred to any treatment and another group that received none-urgent treatment.

Results
72% of all AMI patients reported chest pain as their main symptom followed by breathing problems (7%) and unknown problems (5%). A total of 76% of all AMI patients were correctly recognized and received an emergency ambulance. The proportion of recognized AMIs was 88% at the EMS, but only 55% at the OOHS. The symptom presentation was highly associated with the help provided to the patient and less than 14% of patients reporting musculoskeletal pain, infection/fever or pain in stomach/back/intestine received an emergency ambulance. In comparison, 87% of patients with chest pain and 96% of unconscious patients received an emergency ambulance (Figure 1). Results from a multiple logistic regression showed that chest pain patients had the lowest risk of death at 30-days follow-up compared to all other symptom presentation.

Conclusion
24% of AMI patients were not correctly recognized with an acute life-threatening disease when calling for help. Patients presenting without chest pain and unconsciousness had a much lower chance of being recognized. Similarly, patients calling the OOHS were less likely to be recognized compared to patients calling the EMS. Symptom presentations without chest pain had a dramatically increased 30-day mortality indicating that AMI patients with atypical symptoms truly are a high-risk patient group.
Figure 1

Funding Acknowledgement
Type of funding source: Foundation. Main funding source(s): The Danish Heart Association