Emergency Medical Services Utilization among Patients with ST-Segment Elevation Myocardial Infarction: Observations from the Singapore Myocardial Infarction Registry

Objective: Early activation of emergency medical services (EMS), rapid transport, and treatment of patients experiencing ST-segment elevation myocardial infarction (STEMI) can improve outcomes. The Singapore Myocardial Infarction Registry (SMIR) is a nation-wide registry that collects data on STEMI. We aimed to determine the prevalence, predictors, and outcomes of EMS utilization among STEMI patients presenting to Emergency Departments (ED) in Singapore. Methods: We analyzed STEMI patients enrolled by SMIR from January 2010 to December 2012. We excluded patients who were transferred, developed STEMI in-hospital or suffered cardiac arrest out-of-hospital or in the ED. Primary outcome was process-of-care timings. Secondary outcomes included the occurrence of cardiac complications. Multivariate analysis was used to examine independent factors associated with EMS transport. Results: 6412 patients were enrolled into the study; 4667 patients were eligible for analysis. 49.8% of patients utilized EMS transport. EMS transport was associated with higher rate of reperfusion therapy (74.3% vs. 65.1%, p < 0.01), shorter median symptom-to-door time (119 vs. 182 minutes, p < 0.01), door-to-balloon time (59 vs. 70 minutes, p < 0.01), and symptom-to-balloon time (185 vs. 233 minutes, p < 0.01). EMS transport had more patients with Killip Class 4 (7.5% vs 4.0%, p < 0.01) and was associated with greater presentation of heart failure, arrhythmias, and complete heart block. Independent predictors of EMS transport were age, syncope and Killip score; after-office-hour presentation was a negative predictor. Conclusion: Less than half of STEMI patients utilized EMS and EMS patients had faster receipt of initial reperfusion therapies. Targeted public education to reduce time to treatment may improve the care of STEMI patients.     

Model Curriculum in Emergency Medical Services for Emergency Medicine Residency Programs

An emergency medical services (EMS) curriculum, as developed by the SAEM Emergency Medical Services Committee, is provided for the training of emergency medicine residents in EMS.     

Medical Direction for Operational Emergency Medical Services Programs

Abstract

This is the official position statement of the National Association of EMS Physicians and the National Association of State EMS Officials on medical direction for operational emergency medical services (EMS) programs.     

Prehospital 12-lead Electrocardiography Impact on Acute Myocardial Infarction Treatment Times and Mortality: A Systematic Review

Objectives: Prehospital 12‐lead electrocardiogram (PHECG) interpretation and advance emergency department (ED) notification may improve time‐to‐treatment intervals for a variety of treatment strategies to improve outcome in acute myocardial infarction. Despite consensus guidelines recommending this intervention, few emergency medical services (EMS) employ this. The authors systematically reviewed the literature to report whether mortality or treatment time intervals improved when compared with standard care. Methods: The authors used the Cochrane strategy to search MEDLINE, EMBASE, Current Contents, Dissertation Abstracts, Cochrane Library, and Index of Scientific and Technical Proceedings. Bibliographies and grant‐agency Websites were reviewed, and primary investigators and industry were contacted for published and unpublished studies. Inclusion criteria included PHECG and advance ED notification versus standard EMS care; controlled trials; English only; and evaluation of treatment time intervals, all‐cause mortality, or both. Study selection was hierarchical, blinded, and independent. Agreement at each level of review was evaluated by using a kappa statistic. Study quality was measured with a validated scale and was interpreted by two independent reviewers. Results: A total of 1,283 citations were identified, and five studies met the inclusion criteria. The weighted kappa for selection was 0.61 (standard error [SE], 0.045) for titles, 0.63 (SE, 0.051) for abstracts, and 0.79 (SE, 0.146) for full articles. Mean study quality measures by two independent reviewers were 6.0/15 and 5.5/15 (correlation coefficient, 0.85; p = 0.06). PHECG and advance ED notification increased the weighted mean on‐scene time by 1.2 minutes (95% confidence interval [95% CI] =?0.84 to 3.2). The weighted mean door‐to‐needle interval was shortened by 36.1 minutes (95% CI = 9.3 to 63.0: range of means, 22–48 minutes vs. 50–97 minutes). One study reported all‐cause mortality, with a statistically nonsignificant reduction from 15.6% to 8.4%. Conclusions: For patients with AMI, the literature would suggest that PHECG and advanced ED notification reduces in hospital time to fibrinolysis. One controlled trial found no difference in mortality with this out‐of‐hospital intervention.     

Causes of Prehospital Misinterpretations of ST Elevation Myocardial Infarction

Objectives: To determine the causes of software misinterpretation of ST elevation myocardial infarction (STEMI) compared to clinically identified STEMI to identify opportunities to improve prehospital STEMI identification. Methods: We compared ECGs acquired from July 2011 through June 2012 using the LIFEPAK 15 on adult patients transported by the Los Angeles Fire Department. Cases included patients ≥18 years who received a prehospital ECG. Software interpretation of the ECG (STEMI or not) was compared with data in the regional EMS registry to classify the interpretation as true positive (TP), true negative (TN), false positive (FP), or false negative (FN). For cases where classification was not possible using registry data, 3 blinded cardiologists interpreted the ECG. Each discordance was subsequently reviewed to determine the likely cause of misclassification. The cardiologists independently reviewed a sample of these discordant ECGs and the causes of misclassification were updated in an iterative fashion. Results: Of 44,611 cases, 50% were male (median age 65; inter-quartile range 52–80). Cases were classified as 482 (1.1%) TP, 711 (1.6%) FP, 43371 (97.2%) TN, and 47 (0.11%) FN. Of the 711 classified as FP, 126 (18%) were considered appropriate for, though did not undergo, emergent coronary angiography, because the ECG showed definite (52 cases) or borderline (65 cases) ischemic ST elevation, a STEMI equivalent (5 cases) or ST-elevation due to vasospasm (4 cases). The sensitivity was 92.8% [95% CI 90.6, 94.7%] and the specificity 98.7% [95% CI 98.6, 98.8%]. The leading causes of FP were ECG artifact (20%), early repolarization (16%), probable pericarditis/myocarditis (13%), indeterminate (12%), left ventricular hypertrophy (8%), and right bundle branch block (5%). There were 18 additional reasons for FP interpretation (<4% each). The leading causes of FN were borderline ST-segment elevations less than the algorithm threshold (40%) and tall T waves reducing the ST/T ratio below threshold (15%). There were 11 additional reasons for FN interpretation occurring ≤3 times each. Conclusion: The leading causes of FP automated interpretation of STEMI were ECG artifact and non-ischemic causes of ST-segment elevation. FN were rare and were related to ST-segment elevation or ST/T ratio that did not meet the software algorithm threshold.     

Door-to-Balloon Times from Freestanding Emergency Departments Meet ST-Segment Elevation Myocardial Infarction Reperfusion Guidelines

Background

Freestanding emergency departments (FEDs) introduce a challenge to physicians who care for the patient with an ST-segment elevation myocardial infarction (STEMI) because treatment is highly time dependent. FEDs have no percutaneous coronary intervention (PCI) capabilities, which necessitates transfer to a PCI-capable facility or fibrinolysis.

Study Objective

Our aim was to determine the proportion of STEMI patients who arrived to an FED and were subsequently transferred for PCI and met the door-to-balloon reperfusion guidelines of 90 min.

Methods

This was a dual-center retrospective cohort review of all patients 18 years and older who were diagnosed with an STEMI and presented to the main hospital−affiliated FEDs. Electronic medical records and emergency medical services documentation were reviewed for all cases since the opening of the FEDs in July 2007 and August 2009, respectively. Key time points were abstracted and statistical evaluation was performed using Fisher's exact test.

Results

A total of 47 patients met inclusion criteria. Median door-to-transport time was 34 min (interquartile range [IQR] 15 min). Median transport time from the FEDs to the main hospital catheterization laboratory was 21 min (IQR 5 min). Median arrival at the catheterization laboratory-to-balloon time was 25 min (IQR 13 min). Median total door-to-balloon time was 83 min (IQR 10.5 min), with 78.7% meeting the American Heart Association's recommended guidelines of ≤ 90 min.

Conclusion

STEMI patients initially seen at two FEDs achieved door-to-balloon time goals of < 90 min.     

Feasibility of Remote Ischemic Peri-conditioning during Air Medical Transport of STEMI Patients

Remote ischemic peri-conditioning (RIPC) has gained interest as a means of reducing ischemic injury in patients with acute ST-elevation myocardial infarction (STEMI) who are undergoing emergent primary percutaneous coronary intervention (pPCI). We aimed to evaluate the feasibility, process, and patient-related factors related to the delivery of RIPC during air medical transport of STEMI patients to tertiary pPCI centers. We performed a retrospective review of procedural outcomes of a cohort of STEMI patients who received RIPC as part of a clinical protocol in a multi-state air medical service over 16 months (March 2013 to June 2014). Eligible patients were transported to two tertiary PCI centers and received up to four cycles of RIPC by inflating a blood pressure cuff on an upper arm to 200 mmHg for 5 minutes and subsequently deflating the cuff for 5 minutes. Data regarding feasibility, process variables, patient comfort, and occurrence of hypotension were obtained from prehospital records and prospectively completed quality improvement surveys. The primary outcome was whether at least 3 cycles of RIPC were completed by air medical transport crews prior to pPCI. Secondary outcomes included the number of cycles completed prior to pPCI, time spent with the patient prior to transport (bedside time), patient discomfort level, and incidence of hypotension (systolic blood pressure <90 mmHg) during the procedure. RIPC was initiated in 99 patients (91 interfacility, 8 scene transports) and 83 (83.3%) received 3 or 4 cycles of RIPC, delivered over 25–35 minutes. Median bedside time for interfacility transfers was 8 minutes (IQR 7, 10). More than half of patients reported no pain related to the procedure (N = 53, 53.3%), whereas 5 (5.1%) patients reported discomfort greater than 5 out of 10. Two patients developed hypotension while receiving RIPC and both had experienced hypotension prior to initiation of RIPC. RIPC is feasible and safe to implement for STEMI patients undergoing air medical transport for pPCI, without occurrence of prolonged bedside times. The incidence of excessive RIPC-related discomfort or hemodynamic instability is rare. STEMI patients requiring on average >30 minutes transport for pPCI may be the ideal group for RIPC utilization.     

Case Report: Transient Stress Hyperglycemia in the Patient With ST-Elevation Myocardial Infarction

Transient stress hyperglycemia in the setting of acute myocardial infarction is a frequent phenomenon. Its transient nature should not dissuade the clinician from management of elevated blood glucose in a patient after an ST-elevation myocardial infarction. This case presents an adult patient after an ST-elevation myocardial infarction with transient stress hyperglycemia and the evidence used to identify optimal pharmacologic management and secondary prevention.     

The Outcomes of Emergency Pharmacist Participation during Acute Myocardial Infarction

Background

Current guidelines recommend door-to-balloon times of 90 min or less for patients presenting to the emergency department (ED) with ST-segment elevation myocardial infarction (STEMI).

Objectives

To determine if a clinical pharmacist for the ED (EPh) is associated with decreased door/diagnosis-to-cardiac catheterization laboratory (CCL) time and decreased door-to-balloon time.

Methods

A retrospective observational cohort study of ED patients with STEMI requiring urgent cardiac catheterization was conducted. Blinded data collection included timing of ED and CCL arrival, diagnostic electrocardiogram (ECG), and balloon angioplasty. For cases diagnosed after ED arrival, diagnosis time was substituted for door time. Diagnosis was the time ST elevations were evident on serial ECG. EPh present and not-present groups were compared. During the study period there were two EPhs and presence was determined by their scheduled time in the ED. Univariate and multivariate analyses was used to detect differences.

Results

Multivariate analysis of 120 patients, controlled for CCL staff presence and arrival by pre-hospital services, determined that EPh presence is associated with a mean 13.1-min (95% confidence interval [CI] 6.5–21.9) and 11.5-min (95% CI 3.9–21.5) decrease in door/diagnosis-to-CCL and door-to-balloon times, respectively. Patients were more likely to achieve a door/diagnosis-to-CCL time ≤ 30 min (odds ratio [OR] 3.1, 95% CI 1.3–7.8) and ≤ 45 min (OR 2.9, 95% CI–1.0, 8.5) and a door-to-balloon time ≤ 90 min (OR 1.9, 95% CI 0.7–5.5) more likely when the EPh was present.

Conclusions

EPh presence during STEMI presentation to the ED is independently associated with a decrease in door/diagnosis-to-CCL and door-to-balloon times.     

ST-Elevation Myocardial Infarction in the Presence of Biventricular Paced Rhythm

Background

In the diagnosis of acute myocardial infarction (AMI), the presence of baseline left bundle branch block or a permanent pacemaker rhythm poses a challenge.

Objective

We present a case report highlighting this challenge, along with a review of pertinent literature.

Case Report

A 70-year-old female with known severe idiopathic dilated cardiomyopathy and moderate coronary artery disease who was status post−biventricular pacemaker/implantable cardioverter defibrillator insertion was brought to our institution via Emergency Medical Services with recurrent firing of her implantable cardioverter defibrillator and syncope. After stabilization in the Emergency Department and treatment with intravenous amiodarone, the patient admitted to having ongoing chest pains. The electrocardiogram revealed evidence of biventricular pacing with superimposed ST-segment elevations in the anterolateral leads indicative of myocardial injury. She underwent prompt angiography, thrombectomy, and bare-metal stent insertion to a totally occluded proximal left anterior descending coronary artery, with resolution of her chest pain and improvement in the ST-segment changes.

Conclusions

Despite proposed criteria that aid in the recognition of AMI with underlying left bundle branch block and paced rhythm; the advent of new pacing modalities and the potential variability of pacing sites impose additional diagnostic challenges requiring higher level of suspicion and better physician awareness.     

Prehospital Nitroglycerin Safety in Inferior ST Elevation Myocardial Infarction

Patients with inferior ST elevation myocardial infarction (STEMI), associated with right ventricular infarction, are thought to be at higher risk of developing hypotension when administered nitroglycerin (NTG). However, current basic life support (BLS) protocols do not differentiate location of STEMI prior to NTG administration. We sought to determine if NTG administration is more likely to be associated with hypotension (systolic blood pressure < 90 mmHg) in inferior STEMI compared to non-inferior STEMI. We conducted a retrospective chart review of prehospital patients with chest pain of suspected cardiac origin and computer-interpreted prehospital ECGs indicating “ACUTE MI.” We included all local STEMI cases identified as part of our STEMI registry. Univariate analysis was used to compare differences in proportions of hypotension and drop in systolic blood pressure ≥ 30 mmHg after nitroglycerin administration between patients with inferior wall STEMI and those with STEMI in another region (non-inferior). Multiple variable logistic regression analysis was also used to assess the study outcomes while controlling for various factors. Over a 29-month period, we identified 1,466 STEMI cases. Of those, 821 (56.0%) received NTG. We excluded 16 cases because of missing data. Hypotension occurred post NTG in 38/466 inferior STEMIs and 30/339 non-inferior STEMIs, 8.2% vs. 8.9%, p = 0.73. A drop in systolic blood pressure ≥ 30 mmHg post NTG occurred in 23.4% of inferior STEMIs and 23.9% of non-inferior STEMIs, p = 0.87. Interrater agreement for chart review of the primary outcome was excellent (κ = 0.94). NTG administration to patients with chest pain and inferior STEMI on their computer-interpreted electrocardiogram is not associated with a higher rate of hypotension compared to patients with STEMI in other territories. Computer interpretation of inferior STEMI cannot be used as the sole predictor for patients who may be at higher risk for hypotension following NTG administration.     

急诊静脉溶栓救治急性心肌梗塞

目的:探讨在急诊室开展静脉溶栓治疗急性心肌梗塞(AMI)的疗效及安全性。方法:对76例AMI患者随机地分为尿激酶组(UK组)与对照组各38例。UK组在常规治疗的基础上选用国产UK150万U溶于0.9％的生理盐水100ml中30min静脉滴入。对照组为常规治疗。又将UK组根据开始溶栓距发病时间分为<3h、3～6h、<6h及6～12h的4个亚组。结果:冠脉再通率:总再通率UK组极显著优于对照组(57.9％与18.4％,P<0.005),UK组的亚组中,<3h者显著优于3～6h者(77.3％与37.5％,P<0.05),<6h显著优于6～12h者(66.7％与25％,P<0.05)。治疗3周时,原梗塞区R波存在例数:UK组极显著优于对照组,(42％与13％,P<0.01);异常O波导联未增加例数:UK组显著优于对照组,(47％与20％,P<0.05);心功能改善:UK组极显著优于对照组(5.3％与28.9％,P<0.01);病死率:UK组低于对照组(10.5％与15.8％,P>0.05),并低于本院开展溶栓治疗前的14％(P>0.05)。UK的副作用仅为轻度出血,无1例死于出血及严重再灌注性心律失常,溶栓及抗凝后再转入病房途中无1例危险事件发生。结论:在急诊室内开展紧急静脉溶栓治疗急性心肌梗塞有效,安全。     

Emergency Medical Services Education,Community Outreach,andProtocols for Stroke andChest Pain in North Carolina

Objective. Prehospital care of stroke andchest pain patients is dependent on adequate emergency medical services (EMS) education andevidence-based protocols. We sought to describe the amount of education offered, community outreach implemented, andprotocols established for stroke andfor chest pain among North Carolina EMS agencies andpersonnel. Methods. A survey was developed to measure EMS system characteristics regarding the prehospital care of stroke andchest pain patients. Each of the 83 primary EMS agencies in North Carolina was asked to participate. Results. Of the 83 agencies surveyed, 72 (87%) responded. Both advanced life support (ALS) andbasic life support (BLS) services were provided by 54% of agencies; 44% offered ALS only and1% offered BLS only. While 89% of the EMS agencies provided stroke education to EMS personnel and96% chest pain education to EMS personnel in the previous two years, the median hours devoted to stroke was one-half that for chest pain (6.0 vs. 12.0 hours, respectively). In the previous six months, 14% of EMS agencies had conducted community outreach programs for stroke compared with 17% for chest pain. The majority of EMS agencies had protocols specifically for managing stroke (83%) andfor managing chest pain (99%). Diagnostic scales to identify stroke patients were used by 54% of agencies (20% Los Angeles Prehospital Stroke Screen, 20% Cincinnati Prehospital Stroke Scale, and14% a locally developed scale). Thrombolytic checklists were used to identify eligible stroke patients at 37% of the EMS agencies, compared with 28% for eligible chest pain patients. Conclusions. In North Carolina, primary EMS agencies appear to have stroke andchest pain protocols in approximately the same frequency, yet their personnel receive only one-half as much education about stroke as they do about chest pain. Many stroke protocols were lacking basic components andwould benefit from standardization across the state. Community outreach programs for both stroke andchest pain are minimal.