Prehospital triage and direct transport of patients with ST-elevation myocardial infarction to primary percutaneous coronary intervention centres: a systematic review and meta-analysis

Field triage to primary percutaneous coronary intervention: Factors influencing health-related quality of life for patients aged ≥70 and <70 years with non-complicated ST-elevation myocardial infarction

OBJECTIVE

To examine clinical and health-related quality of life (HRQOL) outcomes and predictors of HRQOL for uncomplicated field triage ST-elevation myocardial infarction (STEMI) patients aged ≥70 years and <70 years after primary percutaneous coronary intervention (PPCI).

BACKGROUND

Pre-hospital field triage for PPCI is associated with lower mortality but the impact of age and other factors on HRQOL remains unknown.

METHODS

77 field triage STEMI patients were assessed for HRQOL using the Short Form-12 (SF-12) and the Seattle Angina Questionnaire (SAQ) at 4 weeks and 6 months after PPCI.

RESULTS

Regression analysis showed improvements in SF-12 domains and angina stability for older people. Age predicted lower physical function (p = 0.001) and better SAQ QOL at 6 months (p = 0.003).

CONCLUSION

Age, length of hospitalization, recurrent angina and hypertension were important predictors of HRQOL with PPCI. Assessment of HRQOL combined with increased support for physical and emotional recovery is needed to improve clinical care for field triage PPCI patients.

Field triage in the ambulance versus referral via non-percutaneous coronary intervention centre in ST-elevation myocardial infarction patients undergoing primary percutaneous coronary intervention: A systematic review

AIMS

The purpose of this study was to determine whether direct ambulance transport of ST-elevation myocardial infarction (STEMI) patients to a percutaneous coronary intervention (PCI) hospital (field triage) leads to a lower 30-day mortality compared to transport via a referral non-PCI hospital (referral via a spoke centre) in STEMI patients.

METHODS AND RESULTS

We performed a systematic review of interventions. An experienced librarian searched in PubMed, EMBASE.com and The Cochrane Library (via Wiley) from January 1980-February 2013. Studies that examined field triage and/or referral via a spoke centre in STEMI patients treated with primary or facilitated PCI were included. Two authors independently conducted the study selection and data extraction. Multivariable frequency weighted logistic regression analysis was performed to assess the effect of the type of transfer on the outcome measures. We identified 14 randomised clinical trials (RCTs), including 20 transfer groups and 4474 participants. Thirty-day mortality was lower in patients who underwent field triage (3.0%; 95% confidence interval (CI) 2.2-4.2) compared to patients who were referred via a spoke centre (4.7%; 95% CI 4.0-5.5). In multivariable frequency weighted logistic regression analysis, field triage was independently associated with a lower incidence of 30-day mortality (odds ratio (OR): 0.58; 95% CI 0.37-0.89).

CONCLUSION

Field triage compared to referral via a spoke centre leads to a lower 30-day mortality in STEMI patients. Therefore, direct ambulance transport to a PCI hospital should become the transfer type for STEMI patients.

The availability of prior ECGs improves paramedic accuracy in recognizing ST-segment elevation myocardial infarction

INTRODUCTION

Early and accurate identification of ST-elevation myocardial infarction (STEMI) by prehospital providers has been shown to significantly improve door to balloon times and improve patient outcomes. Previous studies have shown that paramedic accuracy in reading 12 lead ECGs can range from 86% to 94%. However, recent studies have demonstrated that accuracy diminishes for the more uncommon STEMI presentations (e.g. lateral). Unlike hospital physicians, paramedics rarely have the ability to review previous ECGs for comparison. Whether or not a prior ECG can improve paramedic accuracy is not known.

STUDY HYPOTHESIS

The availability of prior ECGs improves paramedic accuracy in ECG interpretation.

METHODS

130 paramedics were given a single clinical scenario. Then they were randomly assigned 12 computerized prehospital ECGs, 6 with and 6 without an accompanying prior ECG. All ECGs were obtained from a local STEMI registry. For each ECG paramedics were asked to determine whether or not there was a STEMI and to rate their confidence in their interpretation. To determine if the old ECGs improved accuracy we used a mixed effects logistic regression model to calculate p-values between the control and intervention.

RESULTS

The addition of a previous ECG improved the accuracy of identifying STEMIs from 75.5% to 80.5% (p=0.015). A previous ECG also increased paramedic confidence in their interpretation (p=0.011).

CONCLUSIONS

The availability of previous ECGs improves paramedic accuracy and enhances their confidence in interpreting STEMIs. Further studies are needed to evaluate this impact in a clinical setting.

Long-term prognostic benefit of field triage and direct transfer of patients with ST-segment elevation myocardial infarction treated by primary percutaneous coronary intervention

Direct transfer (DT) to the catheterization laboratory has been demonstrated to reduce delays in primary percutaneous coronary intervention (PPCI). However, data with regard to its effect on long-term mortality are sparse. The aim of this study was to investigate the effect of DT on long-term mortality in patients with ST-segment elevation myocardial infarctions treated with PPCI. A cohort study was conducted of 1,859 patients (mean age 63.1 ± 13 years, 80.2% men) who underwent PPCI from May 2005 to December 2010. From the whole series, 425 patients (23%) were admitted by DT and 1,434 (77%) by emergency departments. DT patients were younger (mean age 61 ± 12 vs 64 ± 12 years, p = 0.017), were more frequently men (86% vs 76%, p = 0.001), and had a higher proportion of abciximab use (77% vs 64%, p <0.0001). The DT group had a shorter median contact-to-balloon time (105 vs 122 minutes, p <0.0001) and a shorter time to treatment (185 vs 255 minutes, p <0.0001) compared with the emergency department group. Thirty-day and long-term mortality (median follow-up 2.4 years, interquartile range 1.6 to 3.2) were lower in the DT group (3% vs 6%, p = 0.049, and 9.4% vs 14.4%, p = 0.008, respectively). An adjusted Cox regression analysis proved that the DT group had an improved prognosis during follow-up (hazard ratio 0.71, 95% confidence interval 0.50 to 0.99). In conclusion, DT of patients with ST-segment elevation myocardial infarctions for PPCI was associated with fewer delays and improved survival. This benefit was maintained after long follow-up. This strategy should be emphasized in all networks of ST-segment elevation myocardial infarction care.

Endothelin-B Receptors and Left Ventricular Dysfunction after Regional versus Global Ischaemia-Reperfusion in Rat Hearts

Background. Endothelin-1 (ET-1) is implicated in left ventricular dysfunction after ischaemia-reperfusion. ETA and ETB receptors mediate diverse actions, but it is unknown whether these actions depend on ischaemia type and duration. We investigated the role of ETB receptors after four ischaemia-reperfusion protocols in isolated rat hearts. Methods. Left ventricular haemodynamic variables were measured in the Langendorff-perfused model after 40- and 20-minute regional or global ischaemia, followed by 30-minute reperfusion. Wild-type (n = 39) and ETB-deficient (n = 41) rats were compared. Infarct size was measured using fluorescent microspheres after regional ischaemia-reperfusion. Results. Left ventricular dysfunction was more prominent in ETB-deficient rats, particularly after regional ischaemia. Infarct size was smaller (P = 0.006) in wild-type (31.5 ± 4.4%) than ETB-deficient (45.0 ± 7.3%) rats after 40 minutes of regional ischaemia-reperfusion. Although the recovery of left ventricular function was poorer after 40-minute ischaemia-reperfusion, end-diastolic pressure in ETB-deficient rats was higher after 20 than after 40 minutes of regional ischaemia-reperfusion. Conclusion. ETB receptors exert cytoprotective effects in the rat heart, mainly after regional ischaemia-reperfusion. Longer periods of ischaemia suppress the recovery of left ventricular function after reperfusion, but the role of ETB receptors may be more important during the early phases.

Defining and measuring successful emergency care networks: a research agenda

The demands on emergency services have grown relentlessly, and the Institute of Medicine (IOM) has asserted the need for "regionalized, coordinated, and accountable emergency care systems throughout the country." There are large gaps in the evidence base needed to fix the problem of how emergency care is organized and delivered, and science is urgently needed to define and measure success in the emerging network of emergency care. In 2010, Academic Emergency Medicine convened a consensus conference entitled "Beyond Regionalization: Integrated Networks of Emergency Care." This article is a product of the conference breakout session on "Defining and Measuring Successful Networks"; it explores the concept of integrated emergency care delivery and prioritizes a research agenda for how to best define and measure successful networks of emergency care. The authors discuss five key areas: 1) the fundamental metrics that are needed to measure networks across time-sensitive and non-time-sensitive conditions; 2) how networks can be scalable and nimble and can be creative in terms of best practices; 3) the potential unintended consequences of networks of emergency care; 4) the development of large-scale, yet feasible, network data systems; and 5) the linkage of data systems across the disease course. These knowledge gaps must be filled to improve the quality and efficiency of emergency care and to fulfill the IOM's vision of regionalized, coordinated, and accountable emergency care systems.

Prediction of critical illness during out-of-hospital emergency care

CONTEXT

Early identification of nontrauma patients in need of critical care services in the emergency setting may improve triage decisions and facilitate regionalization of critical care.

OBJECTIVES

To determine the out-of-hospital clinical predictors of critical illness and to characterize the performance of a simple score for out-of-hospital prediction of development of critical illness during hospitalization.

DESIGN AND SETTING

Population-based cohort study of an emergency medical services (EMS) system in greater King County, Washington (excluding metropolitan Seattle), that transports to 16 receiving facilities.

PATIENTS

Nontrauma, non-cardiac arrest adult patients transported to a hospital by King County EMS from 2002 through 2006. Eligible records with complete data (N = 144,913) were linked to hospital discharge data and randomly split into development (n = 87,266 [60%]) and validation (n = 57,647 [40%]) cohorts.

MAIN OUTCOME MEASURE

Development of critical illness, defined as severe sepsis, delivery of mechanical ventilation, or death during hospitalization.

RESULTS

Critical illness occurred during hospitalization in 5% of the development (n = 4835) and validation (n = 3121) cohorts. Multivariable predictors of critical illness included older age, lower systolic blood pressure, abnormal respiratory rate, lower Glasgow Coma Scale score, lower pulse oximetry, and nursing home residence during out-of-hospital care (P < .01 for all). When applying a summary critical illness prediction score to the validation cohort (range, 0-8), the area under the receiver operating characteristic curve was 0.77 (95% confidence interval [CI], 0.76-0.78), with satisfactory calibration slope (1.0). Using a score threshold of 4 or higher, sensitivity was 0.22 (95% CI, 0.20-0.23), specificity was 0.98 (95% CI, 0.98-0.98), positive likelihood ratio was 9.8 (95% CI, 8.9-10.6), and negative likelihood ratio was 0.80 (95% CI, 0.79- 0.82). A threshold of 1 or greater for critical illness improved sensitivity (0.98; 95% CI, 0.97-0.98) but reduced specificity (0.17; 95% CI, 0.17-0.17).

CONCLUSIONS

In a population-based cohort, the score on a prediction rule using out-of-hospital factors was significantly associated with the development of critical illness during hospitalization. This score requires external validation in an independent population.