Prehospital transport of patients with acute myocardial infarction: a community-wide perspective

STEMI Equivalents and Their Incidence during EMS Transport

Objective: The management of patients with ST-elevation myocardial infarction (STEMI) is time-critical, with a focus on early reperfusion to decrease morbidity and mortality. It is imperative that prehospital clinicians recognize STEMI early and initiate transport to hospitals capable of percutaneous coronary intervention (PCI) with a door-to-balloon time of ≤90 minutes. Three patterns have been identified as STEMI equivalents that also likely warrant prompt attention and potentially PCI: Wellens syndrome, De Winter T waves, and aVR ST elevation. The goal of our study was to assess the incidence of these findings in prehospital patients presenting with chest pain. Methods: We conducted a retrospective chart review from a large urban tertiary care emergency department. We reviewed the prehospital ECG, or ECG upon arrival, of 861 patients who were hospitalized and required cardiac catheterization between 4/10/18 and 5/7/19. Patients who had field catheterization lab activation by EMS for STEMI were excluded. If a prehospital ECG was not available for review, the first ECG obtained in the hospital was used as a proxy. Each ECG was screened for aVR elevation, De Winter T waves, and Wellens syndrome. Results: Of 278 charts with prehospital ECGs available, 12 met our criteria for STEMI equivalency (4.4%): 6 Wellens syndrome and 6 aVR STEMI. There were no cases of De Winters T waves. Of 573 charts with no prehospital ECG available, 27 had initial hospital ECGs that met our STEMI equivalent criteria (4.7%): 7 Wellens syndrome and 20 aVR STEMI. Again, there were no cases of De Winters T waves. Conclusions: These preliminary data suggest that there are significant numbers of patients whose prehospital ECG findings do not currently meet criteria for field activation of the cardiac catheterization lab, but who may require prompt catheterization. Further studies are needed to look at outcomes, but these results could support the need for further education of prehospital clinicians regarding recognition of these STEMI equivalents, as well as quality initiatives aimed at decreasing door-to-balloon time for patients with STEMI equivalents.

Factors influencing choice of pre-hospital transportation of patients with potential acute coronary syndrome: An observational study

OBJECTIVE

To determine factors associated with ambulance use in patients with confirmed and potential acute coronary syndrome presenting to the ED.

METHODS

A convenience sample of patients (n = 247) presenting to the ED from April 2014 to January 2015 with suspected acute coronary syndrome were included in the study. Data on mode of transport and patient demographics were collected from the Emergency Department Information System database. Clinical data were collected from chart records and information systems. A questionnaire assessed reasons for using a chosen method of transport, symptom timing and characteristics, acute coronary syndrome knowledge, and awareness of the National Heart Foundation Early Warning Symptoms campaign.

RESULTS

Approximately half the patients (49.4%) assessed with symptoms of potential acute coronary syndrome used ambulance transport to the ED. Patients who arrived by ambulance were older than those not arriving by ambulance (mean 56.7 years vs 51.7 years, P = 0.01). Risk factors were not associated with ambulance use. Dizziness (P < 0.01), sweating (P = 0.03), nausea (P = 0.03) and vomiting (P = 0.04) were associated with increased ambulance use. Mean systolic blood pressure was lower in the ambulance group (136 mmHg, standard deviation [SD] = 19.8) than in the non-ambulance group (143 mmHg, SD = 25.9). Awareness of the National Heart Foundation Heart Attack Warning Signs campaign was not associated with ambulance use.

CONCLUSIONS

Patients with possible ischaemic symptoms who are at a high risk of cardiac disease do not utilise ambulance services more than low risk patients. In general, transport to hospital using ambulance services by patients with symptoms of possible acute coronary syndrome is low despite community campaigns.

Characteristics and outcome among patients who dial for the EMS due to chest pain

OBJECTIVES

This study aims to describe patients who called for the emergency medical service (EMS) due to chest discomfort, in relation to gender and age.

METHODS

All patients who called the emergency dispatch centre of western Sweden due to chest discomfort, between May 2009 and February 2010, were included. Initial evaluation, aetiology and outcome are described as recorded in the databases at the dispatch centre, the EMS systems and hospitals. Patients were divided into the following age groups: ≤50, 51-64 and ≥65 years.

RESULTS

In all, 14,454 cases were enrolled. Equal proportions of men (64%) and women (63%) were given dispatch priority 1. The EMS clinicians gave priority 1 more frequently to men (16% versus 12%) and older individuals (10%, 15% and 14%, respective of age group). Men had a significantly higher frequency of central chest pain (83% versus 81%); circulatory compromise (34% versus 31%); ECG signs of ischaemia (17% versus 11%); a preliminary diagnosis of acute coronary syndrome (40% versus 34%); a final diagnosis of acute myocardial infarction (14% versus 9%) and any potentially life-threatening condition (18% versus 12%). Individuals aged ≥65 years were given a lower priority than individuals aged 51-64 years, despite poorer characteristics and outcome. In all, 78% of cases with a potentially life-threatening condition and 67% of cases that died within 30 days of enrolment received dispatch priority 1. Mortality at one year was 1%, 4% and 18% in each individual age group.

CONCLUSION

Men and the elderly were given a disproportionately low priority by the EMS.

Inconsistent measurement of acute coronary syndrome patients' pre-hospital delay in research: a review of the literature

BACKGROUND

Patients' treatment-seeking delay remains a significant barrier to timely initiation of reperfusion therapy. Measurement of treatment-seeking delay is central to the large body of research that has focused on pre-hospital delay (PHD), which is primarily patient-related. This research has aimed to quantify PHD and its effects on morbidity and mortality, identify contributing factors, and evaluate interventions to reduce such delay. A definite time of symptom onset in acute coronary syndrome (ACS) is essential for determining delay, but difficult to establish. This literature review aimed to explore the variety of operational definitions of both PHD and symptom onset in published research.

METHODS AND RESULTS

We reviewed the English-language literature from 1998-2013 for operational definitions of PHD and symptom onset. Of 626 papers of possible interest, 175 were deemed relevant. Ninety-seven percent reported a delay time and 84% provided an operational definition of PHD. Three definitions predominated: (a) symptom onset to decision to seek help (18%); (b) symptom onset to hospital arrival (67%), (c) total delay, incorporating two or more intervals (11%). Of those that measured delay, 8% provided a definition of which symptoms triggered the start of timing.

CONCLUSION

We found few and variable operational definitions of PHD, despite American College of Cardiology/American Heart Association recommendations to report specific intervals. Worryingly, definitions of symptom onset, the most elusive component of PHD to establish, are uncommon. We recommend that researchers (a) report two PHD delay intervals (onset to decision to seek care, and decision to seek care to hospital arrival), and (b) develop, validate and use a definition of symptom onset. This will increase clarity and confidence in the conclusions from, and comparisons within and between studies.

Myocardial infarction: sex differences in symptoms reported to emergency dispatch

BACKGROUND

Emergency management of myocardial infarction (MI) is time-critical, because improved patient outcomes are associated with reduced time from symptom onset to definitive care. Previous studies have identified that women are less likely to present with chest pain.

OBJECTIVE

We sought to measure the effect of sex on symptoms reported to the ambulance dispatch and ambulance times for MI patients.

METHODS

The Western Australia Emergency Department Information System (EDIS) was used to identify patients with emergency department (ED) diagnoses of MI (ST-segment elevation MI and non-ST-segment elevation MI) who arrived by ambulance between January 1, 2008, and October 31, 2009. Their emergency telephone calls to the ambulance service were transcribed to identify presenting symptoms. Ambulance data were used to examine ambulance times. Sex differences were analyzed using descriptive and age-adjusted regression analysis.

RESULTS

Of 3,329 MI patients who presented to Perth EDs, 2,100 (63.1%) arrived by ambulance. After predefined exclusions, 1,681 emergency calls were analyzed. The women (n = 621; 36.9%) were older than the men (p < 0.001) and, even after age adjustment, were less likely to report chest pain (odds ratio [OR] = 0.70; 95% confidence interval [CI] 0.57, 0.88). After age adjustment, ambulance times did not differ between the male and female patients with chest pain. The women with chest pain were less likely than the men with chest pain to be allocated a "priority 1" (lights and sirens) ambulance response (men 98.3% vs. women 95.5%; OR = 0.39; 95% CI 0.18, 0.87).

CONCLUSION

Ambulance dispatch officers (and paramedics) need to be aware of potential sex differences in MI presentation in order to ensure appropriate ambulance response.

Community trends in the use and characteristics of persons with acute myocardial infarction who are transported by emergency medical services

OBJECTIVE

Limited data exist on recent trends in ambulance use and factors associated with ambulance use in patients hospitalized with acute myocardial infarction (AMI), particularly from the more generalizable perspective of a community-wide investigation. This population-based prospective epidemiologic study describes the decade-long trends (1997-2007) in the use of emergency medical services (EMS) by residents of the Worcester, Massachusetts, metropolitan area who are hospitalized for AMI and the characteristics of patients with AMI who are transported to the hospital by EMS (n = 3789) compared with those transported by other means (n = 1505).

METHODS

The study population consisted of 5294 patients hospitalized for AMI at 11 greater Worcester medical centers in 5 annual periods between 1997 and 2007. Information on the use of EMS and the factors associated with EMS use was obtained through the review of hospital medical records.

RESULTS

There was a progressive increase in the proportion of greater Worcester residents with AMI who were transported to central Massachusetts hospitals by ambulance over time (66.9% transported in 1997; 74.9% transported in 2007). Patients transported by EMS were older, more likely to be women, and more likely to have a greater prevalence of previously diagnosed comorbidities.

CONCLUSION

Our findings provide encouragement for the use of EMS in residents of a large central New England community hospitalized with AMI. Despite increasing trends in ambulance use, more research is needed to explore the reasons why patients with AMI do not use EMS in the setting of an acute cardiac emergency.

Reviewing time intervals from onset of the symptoms to thrombolytic therapy in patients with ST segment elevation myocardial infarction (STEMI)

BACKGROUND

Coronary artery diseases are one of the causes of early death all over the world. In developed countries, ischemic heart disease is responsible for half of the entire mortalities; however in developing countries it is estimated that from 9 million deaths per year, 32 percent are due to coronary artery disease. Acute coronary syndromes are responsible for over 250,000 deaths per year caused by progressive atherosclerotic process which would lead to rupture of the atherosclerotic plaque and establishing thrombosis. This study aimed to determine time intervals between the onset of the heart attack symptoms to thrombolytic therapy in patients with ST segment elevation myocardial infarction (STEMI) in selected hospitals of Isfahan University of Medical Sciences.

METHODS

In this study, 180 subjects with first time STEMI were enrolled by categorized random sampling in cardiac care units of four hospitals affiliated to Isfahan University of Medical Sciences during 9 months. Necessary information were collected by asking the patients and reviewing their records. The data included demographic, prehospital and in-hospital data of the patients.

RESULTS

The mean duration of time interval from the onset of heart attack symptoms to the first action in order to seek medical care was 01:16'(01:36') (h:m [SD]), from the symptoms onset to admission in emergency unit was 02:29'(02:00') and from admission in emergency unit to administration of thrombolytic drug was 01:04'(01:14').

CONCLUSIONS

Time interval between onset of the acute coronary symptoms and seek for medical care and arrival to the emergency unit in this study had a better condition than other studies, but the interval between the emergency admission and thrombolytic therapy was longer than other studies.

Utilization of emergency medical services by patients with acute coronary syndromes in the Arab Gulf States

BACKGROUND

Emergency Medical Services (EMS) play a central role in caring for patients with acute coronary syndromes (ACS). To date, no data exist on utilization of EMS systems in the Arab Gulf States.

OBJECTIVE

To examine EMS use by patients with ACS in the Gulf Registry of Acute Coronary Events (Gulf RACE).

METHODS

Gulf RACE was a prospective, multinational study conducted in 2007 of all patients hospitalized with ACS in 65 centers in six Arab countries. Data were analyzed based on mode of presentation (EMS vs. other).

RESULTS

Of 7859 patients hospitalized with ACS through the emergency department (ED), only 1336 (17%) used EMS, with wide variation among countries (2% in Yemen to 37% in Oman). Younger age (odds ratio [OR] 1.09; 95% confidence interval [CI] 1.03-1.15 per 10-year decrement), presence of chest pain (OR 1.73; 95% CI 1.48-2.03), prior myocardial infarction (OR 1.58; 95% CI 1.34-1.86), prior percutaneous coronary intervention (OR 1.27; 95% CI 1.02-1.59), family history of premature coronary disease (OR 1.25; 95% CI 1.09-1.51), and current smoking (OR 1.30; 95% CI 1.13-1.50) were independently associated with not utilizing EMS. Patients with ST-segment elevation myocardial infarction/left bundle branch block myocardial infarction who were transported by EMS were significantly less likely to exhibit major delay in presentation, and were significantly more likely to receive favorable processes of care, including shorter door-to-electrocardiogram time, more frequent coronary reperfusion therapy, and thrombolytic therapy within 30 min of arrival at the ED.

CONCLUSION

Despite current recommendations, fewer than 1 in 5 patients with ACS use EMS in the Arab Gulf States, highlighting a significant opportunity for improvement. Factors causing this underutilization deserve further investigation.