A Novel Algorithm for Improving the Prehospital Diagnostic Accuracy of ST-Segment Elevation Myocardial Infarction.

INTRODUCTION: Early detection of ST-segment elevation myocardial infarction (STEMI) on the prehospital electrocardiogram (ECG) improves patient outcomes. Current software algorithms optimize sensitivity but have a high false-positive rate. The authors propose an algorithm to improve the specificity of STEMI diagnosis in the prehospital setting. METHODS: A dataset of prehospital ECGs with verified outcomes was used to validate an algorithm to identify true and false-positive software interpretations of STEMI. Four criteria implicated in prior research to differentiate STEMI true positives were applied: heart rate <130, QRS <100, verification of ST-segment elevation, and absence of artifact. The test characteristics were calculated and regression analysis was used to examine the association between the number of criteria included and test characteristics. RESULTS: There were 44,611 cases available. Of these, 1,193 were identified as STEMI by the software interpretation. Applying all four criteria had the highest positive likelihood ratio of 353 (95% CI, 201-595) and specificity of 99.96% (95% CI, 99.93-99.98), but the lowest sensitivity (14%; 95% CI, 11-17) and worst negative likelihood ratio (0.86; 95% CI, 0.84-0.89). There was a strong correlation between increased positive likelihood ratio (r2 = 0.90) and specificity (r2 = 0.85) with increasing number of criteria. CONCLUSIONS: Prehospital ECGs with a high probability of true STEMI can be accurately identified using these four criteria: heart rate <130, QRS <100, verification of ST-segment elevation, and absence of artifact. Applying these criteria to prehospital ECGs with software interpretations of STEMI could decrease false-positive field activations, while also reducing the need to rely on transmission for physician over-read. This can have significant clinical and quality implications for Emergency Medical Services (EMS) systems.

Association of the COVID-19 Pandemic on Treatment Times for ST-Elevation Myocardial Infarction: Observations from the Los Angeles County Regional System.

Previous studies have documented longer treatment times and worse outcomes for patients with ST-elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI) during the COVID-19 pandemic. The objective of the present study was to evaluate the impact of the COVID-19 pandemic on treatment times and outcomes for patients with STEMI who underwent primary PCI within a regional system of care. This was a retrospective study using data from the Los Angeles County Emergency Medical Services Agency. Data on the emergency medical service activations were abstracted for patients with STEMI from March 19, 2020 to January 31, 2021, during the COVID-19 pandemic and for the same interval the previous year. All adult patients (≥18 years) with STEMI who underwent emergent coronary angiography were included. The primary end point was the first medical contact (FMC) to device time. The secondary end points included treatment time intervals, vascular complications, need for emergent coronary artery bypass surgery, length of hospital stay, and in-hospital mortality. During the study period, 3,017 patients underwent coronary angiography for STEMI, 1,893 patients pre-COVID-19 and 1,124 patients during COVID-19 (40% lower). A total of 2,334 patients (77%) underwent PCI. During the COVID-19 period, rates of PCI were significantly lower compared with the control period (75.1% vs 78.7%, p = 0.02). FMC to device time was shorter during the COVID-19 period compared with the control period (median 77.0 vs 81.0 minutes, p = 0.004). For patients with STEMI complicated by out-of-hospital cardiac arrest, FMC to device time was similar during the COVID-19 period compared with the control period (median 95.0 [33.0] vs 100.0 [40.0] minutes, p = 0.34). Vascular complications, the need for emergent bypass surgery, length of hospital stay, and in-hospital mortality were similar between the periods. In conclusion, in this large regional system of care, we found a relatively small but significant decrease in treatment times, yet overall, similar clinical outcomes for patients with STEMI who underwent primary PCI and were treated during the COVID-19 period compared with a control period. These findings suggest that mature cardiac systems of care were able to maintain efficient care despite the challenges of the COVID-19 pandemic.

The Correlation between COVID-19 Hospitalizations and Emergency Medical Services Responses for Time-Sensitive Emergencies during the COVID-19 Pandemic.

OBJECTIVE: COVID-19 has had significant secondary effects on health care systems, including effects on emergency medical services (EMS) responses for time-sensitive emergencies. We evaluated the correlation between COVID-19 hospitalizations and EMS responses for time-sensitive emergencies in a large EMS system. METHODS: This was a retrospective study using data from the Los Angeles County EMS Agency. We abstracted data on EMS encounters for stroke, ST-elevation myocardial infarction (STEMI), out-of-hospital cardiac arrest (OHCA), and trauma from April 5, 2020 to March 6, 2021 and for the same time period in the preceding year. We also abstracted daily hospital admissions and censuses (total and intensive care unit [ICU]) for COVID-19 patients. We designated November 29, 2020 to February 27, 2021 as the period of surge. We calculated Spearman's correlations between the weekly averages of daily hospital admissions and census and EMS responses overall and for stroke, STEMI, OHCA, and trauma. RESULTS: During the study period, there were 70,616 patients admitted for confirmed COVID-19, including 12,467 (17.7%) patients admitted to the ICU. EMS responded to 899,794 calls, including 9,944 (1.1%) responses for stroke, 3,325 (0.4%) for STEMI, 11,207 (1.2%) for OHCA, and 114,846 (12.8%) for trauma. There was a significant correlation between total hospital COVID-19 positive patient admissions and EMS responses for all time-sensitive emergencies, including a positive correlation with stroke (0.41), STEMI (0.37), OHCA (0.78), and overall EMS responses (0.37); and a negative correlation with EMS responses for trauma (-0.48). ICU COVID-19 positive patient admissions also correlated with increases in EMS responses for stroke (0.39), STEMI (0.39), and OHCA (0.81); and decreased for trauma (-0.53). Similar though slightly weaker correlations were found when evaluating inpatient census. During the period of surge, the correlation with overall EMS responses increased substantially (0.88) and was very strong with OHCA (0.95). CONCLUSION: We found significant correlation between COVID-19 hospitalizations and the frequency of EMS responses for time-sensitive emergencies in this regional EMS system. EMS systems should consider the potential effects of this and future pandemics on EMS responses and prepare to meet non-pandemic resource needs during periods of surge, particularly for time-sensitive conditions.

Establishing a multicenter, preclinical consortium in resuscitation: A pilot experimental trial evaluating epinephrine in cardiac arrest.

BACKGROUND: Large animal studies are an important step in the translation pathway, but single laboratory experiments do not replicate the variability in patient populations. Our objective was to demonstrate the feasibility of performing a multicenter, preclinical, randomized, double-blinded, placebo-controlled cardiac arrest trial. We evaluated the effect of epinephrine on coronary perfusion pressure (CPP) as previous single laboratory studies have reported mixed results. METHODS: Forty-five swine from 5 different laboratories (Ann Arbor, MI; Baltimore, MD; Los Angeles, CA; Pittsburgh, PA; Toronto, ON) using a standard treatment protocol. Ventricular fibrillation was induced and left untreated for 6 min before starting continuous cardiopulmonary resuscitation (CPR). After 2 min of CPR, 9 animals from each lab were randomized to 1 of 3 interventions given over 12 minutes: (1) Continuous IV epinephrine infusion (0.00375 mg/kg/min) with placebo IV normal saline (NS) boluses every 4 min, (2) Continuous placebo IV NS infusion with IV epinephrine boluses (0.015 mg/kg) every 4 min or (3) Placebo IV NS for both infusion and boluses. The primary outcome was mean CPP during the 12 mins of drug therapy. RESULTS: There were no significant differences in mean CPP between the three groups: 14.4 ± 6.8 mmHg (epinephrine Infusion), 16.9 ± 5.9 mmHg (epinephrine bolus), and 14.4 ± 5.5 mmHg (placebo) (p = NS). Sensitivity analysis demonstrated inter-laboratory variability in the magnitude of the treatment effect (p = 0.004). CONCLUSION: This study demonstrated the feasibility of performing a multicenter, preclinical, randomized, double-blinded cardiac arrest trials. Standard dose epinephrine by bolus or continuous infusion did not increase coronary perfusion pressure during CPR when compared to placebo.

Elevated prehospital point-of-care glucose is associated with worse neurologic outcome after out-of-hospital cardiac arrest.

OBJECTIVES: Hyperglycemia is associated with poor outcomes in critically-ill patients. This has implications for prognostication of patients with out-of-hospital cardiac arrest (OHCA) and for post-resuscitation care. We assessed the association of hyperglycemia, on field point-of-care (POC) testing, with survival and neurologic outcome in patients with return of spontaneous circulation (ROSC) after OHCA. METHODS: This was a retrospective analysis of data in a regional cardiac care system from April 2011 through December 2017 of adult patients with OHCA and ROSC who had a field POC glucose. Patients were excluded if they were hypoglycemic (glucose <60 mg/dl) or received empiric dextrose. We compared hyperglycemic (glucose >250 mg/dL) with euglycemic (glucose 60-250 mg/dL) patients. Primary outcome was survival to hospital discharge (SHD). Secondary outcome was survival with good neurologic outcome (cerebral performance category 1 or 2 at discharge). We determined the adjusted odds ratios (AORs) for SHD and survival with good neurologic outcome. RESULTS: Of 9008 patients with OHCA and ROSC, 6995 patients were included; 1941 (28%) were hyperglycemic and 5054 (72%) were euglycemic. Hyperglycemic patients were more likely to be female, of non-White race, and have an initial non-shockable rhythm compared to euglycemic patients (p < 0.0001 for all). Hyperglycemic patients were less likely to have SHD compared to euglycemic survivors, 24.4% vs 32.9%, risk difference (RD) -8.5% (95 %CI -10.8%, -6.2%), p < 0.0001. Hyperglycemic survivors were also less likely to have good neurologic outcome compared to euglycemic survivors, 57.0% vs 64.6%, RD -7.6% (95 %CI -12.9%, -2.4%), p = 0.004. The AOR for SHD was 0.72 (95 %CI 0.62, 0.85), p < 0.0001 and for good neurologic outcome, 0.70 (95 %CI 0.57, 0.86), p = 0.0005. CONCLUSION: In patients with OHCA, hyperglycemia on field POC glucose was associated with lower survival and worse neurologic outcome.

Variation in Post-Cardiac Arrest Care Within a Regional EMS System.

Objective: Within Emergency Medical Systems (EMS) regional systems, there may be significant differences in the approach to patient care despite efforts to promote standardization. Identifying hospital-level factors that contribute to variations in care can provide opportunities to improve patient outcomes. The purpose of this analysis was to evaluate variation in post-cardiac arrest care within a large EMS system and explore the contribution of hospital-level factors. Methods: This was a retrospective analysis from a regional cardiac system serving over 10 million persons. Patients with out-of-hospital cardiac arrest (OHCA) with return of spontaneous circulation (ROSC) are transported to 36 cardiac arrest centers with 24/7 emergent coronary angiography (CAG) capabilities and targeted temperature management (TTM) policies based on regional guidelines. We included adult patients ≥18 years with non-traumatic OHCA from 2016-2018. Patients with a Do-Not-Resuscitate order and those who died in the emergency department (ED) were excluded. For the TTM analysis, we also excluded patients who were alert in the ED. The primary outcome was receiving CAG or TTM after cardiac arrest. The secondary outcome was neurologic recovery (dichotomized to define a "good" outcome as cerebral performance category (CPC) 1 or 2). We used generalized estimating equations including patient-level factors (age, sex, witnessed arrest, initial rhythm) and hospital-level factors (academic status, hospital size based on licensed beds, annual OHCA patient volume) to estimate the odds ratios associated with these variables. Results: There were 7831 patients with OHCA during the study period; 4694 were analyzed for CAG and 3903 for TTM. The median and range for treatment with CAG and TTM after OHCA was 23% (12-49%) and 58% (17-92%) respectively. Hospital size was associated with increased likelihood of CAG, adjusted odds ratio 1.71, 95% CI 1.05-2.86, p = 0.03. Academic status approached significance in its association with TTM, adjusted odds ratio 1.69, 95% CI 0.98-2.91, p = 0.06. Overall, 28% of patients survived with good neurologic outcome, ranging from 17 to 43% across hospitals. Conclusion: Within this regional cardiac system, there was significant variation in use of CAG and TTM after OHCA, which was not fully explained by patient-level factors. Hospital size was associated with increased CAG.

Prehospital Predictors of Atypical STEMI Symptoms.

Introduction: Rapid prehospital identification of patients with ST-elevation myocardial infarction (STEMI) is a critical step to reduce time to treatment. Broad screening with field 12-lead ECGs can lead to a high rate of false positive STEMI activations due to low prevalence. One strategy to reduce false positive STEMI interpretations is to limit acquisition of 12-lead ECGs to patients who have symptoms strongly suggestive of STEMI, but this may delay care in patients who present atypically and lead to disparities in populations with more atypical presentations. We sought to assess patient factors associated with atypical STEMI presentation.Methods: We retrospectively analyzed consecutive adult patients for whom Los Angeles Fire Department paramedics obtained a field 12-lead ECG from July 2011 through June 2012. The regional STEMI receiving center registry was used to identify patients with STEMI. Patients were designated as having typical symptoms if paramedics documented provider impressions of chest pain/discomfort, cardiac arrest, or cardiac symptoms, otherwise they were designated as having atypical symptoms. We utilized logistic regression to determine patient factors (age, sex, race) associated with atypical STEMI presentation.Results: Of the 586 patients who had STEMI, 70% were male, 43% White, 16% Black, 20% Hispanic, 5% Asian and 16% were other or unspecified race. Twenty percent of STEMI patients (n = 117) had atypical symptoms. Women who had STEMI were older than men (74 years [IQR 62-83] vs. 60 years [IQR 53-70], p < 0.001). Univariate predictors of atypical symptoms were older age and female sex (p < 0.0001), while in multivariable analysis older age [odd ratio (OR) 1.05 per year, [95%CI 1.04-1.07, p < 0.0001] and black race (OR vs White 2.18, [95%CI 1.20-3.97], p = 0.011) were associated with atypical presentation.Conclusion: Limiting prehospital acquisition of 12-lead ECGs to patients with typical STEMI symptoms would result in one in five patients with STEMI having delayed recognition, disproportionally impacting patients of older age, women, and Black patients. Age, not sex, may be a better predictor of atypical STEMI presentation.

Emergency Medical Services Responses to Out-of-Hospital Cardiac Arrest and Suspected ST-Segment-Elevation Myocardial Infarction During the COVID-19 Pandemic in Los Angeles County.

Background Public health emergencies may significantly impact emergency medical services responses to cardiovascular emergencies. We compared emergency medical services responses to out-of-hospital cardiac arrest (OHCA) and ST-segment‒elevation myocardial infarction (STEMI) during the 2020 COVID-19 pandemic to 2018 to 2019 and evaluated the impact of California's March 19, 2020 stay-at-home order. Methods and Results We conducted a population-based cross-sectional study using Los Angeles County emergency medical services registry data for adult patients with paramedic provider impression (PI) of OHCA or STEMI from February through May in 2018 to 2020. After March 19, 2020, weekly counts for PI-OHCA were higher (173 versus 135; incidence rate ratios, 1.28; 95% CI, 1.19‒1.37; P<0.001) while PI-STEMI were lower (57 versus 65; incidence rate ratios, 0.87; 95% CI, 0.78‒0.97; P=0.02) compared with 2018 and 2019. After adjusting for seasonal variation in PI-OHCA and decreased PI-STEMI, the increase in PI-OHCA observed after March 19, 2020 remained significant (P=0.02). The proportion of PI-OHCA who received defibrillation (16% versus 23%; risk difference [RD], -6.91%; 95% CI, -9.55% to -4.26%; P<0.001) and had return of spontaneous circulation (17% versus 29%; RD, -11.98%; 95% CI, -14.76% to -9.18%; P<0.001) were lower after March 19 in 2020 compared with 2018 and 2019. There was also a significant increase in dead on arrival emergency medical services responses in 2020 compared with 2018 and 2019, starting around the time of the stay-at-home order (P<0.001). Conclusions Paramedics in Los Angeles County, CA responded to increased PI-OHCA and decreased PI-STEMI following the stay-at-home order. The increased PI-OHCA was not fully explained by the reduction in PI-STEMI. Field defibrillation and return of spontaneous circulation were lower. It is critical that public health messaging stress that emergency care should not be delayed.

Mastering Electrocardiogram Interpretation Skills Through a Perceptual and Adaptive Learning Module.

Although accurate interpretation of the standard 12-lead electrocardiogram (ECG) is fundamental to diagnosing heart disease, several prior studies report low accuracy rates among medical students, residents, and practicing physicians. The objective of this study was to determine if an online ECG Perceptual and Adaptive Learning Module (ECG PALM) is an efficient instrument to teach ECG interpretation. The ECG PALM consists of 415 unique ECG tracings with associated pretest, posttest, and delayed tests, each using 30 additional ECGs to gauge the effectiveness and durability of training. Between 2013 and 2015, a total of 113 third-year and 156 fourth-year medical students and 34 first-year, 41 second-year, and 37 third-year emergency medicine residents completed the PALM and associated tests. We measured two mastery criteria: accuracy, the percentage of correct interpretations, and fluency, the percentage of images interpreted accurately within 15 seconds. The ECG PALM produced statistically significant improvements (0.0001 < p < 0.0045) in student and resident performance for both accuracy (effect size = 0.9 to 3.2) and fluency (effect size = 2.5 to 3.1) following training ranging from 46 ± 24 minutes (R3s) to 88 ± 32 minutes (third-year medical students). Medical students and residents performed significantly better on a test the year following training (delayed test) than those without prior ECG PALM training (pretest). The fluency of R3 residents in classifying the 15 diagnostic categories was less than 60% for nine of the 15 diagnoses and greater than 80% for only one. Following PALM training, fluency was higher than 80% for seven of the 15 categories and less than 60% for only two categories. Accuracy in recognizing ST-elevation myocardial infarctions (STEMIs) was high both before and after PALM training for R3s, but fluency was only 64% for anterior STEMIs on the pretest, increasing to 93% following PALM training. These observations suggest that the ECG PALM is an effective and durable supplemental tool for developing mastery in interpreting common ECG abnormalities.

Implementation of Targeted Temperature Management After Out-of-Hospital Cardiac Arrest: Observations From the Los Angeles County Regional System.

Background Despite the benefits of targeted temperature management (TTM) for out-of-hospital cardiac arrest), implementation within the United States remains low. The objective of this study was to evaluate the prevalence and factors associated with TTM use in a large, urban-suburban regional system of care. Methods and Results This was a retrospective analysis from the Los Angeles County regional cardiac system of care serving a population of >10 million residents. All adult patients aged ≥18 years with non-traumatic out-of-hospital cardiac arrest transported to a cardiac arrest center from April 2011 to August 2017 were included. Patients awake and alert in the emergency department and patients who died in the emergency department before consideration for TTM were excluded. The primary outcome measure was prevalence of TTM use. The secondary analysis were annual trends in TTM use over the study period and factors associated with TTM use. The study population included 8072 patients; 4154 patients (51.5%) received TTM and 3767 patients (46.7%) did not receive TTM. Median age was 67 years, 4780 patients (59.2%) were men, 4645 patients (57.5%) were non-White, and the most common arrest location was personal residence in 4841 patients (60.0%). In the adjusted analysis, younger age, male sex, an initial shockable rhythm, witnessed arrest, and receiving coronary angiography were associated with receiving TTM. Conclusions Within this regional system of care, use of TTM was higher than previously reported in the literature at just over 50%. Use of integrated systems of care may be a novel method to increase TTM use within the United States.

Racial and ethnic differences in outcomes after out-of-hospital cardiac arrest: Hispanics and Blacks may fare worse than non-Hispanic Whites.

BACKGROUND: This study evaluates differences in out-of-hospital cardiac arrest (OHCA) characteristics, interventions, and outcomes by race/ethnicity. METHODS: This is a retrospective analysis from a regionalized cardiac system. Outcomes for all adult patients treated for OHCA with return of spontaneous circulation (ROSC) were identified from 2011-2014. Stratifying by race/ethnicity with White as the reference group, patient characteristics, treatment, and outcomes were evaluated. The adjusted odds ratios (OR) for survival with good neurologic outcome (cerebral performance category 1 or 2) were calculated. RESULTS: There were 5178 patients with OHCA; 290 patients excluded for unknown race, leaving 4888 patients: 50% White, 14% Black, 12% Asian, 23% Hispanic. In univariate analysis, compared with Whites, Blacks had fewer witnessed arrests (83% vs 86%, p = 0.03) and less bystander CPR (37% vs 44%, p = 0.005), were less likely to undergo coronary angiography (14% vs 22%, p < 0.0001), and less likely to receive PCI (32% vs 54%, p < 0.0001). Asians presented less often with a shockable rhythm (27% vs 34%, p = 0.001) and were less likely to undergo angiography (15% vs 22%, p < 0.0001). Hispanics presented less often with a shockable rhythm (31% vs 34%, p = 0.03), had fewer witnessed arrests (82% vs 86%, p = 0.001) and less bystander CPR (37% vs 44%, p = 0.0001). In multivariable analysis, Hispanic ethnicity was associated with decreased favorable neurologic outcome (OR 0.78 [95%CI 0.63-0.96]). Outcomes for Asians and Blacks did not differ from Whites. When accounting for clustering by hospital, race was no longer statistically significantly associated with survival with good neurologic outcome. CONCLUSION: We identified important differences in patients with OHCA according to race/ethnicity. Such differences may have implications for interventions; for example, emphasis on bystander CPR instruction in Black and Hispanic communities.

Safety and Effectiveness of Field Nitroglycerin in Patients with Suspected ST Elevation Myocardial Infarction.

Objective: While widely used in the treatment of cardiac conditions, only limited data characterize out-of-hospital nitroglycerin (NTG) use. We sought to determine the safety of out-of-hospital sublingual NTG administered for suspected ST-segment elevation myocardial infarction (STEMI) and its effect on the patient's pain score. Methods: We prospectively identified adult patients with suspected STEMI transported by paramedics to three percutaneous Coronary Intervention PCI-capable hospitals in a large urban-suburban emergency medical services (EMS) system. We compared patients who received field NTG to those who did not. The primary outcome was the change in systolic blood pressure (SBP) between initial EMS measurement and emergency department (ED) triage vital signs. Secondary outcomes included the frequency of hypotension (SBP < 100 mmHg) and bradycardia (HR < 60) on ED arrival, drop in SBP ≥ 30 mmHg, out-of-hospital cardiac arrest (OHCA), and the change in pain score compared to an a priori threshold of -1.39. Results: Among 940 EMS transports for suspected STEMI, we excluded 160 for initial SBP < 100 mmHg, leaving 780 subjects for the analysis. Median age was 67 with 61% male. NTG was administered to 340 (44%) patients. The median change in SBP was -10 mmHg (IQR -27, 2) and -3 mmHg (IQR -20, 9) in patients treated with and without NTG, respectively. The median difference in the decrease in SBP was 6 mmHg (95% CI 3, 9 mmHg). The frequencies of ED hypotension and bradycardia, the drop in SBP ≥ 30 mmHg, and the OHCA did not differ between groups. For patients with an initial pain score > 0, the average change in pain score for patients treated with NTG was -2.6 (95% CI -3.0, -2.2), while patients who did not receive NTG had a change in pain score of -1.4 (95% CI -1.8, -1.0). Conclusion: In this cohort, field NTG did not result in a clinically significant decrease in blood pressure when compared with patients who did not receive NTG. However, NTG did cause a clinically significant reduction in pain.

Weekly Checks Improve Real-Time Prehospital ECG Transmission in Suspected STEMI.

IntroductionField identification of ST-elevation myocardial infarction (STEMI) and advanced hospital notification decreases first-medical-contact-to-balloon (FMC2B) time. A recent study in this system found that electrocardiogram (ECG) transmission following a STEMI alert was frequently unsuccessful.HypothesisInstituting weekly test ECG transmissions from paramedic units to the hospital would increase successful transmission of ECGs and decrease FMC2B and door-to-balloon (D2B) times. METHODS: This was a natural experiment of consecutive patients with field-identified STEMI transported to a single percutaneous coronary intervention (PCI)-capable hospital in a regional STEMI system before and after implementation of scheduled test ECG transmissions. In November 2014, paramedic units began weekly test transmissions. The mobile intensive care nurse (MICN) confirmed the transmission, or if not received, contacted the paramedic unit and the department's nurse educator to identify and resolve the problem. Per system-wide protocol, paramedics transmit all ECGs with interpretation of STEMI. Receiving hospitals submit patient data to a single registry as part of ongoing system quality improvement. The frequency of successful ECG transmission and time to intervention (FMC2B and D2B times) in the 18 months following implementation was compared to the 10 months prior. Post-implementation, the time the ECG transmission was received was also collected to determine the transmission gap time (time from ECG acquisition to ECG transmission received) and the advanced notification time (time from ECG transmission received to patient arrival). RESULTS: There were 388 patients with field ECG interpretations of STEMI, 131 pre-intervention and 257 post-intervention. The frequency of successful transmission post-intervention was 73% compared to 64% prior; risk difference (RD)=9%; 95% CI, 1-18%. In the post-intervention period, the median FMC2B time was 79 minutes (inter-quartile range [IQR]=68-102) versus 86 minutes (IQR=71-108) pre-intervention (P=.3) and the median D2B time was 59 minutes (IQR=44-74) versus 60 minutes (IQR=53-88) pre-intervention (P=.2). The median transmission gap was three minutes (IQR=1-8) and median advanced notification time was 16 minutes (IQR=10-25). CONCLUSION: Implementation of weekly test ECG transmissions was associated with improvement in successful real-time transmissions from field to hospital, which provided a median advanced notification time of 16 minutes, but no decrease in FMC2B or D2B times. D'ArcyNT, BossonN, KajiAH, BuiQT, FrenchWJ, ThomasJL, ElizarrarazY, GonzalezN, GarciaJ, NiemannJT. Weekly checks improve real-time prehospital ECG transmission in suspected STEMI. Prehosp Disaster Med. 2018;33(3):245-249.

Regional "Call 911" Emergency Department Protocol to Reduce Interfacility Transfer Delay for Patients With ST-Segment-Elevation Myocardial Infarction.

BACKGROUND: We evaluated the first-medical-contact-to-balloon (FMC2B) time after implementation of a "Call 911" protocol for ST-segment-elevation myocardial infarction (STEMI) interfacility transfers in a regional system. METHODS AND RESULTS: This is a retrospective cohort study of consecutive patients with STEMI requiring interfacility transfer from a STEMI referring hospital, to one of 35 percutaneous coronary intervention-capable STEMI receiving centers (SRCs). The Call 911 protocol allows the referring physician to activate 911 to transport a patient with STEMI to the nearest SRC for primary percutaneous coronary intervention. Patients with interfacility transfers were identified over a 4-year period (2011-2014) from a registry to which SRCs report treatment and outcomes for all patients with STEMI transported via 911. The primary outcomes were median FMC2B time and the proportion of patients achieving the 120-minute goal. FMC2B for primary 911 transports were calculated to serve as a system reference. There were 2471 patients with STEMI transferred to SRCs by 911 transport during the study period, of whom 1942 (79%) had emergent coronary angiography and 1410 (73%) received percutaneous coronary intervention. The median age was 61 years (interquartile range [IQR] 52-71) and 73% were men. The median FMC2B time was 111 minutes (IQR 88-153) with 56% of patients meeting the 120-minute goal. The median STEMI referring hospital door-in-door-out time was 53 minutes (IQR 37-89), emergency medical services transport time was 9 minutes (IQR 7-12), and SRC door-to-balloon time was 44 minutes (IQR 32-60). For primary 911 patients (N=4827), the median FMC2B time was 81 minutes (IQR 67-97). CONCLUSIONS: Using a Call 911 protocol in this regional cardiac care system, patients with STEMI requiring interfacility transfers had a median FMC2B time of 111 minutes, with 56% meeting the 120-minute goal.

Outcomes of ST Elevation Myocardial Infarction Complicated by Out-of-Hospital Cardiac Arrest (from the Los Angeles County Regional System).

The objective of this study was to evaluate the time to primary percutaneous coronary intervention (PCI) and the outcome for patients with ST elevation myocardial infarction (STEMI) complicated by out-of-hospital cardiac arrest (OHCA). In this regional system, all patients with STEMI and/or OHCA with return of spontaneous circulation were transported to STEMI Receiving Centers. The outcomes registry was queried for patients with STEMI with underwent primary PCI from April 2011 to December 2014. Patients with STEMI complicated by OHCA were compared with a reference group of STEMI without OHCA. The primary end point was the first medical contact-to-device time. Of 4,729 patients with STEMI who underwent primary PCI, 422 patients (9%) suffered OHCA. Patients with OHCA were on average 2 years (95% confidence interval 0.7 to 3.0) older and had a slightly higher male predominance. The first medical contact-to-device time was longer in STEMI with OHCA compared with STEMI alone (94 ± 37 vs. 86 ± 34 minutes, p < 0.0001). In-hospital mortality was higher after OHCA, 38% versus 6% in STEMI alone, odds ratio 6.3 (95% confidence interval 5.3 to 7.4). Among OHCA survivors, 193 (73%) were discharged with a cerebral performance category score of 1 or 2. In conclusion, despite longer treatment intervals, neurologic outcome was good in nearly half of the surviving patients with STEMI complicated by OHCA, suggesting that these patients can be effectively treated with primary PCI in a regionalized system of care.

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.

Sex Differences in Survival From Out-of-Hospital Cardiac Arrest in the Era of Regionalized Systems and Advanced Post-Resuscitation Care.

BACKGROUND: The purpose of this study was to evaluate sex differences in out-of-hospital cardiac arrest (OHCA) characteristics, interventions, and outcomes. METHODS AND RESULTS: This is a retrospective analysis from a regionalized cardiac arrest system. Data on patients treated for OHCA are reported to a single registry, from which all adult patients were identified from 2011 through 2014. Characteristics, treatment, and outcomes were evaluated with stratification by sex. The adjusted odds ratio (OR) for survival with good neurological outcome (cerebral performance category 1 or 2) was calculated for women compared to men. There were 5174 out-of-hospital cardiac arrests (OHCAs; 3080 males and 2094 females). Women were older, median 71 (interquartile range [IQR], 59-82) versus 66 years (IQR, 55-78). Despite similar frequency of witnessed arrest, women were less likely to present with a shockable rhythm (22% vs 35%; risk difference [RD], 13%; 95% CI, 11-15), have ST-segment elevation myocardial infarction (23% vs 32%; RD, 13%; 95% CI, 7-11), or receive coronary angiography (11% vs 25%; RD, 14%; 95% CI, 12-16), percutaneous coronary intervention (5% vs 14%; RD, 9%; 95% CI, 7-11), or targeted temperature management (33% vs 40%; RD, 7%; 95% CI, 4-10). Women had decreased survival to discharge (33% vs 40%; RD, 7%; 95% CI, 4-10) and a lower proportion of good neurological outcome (16% vs 24%; RD, 8%; 95% CI, 6-10). In multivariable modeling, female sex was not associated with decreased survival with good neurological outcome (OR, 0.9; 95% CI, 0.8-1.1). CONCLUSIONS: Sex-related differences in OHCA characteristics and treatment are predictors of survival outcome disparities. With adjustment for these factors, sex was not associated with survival or neurological outcome after OHCA.

High Serum Tumor Necrosis Factor Levels in the Early Post-Cardiac Arrest Period Are Associated with Poor Short-Term Survival in a Swine Model of Ventricular Fibrillation.

Most resuscitated victims of out-of-hospital cardiac arrest who survive to hospital expire due to the postresuscitation syndrome. This syndrome is characterized by a sepsis-like proinflammatory state. The objective of this investigation was to determine whether a relationship exists between the rise of tumor necrosis factor (TNF), a proinflammatory cytokine, following return of spontaneous circulation (ROSC), and early postarrest survival in a clinically relevant animal model of spontaneous ventricular fibrillation (VF). Mixed-breed Yorkshire swine (n = 20), weighing 39 ± 5 kg, were anesthetized and catheters placed in the right atrium and left ventricle/ascending aorta for continuous pressure monitoring. VF was induced by occluding the left anterior descending coronary artery with an angioplasty balloon. After 7 min of untreated VF, advanced life support resuscitation attempts were made for up to 20 min. Animals achieving ROSC were monitored for 3 h and fluid and pressor support was administered as needed. TNF levels were measured before VF and at 0, 15, and 30 min after ROSC using quantitative sandwich enzyme-linked immunosorbent assay. Twelve (60%) animals experienced early death, expiring during the 3 hour postarrest period (9 pulseless electrical activity, 2 VF, and 1 asystole). The TNF level at 15 min post-ROSC was significantly associated with death within the first 3 h post-ROSC with a univariate odds ratio of 1.4 [95% confidence interval (CI) 1.05-2.2, P = 0.01]. Using a cutoff TNF level of 525 pg/mL at 15 min post-ROSC had 100% negative predictive value (95% CI 0%-37%) and 67% positive predictive value (95% CI 35%-90%) for early death with a hazard ratio of 6.6 (95% CI 1.9-23.5). TNF increases shortly after ROSC and is predictive of early death. Early identification of resuscitated victims at greatest risk for hemodynamic collapse and recurrent arrest might facilitate the use of early hospital-based interventions to decrease the likelihood of a poor outcome.

Effect of Therapeutic Hypothermia on Survival and Neurologic Outcome in the Elderly.

Old age is considered a negative prognostic factor after out-of-hospital cardiac arrest (OHCA). The purpose of this study was to assess the benefit of therapeutic hypothermia (TH) on survival and neurologic outcome in the elderly. This is a retrospective study of patients treated for OHCA from April 2011 to August 2013 in a regional cardiac system. Patients with return of spontaneous circulation (ROSC) are directed to designated cardiac receiving centers with established TH protocols. The decision to initiate TH is determined by the treating physician. All patients 65 years or older were identified. Patients were excluded if awake and responsive in the emergency department, died before hospital admission, or had preexisting coma. The adjusted odds ratio for survival with good neurologic outcome (defined as cerebral performance category [CPC] 1 or 2) was calculated for patients who received TH compared to a reference group without TH. There were 1612 patients, of whom 552 (34%) received TH. Median age was 78 (inter-quartile range [IQR] 71-85); 56% was male. 493 (31%) patients survived to hospital discharge, 266 (17%) with CPC of 1 or 2. Of 1292 patients considered for TH, 192 (25%) of 552 patients who received TH survived to hospital discharge and 97 (18%) with good neurologic outcome compared to 150 (20%) and 57 (8%), respectively, without TH. The adjusted odds ratio for survival with good neurologic outcome for TH was 2.0 (95% CI 1.3-3.3). TH is associated with improved neurologic outcome in the elderly population.