Prehospital 12-Lead ECG to Triage ST-Elevation Myocardial Infarction and Emergency Department Activation of the Infarct Team Significantly Improves Door-to-Balloon Times

Mortality and ST resolution in patients admitted with STEMI: the MOMI survey of emergency service experience in a complex urban area

BACKGROUND

Since 2001, the urban area of Milan has been operating a network among 23 cardiac care units, the 118 dispatch centre (national free number for medical emergencies), and the county government health agency called Group for Prehospital Cardiac Emergency.

METHODS AND RESULTS

In order to monitor the network activity, time to treatment, and clinical outcome, a periodic survey, called MOMI(2), was repeated two or three times a year. Each survey lasted 30 days and was repeated in comparable periods. Data were stratified for hospital admission mode. We collected data concerning 708 consecutive ST-elevation myocardial infarction (STEMI) patients (male 72.6%; mean age 64.4 years). In these six surveys, we observed a high rate of primary percutaneous coronary intervention (73.2%) and a mortality rate of 6.3%. Using advanced statistical models, we identified age, Killip class, and the symptom onset-to-balloon time as most relevant prognostic factors. Nonparametric test showed that the modality of hospital admittance was the most critical determinant of door-to-balloon time. 12-lead ECG tele-transmission and activation of a fast track directly to the catheterization laboratory are easy action to reduce time to treatment.

CONCLUSIONS

The experience of the Milan network for cardiac emergency shows how a network coordinating the community, rescue units, and hospitals in a complex urban area and making use of medical technology contributes to the health care of patients with STEMI.

Comparative Effectiveness of Population Interventions to Improve Access to Reperfusion for ST-Segment–Elevation Myocardial Infarction in Australia

Background—

Improving timely access to reperfusion is a major goal of ST-segment–elevation myocardial infarction care. We sought to compare the population impact of interventions proposed to improve timely access to reperfusion therapy in Australia.

Methods and Results—

Australian hospitals, population, and road network data were integrated using Geographical Information Systems. Hospitals were classified into those that provided primary percutaneous coronary intervention (PPCI) or fibrinolysis. Population impact of interventions proposed to improve timely access to reperfusion (PPCI, fibrinolysis, or both) were modeled and compared. Timely access to reperfusion was defined as the proportion of the population capable of reaching a fibrinolysis facility ≤60 minutes or a PPCI facility ≤120 minutes from emergency medical services activation. The majority (93.2%) of the Australian population has timely access to reperfusion, mainly (53%) through fibrinolysis. Only 40.2% of the population had timely access to PPCI, and access to PPCI services is particularly limited in regional and nonexistent in remote areas. Optimizing the emergency medical services’ response or increasing PPCI services resulted in marginal improvement in timely access (1.8% and 3.7%, respectively). Direct transport to PPCI facilities and interhospital transfer for PPCI improves timely access to PPCI for 19.4% and 23.5% of the population, respectively. Prehospital fibrinolysis markedly improved access to timely reperfusion in regional and remote Australia.

Conclusions—

Significant gaps in timely provision of reperfusion remain in Australia. Systematic implementation of changes in service delivery has potential to improve timely access to PPCI for a majority of the population and improve access to fibrinolysis to those living in regional and remote areas.

Rates of Cardiac Catheterization Cancelation for ST-Segment Elevation Myocardial Infarction After Activation by Emergency Medical Services or Emergency Physicians

Background—

For patients with an acute ST-segment elevation myocardial infarction, cardiac catheterization laboratory (CCL) activation by emergency medical technicians or emergency physicians has been shown to substantially reduce treatment times. One drawback to this approach involves overtriage, whereby CCL staffs are activated for patients who ultimately do not require emergent coronary angiography or for patients who undergo angiography but are not found to have coronary artery occlusion.

Methods and Results—

We examined CCL activation at 14 primary angioplasty hospitals to determine the course of management, including the rate of inappropriate activation. Among 3973 activations (29% by emergency medical technicians, 71% by emergency physicians) between December 2008 and December 2009, appropriate CCL activations occurred for 3377 patients (85%), with 2598 patients (76.9% of appropriate activations) receiving primary percutaneous coronary intervention. Reasons for inappropriate activations (596 patients; 15%) included ECG reinterpretations (427 patients; 72%) or the fact that the patient was not a CCL candidate (169 patients; 28%). The rate of cancellation because of reinterpretation of emergency medical technicians' ECG (6% of all activations) was more common than for cancellation because of reinterpretation of emergency physicians' ECG (4.6%).

Conclusions—

This represents the first report of the rates of CCL cancellation for ST-segment elevation myocardial infarction system activation by emergency medical technicians and emergency physicians in a large group of hospitals organized within a statewide program. The high rate of coronary intervention and relatively low rate of inappropriate activation suggest that systematic CCL activation by emergency personnel on a broad scale is feasible and accurate, and these rates set a benchmark for ST-segment elevation myocardial infarction systems.

Most Important Papers in ST-Elevation Myocardial Infarction

The following are highlights from the series, Circulation: Cardiovascular Interventions Topic Review. This series summarizes the most important manuscripts, as selected by the editors, that have published in the Circulation portfolio. The studies included in this article represent the most noteworthy research in the area of ST-elevation myocardial infarction. ( Circ Cardiovasc Interv. 2011;4:e55–e66.)

Public awareness of heart attack symptoms: what should we look for and how will it help?

The following article is a correction to a previously published version: Fang J. Public awareness of heart attack symptoms: what should we look for and how will it help? Future Cardiol. 6(5) 563–565 (2010). These corrections were made owing to concerns being raised regarding similarity between sections of the text with previously published works. The bolded sections correspond to the corrected sections and are therefore different to the previously published version. For clarity, the corrected article is published in full below.

Serial prehospital 12-lead electrocardiograms increase identification of ST-segment elevation myocardial infarction

BACKGROUND

Many prehospital protocols require acquisition of a single 12-lead electrocardiogram (ECG) when assessing a patient for ST-segment elevation myocardial infarction (STEMI). However, it is known that ECG evidence of STEMI can evolve over time.

OBJECTIVES

To determine how often the first and, if necessary, second or third prehospital ECGs identified STEMI, and the time intervals associated with acquiring these ECGs and arrival at the emergency department (ED).

METHODS

We retrospectively analyzed 325 consecutive prehospital STEMIs identified between June 2008 and May 2009 in a large third-service emergency medical services (EMS) system. If the first ECG did not identify STEMI, protocol required a second ECG just before transport and, if necessary, a third ECG before entering the receiving ED. Paramedics who identified STEMI at any time bypassed participating local EDs, taking patients directly to the percutaneous coronary intervention (PCI) center. Paramedics used computerized ECG interpretation with STEMI diagnosis defined as an "acute MI" report by GE/Marquette 12-SL software in ZOLL E-series defibrillator/cardiac monitors (ZOLL Medical, Chelmsford, MA). We recorded the time of each ECG, and the ordinal number of the diagnostic ECG. We then determined the number of cases and frequency of STEMI diagnosis on the first, second, or third ECG. We also measured the interval between ECGs and the interval from the initial positive ECG to arrival at the ED. Results. STEMI was identified on the first prehospital ECG in 275 cases, on the second ECG in 30 cases, and on the third ECG in 20 cases (cumulative percentages of 84.6%, 93.8%, and 100%, respectively). For STEMIs identified on the second or third ECG, 90% were identified within 25 minutes after the first ECG. The median times from identification of STEMI to arrival at the ED were 17.5 minutes, 11.0 minutes, and 0.7 minutes for STEMIs identified on the first, second, and third ECGs, respectively.

CONCLUSIONS

A single prehospital ECG would have identified only 84.6% of STEMI patients. This suggests caution using a single prehospital ECG to rule out STEMI. Three serial ECGs acquired over 25 minutes is feasible and may be valuable in maximizing prehospital diagnostic yield, particularly where emergent access to PCI exists.

Effect of emergency department in-hospital tele-electrocardiographic triage and interventional cardiologist activation of the infarct team on door-to-balloon times in ST-segment-elevation acute myocardial infarction

Current guidelines recommend that >75% of patients with ST-elevation myocardial infarction (STEMI) receive primary percutaneous coronary intervention (PPCI) within 90 minutes. The goal has been hardly achievable, so we conducted a 2-year before-and-after study to determine the impact of emergency department (ED) tele-electrocardiographic (tele-ECG) triage and interventional cardiologist activation of the infarct team at door-to-balloon time (D2BT) and the proportion of patients undergoing PPCI within 90 minutes since arrival. In total 105 consecutive patients with acute STEMI (mean age 62 ± 13 years, 82% men) were studied, 54 before and 51 after the change in protocol. The 51patients in the tele-ECG group underwent tele-electrocardiography at the ED and electrocardiograms were transmitted to a third-generation mobile telephone of an on-call interventional cardiologist within 10 minutes of ED arrival. The infarct team was activated and PPCI was performed by the interventional cardiologist. Fifty-four patients with acute STEMI who underwent PPCI in the year before implementation of tele-electrocardiography served as control subjects. Median D2BT of the tele-ECG group was 86 minutes, significantly shorter than the median time of 125 minutes of the control group (p <0.0001). The proportion of patients who achieved a D2BT <90 minutes increased from 44% in the control group to 76% in the tele-ECG group (p = 0.0001). In conclusion, implementation of ED tele-ECG triage and interventional cardiologist activation of the infarct team can significantly shorten D2BT and result in a larger proportion of patients achieving guideline recommendations.

[Analysis of reperfusion delay in patients with acute myocardial infarction treated with primary angioplasty based on first medical contact and time of presentation]

INTRODUCTION AND OBJECTIVES

In primary angioplasty, the interval between first medical contact (FMC) and reperfusion should be less than 120 minutes. The time to reperfusion varies depending on where FMC is established. Recent studies suggest longer times in patients presenting in off-hours. The objective is to evaluate the time intervals between the onset of symptoms and reperfusion according to where the FMC occurs and time of day of patient presentation.

METHODS

Prospective observational study of acute myocardial infarction patients treated with primary angioplasty (February 2007 to May 2009). Depending on the FMC, patients were classified as belonging to the hospital group (hospital with primary angioplasty), the transfer group (hospital without primary angioplasty), or the emergency medical system (EMS) group (out-of-hospital care). For each group, the prehospital delay, diagnostic delay, delay in activation and/or transfer, and procedure delay were recorded.

RESULTS

Primary angioplasty was performed in 457 patients: 155 in the hospital group, 228 in the transfer group and 72 in the EMS group. The median [interquartile range] door-to-reperfusion times were 80 [63-107], 148 [118-189] and 81 [66-98] minutes, respectively (P<.0001). The transfer group showed a greater delay in diagnosis (P<.0001) and delayed activation and/or transfer (P<.0001). The EMS group had the shortest total time due to a reduced prehospital delay (P=.001). No difference was found with regard to the time of presentation (P=.42).

CONCLUSIONS

Transfer group patients were treated later and EMS group patients much earlier. There were no differences in association with the time of presentation. The identification of inappropriate delays should enable the introduction of measures to improve the efficiency of treatment.

Delays in presentation with acute coronary syndrome in people with coronary artery disease in Australia and New Zealand

OBJECTIVES

To report time from the onset of symptoms to hospital presentation in Australian and New Zealand patients with subsequently confirmed acute coronary syndrome, and to identify factors associated with prehospital delay time in these patients.

METHODS

Patients with coronary artery disease enrolled in a randomized clinical trial testing an intervention to reduce delay in responding to acute coronary syndrome symptoms had been followed for 24 months. In cases of admission to the ED for possible acute coronary syndrome, medical records were reviewed to determine the diagnosis, prehospital delay time, mode of transport to the hospital and aspirin use before admission. Clinical and demographic data were taken from the trial database.

RESULTS

Patients (n= 140) had an average (SD) age of 67.3 (11.5) years; 36% were female. Two-thirds of patients went to hospital by ambulance and 89.3% had a final diagnosis of unstable angina. The median time from onset of symptoms to arrival at the ED was 2 h and 25 min (interquartile range 1:25-4:59); 12.1% arrived ≤ 1 h and 66% within 4 h. Multiple linear regression analysis showed that use of ambulance (Beta = 0.247, P= 0.012) and younger age (Beta = 0.198, P= 0.043) were independent predictors of shorter delay times.

CONCLUSION

The time from the onset of symptoms to hospital presentation was too long for maximal benefit from treatment in most patients. Further efforts are needed to reduce treatment-seeking delay in response to symptoms of acute coronary syndrome.