Emergency medical services as a strategy for improving ST-elevation myocardial infarction system treatment times

Characterization of prehospital time delay in primary percutaneous coronary intervention for acute myocardial infarction: analysis of geographical infrastructure-dependent and -independent components

BACKGROUND

Prehospital delay in reaching a percutaneous coronary intervention (PCI) facility is a major problem preventing early coronary reperfusion in patients with ST-elevation myocardial infarction (STEMI). The aim of this study was to identify modifiable factors that contribute to the interval from symptom onset to arrival at a PCI-capable center with a focus on geographical infrastructure-dependent and -independent factors.

METHODS

We analyzed data from 603 STEMI patients who received primary PCI within 12 h of symptom onset in the Hokkaido Acute Coronary Care Survey. We defined onset-to-door time (ODT) as the interval from the onset of symptoms to arrival at the PCI facility and we defined door-to-balloon time (DBT) as the interval from arrival at the PCI facility to PCI. We analyzed the characteristics and factors of each time interval by type of transportation to PCI facilities. In addition, we used geographical information system software to calculate the minimum prehospital system time (min-PST), which represents the time required to reach a PCI facility based on geographical factors. We then subtracted min-PST from ODT to find the estimated delay-in-arrival-to-door (eDAD), which represents the time required to reach a PCI facility independent of geographical factors. We investigated the factors related to the prolongation of eDAD.

RESULTS

DBT (median [IQR]: 63 [44, 90] min) was shorter than ODT (median [IQR]: 104 [56, 204] min) regardless of the type of transportation. However, ODT was more than 120 min in 44% of the patients. The min-PST (median [IQR]: 3.7 [2.2, 12.0] min) varied widely among patients, with a maximum of 156 min. Prolongation of eDAD (median [IQR]: 89.1 [49, 180] min) was associated with older age, absence of a witness, onset at night, no emergency medical services (EMS) call, and transfer via a non-PCI facility. If eDAD was zero, ODT was projected to be less than 120 min in more than 90% of the patients.

CONCLUSIONS

The contribution of geographical infrastructure-dependent time in prehospital delay was substantially smaller than that of geographical infrastructure-independent time. Intervention to shorten eDAD by focusing on factors such as older age, absence of a witness, onset at night, no EMS call, and transfer via a non-PCI facility appears to be an important strategy for reducing ODT in STEMI patients. Additionally, eDAD may be useful for evaluating the quality of STEMI patient transport in areas with different geographical conditions.

Optimizing an Emergency Medical Dispatch System to Improve Prehospital Diagnosis and Treatment of Acute Coronary Syndrome: Nationwide Retrospective Study in China

Background

Acute coronary syndrome (ACS) is the most time-sensitive acute cardiac event that requires rapid dispatching and response. The medical priority dispatch system (MPDS), one of the most extensively used types of emergency dispatch systems, is hypothesized to provide better-quality prehospital emergency treatment. However, few studies have revealed the impact of MPDS use on the process of ACS care.

Objective

This study aimed to investigate whether the use of MPDS was associated with higher prehospital diagnosis accuracy and shorter prehospital delay for patients with ACS transferred by an emergency medical service (EMS), using a national database in China.

Methods

This retrospective analysis was based on an integrated database of China’s MPDS and hospital registry. From January 1, 2016, to December 31, 2020, EMS-treated ACS cases were divided into before MPDS and after MPDS groups in accordance with the MPDS launch time at each EMS center. The primary outcomes included diagnosis consistency between hospital admission and discharge, and prehospital delay. Multivariable logistic regression and propensity score–matching analysis were performed to compare outcomes between the 2 groups for total ACS and subtypes.

Results

A total of 9806 ACS cases (3561 before MPDS and 6245 after MPDS) treated by 43 EMS centers were included. The overall diagnosis consistency of the after MPDS group (Cohen κ=0.918, P<.001) was higher than that of the before MPDS group (Cohen κ=0.889, P<.001). After the use of the MPDS, the call-to-EMS arrival time was shortened in the matched ACS cases (20.0 vs 16.0 min, P<.001; adjusted difference: –1.67, 95% CI –2.33 to –1.02; P<.001) and in the subtype of ST-elevation myocardial infarction (adjusted difference: –3.81, 95% CI –4.63 to –2.98, P<.001), while the EMS arrival-to-door time (20.0 vs 20.0 min, P=.31) was not significantly different in all ACS cases and subtypes.

Conclusions

The optimized use of MPDS in China was associated with increased diagnosis consistency and a reduced call-to-EMS arrival time among EMS-treated patients with ACS. An emergency medical dispatch system should be designed specifically to fit into different prehospital modes in the EMS system on a regional basis.

The impact of the emergency medical services (EMS) automation system on patient care process and user workflow

Background

One of the important components of the health system is the emergency medical services (EMS) system. The EMS system was implemented at Kerman University of Medical Sciences teaching hospitals to communicate the situation of patients being transferred to the hospital by EMS and to provide facilities tailored to the patient's condition. The objective of this study was to investigate the impact of the EMS system on the patient care process and the workflow of users.

Methods

The hospital information system (HIS) report was used to investigate the impact of the EMS system on the patient care process and a questionnaire was distributed among 244 participants to determine its impact on the workflow of the users. Mann–Whitney U was used to analyze HIS reports, and Chi-square was used to analyze the data collected by questionnaires.

Results

The EMS system reduced the patient's stay in hospital by an average of 3 h and 45 min. It also increased the number of patients' discharge from the emergency room to 2.2% and reduced the death rate by 1.3% (p < 0.001). Besides, 78% of physicians, 75% of nurses and 83% of technicians stated that this system has positively influenced their workflow.

Conclusions

The EMS system reduced the patient's stay in hospital and mortality, and increased the speed of patient service, readiness of users to provide patient care and the number of discharged patients. However, problems such as inappropriate technical infrastructure of the EMS system should be solved to improve patients' recovery, reduce mortality and improve user satisfaction.

Meta-Analysis of Gender Disparities in In-hospital Care and Outcomes in Patients with ST-Segment Elevation Myocardial Infarction

Gender disparities in ST-segment elevation myocardial infarction (STEMI) outcomes continue to be reported worldwide; however, the magnitude of this gap remains unknown. To evaluate gender-based discrepancies in clinical outcomes and identify the primary driving factors a global meta-analysis was performed. Studies were selected if they included all comers with STEMI, reported gender specific patient characteristics, treatments, and outcomes, according to the registered PROSPERO protocol: CRD42020161469. A total of 56 studies (705,098 patients, 31% females) were included. Females were older, had more comorbidities and received less antiplatelet therapy and primary percutaneous coronary intervention (PCI). Females experienced significantly longer delays to first medical contact (mean difference 42.5 min) and door-to-balloon time (mean difference 4.9 min). In-hospital, females had increased rates of mortality (odds ratio [OR] 1.91, 95% confidence interval [CI] 1.84 to 1.99, p <0.00001), repeat myocardial infarction (MI) (OR 1.25, 95% CI 1.00 to 1.56, p=0.05), stroke (OR 1.67, 95% CI 1.27 to 2.20, p <0.001), and major bleeding (OR 1.82, 95% CI 1.56 to 2.12, p <0.00001) compared with males. Older age at presentation was the primary driver of excess mortality in females, although other factors including lower rates of primary PCI and aspirin usage, and longer door-to-balloon times contributed. In contrast, excess rates of repeat MI and stroke in females appeared to be driven, at least in part, by lower use of primary PCI and P2Y12 inhibitors, respectively. In conclusion, despite improvements in STEMI care, women continue to have in-hospital rates of mortality, repeat MI, stroke, and major bleeding up to 2-fold higher than men. Gender disparities in in-hospital outcomes can largely be explained by age differences at presentation but comorbidities, delays to care and suboptimal treatment experienced by women may contribute to the gender gap.

Survival in Patients with Paramedic-Identified ST-Segment Elevation Myocardial Infarction

BACKGROUND

Field identification and treatment of ST-segment elevation myocardial infarction (STEMI) by paramedics is an important component of care for these patients. There is a paucity of studies in the setting of paramedic-identified STEMI. This study investigated mortality and factors associated with mortality in a large state-wide prehospital STEMI sample. Methods: Included were adult STEMI patients identified and treated with reperfusion therapy by paramedics in the field between January 2016 and December 2018 in Queensland, Australia. 30-day and one-year all-cause mortality was compared between two prehospital reperfusion pathways: prehospital fibrinolysis versus direct referral to a hospital for primary percutaneous coronary intervention (direct percutaneous coronary intervention [PCI] referral). For prehospital fibrinolysis patients, factors associated with failed fibrinolysis were investigated. For direct PCI referral patients, factors associated with mortality were examined. Results: The 30-day mortality was 2.2% for prehospital fibrinolysis group and 1.8% for direct PCI referral group (p = 0.661). One-year mortality for the two groups was 2.7% and 3.2%, respectively (p = 0.732). Failed prehospital fibrinolysis was observed in 20.1% of patients receiving this therapy, with male gender and history of heart failure being predictors. For direct PCI referral group, low left ventricular ejection fraction (LVEF) on admission and cardiogenic shock prior to PCI were predictors of both 30-day and one-year mortality. Aboriginal and Torres Strait Islander status, and impaired kidney function on admission, were associated with one-year but not 30-day mortality. Being overweight was associated with lower 30-day mortality. Conclusions: Mortality in STEMI patients identified and treated by paramedics was low, and the prehospital fibrinolysis treatment pathway was effective with a mortality rate comparable to that of patients undergoing primary PCI. Key words: prehospital; Queensland; cardiac reperfusion; STEMI.

Response time in the emergency services. Systematic review

The growth of the urban population raises concern about municipal public managers in the sense of providing emergency medical services (EMS) that are aligned with the needs of prehospital emergency medical care demanded by the population. The literature review aims at presenting the response time of emergency medical services in several parts of the world and discussing some factors that interfere in the result of this indicator such as GDP (Gross Domestic Product) percentage spent on health and life expectancy of countries. The study will also show that in some of the consulted articles, authors suggest to EMS recommendations for decreasing the response time using simulations, heuristics and metaheuristics. Response time is a basic indicator of emergency medical services, in such a way that researchers use the descriptive statistics to evaluate this parameter. Europe and the USA outstand in the publication of studies that present this information. Some articles use stochastic and mathematical methods to suggest models that simulate scenarios of response time reduction and suggest such proposals to the local EMS. Countries in which the response time was identified have a high index of human development and life expectancy between 74.7 and 83.7 years.

National Assessment of Quality Programs in Emergency Medical Services

OBJECTIVE

This study aims to understand the adoption of clinical quality measurement throughout the United States on an EMS agency level, the features of agencies that do participate in quality measurement, and the level of physician involvement. It also aims to barriers to implementing quality improvement initiatives in EMS.

METHODS

A 46-question survey was developed to gather agency level data on current quality improvement practices and measurement. The survey was distributed nationally via State EMS Offices to EMS agencies nation-wide using Surveymonkey©. A convenience sample of respondents was enrolled between August and November, 2015. Univariate, bivariate and multiple logistic regression analyses were conducted to describe demographics and relationships between outcomes of interest and their covariates using SAS 9.3©.

RESULTS

A total of 1,733 surveys were initiated and 1,060 surveys had complete or near-complete responses. This includes agencies from 45 states representing over 6.23 million 9-1-1 responses annually. Totals of 70.5% (747) agencies reported dedicated QI personnel, 62.5% (663) follow clinical metrics and 33.3% (353) participate in outside quality or research program. Medical director hours varied, notably, 61.5% (649) of EMS agencies had <5 hours of medical director time per month. Presence of medical director time was correlated with tracking of QI measures. Air medical [OR 9.64 (1.13, 82.16)] and hospital-based EMS agencies [OR 2.49 (1.36, 4.59)] were more likely to track quality measures compared to fire-based agencies. Agencies in rural only environments were less likely to follow clinical quality metrics. (OR 0.47 CI 0.31 -0.72 p < 0.0004). For those that track QI measures, the most common are; Response Time (Emergency) (68.3%), On-Scene Time (66.4%), prehospital stroke screen (64.6%), aspirin administration (64.5%), and 12 lead ECG in chest pain patients (63.0%).

CONCLUSIONS

EMS agencies in the United States have significant practice variability with regard to quality improvement resources, medical direction and specific clinical quality measures. More research is needed to understand the impact of this variation on patient care outcomes.

Chest Pain of Suspected Cardiac Origin: Current Evidence-based Recommendations for Prehospital Care

Introduction

In the United States, emergency medical services (EMS) protocols vary widely across jurisdictions. We sought to develop evidence-based recommendations for the prehospital evaluation and treatment of chest pain of suspected cardiac origin and to compare these recommendations against the current protocols used by the 33 EMS agencies in the state of California.

Methods

We performed a literature review of the current evidence in the prehospital treatment of chest pain and augmented this review with guidelines from various national and international societies to create our evidence-based recommendations. We then compared the chest pain protocols of each of the 33 EMS agencies for consistency with these recommendations. The specific protocol components that we analyzed were use of supplemental oxygen, aspirin, nitrates, opiates, 12-lead electrocardiogram (ECG), ST segment elevation myocardial infarction (STEMI) regionalization systems, prehospital fibrinolysis and β-blockers.

Results

The protocols varied widely in terms of medication and dosing choices, as well as listed contraindications to treatments. Every agency uses oxygen with 54% recommending titrated dosing. All agencies use aspirin (64% recommending 325mg, 24% recommending 162mg and 15% recommending either), as well as nitroglycerin and opiates (58% choosing morphine). Prehospital 12-Lead ECGs are used in 97% of agencies, and all but one agency has some form of regionalized care for their STEMI patients. No agency is currently employing prehospital fibrinolysis or β-blocker use.

Conclusion

Protocols for chest pain of suspected cardiac origin vary widely across California. The evidence-based recommendations that we present for the prehospital diagnosis and treatment of this condition may be useful for EMS medical directors tasked with creating and revising these protocols.

Efficacy and safety of out-of-hospital intravenous metoprolol administration in anterior ST-segment elevation acute myocardial infarction: insights from the METOCARD-CNIC trial

STUDY OBJECTIVE

We seek to examine the efficacy and safety of prereperfusion emergency medical services (EMS)-administered intravenous metoprolol in anterior ST-segment elevation myocardial infarction patients undergoing eventual primary angioplasty.

METHODS

This is a prespecified subgroup analysis of the Effect of Metoprolol in Cardioprotection During an Acute Myocardial Infarction trial population, who all eventually received oral metoprolol within 12 to 24 hours. We studied patients receiving intravenous metoprolol by EMS and compared them with others treated by EMS but not receiving intravenous metoprolol. Outcomes included infarct size and left ventricular ejection fraction on cardiac magnetic resonance imaging at 1 week, and safety by measuring the incidence of the predefined combined endpoint (composite of death, malignant ventricular arrhythmias, advanced atrioventricular block, cardiogenic shock, or reinfarction) within the first 24 hours.

RESULTS

From the total population of the trial (N=270), 147 patients (54%) were recruited during out-of-hospital assistance and transferred to the primary angioplasty center (74 intravenous metoprolol and 73 controls). Infarct size was smaller in patients receiving intravenous metoprolol compared with controls (23.4 [SD 15.0] versus 34.0 [SD 23.7] g; adjusted difference -11.4; 95% confidence interval [CI] -18.6 to -4.3). Left ventricular ejection fraction was higher in the intravenous metoprolol group (48.1% [SD 8.4%] versus 43.1% [SD 10.2%]; adjusted difference 5.0; 95% CI 1.6 to 8.4). Metoprolol administration did not increase the incidence of the prespecified safety combined endpoint: 6.8% versus 17.8% in controls (risk difference -11.1; 95% CI -21.5 to -0.6).

CONCLUSION

Out-of-hospital administration of intravenous metoprolol by EMS within 4.5 hours of symptom onset in our subjects reduced infarct size and improved left ventricular ejection fraction with no excess of adverse events during the first 24 hours.

Reperfusion strategies in acute coronary syndromes

The appropriate timing of angiography to facilitate revascularization is essential to optimize outcomes in patents with ST-segment-elevation myocardial infarction and non-ST-segment-elevation acute coronary syndromes. Timely reperfusion of the infarct-related coronary artery in ST-segment-elevation myocardial infarction both with fibrinolysis or percutaneous coronary intervention minimizes myocardial damage, reduces infarct size, and decreases morbidity and mortality. Primary percutaneous coronary intervention is the preferred reperfusion method if it can be performed in a timely manner. Strategies to reduce health system-related delays in reperfusion include regionalization of ST-segment-elevation myocardial infarction care, performing prehospital ECGs, prehospital activation of the catheterization laboratory, bypassing geographically closer nonpercutaneous coronary intervention-capable hospitals, bypassing the percutaneous coronary intervention-capable hospital emergency department, and early and consistent availability of the catheterization laboratory team. With implementation of such strategies, there has been significant improvement in process measures, including door-to-balloon time. However, despite reductions in door-to-balloon times, there has been little change during the past several years in in-hospital mortality, suggesting additional factors including patient-related delays, optimization of tissue-level perfusion, and cardioprotection must be addressed to improve patient outcomes further. Early angiography followed by revascularization when appropriate also reduces rates of death, MI, and recurrent ischemia in patients with non-ST-segment-elevation acute coronary syndromes, with the greatest benefits realized in the highest risk patients. Among patients with non-ST-segment-elevation acute coronary syndromes with multivessel disease, choice of revascularization modality should be made as in stable coronary artery disease, with a goal of complete ischemic revascularization.