Paramedic Ability to Recognize ST-segment Elevation Myocardial Infarction on Prehospital Electrocardiograms

Implementation of a Novel Prehospital Clinical Decision Tool and ECG Transmission for STEMI Significantly Reduces Door-to-Balloon Time and Sex-Based Disparities

BACKGROUND

An important method employed to reduce door to balloon time (DTBT) for ST segment elevation Myocardial Infarctions (STEMIs) is a prehospital MI alert. The purpose of this retrospective study was to examine the effects of an educational intervention using a novel decision support method of STEMI notification and prehospital electrocardiogram (ECG) transmission on DTBT.

METHODS

An ongoing database (April 4, 2000 - present) is maintained to track STEMI alerts. In 2007, an MI alert program began; emergency medicine physicians could activate a "prehospital MI alert". In October 2015, modems were purchased for Emergency Medical Services personnel to transmit ECGs. There was concurrent implementation of a decision support tool for identifying STEMI. Sex was assigned as indicated in the medical record. Data were analyzed in two groups: Pre-2016 (PRE) and 2016-2022 (POST).

RESULTS

In total, 3,153 patients (1,301 PRE; 1,852 POST) were assessed; the average age was 65.2 years, 32.6% female, 87.7% white with significant differences in age and race between the two cohorts. Of the total 3,153 MI alerts, 239 were false activations, leaving 2,914 for analysis. 2,115 (72.6%) had cardiac catheterization while 16 (6.7%) of the 239 had a cardiac catheterization. There was an overall decrease in DTBT of 27.5% PRE to POST of prehospital ECG transmission (p < 0.001); PRE median time was 74.5 min vs. 55 min POST. There was no significant difference between rates of cardiac catheterization PRE and POST for all patients. After accounting for age, race, and mode of arrival, DTBT was 12.2% longer in women, as compared to men (p < 0.001) PRE vs. POST. DTBT among women was significantly shorter when comparing PRE to POST periods (median 77 min vs. 60 min; p = 0.0001). There was no significant sex difference in the proportion of those with cardiac catheterization between the two cohorts (62.5% vs. 63.5%; p = 0.73).

CONCLUSION

Introduction of a decision support tool with prehospital ECG transmission with prehospital ECG transmission decreased overall DTBT by 20 min (27.5%). Women in the study had a 17-minute decrease in DTBT (22%), but their DTBT remained 12.2% longer than men for reasons that remain unclear.

Paramedic Ability in Interpreting Electrocardiogram with ST-segment Elevation Myocardial Infarction (STEMI) in Saudi Arabia

Objective

To evaluate paramedic ability in recognizing 12-lead Electrocardiogram (ECG) with ST-segment Elevation myocardial infarction (STEMI) in Saudi Arabia.

Methods

This is a quantitative exploratory cross-sectional study using an electronic survey of paramedics was conducted between June and September 2021. The survey included demographics, educational and clinical experiences, and multiple 12-lead ECG strip questions to assess participants’ ability to recognize STEMI. We reported the overall sensitivity, specificity, and correct proportions with 95% Confidence Intervals (CI).

Results

Eighty-four paramedics completed the survey, and 65% of them were between 24 and 29 years old, with a median, of three years of field experience. Overall sensitivity and specificity were 58.39% (95% CI, 50.4% to 66.1%) and 29.01% (95% CI, 25.15% to 33.1%), respectively. In total, 67.1% correctly identified inferior STEMI, whereas only 50% correctly identified lateral STEMI. Both STEMIs were correctly identified by 41%, and the majority misinterpreted STEMI mimics (ECG rhythms with similar ECG morphology to STEMI). The proportion who correctly recognized left bundle branch block was 14.8%, pericarditis was 10.9%, and ventricular pacing was 1.4%. However, almost third of participants correctly identified right bundle branch block (32.9%) and left ventricle hypertrophy (30.7%). Overall, there was no correlation between the correct ECG interpretation of STEMIs and educational and clinical experiences.

Conclusion

Paramedics were able to identify STEMI events in prehospital settings with moderate sensitivity and low specificity with limited ability to differentiate between STEMI and STEMI mimics. Therefore, additional training in ECG interpretation could improve their clinical decision-making, and to ensure that proper care and treatment is provided. Further research on a large, representative sample of paramedics across the country could provide more definitive evidence to establish a greater degree of accuracy in detecting STEMI in prehospital settings.

Systematic Review and Meta-Analysis of Diagnostic Accuracy to Identify ST-Segment Elevation Myocardial Infarction on Interpretations of Prehospital Electrocardiograms

Background: The aim of this study was to assess and discuss the diagnostic accuracy of prehospital ECG interpretation through systematic review and meta-analyses.

Methods and Results: Relevant literature published up to July 2020 was identified using PubMed. All human studies of prehospital adult patients suspected of ST-segment elevation myocardial infarction in which prehospital electrocardiogram (ECG) interpretation by paramedics or computers was evaluated and reporting all 4 (true-positive, false-positive, false-negative, and true-negative) values were included. Meta-analyses were conducted separately for the diagnostic accuracy of prehospital ECG interpretation by paramedics (Clinical Question [CQ] 1) and computers (CQ2). After screening, 4 studies for CQ1 and 6 studies for CQ2 were finally included in the meta-analysis. Regarding CQ1, the pooled sensitivity and specificity were 95.5% (95% confidence interval [CI] 82.5–99.0%) and 95.8% (95% CI 82.3–99.1%), respectively. Regarding CQ2, the pooled sensitivity and specificity were 85.4% (95% CI 74.1–92.3%) and 95.4% (95% CI 87.3–98.4%), respectively.

Conclusions: This meta-analysis suggests that the diagnostic accuracy of paramedic prehospital ECG interpretations is favorable, with high pooled sensitivity and specificity, with an acceptable estimated number of false positives and false negatives. Computer-assisted ECG interpretation showed high pooled specificity with an acceptable estimated number of false positives, whereas the pooled sensitivity was relatively low.

Predictors of Hyperkalemia among Patients on Maintenance Hemodialysis Transported to the Emergency Department by Ambulance

BACKGROUND

Hyperkalemia is common among patients on maintenance hemodialysis (HD) and is associated with mortality. We hypothesized that clinical characteristics available at time of paramedic assessment before emergency department (ED) ambulance transport (ambulance-ED) would associate with severe hyperkalemia (K≥6 mmol/L). Rapid identification of patients who are at risk for hyperkalemia and thereby hyperkalemia-associated complications may allow paramedics to intervene in a timely fashion, including directing emergency transport to dialysis-capable facilities.

METHODS

Patients on maintenance HD from a single paramedic provider region, who had at least one ambulance-ED and subsequent ED potassium from 2014 to 2018, were examined using multivariable logistic regression to create risk prediction models inclusive of prehospital vital signs, days from last dialysis, and the presence of prehospital electrocardiogram (ECG) features of hyperkalemia. We used bootstrapping with replacement to validate each model internally, and performance was assessed by discrimination and calibration.

RESULTS

Among 704 ambulance-ED visits, severe hyperkalemia occurred in 75 (11%); 26 patients with ED hyperkalemia did not have a prehospital ECG. Younger age at transport, longer HD vintage, more days from last hemodialysis session (OR=49.84; 95% CI, 7.72 to 321.77 for ≥3 days versus HD the same day [before] ED transport), and prehospital ECG changes (OR=6.64; 95% CI, 2.31 to 19.12) were independently associated with severe ED hyperkalemia. A model incorporating these factors had good discrimination (c-statistic 0.82; 95% CI, 0.76 to 0.89) and, using a cutoff of 25% probability, correctly classified patients 89% of the time.

CONCLUSIONS

Characteristics available at the time of ambulance-ED were associated with severe ED hyperkalemia. An awareness of these associations may allow health care providers to define novel care pathways to ensure timely diagnosis and management of hyperkalemia.

Prehospital identification of ST-segment elevation myocardial infarction and mortality (ANZACS-QI 61)

BACKGROUND

Early recognition of ST-segment elevation myocardial infarction (STEMI) is needed for timely cardiac monitoring and reperfusion therapy.

METHODS

Three anonymously linked New Zealand national datasets (July 2016-November 2018) were used to assess the utilisation of ambulance transport in STEMI cases, the concordance between ambulance initial clinical impressions and hospital STEMI diagnoses, and the association between initial paramedic clinical impressions and 30-day mortality. The St John Ambulance electronic record captures community call-outs and paramedic initial clinical impressions. The national cardiac (ANZACS-QI) registry and national administrative datasets capture all New Zealand public hospital admission diagnoses and mortality data.

RESULTS

Of 5465 patients with STEMI, 73% were transported to hospital by ambulance. For these patients, the initial paramedic impression was STEMI in 50.7%, another acute coronary syndrome (ACS) diagnosis in 19.9% and non-ACS diagnosis in 29.7%. Only 37% of the 5465 patients with STEMI were both transported by ambulance and clinically suspected of STEMI by paramedics. Compared with patients with paramedic-'suspected STEMI', 30-day mortality was over threefold higher for patients thought to have a non-ACS condition (10.9% and 34.9%, respectively), but after adjustment for available covariates, this was substantially ameliorated (HR 1.48, 95% CI 1.22 to 1.80).

CONCLUSIONS

In this national data linkage study, only 4 out of every 10 patients with STEMI were both transported by ambulance and had STEMI suspected by paramedics. Although patients with STEMI not suspected of an ACS diagnosis by paramedics had the highest mortality rate, this is largely explained by the different risk profile of these patients.

Prehospital ECG with ST-depression and T-wave inversion are associated with new onset heart failure in individuals transported by ambulance for suspected acute coronary syndrome

BACKGROUND

Prehospital electrocardiogram(s) (ECG) can improve early detection of acute coronary syndrome (ST-segment elevation myocardial infarction [STEMI], non-STEMI, and unstable angina) and inform prehospital activation of cardiac catheterization lab; thus, reducing total ischemic time and improving patient outcomes. Less is known, however, about the association of prehospital ECG ischemic findings and long term adverse clinical events. With this in mind, this study was designed to examine the: 1) frequency of prehospital ECGs for acute myocardial ischemia (ST-elevation, ST-depression, and/or T-wave inversion); and, 2) whether any of these specific ECG features are associated with adverse clinical events within 30 day of initial presentation to the emergency department (ED).

METHODS

We included consecutive patients ≥ 21 years during a five-year period (2013-2017), who were transported by ambulance to the ED with non-traumatic chest pain and/or anginal equivalent(s) and had a prehospital 12‑lead ECG. Two cardiologists (LG, EC), blinded to clinical data, interpreted the 12‑lead ECGs applying current guideline based ischemia criteria. Adverse clinical events, return to ED, and rehospitalization evaluated at 30-days.

RESULTS

We identified 3646 patients (mean age, 59.7 years ±15.7; 45% female) with ECGs, of which N = 3587 had data on the three ischemic markers of interest. Of these, 1762 (49.1%) had ECG evidence of ischemia. In adjusted logistic regression models, those with T-wave inversion had a higher odds (OR = 1.59) of new onset heart failure, while ST-elevation was associated with lower odds (OR = 0.69). Patients with ST-depression had higher odds of new onset heart failure and death within 30 days (OR = 1.29, 1.49 respectively), but this association attenuated after controlling for other ECG features.

CONCLUSIONS

ST-depression and/or T-wave inversion are independent predictors of new onset heart failure, within 30 days of initial ED presentation. Our study in a large cohort of patients, suggests that using ECG ST-elevation alone may not capture patients with ischemia who may benefit from aggressive anti-ischemic therapies to reduce myocardial damage with resultant heart failure.

What Adult Electrocardiogram (ECG) Diagnoses or Findings are Most Important for Advanced Care Paramedics to Know?

Introduction: The interpretation of electrocardiograms (ECGs) is an essential competency in modern paramedicine. Although educational guidelines for paramedic ECG interpretation exist, they are broad, not evidence-based, and lack prioritization in a prehospital clinical context. We conducted this study to gain consensus among stakeholders (EMS physicians, paramedic educators, and paramedic clinicians) regarding which ECG diagnoses or findings are most important for a practising advanced care paramedic to know. 

Methods: This study was an internet-based Delphi survey. We purposefully sampled participants in pairs (physician/paramedic) from all 10 Canadian provinces. Individuals rated a previously developed comprehensive list of emergency ECG diagnoses or findings on the importance of paramedic recognition and impact on prehospital care using a 4-point Likert scale. The consensus was achieved with a minimum of 75% agreement on Likert rating for a single diagnosis or finding during survey rounds one to three. When consensus was not reached, stability was defined as a shift of individual ratings between rounds of 20% or less.

Results: All 20 participants completed the first and second rounds of the survey, and 17 (85%) completed three rounds. Overall, 32 (26.4%) of 121 potentially important ECG diagnoses or findings reached consensus, 2 (1.7%) reached stability and 87 (71.9%) reached neither consensus nor stability. Twenty-one (17.4%) diagnoses or findings were considered “Very Important”, six (4.9%) “Important”, and five (4.1%) “Minimally Important”. In the first round of the survey, the mean rating of the importance of a paramedic knowing a specific ECG diagnosis or finding was lower in the physician group than the paramedic group on 85 (72%) of 118 initial diagnoses or findings.

Conclusion: We have created a list of ECG diagnoses or findings prioritized for the prehospital context that may assist paramedic educators in focusing on educational interventions. Many ECG diagnoses or findings failed to reach consensus or stability, demonstrating potential disagreement regarding clinical expectations for ECG knowledge among paramedics or physicians.

Accuracy of ECG chest electrode placements by paramedics: an observational study

Background:

The use of the 12-lead electrocardiogram (ECG) is common in sophisticated pre-hospital emergency medical services but its value depends upon accurate placement of the ECG electrodes. Several studies have shown widespread variation in the placement of chest electrodes by other health professionals but no studies have addressed the accuracy of paramedics. The main objective of this study was to ascertain the accuracy of the chest lead placements by registered paramedics.

Methods:

Registered paramedics who attended the Emergency Services Show in Birmingham in September 2018 were invited to participate in this observational study. Participants were asked to place the chest electrodes on a male model in accordance with their current practice. Correct positioning was determined against the Society for Cardiological Science and Technology’s 2017 clinical guidelines for recording a standard 12-lead ECG, with a tolerance of 19 mm being deemed acceptable based upon previous studies.

Results:

Fifty-two eligible participants completed the study. Measurement of electrode placement in the vertical and horizontal planes showed a high level of inaccuracy, with 3/52 (5.8%) participants able to accurately place all chest electrodes. In leads V₁–V₃, the majority of incorrect placements were related to vertical displacement, with most participants able to identify the correct horizontal position. In V₄, the tendency was to place the electrode too low and to the left of the pre-determined position, while V₅ tended to be below the expected positioning but in the correct horizontal alignment. There was a less defined pattern of error in V₆, although vertical displacement was more likely than horizontal displacement.

Conclusions:

Our study identified a high level of variation in the placement of chest ECG electrodes, which could alter the morphology of the ECG. Correct placement of V₁ improved placement of other electrodes. Improved initial and refresher training should focus on identification of landmarks and correct placement of V₁.

Human-Computer Agreement of Electrocardiogram Interpretation for Patients Referred to and Declined for Primary Percutaneous Coronary Intervention: Retrospective Data Analysis Study

Background

When a patient is suspected of having an acute myocardial infarction, they are accepted or declined for primary percutaneous coronary intervention partly based on clinical assessment of their 12-lead electrocardiogram (ECG) and ST-elevation myocardial infarction criteria.

Objective

We retrospectively determined the agreement rate between human (specialists called activator nurses) and computer interpretations of ECGs of patients who were declined for primary percutaneous coronary intervention.

Methods

Various features of patients who were referred for primary percutaneous coronary intervention were analyzed. Both the human and computer ECG interpretations were simplified to either “suggesting” or “not suggesting” acute myocardial infarction to avoid analysis of complex heterogeneous and synonymous diagnostic terms. Analyses, to measure agreement, and logistic regression, to determine if these ECG interpretations (and other variables such as patient age, chest pain) could predict patient mortality, were carried out.

Results

Of a total of 1464 patients referred to and declined for primary percutaneous coronary intervention, 722 (49.3%) computer diagnoses suggested acute myocardial infarction, whereas 634 (43.3%) of the human interpretations suggested acute myocardial infarction (P<.001). The human and computer agreed that there was a possible acute myocardial infarction for 342 out of 1464 (23.3%) patients. However, there was a higher rate of human–computer agreement for patients not having acute myocardial infarctions (450/1464, 30.7%). The overall agreement rate was 54.1% (792/1464). Cohen κ showed poor agreement (κ=0.08, P=.001). Only the age (odds ratio [OR] 1.07, 95% CI 1.05-1.09) and chest pain (OR 0.59, 95% CI 0.39-0.89) independent variables were statistically significant (P=.008) in predicting mortality after 30 days and 1 year. The odds for mortality within 1 year of referral were lower in patients with chest pain compared to those patients without chest pain. A referral being out of hours was a trending variable (OR 1.41, 95% CI 0.95-2.11, P=.09) for predicting the odds of 1-year mortality.

Conclusions

Mortality in patients who were declined for primary percutaneous coronary intervention was higher than the reported mortality for ST-elevation myocardial infarction patients at 1 year. Agreement between computerized and human ECG interpretation is poor, perhaps leading to a high rate of inappropriate referrals. Work is needed to improve computer and human decision making when reading ECGs to ensure that patients are referred to the correct treatment facility for time-critical therapy.

Multimedia Evaluation of EMT-Paramedic Assessment and Management of Pediatric Respiratory Distress

BACKGROUND

The prehospital care of asthma, bronchiolitis and croup is directed by evidence-based Emergency Medical Services (EMS) protocols. Determining the appropriate intervention for these conditions requires Emergency Medical Technicians-Paramedics (EMT-Ps) to correctly differentiate asthma/bronchospasm, bronchiolitis, and croup. The diagnostic accuracy of EMT-Ps for these pediatric respiratory distress conditions is unknown.

OBJECTIVE

We hypothesized increasing provider age, years of provider experience, higher volume of pediatric cases, self-reported comfort with pediatric patients, and having children of one's own would be associated with increased accuracy in diagnosis on a validated multimedia questionnaire.

METHODS

This is a cross-sectional study of paramedics from a single EMS agency who completed a validated, case-based questionnaire between July and September 2018. The multimedia questionnaire consisted of four cases, each of which included patient videos and lung sound recordings. Paramedics were asked to assess the severity of distress and ascribe the correct diagnosis and prehospital intervention for each case. Each paramedic completed the questionnaire independently. We defined high questionnaire performance a priori as correctly identifying the diagnosis for ≥75% of cases and used multivariate regression to assess factors associated with high questionnaire performance. Provider age and EMS experience were reported in years and analyzed as continuous variables. Volume of pediatric cases was dichotomized to <1 and ≥1 case per shift and having children was dichotomized to either having children or not having children.

RESULTS

Of 514 paramedics, 420 (82%) completed the questionnaire. Overall, paramedics correctly assessed the severity of respiratory distress 92% of the time. However, they only ascribed the correct diagnosis 50% and selected the correct intervention(s) 38% of the time. Increasing age, years of experience, higher volume of pediatric cases, self-reported comfort with pediatric patients, and having children of their own were not associated with questionnaire performance.

CONCLUSION

Paramedics accurately assessed severity of distress in multimedia cases of asthma/bronchospasm, bronchiolitis and croup in children, but showed significant room for improvement in correctly identifying the diagnosis and in selecting appropriate intervention(s). Age, years of EMS experience, higher volume of clinical pediatric cases, self-reported comfort with pediatric patients, and having children of their own were not associated with questionnaire performance.

A Statewide Assessment of Prehospital Electrocardiography Approaches of Acquisition and Interpretation for ST-Elevation Myocardial Infarction Based on Emergency Medical Services Characteristics

Background: The American Heart Association recommends acquiring and interpreting prehospital electrocardiograms (ECG) for patients transported by Emergency Medical Services (EMS) to the emergency department with symptoms highly suspicious of acute coronary syndrome. If interpreted correctly, prehospital ECGs have the potential to improve early detection of ST-elevation myocardial infarction (STEMI) and inform prehospital activation of the cardiac catheterization laboratory, thus reducing total ischemic time and improving patient outcomes. Standardized protocols for prehospital ECG interpretation methods are lacking due to variations in EMS system design, training, and procedures. Objectives: We aimed to describe approaches for prehospital ECG interpretation in EMS systems across North Carolina (NC), and examine potential differences among systems. Methods: A 35-item internet survey was sent to all NC EMS systems (n = 99). Questions pertaining to prehospital ECG interpretation methods included: paramedic, computerized algorithm (i.e., software interpretation), combined approaches, and/or transmission for physician interpretation, transmission capability, cardiac catheterization laboratory activation, and EMS system characteristics (e.g. rural versus urban). Data were summarized and compared. Results: A total of 96 EMS systems across NC responded to the survey (97% response rate); of these, 69% were rural. EMS medical directors (53%) or EMS administrative directors (42%) completed the majority of surveys. While 91% of EMS systems had a prehospital ECG interpretation protocol in place, only 61% had a written cardiac catheterization laboratory activation policy. More than half (55%) of systems reported paramedic interpretation of prehospital ECGs, followed by a combined paramedic and software interpretation approach (39%), physician interpretation (4%), or software interpretation only approach (2%). Nearly 80% of EMS systems transmitted prehospital ECGs to receiving hospitals (always or sometimes), regardless of interpretation method. All EMS systems had some paid versus non-paid EMS personnel and the majority (86%) had both basic and advanced life support capabilities. Conclusions: Most NC EMS systems had a paramedic only ECG interpretation or paramedic in combination with a computerized algorithm approach. Very few used a physician read approach following transmission, even in rural service areas.

ECG pre-hospital teletransmission by emergency teams staffed with an emergency physician and paramedics and its impact on transportation and hospital admission

Electrocardiography (ECG) is essential to detect and diagnose life threatening cardiac conditions and to determine further treatment. Correct interpretation of an ECG can be challenging, especially in the out-of-hospital setting and by less experienced emergency team members.The aim of this study was to compare the rate of ECG transmission from an out-of-hospital emergency scene to an in-hospital cardiologist on call in EMS-B and EMS-S providers and its impact on direct transportation to a cardiac catheterization laboratory and hospital admission.The study was designed as an observational study. Data from 3 separate emergency medical service teams were collected. Two teams are staffed by paramedics only (EMT-B), while another specialized team is staffed with an emergency physician (EMT-S). 5864 out-of-hospital emergencies were performed during a 12-month period and were analyzed for this study.In 124 out of 5864 (2.1%) out-of-hospital emergencies, an ECG transmission from the out-of-hospital scene to an in-hospital cardiologist on call was performed. Rate of transmission was similar between both teams (EMT-B n = 70, 2.2% vs EMT-S n = 54, 2.0%, P = .054). After coordinating with the cardiologist on call, 11 patients (15.7%) of the EMT-B (15.7%) and 24 patients (44.4%) of the EMT-S were directly transported from the scene of emergency to a cardiac catheterization laboratory (P < .001). Overall, 80% of patients treated by EMT-S, compared to 52.5% treated by the EMT-B required subsequent hospital admission (P < .05).Transmission of ECG from the out-of-hospital emergency scene to the in-hospital cardiologist is infrequently performed. The rate of STEMI in transmitted ECG's by emergency teams staffed with an emergency physician was higher compared to emergency teams staffed with paramedics only.

Improving Electrocardiography Diagnostic Accuracy in Emergency Medical Services Personnel

Background

Accuracy of electrocardiogram (ECG) interpretation is important for identification of ST-elevation myocardial infarction (STEMI) by Emergency Medical Services (EMS) personnel who recognize STEMI in the field and activate the coronary catheterization laboratory. According to previous research, there is improvement in diagnosis of STEMIs for healthcare providers who read an average of > 20 ECGs per week. This study evaluated the effectiveness of online ECG modules on improving diagnostic accuracy.

Methods

EMS personnel received 25 ECGs per week to interpret via an online program. Diagnostic accuracy was assessed for improvement via completion of an ECG evaluation package before and after the intervention. Job satisfaction data were collected to determine the impact of the educational initiative.

Results

A total of 64 participants completed the study. Overall, there was an improvement in ECG diagnostic accuracy from 50.8% to 61.2% (95% confidence interval [CI], 7.7-13.2; P < 0.0001). Specifically, there was significant improvement in the diagnosis of STEMI (8.5%; 95% CI, 4.9-12.3; P < 0.003) and supraventricular tachycardia (39.0%; 95% CI, 17.2-60.8; P < 0.008), with a trend toward improvement in all other diagnoses. These effects were sustained to 3 months (9.6%; 95% CI, 6.4-12.7; P < 0.0001). Improvement was seen regardless of employment experience and training. There was no significant impact on job satisfaction.

Conclusions

ECG exposure remains an important factor in improving the accuracy of ECG diagnosis in EMS personnel. Online education modules provide an easily accessible way of improving ECG interpretation with the opportunity for positive downstream effects on patient outcomes and resource use.

Prehospital diagnosis of patients with acute myocardial infarction

Primary percutaneous intervention (PPCI) is the preferred treatment in patients with ST elevation myocardial infarction (STEMI) if this can be performed in a timely manner. The

The Comparison of Physician to Computer Interpreted Electrocardiograms on ST-elevation Myocardial Infarction Door-to-balloon Times

OBJECTIVE

The purpose of the project was to study the impact that immediate physician electrocardiogram (ECG) interpretation would have on door-to-balloon times in ST-elevation myocardial infarction (STEMI) as compared with computer-interpreted ECGs.

METHODS

This was a retrospective cohort study of 340 consecutive patients from September 2003 to December 2009 with STEMI who underwent emergent cardiac catheterization and percutaneous coronary intervention. Patients were stratified into 2 groups based on the computer-interpreted ECG interpretation: those with acute myocardial infarction identified by the computer interpretation and those not identified as acute myocardial infarction. Patients (n = 173) from September 2003 to June 2006 had their initial ECG reviewed by the triage nurse, while patients from July 2006 to December 2009 (n = 167) had their ECG reviewed by the emergency department physician within 10 minutes. Times for catheterization laboratory activation and percutaneous coronary intervention were recorded in all patients.

RESULTS

Of the 340 patients with confirmed STEMI, 102 (30%) patients were not identified by computer interpretation. Comparing the prior protocol of computer ECG to physician interpretation, the latter resulted in significant improvements in median catheterization laboratory activation time {19 minutes [interquartile range (IQR): 10-37] vs. 16 minutes [IQR: 8-29]; P < 0.029} and in median door-to-balloon time [113 minutes (IQR: 86-143) vs. 85 minutes (IQR: 62-106); P < 0.001].

CONCLUSION

The computer-interpreted ECG failed to identify a significant number of patients with STEMI. The immediate review of ECGs by an emergency physician led to faster activation of the catheterization laboratory, and door-to-balloon times in patients with STEMI.

Characteristics of ST Elevation Myocardial Infarction Patients Who Do Not Undergo Percutaneous Coronary Intervention After Prehospital Cardiac Catheterization Laboratory Activation

OBJECTIVES

To assess the clinical and electrocardiographic characteristics of patients diagnosed with ST elevation myocardial infarction (STEMI) that are associated with an increased likelihood of not undergoing percutaneous coronary intervention (PCI) after prehospital Cardiac Catheterization Laboratory activation in a regional STEMI system.

METHODS

We performed a retrospective analysis of prehospital Cardiac Catheterization Laboratory activations in Mecklenburg County, North Carolina, between May 2008 and March 2011. Data were extracted from the prehospital patient record, the prehospital electrocardiogram, and the regional STEMI database. The independent variables of interest included objective patient characteristics as well as documented cardiac history and risk factors. Analysis was performed using descriptive statistics and logistic regression.

RESULTS

Two hundred thirty-one prehospital activations were included in the analysis. Five independent variables were found to be associated with an increased likelihood of not undergoing PCI: increasing age, bundle branch block, elevated heart rate, left ventricular hypertrophy, and non-white race. The variables with the most significance were any type of bundle branch block [adjusted odds ratios (AOR), 5.66; 95% confidence interval (CI), 1.91-16.76], left ventricular hypertrophy (AOR, 4.63; 95% CI, 2.03-10.53), and non-white race (AOR, 3.53; 95% CI, 1.76-7.08). Conversely, the only variable associated with a higher likelihood of undergoing PCI was the presence of arm pain (AOR, 2.94; 95% CI, 1.36-6.25).

CONCLUSIONS

Several of the above variables are expected electrocardiogram mimics; however, the decreased rate of PCI in non-white patients highlights an area for investigation and process improvement. This may guide the development of prehospital STEMI protocols, although avoiding false positive and inappropriate activations.

A comparison of direct and two-stage transportation of patients to hospital in Poland

BACKGROUND

The rapid international expansion of telemedicine reflects the growth of technological innovations. This technological advancement is transforming the way in which patients can receive health care.

MATERIALS AND METHODS

The study was conducted in Poland, at the Department of Cardiology of the Regional Hospital of Louis Rydygier in Torun. The researchers analyzed the delay in the treatment of patients with acute coronary syndrome. The study was conducted as a survey and examined 67 consecutively admitted patients treated invasively in a two-stage transport system. Data were analyzed statistically.

RESULTS

Two-stage transportation does not meet the timeframe guidelines for the treatment of patients with acute myocardial infarction. Intervals for the analyzed group of patients were statistically significant (p < 0.0001).

CONCLUSIONS

Direct transportation of the patient to a reference center with interventional cardiology laboratory has a significant impact on reducing in-hospital delay in case of patients with acute coronary syndrome.

PERSPECTIVES

This article presents the results of two-stage transportation of the patient with acute coronary syndrome. This measure could help clinicians who seek to assess time needed for intervention. It also shows how time from the beginning of pain in chest is important and may contribute to patient disability, death or well-being.

Electrocardiogram interpretation skills among ambulance nurses

BACKGROUND

To describe ambulance nurses' practical electrocardiogram (ECG) interpretation skills and to measure the correlation between these skills and factors that may impact on the level of knowledge.

METHODS

This study was conducted using a prospective quantitative survey with questionnaires and a knowledge test. A convenience sample collection was conducted among ambulance nurses in three different districts in western Sweden. The knowledge test consisted of nine different ECGs. The score of the ECG test were correlated against the questions in the questionnaire regarding both general ECG interpretation skill and ability to identify acute myocardial infarction using Mann-Whitney U test, Kruskal-Wallis test and Spearman's rank correlation.

RESULTS

On average, the respondents had 54% correct answers on the test and identified 46% of the ECGs indicating acute myocardial infarction. The median total score was 9 of 16 (interquartile range 7-11) and 1 of 3 (IQR 1-2) in infarction points. No correlation between ECG interpretation skill and factors such as education and professional experience was found, except that coronary care unit experience was associated with better results on the ECG test.

CONCLUSIONS

Ambulance nurses have deficiencies in their ECG interpretation skills. This also applies to conditions where the ambulance crew has great potential to improve the outcome of the patient's health, such as myocardial infarction and cardiac arrest. Neither education, extensive experience in ambulance service nor in nursing contributed to an improved result. The only factor of importance for higher ECG interpretation knowledge was prior experience of working in a coronary care unit.

Diagnostic accuracy of ST-segment elevation myocardial infarction by various healthcare providers

BACKGROUND

This study aimed to compare the accuracy of ECG interpretation for diagnosis of STEMI by different groups of healthcare professionals involved in the STEMI program at our institution.

METHODS

We selected 21 ECGs from patients with typical symptoms of MI that were diagnosed with STEMI, and 10 ECGs of STEMI mimics. STEMI mimic ECGs were repeated in the package with a story of typical and atypical chest pain. ECGs were interpreted to diagnose STEMI and identify need for initiation of the cardiac catheterization lab (CCL). Participants identified confidence in STEMI recognition, and average number of ECGs read per week.

RESULTS

A total of 64 participants completed the study package. Cardiologists were more likely to provide correct interpretation compared to other groups. False positive diagnoses were more likely made by paramedics when compared to cardiologists (p < 0.01). There was a positive correlation between increased exposure to ECGs and accurate STEMI diagnosis (r = 0.482, p < 0.001). A threshold of ≥ 20 ECGs read per week showed a statistically significant improvement in accuracy (p < 0.001). Self-reported confidence correlated positively with accuracy (r = 0.402, p =< 0.001). Changing the ECG narrative of the STEMI mimic ECGs had a significant effect on interpretation between groups (p = 0.043).

CONCLUSIONS

Our study showed that healthcare profession and number of ECGs reviewed per week are predictive of the accuracy of ECG interpretation of STEMI. Cardiologists are the most accurate diagnosticians, and are the least likely to falsely activate the CCL. Weekly exposure of ≥ 20 ECGs may improve diagnostic accuracy regardless of underlying experience.

The availability of prior ECGs improves paramedic accuracy in recognizing ST-segment elevation myocardial infarction

INTRODUCTION

Early and accurate identification of ST-elevation myocardial infarction (STEMI) by prehospital providers has been shown to significantly improve door to balloon times and improve patient outcomes. Previous studies have shown that paramedic accuracy in reading 12 lead ECGs can range from 86% to 94%. However, recent studies have demonstrated that accuracy diminishes for the more uncommon STEMI presentations (e.g. lateral). Unlike hospital physicians, paramedics rarely have the ability to review previous ECGs for comparison. Whether or not a prior ECG can improve paramedic accuracy is not known.

STUDY HYPOTHESIS

The availability of prior ECGs improves paramedic accuracy in ECG interpretation.

METHODS

130 paramedics were given a single clinical scenario. Then they were randomly assigned 12 computerized prehospital ECGs, 6 with and 6 without an accompanying prior ECG. All ECGs were obtained from a local STEMI registry. For each ECG paramedics were asked to determine whether or not there was a STEMI and to rate their confidence in their interpretation. To determine if the old ECGs improved accuracy we used a mixed effects logistic regression model to calculate p-values between the control and intervention.

RESULTS

The addition of a previous ECG improved the accuracy of identifying STEMIs from 75.5% to 80.5% (p=0.015). A previous ECG also increased paramedic confidence in their interpretation (p=0.011).

CONCLUSIONS

The availability of previous ECGs improves paramedic accuracy and enhances their confidence in interpreting STEMIs. Further studies are needed to evaluate this impact in a clinical setting.

Telemedicine in pre-hospital care: a review of telemedicine applications in the pre-hospital environment

The right person in the right place and at the right time is not always possible; telemedicine offers the potential to give audio and visual access to the appropriate clinician for patients. Advances in information and communication technology (ICT) in the area of video-to-video communication have led to growth in telemedicine applications in recent years. For these advances to be properly integrated into healthcare delivery, a regulatory framework, supported by definitive high-quality research, should be developed. Telemedicine is well suited to extending the reach of specialist services particularly in the pre-hospital care of acute emergencies where treatment delays may affect clinical outcome. The exponential growth in research and development in telemedicine has led to improvements in clinical outcomes in emergency medical care. This review is part of the LiveCity project to examine the history and existing applications of telemedicine in the pre-hospital environment. A search of electronic databases including Medline, Excerpta Medica Database (EMBASE), Cochrane, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) for relevant papers was performed. All studies addressing the use of telemedicine in emergency medical or pre-hospital care setting were included. Out of a total of 1,279 articles reviewed, 39 met the inclusion criteria and were critically analysed. A majority of the studies were on stroke management. The studies suggested that overall, telemedicine had a positive impact on emergency medical care. It improved the pre-hospital diagnosis of stroke and myocardial infarction and enhanced the supervision of delivery of tissue thromboplasminogen activator in acute ischaemic stroke. Telemedicine presents an opportunity to enhance patient management. There are as yet few definitive studies that have demonstrated whether it had an effect on clinical outcome.

Difficult ECGs in STEMI: lessons learned from serial sampling of pre- and in-hospital ECGs

Prehospital interpretation of electrocardiograms (ECGs) is crucial to ensure early diagnosis and optimal treatment of patients with ST elevation myocardial infarction (STEMI). Recognition of ST-segment elevations (STE) by qualified personnel in the prehospital phase has successfully reduced the delay from the first medical contact to reperfusion. A few other ECG patterns without true STE, referred to as "STEMI equivalents", bear the same prognostic significance, reflect imminent or ongoing transmural ischemia, but are less easily identified. Hyperacute T waves, de Winter ST-T complex, Wellens' syndrome, and posterior STEMI, as well as myocardial infarction in the presence of left bundle branch block, paced rhythm or left ventricular hypertrophy, among others are diagnostic challenges. This article reviews some critical examples of ischemic ECG patterns that may be ephemeral, misinterpreted by medical staff or not identified by automated ECG algorithms, and it emphasizes the importance of serial ECG acquisition.

Use of emergency medical services expedites in-hospital care processes in patients presenting with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

To determine whether door-to-balloon (DTB) times of patients presenting with ST-elevation myocardial infarction (STEMI) were reduced in patients transported by emergency medical services (EMS) compared to those who were self-transported. DTB time is an important measure of hospital care processes in STEMI. Use of EMS may expedite in-hospital processing and reduce DTB times. A total of 309 consecutive STEMI patients who underwent primary percutaneous coronary intervention in our institution were analyzed. Excluded were patients who received fibrinolytics, presented in cardiac arrest, were intubated, or were transferred from another hospital. EMS-transported patients (n=83) were compared to self-transported patients (n=226). The primary outcome measure was DTB time and its component time intervals. Secondary end points included symptom-to-door and symptom-to-balloon times, and correlates for DTB >90 minutes. A higher percentage of EMS-transported patients reached the time goal of DTB <90 minutes compared to self-transported patients (83.1 versus 54.3%; p<0.001). EMS-transported patients had shorter DTB times [median (IQR) minutes, 65 (50-86) versus 85 (61-126); p<0.001] due to a reduction of emergency department processing (door-to-call) time, whereas catheterization laboratory processing (call-to-balloon) times were similar in both groups. EMS-transported patients had shorter symptom-to-door [median (IQR) hours, 1.2 (0.8-3.5) versus 2.3 (1.2-7.5); p<0.001] and symptom-to-balloon [median (IQR) hours, 2.5 (1.9-4.7) versus 4.3 (2.6-9.1); p<0.001]. Independent correlates of DTB times >90 minutes were self-transport (odds ratio 5.32, 95% CI 2.65-10.70; p<0.001) and off-hours presentation (odds ratio 2.89, 95% CI 1.60-5.22; p<0.001). Use of EMS transport in STEMI patients significantly shortens time to reperfusion, primarily by expediting emergency department processes. Community education efforts should focus not only on the importance of recognizing symptoms of myocardial infarction, but also taking early action by calling the EMS.

Fatal myocardial ischemia in a 12-year old secondary to fibromuscular dysplasia

Cardiac causes of chest pain in children are rare; however, they continue to account for 1% to 6% of all cases dependent on the practice setting and patient history. Here we describe the case of a 12-year old with fibromuscular dysplasia that died from an acute myocardial infarction. Although this specific etiology is uncommon, the case illustrates the need for broad differentials when treating children with chest pain in the emergency medicine environment. In particular, even if the specific diagnosis cannot be readily made in the prehospital or emergency department (ED) setting, the possibility of cardiac disease should be considered.