Introduction: The accurate interpretation of potential ST-segment elevations on electrocardiograms (ECGs) to diagnose acute myocardial infarction (MI) is a critical competency for emergency physicians (EPs) and cardiologists. There is conflicting evidence on the diagnostic accuracy of EPs and cardiologists interpreting potential STEMI ECGs. Methods: We conducted a web-based assessment of the diagnostic accuracy of potential STEMI ECGs of Canadian EPs and cardiologists. They were identified using the membership lists of the Canadian Association of Emergency Physicians and the academic departments of cardiology at Canadian medical schools. When provided with 20 ECGs of confirmed STEMI patients, EPs and cardiologists were asked to provide a binary Yes/No answer to the question, “In a patient with ischemic chest pain, does this ECG represent a STEMI?” EPs and cardiologists were blinded to the correct answers while completing the web-based assessment. Descriptive statistics were used to described frequencies and counts. Analysis using Rasch Measurement Theory was used to explore the relationship between correct interpretation of ECGs and predictive variables such as age, years in practice or type of practice. Results: Two hundred and fifty EPs and 30 cardiologists (n=280) responded to our survey (total response rate 25%). Average years in practice were 12.5 for EPs (SD 10.6; median 10) and 14.6 for cardiologists (SD 10.6; median 11); 52% of EPs and 93% of cardiologists practiced in an academic setting. Seven of the cardiologists were interventionalists, while 47.6% of EPs and 97% of cardiologists practiced at hospitals with 24-hour catheterization capability. The diagnostic accuracy of EPs for identifying STEMI ECGs was 75% (SD 15%); cardiologists’ accuracy was 76% (SD 15.5%). The ability to correctly interpret the ECGs was independent of age, years in practice, or type of practice (community vs academic). Conclusion: EPs and cardiologists display similar diagnostic accuracy for interpreting STEMI ECGs, regardless of age, years in practice or type of practice. The findings of our study suggest the need for focused ECG education for both EPs and cardiologists.

Introduction:Background: Ischemic ventricular fibrillation (VF) is highly related to ST elevation myocardial infarction (STEMI). Pre-hospital STEMI patients have been shown to also develop VF during ambulance transport. However, there is limited literature exploring the characteristics of this specific population of VF. Objective: To determine the incidence of pre-hospital VF, and evaluate some demographic and electrocardiogram (ECG) characteristics of STEMI patients having VF while transported by ambulance in a Quebec suburban pre-hospital setting. Methods: A retrospective study from 8th August 2006 to 6th December 2015 of 937 STEMI patients transported by ambulance in the Chaudiere-Appalaches region, south of Quebec City. Destination for treatment was either Catherization Laboratory (CL) or the nearest Emergency Department (ED) for reperfusion treatment and was mainly based upon a maximum transport time of 60 minutes, from the first confirmed STEMI-ECG to the CL. Demographics and ECG characteristics were extracted from the patients care records. SPSS-20 was used for descriptive statistics. Results: 937 patients (259 women & 678 men) diagnosed with STEMI were included in the study. Patients were regrouped in V1-V4 leads STEMI (336; 35.9%) and in other leads STEMI (651; 64.1%). 52 (5.55%) of all STEMI patients had FV during ambulance transport. There were 10 women (27,4%) and 42 men (72,6%). Of these, 28 had V1-V4 STEMI (28/336; 8.33%) while 24 had other leads STEMI (24/651; 3.69%). Relative risk of FV is higher (225%) with V1-V4 STEMI compared to other leads STEMI. Regarding age groups, patients from 60 to 70 years old represent 38.4% (20/52) of FV for 25.7% (241/937) of STEMI patients while those over 80 years old had 3.85% (2/52) of FV, but were 17% (159/937) of all STEMI patients. Men seem also more at risk for FV (16/20) especially between 60 and 70 years old compare to other age group. Conclusion: In this suburban area, VF occurred in 5.55% of STEMI patient’s transported by ambulance. STEMI patients over 80 years old had a low rate of FV. Being a man, 60 to 70 years old, with a STEMI located in V1-V4, seems to be associated with a higher risk of VF. More studies are needed to confirm these results and explore other characteristics associated to pre-hospital VF.

Introduction: Compared to pseudo-pulseless electrical activity (PEA with myocardial contractions present), true PEA is hypothesized to carry a poorer prognosis and to show bradycardia and a wide QRS complex on ECG. Our objective was to study the predictive potential of ECG characteristics on survival to hospital discharge (SHD) for out-of-hospital cardiac arrest (OHCA) patients with PEA initial rhythm. Methods: We studied a cohort of OHCA patients prospectively enrolled between Sept. 2007 and Oct. 2009 at the Ottawa/OPALS site (13 cities, 7 EMS, and 6 Fire services) of the ROC PRIMED study. We included adult (≥ 18) non-traumatic OHCA with PEA initial rhythm where resuscitation was attempted, and for which ECG characteristics were available. We measured mean heart rate (HR), mean QRS interval, and presence of P waves (each with kappa agreement) using the first six QRS complex available. We report patient and system characteristics using descriptive statistics and determined the impact of ECG characteristics (HR, QRS width, P waves) on return of spontaneous circulation (ROSC) and SHD using multivariate regression analysis. Results: Demographics of 332 included cases were: mean age 71.7; male 58.4%; home residence 76.5%; bystander witnessed 56.3%; bystander CPR 28.5%; interval from dispatch to paramedic arrival 6min:24sec; ROSC at ED arrival 26.5%; SHD 5.4%. Survivors had higher mean HR (66.1 vs. 52.0 bpm, p=0.83; kappa=0.69) and shorter mean QRS intervals (108.3 vs. 129.6 ms, p=0.01; kappa=0.74) compared to non-survivors. Presence of p waves could not reliably be ascertained (kappa=0.35). Predictors of ROSC were: ALS paramedic on scene (AdjOR=8.90, 95%CI 1.11-71.41; p=0.04), successful intubation (AdjOR=3.35, 1.75-6.39; p=0.0002), and use of atropine (AdjOR=0.27, 0.14 - 0.50; p<0.0001). Predictors of survival were: location of arrest (AdjOR=1.49, 1.11 - 1.99; p=0.007), and use of atropine (AdjOR=0.06, 0.02-0.22; p<0.0001). Despite various cutoff explorations, ECG characteristics were not predictive of ROSC or survival in multivariate analyses. Survivors had HR as low as 6 bpm and QRS as wide as 357 ms. Conclusion: Early ECG characteristics could not predict ROSC or SHD in a population of OHCA PEA victims, and should not be used to terminate resuscitation efforts. Atropine administration was consistently associated with decreased likelihood of ROSC and survival.

Introduction: Survival to hospital discharge is better for PEA than asystole in out-of-hospital cardiac arrest. Point of care ultrasound (PoCUS) is widely used in cardiac arrest, although not mandated by ACLS guidelines. This study examines if initial PoCUS findings combined with cardiac rhythm are predictive of outcomes including return of spontaneous circulation (ROSC), survival to hospital admission (SHA), and hospital discharge (SHD). Methods: A database review was completed for patients arriving to a tertiary ED in asystole or PEA arrest from 2010 to 2014. Patients under 19y or with a previous DNR were excluded. Patients were grouped into those with cardiac activity on PoCUS and PEA on ECG (Positive group); those with no cardiac activity recorded on PoCUS and asystole on ECG (Negative group); and those with a mix of positive and negative findings (Indeterminate group). Data was analyzed for the frequency of ROSC, SHA, and SHD. Results: 186 patients met the study criteria, with 14 (8%) in the positive group, 134 (72%) in the negative group, and 38 (20%) in the indeterminate group. The positive group had significantly better initial outcomes than the negative group: ROSC: 78% (95% CI 49-95%) vs 17% (11-25%); OR 17.70 (4.57-168.5; p < 0.0001) and SHA: 29% (8-58%) vs 7% (3-12%); OR 5.56 (1.45-21.28; p = 0.022), and then the combined negative and indeterminate groups: ROSC: 22% (16-29%), OR 12.93 (3.43-48.73; p < 0.0001; SHA: 8% (5-13%); OR 4.51 (1.25-16.27; p = 0.033). There was no difference between the positive group and either the negative or combined groups for final outcome of SHD: 0% (0-23%) vs 1% (0-5%); OR 1.83 (0.08-39.97; p = 1.00; and vs 1% (0-5%); OR 1.67 (0.08-33.96; p = 1.00). The negative group had worse initial outcomes than the combined positive and indeterminate groups: ROSC 17% (11-25%) vs. 50% (36-64%) OR 0.21 (0.10-0.42; p < 0.0001); SHA 6% (3-12%) vs. 8% (5-13%) OR 0.34 (0.13-0.92; p = 0.0490). There was no difference in SHD: 1% (0-5%) vs. 1% (0-5%) OR 0.77 (0.07-8.71; p = 1.00). Conclusion: Our results suggest that although finding positive cardiac activity on ECG (PEA) and also on PoCUS is associated with greater ROSC and SHA, it does not identify patients with a final outcome of SHD.