Richard Tadeo

Survival and Neurologic Outcome after Out-of-Hospital Cardiac Arrest: Results One Year after Regionalization of Post-Cardiac Arrest Care in a Large Metropolitan Area

Abstract Background. Post-resuscitation care of cardiac arrest patients at specialized centers may improve outcome after out-of-hospital cardiac arrest (OOHCA). This study describes experience with regionalized care of resuscitated patients. Methods. Los Angeles (LA) County established regionalized cardiac care in 2006. Since 2010, protocols mandate transport of nontraumatic OOHCA patients with field return of spontaneous circulation (ROSC) to a STEMI Receiving Center (SRC) with a hypothermia protocol. All SRC report outcomes to a registry maintained by the LA County Emergency Medical Services (EMS) Agency. We report the first years data. The primary outcome was survival with good neurologic outcome, defined by a Cerebral Performance Category (CPC) score of 1 or 2. Results. The SRC treated 927 patients from April 2011 through March 2012 with median age 67; 38% were female. There were 342 patients (37%) who survived to hospital discharge. CPC scores were unknown in 47 patients. Of the 880 patients with known CPC scores, 197 (22%) survived to hospital discharge with a CPC score of 1 or 2. The initial rhythm was VF/VT in 311 (34%) patients, of whom 275 (88%) were witnessed. For patients with an initial shockable rhythm, 183 (59%) survived to hospital discharge and 120 (41%) had survival with good neurologic outcome. Excluding patients who were alert or died in the ED, 165 (71%) patients with shockable rhythms received therapeutic hypothermia (TH), of whom 67 (42%) had survival with good neurologic outcome. Overall, 387 patients (42%) received TH. In the TH group, the adjusted OR for CPC 1 or 2 was 2.0 (95%CI 1.2–3.5, p = 0.01), compared with no TH. In contrast, the proportion of survival with good neurologic outcome in the City of LA in 2001 for all witnessed arrests (irrespective of field ROSC) with a shockable rhythm was 6%. Conclusion. We found higher rates of neurologically intact survival from OOHCA in our system after regionalization of post-resuscitation care as compared to historical data.

Implementation of specialty centers for patients with ST-segment elevation myocardial infarction.

Background. Early percutaneous coronary intervention (PCI) has been shown to be superior to fibrinolytic therapy andis associated with reduced morbidity andmortality for patients with ST-segment elevation myocardial infarction (STEMI). Objective. To determine the performance of a regional system with prehospital 12-lead electrocardiogram (ECG) identification of STEMI patients anddirect paramedic transport to STEMI receiving centers (SRCs) for provision of primary PCI. Methods. This was a prospective study evaluating the first year of implementation of a regional SRC network to determine the key time intervals for patients identified with STEMI in the prehospital setting. Results. During the 12-month study period, 1,220 patients with a suspected STEMI were identified on prehospital 12-lead ECG, of whom 734 (60%) underwent emergency PCI. A door-to-balloon time of 90 minutes or less was achieved for 651 (89%) patients, and459 (62.5%) had EMS–patient contact-to-balloon times ≤ 90 minutes. Transport of suspected STEMI patients to an SRC resulted in ambulance diversion from a closer ED for 31% of patients anda median increase in transport time of 3.8 minutes. Conclusion. Door-to-balloon times within the 90-minute benchmark were achieved for almost 90% of STEMI patients transported by paramedics after implementing our regionalized SRC system

The Utility of Prehospital ECG Transmission in a Large EMS System

Abstract Background. Prehospital identification of STEMI and activation of the catheterization lab can improve door-to-balloon (D2B) times but may lead to decreased specificity and unnecessary resource utilization. The purpose of this study was to examine the effect of electrocardiogram (ECG) transmission on false-positive (FP) cath lab activations and time to reperfusion. Methods. This is a retrospective cohort from a registry in a large metropolitan area with regionalized cardiac care and emergency medical services (EMS) with ECG transmission capabilities. Thirty-four designated STEMI receiving centers (SRC) contribute to this registry, from which patients with a prehospital ECG software interpretation of myocardial infarction (MI) indicated by ****Acute MI****, or manufacturer equivalent, were identified between April 2011 and September 2013. Frequency of FP field activations (defined as not resulting in emergent percutaneous coronary intervention [PCI] or referral for CABG during hospital admission) for patients with ECG transmission received by the SRC was compared to a reference group without successful ECG transmission. FP field activations were compared to the baseline frequency of FP ED activations. We hypothesized that successful transmission would reduce FP field activation to ED activation levels. Door-to-balloon and first medical contact-to-balloon (FMC2B) times were compared. The protocol for field cath lab activation varied by institution. Results. There were 7,768 patients presenting with a prehospital ECG indicating MI. The ECG was received by the SRC for 2,156 patients (28%). Regardless of transmission, the cath lab was activated 77% of the time; this activation occurred from the field in 73% and 74% of the activations in the transmission and reference group, respectively. The overall proportion of FP activation was 57%. Among field activations, successful ECG transmission reduced the FP activation rate compared to without ECG transmission, 55% vs. 61% (RD = −6%, 95%CI −9, −3%). This led to an overall system reduction in FP activations of 5% (95%CI 2, 8%). ECG transmission had no effect on D2B and FMC2B time. Conclusion. Prehospital ECG transmission is associated with a small reduction in false-positive field activations for STEMI and had no effect on time to reperfusion in this cohort. Key words: emergency medical services; myocardial infarction; myocardial reperfusion; electrocardiography

Causes of Prehospital Misinterpretations of ST Elevation Myocardial Infarction

Abstract 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.

Re-examining outcomes after unsuccessful out-of-hospital resuscitation in the era of field termination of resuscitation guidelines and regionalized post-resuscitation care

BACKGROUND Dismal prognosis after failed out-of-hospital resuscitation has previously been demonstrated. Changes in resuscitation and post-resuscitation care may affect patient outcomes. We describe characteristics and outcomes of patients with out-of-hospital cardiac arrest (OOHCA) transported to specialty cardiac centers after failure of out-of-hospital interventions. METHODS In Los Angeles (LA) County, patients with non-traumatic OOHCA with return of spontaneous circulation (ROSC) are transported to specialized cardiac care centers. Outcomes are reported to a registry maintained by the LA County Emergency Medical Services (EMS) Agency. We report patient characteristics and outcomes for the subset of patients treated at these specialty centers in whom initial ROSC was achieved in the ED. The primary outcome was neurologically intact survival, defined by a cerebral performance category (CPC) score of 1 or 2. RESULTS 105 patients transported to the SRC after failure to achieve ROSC with out-of-hospital resuscitation were successfully resuscitated in the ED. The median age was 68 years (IQR 57-78); 74 (70%) were male. The presenting rhythm was ventricular fibrillation or ventricular tachycardia in 40 patients (38%) and 86 (82%) were witnessed. Twenty-two patients (21%) survived to hospital discharge. Of the 103 patients with known CPC scores, 13 (13% [95% CI 7-21%]) survived to hospital discharge with a CPC score of 1 or 2. No patient who survived with good neurologic outcome met criteria for termination of resuscitation in the field. CONCLUSION Failure of out-of-hospital resuscitation is not universally predictive of poor neurologic outcome.

The need for uniform definitions in the regionalized care of ST-segment elevation myocardial infarction.

T reatment modalities for ST segment elevation myocardial infarction (STEMI) have rapidly evolved over the past several years. However, minimizing total coronary ischemia time, defined by symptom onset to reperfusion therapy, has been the cornerstone of treatment. There are currently two types of hospitals that provide reperfusion therapy: those with the ability to provide primary percutaneous coronary intervention (PCI) and those without PCI capability that provide fibrinolytic therapy. Decreasing reperfusion times has been shown to improve morbidity and mortality after STEMI. Thus, identifying which process-of-care strategies improve time to reperfusion is paramount. Launched by the American College of Cardiology (ACC), the ‘‘Door to Balloon (D2B): An Alliance for Quality’’ is a campaign to improve the timeliness of PCI. The ACC goal is to achieve reperfusion within 90 minutes for 75% of patients. Toward that end, various emergency medical services (EMS) systems have begun to regionalize cardiac care by identifying and transporting patients identified with a STEMI in the out-of-hospital setting directly to hospitals capable of providing PCI. In evaluating STEMI process-of-care strategies, there exist problems with consistency in nomenclature and uniformity of definitions. Research involving STEMI management depends on the accurate reporting of clinical events, time intervals and time points, and pathophysiologic changes, yet basic terms and parameters for time measures are vague and ill-defined. Clinical investigators from many different specialties, such as emergency medicine, cardiology, and out-of-hospital care, contribute to the multidisciplinary knowledge base of the management of myocardial ischemia. Examples of terms utilized with variable meaning include the following: ‘‘false-positive cardiac catheterization laboratory (CCL) activation,’’ ‘‘STEMI,’’ ‘‘culprit lesion,’’ ‘‘door-to-balloon time,’’ ‘‘medical contact-to-balloon time,’’ etc. Although diversity in disciplinary backgrounds often promotes research, it can be detrimental if it contributes to the lack of a common language and communication between investigators. Thus, similar to how investigators in resuscitation developed the uniform, ‘‘Utstein style,’’ it will be important to establish consistency in nomenclature and guidelines for reporting coronary revascularization data. A uniform vocabulary of terminology and definitions will help improve the clarity of scientific communication and the comparability of investigations. Changing an entire region’s EMS system to direct STEMI patients to centers providing PCI requires enormous financial and personnel commitment, yet whether or not regionalizing cardiac care is cost-effective can only be determined through systematic comparisons using sound research methodology, which requires standard terminology. The concept of false-positive activation of the CCL warrants discussion. To meet the D2B goal of reperfusion within 90 minutes, PCI-capable hospitals mobilize the 24 ⁄ 7 on-call CCL team as soon as a patient is identified as having a STEMI, whether it is in the out-of-hospital or hospital setting. Maintaining 24 ⁄ 7 response of the CCL team is dependent on willing staff cardiologists and nurses, potential fixed costs for on-call pay, and addition costs incurred for each activation. To minimize expenses, investigators are evaluating process-of-care strategies to minimize ‘‘false-positives.’’ At this time, however, multiple definitions for what constitutes a false-positive CCL activation exist in the literature, and these differing definitions of false-positive CCL activations make it difficult, if not impossible, to compare studies. Depending on the definition used, the false-positive CCL activation rate ranges from 0% to 26% (unpublished data). For example, Larson et al. defined falsepositive in their study as one in which there was any of the following: no culprit artery (14%), no significant coronary artery disease at catheterization (9.5%), or negative cardiac biomarkers (11.2%). With the use of this definition, a patient who has no culprit lesion identified during CCL, with positive biomarkers and an electrocardiogram (ECG) universally interpreted by the field, emergency department (ED), and cardiology services as a STEMI, is included as one of the false-positives. Reporting a 0% (0 ⁄ 51) false-positive rate, Kraft et al. defined false-positive as a lack of an occluded vessel on catheterization, without commenting on biomarkers, or concordance or discordance of ECG interpretations among field providers, ED physicians, and cardiologists. In contrast, Khot et al. reported a 1% (1 ⁄ 97) false-positive rate for catheterization lab activation, which was defined as when catheterization was deemed unnecessary by a cardiologist (one example involved the patient who had flash pulmonary