Prehospital ECG Research Articles

Field triage to primary angioplasty combined with emergency department bypass reduces treatment delays and is associated with improved outcome

We investigated the net benefit in the outcome of reducing treatment delay through field triage and emergency department (ED) bypass in patients with ST-elevation myocardial infarction (STEMI) treated with primary angioplasty. In a prospective registry study, consecutive patients with suspected STEMI were assigned to: (i) pre-hospital ECG and triage or (ii) ECG and triage at the closest ED, solely based on ambulance availability. Four district hospitals and one regional heart centre serviced the 890,000 population metropolitan area and primary angioplasty was the only reperfusion strategy employed. Baseline characteristics were similar in STEMI patients triaged in the field (108) and the EDs (193). Symptom onset to balloon times: 154 [inter-quartile range (IQR) 120-233) vs. 249 (IQR 184-405) min (P<0.001) and peak creatine kinase in early presenters (<2 h): 1435 (95 %CI: 904-1966) U/L vs. 2320 (95% CI: 1881-2762) U/L (P=0.009) were lower in field- than in ED-triaged patients. Mortality in the PCI treated were 1.1 and 8.2% [P=0.025, RR 0.14 (95% CI: 0.01-1.08)] and overall mortality were 1.9 and 7.3% [P=0.046, RR 0.26 (95% CI: 0.05-1.11)]. Field-triage and ED bypass were feasible means of reducing treatment delay in patients with suspected STEMI and resulted in smaller infarct size in early presenters and a trend towards a reduction in mortality.

The Only Constant is Change: The Necessity of Serial Prehospital 12-Lead ECGs

The Only Constant is Change: The Necessity of Serial Prehospital 12-Lead ECGs

The Positive Predictive Value of Paramedic Versus Emergency Physician Interpretation of the Prehospital 12-Lead Electrocardiogram

Background. Obtaining a prehospital 12-lead ECG may improve triage andexpedite care of patients with acute myocardial infarction (AMI). Whether the ECG should undergo physician review prior to activation of a percutaneous intervention (PCI) team is unclear. Objective. To document the positive predictive value (PPV) of the prehospital 12-lead ECG when interpreted by paramedics versus emergency physicians. Methods. This was a prospective, observational study. In November 2003, our local health care andemergency medical services (EMS) systems implemented a prehospital “cardiac alert” program in which patients suspected of having ST-elevation myocardial infarction (STEMI) based on the prehospital 12-lead ECG were diverted away from receiving facilities without emergent PCI capability andthe PCI team was mobilized. For the first year, a cardiac alert was activated by paramedics (Phase I). After the first year, the ECG was transmitted to the ED, with the emergency physician (EP) responsible for activation (Phase II). The PPV for cardiac alerts in Phases I andII were compared by using three different “gold standards”: cardiologist interpretation of the prehospital 12-lead ECG, disposition to emergent PCI, andcoronary lesions on angiography or arrest prior to emergent PCI. Results. A total of 110 patients were enrolled (54 in Phase I, 56 in Phase II). Cardiologist confirmation of a STEMI on the prehospital 12-lead EKG was 42/54 (78%) in Phase I and54/56 (96%) in Phase II. Disposition to emergent PCI occurred in 38/54 (70%) Phase I patients and51/56 (91%) Phase II patients. Lesions at catheterization or arrest prior to emergent PCI were observed in 41/54 (69%) of Phase I patients and50/56 (89%) of Phase II patients. All of these comparisons achieved statistical significance (p < 0.01). Conclusions. Transmission to the ED for EP interpretation improves the PPV of the prehospital 12-lead ECG for triage andtherapeutic decision-making.

Emergency Physicians Are Better Than Paramedics at Interpreting Prehospital ECGs for STEMI

Many emergency medical services systems have implemented protocols for transporting patients with suspected ST-segment-elevation myocardial infarction (STEMI) directly to facilities with capability for emergent percutaneous coronary intervention (PCI). In a prospective, observational study, researchers compared the accuracy of prehospital electrocardiogram interpretations by emergency physicians and by paramedics in a moderate-volume urban service. …

Benefit of direct ambulance to coronary care unit admission of acute myocardial infarction patients undergoing primary percutanoues intervention

Background Early reperfusion therapy in ST-segment elevation myocardial infarction (STEMI) patients improves left ventricular (LV) function and survival. However, emergency room (ER) triage may unnecessarily delay this time-dependent treatment. We sought to determine whether direct admission of STEMI patients from the mobile intensive care units to the intensive coronary care unit (ICCU), bypassing the ER, can shorten the time intervals for primary PCI (PPCI) and improve prognosis. Methods All STEMI patients who underwent PPCI between Jan—2002 to Nov—2005 were included. Baseline, clinical and time interval parameters were compared between groups. Mortality rates were obtained through the population register. Results Of 533 admissions, 115 (21%) were admitted directly to the ICCU. These patients were younger (mean (+ S.D.) age of 58 + 13 years) than patients admitted via the ER (62 ± 13 years, P < 0.01) and had a lower proportion of women (9% vs. 22%, P < 0.01), hypertension (45% vs. 62%, P < 0.01) and diabetes (15% vs. 27%, P = 0.01). Directly admitted patients had a substantially shorter median pain-to-balloon time (210 vs. 247 min, P = 0.02) as well as s significantly shorter door-to-balloon time (70 vs. 94 min, P < 0.01), a difference that was particularly pronounced during daytime (55 min vs. 90 min, P < 0.01). There were no significant differences in LV function at 24 h as assessed by echocardiography or infarct size as determined by peak creatine kinase levels. We observed a trend towards reduced 30-day (5.2% vs. 9.8%, P = 0.12) and 1-year (11.1% vs. 16.1%, P = 0.25) mortality in directly admitted patients. Conclusions Directly admitted STEMI patients differ from patients admitted via the ER; Direct ICCU admission, based on a pre-hospital ECG, can substantially shorten time to treatment.

Prehospital evaluation in ST-elevation myocardial infarction patients treated with primary percutaneous coronary intervention

In patients with ST-elevation myocardial infarction, fast initiation of reperfusion therapy is mandatory. It is well established that prehospital diagnosis results in earlier initiation of fibrinolysis, but there is limited evidence concerning the value of prehospital evaluation in patients treated with primary percutaneous coronary intervention (PCI). The present paper proposes various prehospital strategies that may be of relevance in treating the latter patients: (1) a substantial reduction in treatment delay may be achieved by prehospital diagnosis, especially if combined with rerouting of patients directly to interventional hospital; (2) use of telemedicine may allow a widespread implementation of a prehospital diagnostic program; (3) a rerouting strategy may result in prolonged transportation. In this setting, continuous real-time 1-lead ECG transmission from ambulance to hospital may allow physicians to support ambulance personnel in the treatment of arrhythmias during transportation; and (4) equipment used for prehospital ECG acquisition and transmission has built-in features for continuous ST-segment monitoring. It is hypothesized that continuous ST-segment monitoring performed in the prehospital phase and during primary PCI may provide important prognostic information, with the potential of triaging future pharmacological and interventional treatment at time of PCI.

Diagnosis and Management of Patients with Suspected Acute Myocardial Infarction

Patients admitted with suspected acute myocardial infarction (MI) constitute a diagnostic, prognostic and therapeutic challenge for the treating physician. Elevation of a marker of myocardial necrosis together with ischemic symptoms and/or ischemic ECG changes are mandatory for the diagnosis of acute MI. Troponin T or I is the preferred marker of myocardial necrosis. The diagnostic process should start as soon as possible. The introduction of prehospital ECG recordings and prehospital administration of thrombolytic treatment in case of ST‐segment elevation MI, have been shown to decrease the time from onset of symptoms till treatment considerably, which also translates into saved lives. In contrast, data of the value of prehospital analyses of biochemical markers are still limited. In patients without ST‐segment elevation on admission the diagnosis is dependent on repeated measurements of markers of myocardial damage, which together with other biochemical markers (e.g. CRP and BNP/NT‐proBNP) also are useful for risk assessment. Patients identified to be at low risk of future cardiac events might be discharged early and, on the contrary, a more intense treatment might be started in patients identified to be at high risk. An elevated troponin concentration is shown to identify patients who benefit from antithrombotic therapy and invasive procedures. Several different risk scoring models based on a combination of clinical variables, ECG‐changes and biochemical markers, have been shown to further improve risk assessment and selection of treatment.

Pre-hospital synthesized 12-lead ECG ischemia monitoring with trans-telephonic transmission in acute coronary syndromes: Pilot study results of the ST SMART trial

Introduction: The aim of the ST SMART trial is to determine whether prehospital ST monitoring with telephone transmission to the target hospital will improve hospital time to treatment in acute coronary syndromes. The present analysis reports results of the feasibility pilot study. Methods: All patients calling 911 for chest pain in Santa Cruz County California were monitored with a synthesized 12-lead ECG. Prehospital ECGs were printed for clinical use in the experimental group; control group patient care used only ECGs recorded after hospital arrival. Results: Five patients with non-ST elevation myocardial infarction or unstable angina had normal ECGs upon hospital arrival but evidence of ischemia in their prehospital ECGs. Three patients with ST elevation myocardial infarction were treated with primary percutaneous coronary intervention, with “door to balloon” times of 47 and 65 minutes in 2 experimental group patients and 148 minutes in the one control group patient. Conclusion: Prehospital ST monitoring appears feasible. Its potential to improve hospital time to diagnosis and treatment in acute coronary syndromes, and the clinical benefits of such improvement will be studied in the larger, ongoing ST SMART trial.

Telemedical transmission of prehospital ECG’s in patients with acute chest pain

Telemedical transmission of prehospital ECG’s in patients with acute chest pain

Diagnosis of acute cardiac ischemia

A better understanding of coronary syndromes allow physicians to appreciate UAP and AMI as part of a continuum of ACI. ACI is a life-threatening condition whose identification can have major economic and therapeutic importance as far as threatening dysrhythmias and preventing or limiting myocardial infarction size. The identification of ACI continues to challenge the skill of even experienced clinicians, yet physicians continue (appropriately) to admit the overwhelming majority of patients with ACI; in the process, they admit many patients without acute ischemia [2], overestimating the likelihood of ischemia in low-risk patients because of magnified concern for this diagnosis for prognostic and therapeutic reasons. Studies of admitting practices from a decade ago have yielded useful clinical information but have shown that neither clinical symptoms nor the ECG could reliably distinguish most patients with ACI from those with other conditions. Most studies have evaluated the accuracy of various technologies for diagnosing ACI, yet only a few have evaluated the clinical impact of routine use. The prehospital 12-lead ECG has moderate sensitivity and specificity for the diagnosis of ACI. It has demonstrated a reduction of the mean time to thrombolysis by 33 minutes and short-term overall mortality in randomized trials. In the general ED setting, only the ACI-TIPI has demonstrated, in a large-scale multicenter clinical trial, a reduction in unnecessary hospitalizations without decreasing the rate of appropriate admission for patients with ACI. The Goldman chest pain protocol has good sensitivity for AMI but was not shown to result in any differences in hospitalization rate, length of stay, or estimated costs in the single clinical impact study performed. The protocol's applicability to patients with UAP has not been evaluated. Single measurement of biomarkers at presentation to the ED has poor sensitivity for AMI, although most biomarkers have high specificity. Serial measurements can greatly increase the sensitivity for AMI while maintaining their excellent specificity. Biomarkers cannot identify most patients with UAP. Finally, diagnostic technologies to evaluate ACI in selected populations, such as echocardiography, sestamibi perfusion imaging, and stress ECG, may have very good to excellent sensitivity; however, they have not been sufficiently studied.

Prehospital 12-lead ECG diagnostic programs

Early reperfusion significantly reduces mortality and morbidity in patients with acute myocardial infarction [2-6]. Prehospital 12-lead ECG programs significantly decrease time to definitive reperfusion therapy [8-13]. The feasibility and safety of prehospital 12-lead ECG programs are well [figure: see text] established [8,11,13,14]. Additional potential benefits include increased diagnostic accuracy in the prehospital setting [14], providing a comparison ECG to the one obtained in-hospital [15], differentiating arrhythmias [16-18], and sensitive and specific computerized ECG interpretation [31,32]. Prehospital 12-lead ECG diagnostic programs also provide the necessary clinical information to implement system changes or interventions such as prehospital thrombolytic therapy, direct CCU admission, or triage to tertiary cardiac care centers [22,30,34,35]. The information acquired should be used optimally to effect significant improvements in patient care through a well planned and coordinated program.

Now evaluate chest pain with 12-lead electrocardiograms and rapid markers for early recognition of myocardial infarctions in the ambulance (NEW ERA)

Introduction: Paramedics play a vital role in the diagnosis of acute myocardial infarction (AMI). Rapid bedside cardiac markers (RBCMs) are an additional tool that may be used to identify patients with AMI and non-diagnostic ECGs. Study Objectives: This study was performed to determine if paramedics can identify patients with AMI by using 12-lead ECG and RBCMs. Methods: In this multi-center trial, 12-lead ECGs and RBCMs were performed before arrival to the emergency department (ED). AMI was identified if either pre-hospital 12-lead ECG or RBCM were positive. Results: Of the 247 enrolled patients, 28 (11.3%) patients were identified with AMI in the pre-hospital setting. Of the 9 AMI missed by EMS, all had initial pre-hospital negative RBCMs but subsequent positive RBCMs in the ED. Conclusion: Paramedics can identify AMI in the pre-hospital setting using 12-lead ECG and RBCMs. Presented at: American College of Emergency Physicians Research Forum, Las Vegas, October 1999 Funding: Rapid Bedside Cardiac Markers were supplied by Spectral Diagnostics. Cellular phones were supplied by Motorola. Airtime was donated by Ameritech. The 12-Lead ECG Monitors were supplied by Physio-Control. No additional compensation was obtained.

Test of the Acute Cardiac Ischemia Time-Insensitive Predictive Instrument (ACI-TIPI) for Prehospital Use

Study objectives: To test diagnostic performance for acute cardiac ischemia (ACI) in a manually calculated and in a computerized, ECG-calculated ACI time-insensitive predictive instrument (ACI-TIPI) in prehospital chest pain patients. Methods: We carried out prospective inclusion and data acquisition with retrospective analysis. Over a 6-month period, 439 adult emergency medical services patients with chest pain underwent prehospital electrocardiography. Because of incomplete data, 77 cases were excluded, leaving a study sample of 362 patients. Excluded patients did not differ significantly with respect to age, sex, final diagnosis, or history of myocardial infarction, heart surgery, diabetes, or stroke. ACI-TIPI probabilities of ACI were computed on the basis of the prehospital ECGs as interpreted retrospectively and independently by two study investigators blinded to patient outcome, with a specially programmed electrocardiograph, and with a computer algorithm further modified by logistic-regression analysis. Results: Diagnostic performance on the basis of receiver operating characteristic (ROC) curve areas of the ACI-TIPI was scored, by the two physician readers, .73 and .74; and by ECG, .75. Patients with low ACI-TIPI probability (0% to 9%) had no acute myocardial infarctions, a 2.3% incidence of angina, and no prehospital life-threatening events. Conclusion: ACI-TIPI probabilities of ACI as generated by a specially programmed electrocardiograph are comparable to those based on physician ECG interpretations and may be useful in the prehospital evaluation of chest pain. [Aufderheide TP, Rowlandson I, Lawrence SW, Kuhn EM, Selker HP: Test of the acute cardiac ischemia time-insensitive predictive instrument (ACI-TIPI) for prehospital use. Ann Emerg Med February 1996;27:193-198.]

Evaluation of ST segment elevation criteria for the prehospital electrocardiographic diagnosis of acute myocardial infarction

To determine retrospectively the diagnostic accuracy of various ECG ST segment elevation criteria for the prehospital ECG diagnosis of acute myocardial infarction. During a six-month period, paramedics acquired prehospital 12-lead ECGs on adult chest pain patients. Investigators interpreted ECGs independently, retrospectively, and blinded to patient outcome. ECGs were classified as meeting or not meeting the six ST segment elevation criteria regardless of ECG morphology if the criteria were present in two or more anatomically contiguous leads: 1 mm or more ST segment elevation; 2 mm or more ST segment elevation; 1 mm or more ST segment elevation in the limb leads or 2 mm or more ST segment elevation in the precordial leads; and the first three criteria with the simultaneous presence of reciprocal changes. ECGs that did not meet any ST segment elevation criteria were classified as normal, nonspecific ST/T wave changes, abnormal but not ischemic, and ischemic. Hospital charts were reviewed for final cardiac diagnosis. Four hundred twenty-eight stable adult prehospital chest pain patients in whom paramedics acquired prehospital 12-lead ECGs. None. Of the 428 cases, 123 (29%) met 1 mm or more ST segment elevation criteria. Sixty-three (51%) of these 123 patients did not have myocardial infarctions. ECG characteristics most frequently associated with these non-myocardial infarction ECGs were left bundle branch block (21%) and left ventricular hypertrophy (33%). The three criteria that required the presence of reciprocal changes had the highest positive predictive values (93% to 95%), with sensitivities ranging from 20% to 33%. The criteria of 1 mm or more ST segment elevation with the simultaneous presence of reciprocal changes had a positive predictive value of 94% and included 18 of the 21 (86%) myocardial infarction patients who had ST segment elevation and received thrombolytic therapy within five hours after hospital arrival. Of the 428 cases, 305 (71%) did not meet any ST segment elevation criteria and had a sensitivity of 81% and a negative predictive value of 49% for the absence of acute myocardial infarction. Fifty-one percent of patients whose prehospital 12-lead ECG met 1 mm or more ST segment elevation criteria had non-myocardial infarction diagnoses. ST segment elevation alone lacks the positive predictive value necessary for reliable prehospital myocardial infarction diagnosis. Inclusion of reciprocal changes in prehospital ECG myocardial infarction criteria improved the positive predictive value to more than 90% and included a significant majority (62% to 86%) of acute myocardial infarction patients with ST segment elevation who received thrombolytic therapy within five hours after hospital arrival. ST segment elevation criteria that include reciprocal changes identify patients who stand to benefit most from early interventional strategies.

Feasibility of prehospital r-TPA therapy in chest pain patients

Study objective: The purpose of this study was to determine the number of eligible prehospital thrombolytic candidates and to estimate the potential time saved if field thrombolysis had been initiated in a series of prehospital chest pain patients. Design and setting: Prehospital 12-lead ECGs were obtained by paramedics during initial evaluation of chest pain patients and stored in the computerized ECG. Prehospital 12-lead ECGs, prehospital charts, and hospital charts then were reviewed retrospectively for final hospital diagnosis, prehospital and emergency department times, and historical exclusion criteria for prehospital treatment with recombinant tissue-type plasminogen activator (r-TPA). Type of participants: One hundred fifty-seven stable adult prehospital patients with a chief complaint of nontraumatic chest pain were enrolled. Six patients were excluded. Two had unretrievable 12-lead ECGs, and four refused paramedic transport and thus provided no further data. There were complete data on 151 patients making up the final study population. Interventions: Prehospital care was unaltered except for acquisition of 12-lead ECGs. No prehospital thrombolytic therapy was administratered during this study. Measurements and main results: The incidence of r-TPA exclusion criteria was as follows: 45 patients (29%) were 75 years of age or older, 57 (38%) had chest pain for more than six hours, 24 (16%) had hypertension with blood pressure of more than 180/110 mm Hg, and six (4%) had a history of a cerebrovascular accident. The time from paramedic scene arrival to prehospital ECG (8.4±5.1 minutes) was significantly shorter than the time from ED arrival to ED ECG (24.2+21.6 minutes, P<.001). Prehospital ECGs increased paramedic scene time over a retrospective control by 5.2 minutes. Mean time from prehospital ECG to ED ECG (potential time saved) was 50.2+22.4 minutes in all patients and 43.4±7.7 minutes in patients with a final diagnosis of acute myocardial infarction ( P=NS). Thirteen of 151 patients (8.6%) had prehospital ECGs diagnostic for acute myocardial infarction; eight of these (5.3% overall) met criteria for prehospital r-TPA therapy. Conclusion: Prehospital 12-lead ECGs provide an ECG diagnosis 40 to 50 minutes earlier than ED ECGs. However, with current exclusion criteria, the number of prehospital r-TPA candidates is limited.

The diagnostic impact of prehospital 12-lead electrocardiography

It is feasible to apply prehospital 12-lead electrocardiography to most stable prehospital chest pain patients. Prehospital diagnostic accuracy is improved compared with single-lead telemetry. One-hundred sixty-six stable adult patients who sought paramedic evaluation for a chief complaint of nontraumatic chest pain. One-hundred fifty-one prehospital 12-lead ECGs of diagnostic quality were obtained by paramedics on 166 adult patients presenting with nontraumatic chest pain. Paramedics and base station physicians were blinded to the information on acquired prehospital 12-lead ECGs and treated patients according to current standard of care-clinical diagnosis and single-lead telemetry. Final hospital diagnoses were classified into three groups: acute myocardial infarction (24); suspected angina or ischemia (61); and nonischemic chest pain (66). Paramedics and base station physicians' clinical diagnoses and prehospital and emergency department ECGs were similarly classified and compared. Prehospital and ED 12-lead ECGs were read retrospectively by two cardiologists. Paramedics achieved a high success rate (98.7%) in obtaining diagnostic quality prehospital 12-lead ECGs in 94.6% of eligible prehospital patients. For patients with acute myocardial infarction, prehospital ECG alone had significantly higher specificity than did the paramedic clinical diagnosis (99.2% vs 70.9%; P less than .001), and significantly higher positive predictive value (92.9% vs 32.7%; P less than .001). For patients with angina, combining the paramedic clinical diagnosis and the prehospital ECG significantly improved sensitivity (90.2% vs 62.3%; P less than .001) and increased negative predictive value (88.9% vs 71.3%; P less than .02) compared with paramedic clinical diagnosis alone. There was a high concordance between prehospital and ED ECG diagnosis (99.3% for acute myocardial infarction and 92.8% for angina). Furthermore, ten patients whose prehospital ECGs demonstrated ischemia and who had final hospital diagnoses of angina or acute myocardial infarction were mistriaged by paramedics and/or received no base station physician-directed therapy. It is feasible to apply prehospital 12-lead electrocardiography to most stable prehospital chest pain patients. Prehospital 12-lead ECGs have the potential to significantly increase the diagnostic accuracy in chest pain patients, approach congruity with ED 12-lead ECG diagnoses, and may allow for consideration of altering and improving prehospital and hospital-based management in this patient population.

Time delays in the diagnosis and treatment of acute myocardial infarction: A tale of eight cities Report from the Pre-hospital Study Group and the Cincinnati Heart Project

To establish the magnitude of prehospital and hospital delays in initiating thrombolytic therapy for acute myocardial infarction, the time from telephone 911 emergency medical system (EMS) activation to treatment and its components were analyzed from eight separate ongoing trials. This included estimates of ambulance response time, prehospital evaluation and treatment time, and time from admission to the hospital to initiation of thrombolytic therapy. The average time from EMS activation to patient arrival at the hospital was prospectively determined to be 46.1 ± 8.2 minutes in 3715 patients from eight centers. The time from admission to the hospital to initiation of thrombolytic therapy was retrospectively determined to be 83.8 ± 55.0 minutes in a separate group of 730 patients from six centers. Both the prehospital and hospital time delays were much longer than those perceived by paramedics and emergency department directors. Shorter hospital time delays were observed in patients in whom a prehospital ECG was obtained as part of a protocol-driven prehospital diagnostic strategy and a diagnosis of acute infarction made before arrival at the hospital (36.3 ± 11.3 minutes in 13 patients). These results show that the magnitude of time required to evaluate, transport, and initiate thrombolytic therapy will preclude initiation of treatment to most patients within the first hour of symptoms. Implementation of a protocol-driven prehospital diagnostic strategy may be associated with a reduction in time to thrombolytic therapy.

Evaluation of patients for the need of thrombolytic therapy in the prehospital setting

Maximum benefit from thrombolytic therapy in acute myocardial infarction is obtained with early therapy. The earliest possible time to treat is during the initial evaluation of the patient in the home or ambulance, which requires accurate diagnosis of acute myocardial infarction in the prehospital setting. In our study, paramedics evaluated patients who had chest pain with a 12-lead ECG transmitted by cellular telephone and a checklist for inclusion and exclusion criteria for thrombolytic therapy. This information was transmitted to a hospital-based telemetry physician who diagnosed or excluded acute myocardial infarction and made a mock decision to withhold or administer a thrombolytic agent. Forty-eight patients with chest pain were evaluated. Six were diagnosed as having overt acute myocardial infarction by the hospital-based telemetry physician. All six patients had the diagnosis substantiated by both ECG and enzyme studies on hospital admission. Based on the data supplied by paramedics, two of these six patients were considered eligible for thrombolytic therapy by the physician. Hospital evaluation confirmed the prehospital decision to treat with a thrombolytic agent. In addition, all other patients were appropriately diagnosed as ineligible. Prehospital ECG diagnosis resulted in two patients going directly to the catheterization lab, thereby bypassing the emergency department. Overt acute myocardial infarction can be accurately identified by a prehospital-acquired 12-lead ECG transmitted to a hospital-based physician. Our study demonstrates that in conjunction with specially trained paramedics, the hospital physician can decide whether to administer thrombolytic therapy to such patients in the prehospital setting.