Digitally-Assisted Reperfusion Strategy Leads to Faster Treatment of Heart Attacks

Digitally-Assisted Reperfusion Strategy Leads to Faster Treatment of Heart Attacks

Guidelines for reperfusion in ST-elevation myocardial infarction (STEMI) were recently adopted by the Canadian Cardiovascular Society. We have developed a blended model of prehospital thrombolytic (PHL) therapy or primary percutaneous coronary intervention (PPCI) activation, in order to achieve guideline times.

Methods

In our urban centre of 658,700 people, emergency medical services (EMS) were trained to perform and screen electrocardiograms (ECGs) for suspected STEMI. Suspected ECGs were transmitted to a physician’s hand-held device. If the physician confirmed the diagnosis they coordinated initiation of either PHL or PPCI. In cases where physicians found the prehospital ECG negative for STEMI (PHENST), patients were transported to the closest emergency room.

Results

From July 21, 2008 to July 21, 2010, the Cardiac Outcomes Through Digital Evaluation (CODE) STEMI project received 380 transmitted calls. There were 226 confirmed STEMI by the on-call physician, 158 (70%) received PPCI, 48 (21%) received PHL, and 20 (9%) had angiography but no revascularization. The PPCI, median time from first medical contact to reperfusion was 76 minutes (interquartile range [IQR], 64-93). For PHL, median time from first medical contact to needle was 32 minutes (IQR, 29-39). The overall mortality rate for the STEMI patients was 8% (PHL = 4 [8.3%], PPCI = 8 [5%], medical therapy = 7 [35%]). There were 154 PHENST patients, 44% later diagnosed with acute coronary syndrome. The mortality rate for PHENST was 14%.

Conclusions

Through a model of EMS prehospital ECG interpretation, digital transmission, direct communication with a physician, and rapid coordinated service, we demonstrate that benchmark reperfusion times in STEMI can be achieved.

Résumé

Introduction

Des lignes directrices sur la reperfusion dans l’infarctus du myocarde (IM) avec sus-décalage du segment ST ont été récemment adoptées par la Société canadienne de cardiologie (SCC). Nous avons élaboré un modèle mixte d’activation du traitement thrombolytique préhospitalier (TPH) ou de l’intervention coronarienne percutanée primaire (ICPP) pour atteindre les délais recommandés par les lignes directrices.

Méthodes

Dans notre centre urbain de 658 700 personnes, les services médicaux d’urgence (SMU) étaient formés pour exécuter et évaluer les électrocardiogrammes (ECG) lors de suspicion d’IM avec sus-décalage du segment ST. Les ECG suspects étaient transmis au terminal mobile d’un médecin. Si le médecin confirmait le diagnostic, ils coordonnaient le TPH ou l’ICPP. Dans les cas où les médecins trouvaient un ECG préhospitalier négatif pour l’IM avec sus-décalage du segment ST (PHENST), les patients étaient transportés à la salle des urgences la plus proche.

Résultats

Du 21 juillet 2008 au 21 juillet 2010, le projet STEMI (ST-elevation myocardial infarction : IM avec sus-décalage du segment ST) de la Cardiac Outcomes Through Digital Evaluation (CODE) a reçu 380 appels. Il y eu 226 cas d’IM avec sus-décalage du segment ST confirmés par le médecin sur appel, 158 (70 %) ont subi une ICPP, 48 (21 %) ont subi un TPH et 20 (9 %) ont passé une angiographie, mais n’ont pas eu de revascularisation. Pour l’ICPP, le temps médian du premier contact médical à la reperfusion a été de 76 minutes (intervalle interquartile [IIQ], 64-93). Pour le TPH, le temps médian du premier contact médical à l’injection a été de 32 minutes (IIQ, 29-39). Le taux de mortalité global des patients ayant un IM avec sus-décalage du segment ST a été de 8 % (TPH = 4 [8,3 %], ICPP = 8 [5 %], traitement médical = 7 [35 %]). Des 154 patients qui ont eu une PHENST, 44 % ont reçu plus tard un diagnostic de syndrome coronarien aigu. Le taux de mortalité des patients ayant eu une PHENST a été de 14 %.

Conclusions

Par un modèle d’interprétation d’ECG préhospitalières par les SMU, la transmission numérique, la communication directe avec un médecin et un service rapide bien coordonné, nous avons démontré que les délais de référence pour la reperfusion lors d’IM avec sus-décalage du segment ST peuvent être atteints.

Philadelphia, PA, July 20, 2012– A new program that trains emergency medical service technicians (EMS) to read electrocardiograms so that they can evaluate patients with chest pain, and expedite treatment for the severe heart condition known as ST-segment elevation myocardial infarction (STEMI), a serious form of heart attack, has excellent results and should become the standard of care, according to two studies published in the current issue of the Canadian Journal of Cardiology.

“It’s well established that morbidity and mortality in myocardial infarctions is directly related to the duration of ischemia, and delays in restoring the flow of blood to the heart of even 30 minutes have been associated with an increase in mortality,” says lead investigator Robin A. Ducas, MD, of the University of Manitoba, Winnipeg, Canada. “By training EMS to administer and interpret ECGs at the scene, with oversight from an on-call physician, we demonstrated that we could achieve benchmark times from first medical contact to treatment.”

An audit of hospitals in Manitoba in 2005 had previously revealed that only 14% of patients received thrombolysis, the administration of drugs to dissolve blood clots, within 30 minutes from first medical contact, and only 11% received primary percutaneous coronary intervention (PPCI, or angioplasty) within 90 minutes of first medical contact, the benchmark established by leading heart associations, including the Canadian Cardiovascular Society.

To address this, a system of pre-hospital ECG interpretation and triage was developed. EMS receive additional training in administering and interpreting ECGs for signs of STEMI. When EMS suspect STEMI, the ECG is transmitted to the hand-held device of the on-call physician for confirmation. When STEMI is confirmed, the physician directs EMS to begin pre-hospital thrombolysis (PHL) or to alert the PPCI laboratory at the hospital to prepare for the patient. Transmission of the ECG allows for a real-time conversation between the physician and EMS, decreases false positive test results for STEMI, and improves resource allocation by decreasing activation of the catheterization laboratory when it is not warranted. The emergency room is bypassed in positive cases, and patients are directly transported to the cardiology department or the PPCI laboratory. In cases in which the physician finds the ECG negative for STEMI (PHENST), patients are transported to the nearest emergency room.

The investigators evaluated 380 cases from July 2008 to July 2010. Of 226 patients confirmed with STEMI, 70% received PPCI, 21% received PHL, and 20% underwent coronary angiography without revascularization. The median time from first medical contact to treatment in the PHL treatment group was 32 minutes. In the PPCI group, the median time was 76 minutes. In the PHENST group, 41% were directed to a hospital capable of PPCI and 59% were sent to one of the six other hospitals in the system. They presented more often outside of normal catheterization laboratory hours. 44% were diagnosed with acute coronary syndromes, including seven cases of missed STEMI, and a higher mortality rate.

“The adoption of similar strategies in other urban areas could allow for achievement of guideline times, particularly for PPCI and regardless of the time of day,” says Dr. Ducas. “Transfer of patients with suspicious but negative ECG for STEMI (PHENST) to hospitals with comprehensive cardiac care may be warranted, and deserves further consideration.”

In a related study, Dr. Ducas and her team audited 703 cases evaluated by EMS. 323 cases were evaluated as negative for STEMI and therefore were not transmitted to the on-call physician. Upon arrival at the nearest emergency room, 52% received a diagnosis of “nonspecific chest pain” and were subsequently discharged; one case of STEMI was missed, and 2 other patients developed STEMI after arrival at the hospital. 25% had a cardiovascular diagnosis after physician evaluation.

The ECGs of 380 patients were evaluated as positive and transmitted. Of this group, physicians suspected 226 cases of STEMI, of which 96.9% were confirmed. The false activation of the catheterization lab occurred in only seven of the 226 cases, and the physician missed the diagnosis in seven cases.

“The high level of false positives is a concern, given the risk of treatment,” notes Dr. Ducas. “We do not have a clear guide as to what are acceptable levels of false positives and negatives. However, we have found both in the literature and in our own study that EMS pre-hospital ECG interpretation is fast, reliable, and plays a pivotal role in the care for patients with STEMI.”

In an editorial accompanying the articles, Robert C. Welsh, MD, FRCPC, FAHA, FACC, of the Department of Medicine, University of Alberta and the Mazankowski Alberta Heart Institute, Edmonton, Alberta, Canada, says, “Our colleagues describe a program which provides the optimal platform to advance STEMI care in Canada. Although this approach is dependent on a motivated group of physicians willing to invest additional time and energy to deliver enhanced STEMI care, it allows pre-hospital confirmation of diagnosis, individual patient risk stratification, immediate decision regarding the optimal mode of reperfusion, and expansion of optimal systems of care to rural patients.”

A mobile technology allowing for immediate review of ECGs in the field has led to faster treatment of heart attacks and has saved many lives. Myocardial infarction (MI) is a leading cause of death in both men and women in the United States. Standards of care in treating acute MI include administration of thrombolytics within 30 minutes of symptoms and/or cardiac catheterization within 90 minutes. Unfortunately, these quality measures are often not met due to constraints such as travel time to the clinic.

Investigators at the University of Manitoba in Canada have addressed this issue by pioneering a strategy whereby trained emergency medical technicians (EMTs) who suspect a heart attack can transmit the patient’s ECG to a physician’s mobile phone. After confirming that the patient is indeed having a heart attack, the physician instructs the EMTs to initiate thrombolysis or to alert the catheterization lab to get ready. Furthermore, the number of false positive test results has decreased, improving resource allocation and potentially saving millions of dollars in unneeded procedures. Published recently in the Canadian Journal of Cardiology, results of the study showed that the program doubled the number of patients who received appropriate thrombolysis. Furthermore, the number who received appropriate catheterization increased by nearly 7-fold. The authors now recommend that this “Cardiac Outcomes Through Digital Evaluation (CODE) STEMI” program be the standard of care in ER settings.

Source : http://www.sciencedirect.com/science/article/pii/S0828282X12000542

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