CORONARY ARTERY DISEASE

Original Studies

Feasibility of Early Emergency Room Notificationto Improve Door-to-Balloon Times for Patients

With Acute ST Segment ElevationMyocardial Infarction

Milan Sekulic, MD, Bischan Hassunizadeh, MD, Steve McGraw, DO, and Shukri David,* MD

An algorithm to lower time from first contact in the field by EMS personnel to in-hospi-tal mechanical reperfusion is described. ECG tracings were telemetered via cellularphone to an emergency room physician, who then activated the cardiac catheterizationcall team to bypass usual delays seen during ER triage. Seventy-one ECGs were sentto the ER in the time interval from October 2003 to October 2004. Five ECGs (7.0%)failed to transmit due to failure of the cellular phone to receive an adequate signal.Sixty-six patients (93.0%) had an adequate ECG transmitted to the ER and six patientswith ST elevation myocardial infarction were identified. Door-to-balloon times werelowered to 44 6 17.4 min, a substantial decrease over historical norms that range from120 min (25th percentile) to 289 min (75th percentile). ' 2005 Wiley-Liss, Inc.

Key words: prehospital ECG; telemedicine; emergency room

INTRODUCTION

The goal of mechanical reperfusion therapy in thesetting of acute ST segment elevation myocardial in-farction (MI) is to reestablish blood flow to the af-fected vascular bed as quickly as possible. Primaryangioplasty has been shown to be superior to fibrinoly-sis when door-to-balloon time is less then 60 min [1].The DANAMI-2 trial [2] demonstrated that primaryangioplasty is superior to fibrinolytic therapy evenwhen patients needed transport from local hospitals tocenters experienced in providing mechanical reperfusiontherapy, provided that the transport time is 120 min orless. Unfortunately, according to the U.S. report fromthe National Registry of Myocardial Infarction (NRMI)4, median door-to-balloon time in the United States is185 min [3] and only 3% of patients are currently beingmechanically reperfused within the 90-min time windowas recommended by ACC/AHA guidelines [4]. Due to avariety of practical and logistical issues, timely accessto primary percutaneous coronary intervention is stillnot available for the majority of patients suffering fromacute ST segment elevation MI. To see if a moreaggressive approach involving emergency medical serv-

ices (EMS), emergency room (ER) personnel, and thecardiac interventional team could improve reperfusiontimes, patients were transported from the field directlyto the catheterization laboratory by EMS without thedelay necessitated by ER admission and triage.

MATERIALS AND METHODS

This was a pilot study to evaluate the feasibility ofprehospital electrocardiogram (ECG) utilization to tri-age patients with ST segment elevation MI (STEMI)directly to the cardiac catheterization laboratory. A 12-

Providence Heart Institute, Southfield, Michigan

*Correspondence to: Dr. Shukri W. David, Providence Heart Institute,

16001 West Nine Mile Road, Southfield, MI 48075.

E-mail: Shukri.David@providence-stjohnhealth.org

Received 16 December 2004; Revision accepted 31 May 2005

DOI 10.1002/ccd.20505

Published online 13 October 2005 in Wiley InterScience (www.

interscience.wiley.com).

' 2005 Wiley-Liss, Inc.

Catheterization and Cardiovascular Interventions 66:316–319 (2005)

lead ECG in patients with symptoms suggestive ofacute myocardial infarction was obtained by EMS per-sonnel during initial patient assessment in the field andimmediately transmitted to the ER physician by cellu-lar link. A Lifepak 12 defibrillator/monitor unit (Med-tronic, Minneapolis, MN), part of routine monitoringequipment in many EMS vehicles in the United Statesand capable of generating 12-lead ECGs in the field, aconventional cellular phone, and a computer receivingstation (Lifenet RS receiving station; Medtronic) lo-cated in the ER were used to receive analog ECG data,convert to a digital tracing, and generate a hardcopyfor review by the ER physician. The protocol wasapproved by the Providence Hospital and Medical Cen-ter Institutional Review Board.

RESULTS

From October 2003 to October 2004, 71 ECGs weretransmitted to the ER. Five ECGs (7.0%) failed totransmit most commonly because of failure of the cellu-lar phone to receive an adequate signal. Out of the 66(93.0%) patients who had an adequate ECG transmittedto the ER, 6 patients with ST elevation myocardialinfarction were enrolled. Five patients had an acuteinferior wall MI and one patient had an acute anteriorwall MI. After transmission of a 12-lead ECG from thefield, the ER physician reviewed the tracing and acti-vated the interventional call team. Cellular transmissiontime of the ECGs was less than 1 min and the qualityof the transmitted tracings was excellent (Fig. 1). Threepatients were transported to the ER during daytimehours and the remaining patients were treated duringoff-hours (5:00 PM to 7:00 AM). Patients were trans-ported to the hospital with an average combined fieldand transport time of 32 6 6.7 min (Table I).Upon arrival to the hospital, patients underwent brief

medical examination by the ER physician. Subse-quently, they were transported to the cardiac catheter-ization laboratory with an average door-to-catheteriza-

tion laboratory transit time of 18 6 13.1 min. Becausethe catheterization team was mobilized when the trac-ing was received from the field, the laboratory teamwas already prepared to accept the patient. Five pa-tients had a complete occlusion of their proximal rightcoronary artery (RCA). The remaining patient had asubtotal occlusion of the ostial segment of the leftanterior descending artery (LAD) with a large clot bur-den (Table I). Reperfusion was achieved by predilationwith a balloon and subsequent stent placement in fivepatients. Rheolytic thrombectomy was performed inthe patient with large LAD thrombus burden and onlyminimal residual stenosis was seen in the procedure.All six patients had brisk TIMI grade 3 flow to theaffected vascular bed, resolution of ECG changes, andcomplete relief of chest discomfort. Mean door-to-bal-loon time was 44 6 17.4 min. Subsequent enzyme val-ues confirmed acute myocardial infarction. All sixpatients were discharged within 72 hr of admission.

DISCUSSION

There is a large evidence base supporting the findingthat reducing time to reperfusion in patients with acutemyocardial infarction reduces morbidity and mortality.This has been shown for coronary reperfusion therapyutilizing thrombolytics as well as mechanical reperfu-sion by percutaneous coronary intervention. Severalrandomized trials of thrombolytic therapy have demon-strated that mortality benefit as well as improved leftventricular function post myocardial infarction arestrongly dependent on the time from symptom onset toreperfusion therapy [5–7]. Similarly, Brodie et al. [8]demonstrated that 30-day mortality was lower andimprovement in left ventricular function was greater inpatients in whom mechanical reperfusion was achievedwithin 2 hr of symptom onset compared to patientsreperfused after 2 hr. Unfortunately, according to areport by Sutter [9] utilizing data from the NRMI 2[10] and NRMI 3 [11] databases, all of the participat-

Fig. 1. ECG obtained in the field.

Expedited Treatment of ST Elevation AMI 317

ing 1,876 U.S. hospitals in the study intervals from1994 through 2000 were found to deliver myocardialreperfusion therapy that did not meet the ACC/AHAguidelines [4]. More recently, in the NRMI 4, a major-ity of cardiac centers in the United States were still un-able to establish timely reperfusion therapy; median door-to-balloon time in the United States remained 185 min[3]. The use of a prehospital ECG in patients withacute MI has been shown to help reduce door-to-ther-apy time. Kereiakes et al. [12] found a significantreduction in in-hospital delay to thrombolytic therapywhen a prehospital ECG was transmitted from the fieldto the hospital. In this study, median in-hospital delaywas 30 min with the use of prehospital ECGs com-pared to 50 min in patients transported to the hospitalby EMS without prehospital ECG. In the NRMI2 [13],patients who received a prehospital 12-lead ECG had ashorter median time to either fibrinolytic therapy (30vs. 40 min) or primary angioplasty (92 vs. 115 min)and improved in-hospital mortality. There was also a

significant reduction of in-hospital mortality in patientsin whom prehospital ECGs had been utilized (12% vs.8%). In a study by Wall et al. [14], prehospital ECGswere obtained by EMS and transmitted to the ER in50 consecutive patients with acute MI. Door-to-balloontime was found to be 80 min in this group of patients,which compared favorably to a historical control groupof patients that were treated by the same investigatorsearlier without the use of prehospital ECG (door-to-balloon time of 109 min).In this pilot study, prehospital ECGs were transmitted

from the field to the ER utilizing cellular phone technol-ogy in patients who subsequently underwent stent place-ment (five patients) or rheolytic thrombectomy (onepatient) for acute myocardial infarction. By advancedtransmission of electrocardiograms to the ER while thepatient was in the field, the transit time through the ERwas minimized and the on-call team activated much ear-lier than would otherwise have been the case (Fig. 2).Our historical door-to-balloon time was reduced from a

Fig. 2. Modified diagram from Antman et al. [4].

TABLE I. Timing and Characteristics of Mechanical Revascularization

Patient 1 Patient 2 Patient 3 Patient 4 Patient 5 Patient 6

EMS response time 4 min 4 min 6 min 6 min 7 min 7 min

Triage and transport

by EMS

38 min 38 min 26 min 36 min 22 min 33 min

Door-to-balloon time 25 min 23 min 39 min 61 min 57 min 59 min

Vessel involved Ostial RCA Proximal RCA Ostial LAD Proximal RCA Proximal RCA Proximal RCA

Pre-procedure flow TIMI 0 TIMI 0 TIMI 1 TIMI 0 TIMI 0 TIMI 0

Post-procedure flow TIMI 3 TIMI 3 TIMI 3 TIMI 3 TIMI 3 TIMI 3

PCI treatment 4.0 3 18 mm stent 3.0 3 23 mm stent Rheolytic

thrombectomy

3.5 3 18 mm stent 3.0 3 33 mm and

3.0 3 12 mm stents

3.5 3 15 mm and

3.0 3 15 mm

Length of hospital stay 1 day 1 day 2 days 2 days 2 days 3 days

318 Sekulic et al.

previous 88 6 35 min without the use of prehospitalECG (data not shown) to 44 6 17.4 min in this study.All six patients were discharged from the hospitalwithin 72 hr in excellent condition. With the help ofcellular phone transmission technology, we were able totransmit the prehospital 12-lead ECGs to the hospital innear real time and generate high-quality ECG printoutsfor review by the ER physician. This resulted in signifi-cantly shorter door-to-balloon times than was previouslyreported in the literature. As a potential limitation ofthis technology, we noted that 7.0% of ECGs were notsuccessfully transmitted due to lack of adequate cellularphone signal.Widespread use of this technology has the potential

to expedite reperfusion therapy significantly in patientssuffering from out-of-hospital acute MI. These patientscould be preferentially transported to centers capableof delivering immediate mechanical reperfusion. Part-nership with the local EMS and close cooperationbetween emergency and cardiac services, along with in-novative technology, may offer the most timely accessto mechanical reperfusion for patients suffering fromacute ST elevation MI.

ACKNOWLEDGMENTS

The authors thank Dr. Zoltan Turi for reviewing thisarticle and Mr. Christopher Bissell for help in coordi-nating technical aspects of the project.

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