CARDIOLOGY/REVIEW ARTICLE
Systematic Review and Meta-analysis of the Benefits of Out-of-Hospital 12-Lead ECG and Advance Notification in ST-Segment Elevation Myocardial Infarction Patients Julian Nam, MSc; Kyla Caners, MD; James M. Bowen, BScPhm, MSc; Michelle Welsford, MD, ABEM, FRCP; Daria O’Reilly, PhD, MSc Study objective: To present a review of out-of-hospital identification of ST-segment elevation myocardial infarction patients transported by emergency medical services with 12-lead ECG and advance notification versus standard or no cardiac monitoring. Methods: EMBASE, PubMed, and the Cochrane Library were searched, using controlled vocabulary and keywords. Randomized controlled trials and observational studies were included. Outcomes included short-term mortality (30 days), door-to-balloon/needle time and/or first medical contact–to-balloon/needle time. Pooled estimates were determined, where appropriate. Results were stratified by percutaneous coronary intervention or fibrinolysis. Results: The search yielded 1,857 citations, of which 68 full-texts were reviewed and 16 studies met the final criteria: 15 included data on percutaneous coronary intervention and 3 on fibrinolysis (2 included both). Where percutaneous coronary intervention was performed, out-of-hospital 12-lead ECG and advance notification was associated with a 39% reduction in short-term mortality (8 studies; n¼6,339; risk ratio 0.61; 95% confidence interval 0.42 to 0.89; P¼.01; I2¼30%) compared with standard or no cardiac monitoring. Where fibrinolysis was performed, out-of-hospital 12-lead ECG and advance notification was associated with a 29% reduction in short-term mortality (1 study; n¼17,026; risk ratio 0.71; 95% confidence interval 0.54 to 0.93; P¼.01). First medical contact–to-balloon, door-to-balloon, and door-toneedle times were consistently reduced, though large heterogeneity generally precluded pooling. Conclusion: The present study adds to previous reviews by identifying and appraising the strength and quality of a larger body of evidence. Out-of-hospital identification with 12-lead ECG and aadvance notification was found to be associated with reductions in short-term mortality and first medical contact–to-balloon, door-to-balloon, and door-toneedle time. [Ann Emerg Med. 2013;-:1-20.] Please see page XX for the Editor’s Capsule Summary of this article. 0196-0644/$-see front matter Copyright © 2013 by the American College of Emergency Physicians. http://dx.doi.org/10.1016/j.annemergmed.2013.11.016
INTRODUCTION Background In patients with ST-segment elevation myocardial infarction (STEMI), ischemic time has been shown to be positively associated with mortality.1-6 In an effort to reduce ischemic time, many ambulances are now equipped to rapidly identify and triage a STEMI patient with the use of an out-of-hospital 12-lead ECG and advance notification. Out-of-hospital 12-lead ECG is a Class I recommendation from the American Heart Association/ American College of Cardiology and is similarly recommended by the Canadian Cardiovascular Society.7,8 These recommendations were largely based on historical studies and previous reviews of the utility of out-of-hospital 12lead ECG, but they had considerable imprecision in pooled mortality effectiveness estimates,9,10 perhaps owing to the limited number of included studies.11,12 Similarly, these reviews were primarily based on studies before the era of out-of-hospital triage of STEMI patients for percutaneous coronary intervention, which may enhance the effect of STEMI recognition. Finally,
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these reviews also included studies investigating out-of-hospital combination fibrinolysis with facilitated percutaneous coronary intervention. Current treatment guidelines, however, recommend against full-dose fibrinolytic therapy followed by routine, immediate percutaneous coronary intervention and recommend only selective use of facilitated strategies.13,14 When assessing interventions to reduce mortality in STEMI patients, previous reviews have focused on the surrogate time-toreperfusion outcomes of door-to-needle or door-to-balloon times.10,15 However, in recognition that emergency medical services (EMS) play an important role in the continuum of STEMI patient care, first medical contact–to-balloon or first medical contact–to-needle time—measured from the time EMS first assesses the patient—may be a preferred measure of system performance.3,4,8 Despite these limitations, the strong recommendations for out-of-hospital 12-lead ECG have had an influence on its implementation in the United States, Canada, and around the world. Although the use of out-of-hospital 12-lead ECG has
Annals of Emergency Medicine 1
Nam et al
Benefits of Out-of-Hospital 12-Lead ECG in STEMI Patients
Editor’s Capsule Summary
What is already known on this topic Rapid treatment of ST-elevation myocardial infarction decreases mortality and produces better outcomes. What question this study addressed This meta-analysis of 16 observational studies of outof-hospital 12-lead ECG compared with 3-lead or no monitoring was performed to refine the estimated mortality benefit in the percutaneous coronary intervention era and the temporal benefit from first (out-of-hospital) medical contact to reperfusion. What this study adds to our knowledge Out-of-hospital 12-lead ECG was associated with a 39% reduction in relative risk of 30-day mortality for percutaneous coronary intervention patients and a 21- to 78-minute reduction in first medical contact– to-balloon time. How this is relevant to clinical practice The existing literature confirms an important mortality benefit of out-of-hospital 12-lead ECG and advance emergency department notification in the percutaneous coronary intervention era, limited as in all meta-analyses by the validity of the individual studies and absence of publication bias.
expanded significantly in the last 10 years, not all ambulances have this capability and thus not all STEMI patients receive an out-of-hospital 12-lead ECG.16-18 The objective of the current review was to address the aforementioned issues and present an updated review of the literature related to out-of-hospital identification of STEMI patients transported by EMS with 12-lead ECG and advance notification compared with standard or no cardiac monitoring (no out-of-hospital identification and no advance notification).
MATERIALS AND METHODS Reporting of the present review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.19 A search strategy was constructed with controlled vocabulary (Medical Subject Headings or Emtree) and key words focusing on the concepts of “electrocardiogram,” “advance notification,” “emergency medical services,” and “myocardial infarction.” The search was limited to English-language publications and studies of humans. Search strategies are presented in Appendix E1 (available online at http://www.annemergmed.com). The 2 Annals of Emergency Medicine
following bibliographic databases were searched: EMBASE through OVID (1988 to 2013 week 10), PubMed (1988 to 2013 week 10), and Cochrane Central Register for Controlled Trials through Wiley (1988 to 2013 week 10). The search was restricted to 1988 onward because the landmark Second International Study of Infarct Survival–2 trial was published at this time, showing the benefits of streptokinase, aspirin, and combination streptokinase with aspirin in patients with acute myocardial infarction.20 Included studies of identified systematic reviews and meta-analyses were hand searched for inclusion. Studies were included if they had a comparative observational or randomized study design, if patients with STEMI were treated with primary percutaneous coronary intervention or fibrinolysis, if the intervention group included out-of-hospital identification with 12-lead ECG and advance notification, and if the control group included standard cardiac monitoring (3-lead ECG) or no monitoring. Outcomes of interest included short-term mortality (mortality within 30 days), first medical contact–to-balloon time (in minutes), first medical contact–to-needle time (in minutes), door-to-balloon time (in minutes), and door-to-needle time (in minutes). These outcomes were chosen after consideration of the intended effect of out-of-hospital management strategies on STEMI patients, as well as outcomes used in previous reviews. Inhospital mortality has been thought to closely approximate 30-day mortality and the 2 have been combined in a previous review.10 Mean values were abstracted where available. “First medical contact” was EMS contact, whereas “door” was the first hospital door. These definitions follow recommendations to address the larger system delay that is more relevant to the system than only a hospital delay metric. Studies were excluded if the control group included out-ofhospital identification, advance notification or activation protocols, or transportation to a destination other than the local emergency department (ED) (which may also have been a percutaneous coronary intervention center), either cohort group made use of out-of-hospital fibrinolysis, either cohort group included self-transported/walk-in patients, or the study enrolled fewer than 30 participants. A minimum sample size of 30 was chosen because a mean difference statistic relies on the samples behaving approximately normally; a general cutoff of 30 has been previously suggested.21 Titles and abstracts that met the inclusion criteria and were not excluded were selected for full-text screening. Afterward, citations that still met the inclusion criteria and were not excluded were included for final review. Title and abstract, as well as full-text screening, were assessed independently by 2 reviewers (J.N. and K.C.) in 2 stages, using predetermined screening forms. The reviewers were not blinded to authorship, journal, or year. Disagreements were resolved by consensus-based discussion. Data Collection and Processing The following study characteristics were abstracted by 1 reviewer: study design, country of origin, jurisdiction size, Volume
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no.
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:
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2013
Nam et al
Benefits of Out-of-Hospital 12-Lead ECG in STEMI Patients
protocol for ECG interpretation, protocol for advance notification or activation, presence of bypass eligibility, protocol for transport destination, presence of interhospital transfer, and patient inclusion and exclusion criteria. The reported outcomes for mortality and time intervals were abstracted by 1 reviewer. To validate the abstracted outcomes, a second reviewer compared the abstracted values to the original full text. Disagreements were resolved by consensus-based discussion. Study authors were contacted by e-mail for unpublished data when an outcome was incompletely reported (eg, the mean was reported but not the measure of variation) or where conference abstracts were included but no corresponding full text could be identified. Study quality was assessed with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology,22 which assesses the strength and quality of evidence with standardized criteria such as risk of bias, inconsistency, indirectness, imprecision, and publication bias. Funnel plots and Egger’s tests, using R 2.15.2 (R Foundation for Statistical Computing, Vienna, Austria), were performed where appropriate. Primary Data Analysis Agreement was calculated with the k statistic. For outcomes with nonsignificant c2 values for heterogeneity, pooled estimates were completed. All estimates were pooled with Review Manager 5.1.6 (Cochrane Collaboration). Short-term mortality was assessed with random-effects Mantel-Haenszel risk ratios. Time differences were assessed with random-effects inverse variance mean differences. Where the mean and SD were not reported, they were estimated with a previously proposed method by Hozo et al.23 In trials reporting only the interquartiles, the minimum and maximum were estimated by extending the interquartiles by half the interquartile range. Subgroup analyses were conducted for jurisdiction type, activation protocol, and country.
RESULTS The literature search was completed December 2012, with updates until March 2013. A flow diagram of the literature search results is presented in Figure 1. After duplicates were removed, there were 1,338 unique citations. The full texts of 68 citations were screened,11,12,16,17,24-87 with 16 studies included in the review12,16,74-87 and 52 studies excluded.11,17,24-73 Two studies reported outcomes separately for patients who received primary percutaneous coronary intervention and fibrinolysis.16,75 Therefore, although there were 16 studies included for qualitative review, 2 included data on percutaneous coronary intervention and fibrinolysis. In addition, in 2 studies it was not clear whether advance notification occurred.16,75 These were included in the analysis for 2 reasons. First, no risk of bias was determined because any potential effect of no advance notification would work against the observed reductions in Volume
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2013
Figure 1. Flow diagram of study inclusion. PCI, Percutaneous coronary intervention.
treatment delay. Second, in the more recent study conducted in 2007,16 it was likely that most, if not all, EMS that performed out-of-hospital identification also performed advance notification, which is indicative of EMS during the mid to late 2000s. In another study,75 sample sizes had to be inferred from the proportion of patients who received out-of-hospital ECG, stratified by primary intervention received (details in Appendix E1, available online at http://www.annemergmed.com). Although this practice had an effect on precision, it did not affect the point estimates themselves because they were reported directly. The k statistic for agreement was 0.81 for titles and abstracts screening and 0.80 for full-text screening. The raw agreement was 0.98 for titles and abstracts and 0.91 for full-text screening. Study characteristics of included studies are presented in Tables 1 and 2 for patients who received percutaneous coronary intervention and fibrinolysis, respectively. Generally, eligibility criteria were appropriately developed and applied in all studies. It was not clear whether the door-to-balloon time included the first hospital door for interhospital transfers in 1 study.16 This omission would favor the standard cardiac monitoring group. Finally, in one study, 1-year mortality was reported; authors provided 30-day estimates.83 In another, measures of dispersion were not available; authors provided the median and interquartile ranges.86 Annals of Emergency Medicine 3
Study
Type of Study/Setting
Intervention Group
Canto, 1997, n¼4,932, US75
Registry study; regional Diagnosis: source unclear; advance notification: jurisdiction of multiple PCI protocol unclear; bypass eligibility unclear; EMS centers transport protocol unclear
Diercks, 2009, n¼5,117, US16
Registry study; regional Diagnosis: source unclear; advance notification: jurisdiction of multiple PCI protocol unclear; bypass eligibility unclear; EMS transport protocol unclear. centers
Martinoni, 2011, n¼1,529, Italy81
Registry study; regional jurisdictions of multiple PCI centers
Carstensen, 2007, n¼301, Australia76
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Unclear. Likely EMS direct to local ED (PCI or non-PCI center); interhospital transfer excluded. Unclear, likely EMS direct to local ED (PCI or non-PCI center); interhospital transfer protocol unclear
Other Incl/Exclusion Incl: STEMI transported by EMS Excl: interhospital transfer
Outcomes Inhospital mortality, DTB, DTN
Incl: STEMI transported by EMS to DTB, DTN an ACTION hospital. Excl: pts not evaluated first in ED or cath lab, pts transferred to nonACTION hospital Diagnosis: cardiologist by telemetry, advance EMS direct to ED of PCI center; Incl: STEMI/LBBB, SO 10 PCI in STEMI/year. Diagnosis: emergency physician by telemetry; EMS direct to local ED (PCI/ Incl: STEMI, SO
Systematic Review and Meta-analysis of the Benefits of Out-of-Hospital 12-Lead ECG and Advance Notification in ST-Segment Elevation Myocardial Infarction Patients Julian Nam, MSc; Kyla Caners, MD; James M. Bowen, BScPhm, MSc; Michelle Welsford, MD, ABEM, FRCP; Daria O’Reilly, PhD, MSc Study objective: To present a review of out-of-hospital identification of ST-segment elevation myocardial infarction patients transported by emergency medical services with 12-lead ECG and advance notification versus standard or no cardiac monitoring. Methods: EMBASE, PubMed, and the Cochrane Library were searched, using controlled vocabulary and keywords. Randomized controlled trials and observational studies were included. Outcomes included short-term mortality (30 days), door-to-balloon/needle time and/or first medical contact–to-balloon/needle time. Pooled estimates were determined, where appropriate. Results were stratified by percutaneous coronary intervention or fibrinolysis. Results: The search yielded 1,857 citations, of which 68 full-texts were reviewed and 16 studies met the final criteria: 15 included data on percutaneous coronary intervention and 3 on fibrinolysis (2 included both). Where percutaneous coronary intervention was performed, out-of-hospital 12-lead ECG and advance notification was associated with a 39% reduction in short-term mortality (8 studies; n¼6,339; risk ratio 0.61; 95% confidence interval 0.42 to 0.89; P¼.01; I2¼30%) compared with standard or no cardiac monitoring. Where fibrinolysis was performed, out-of-hospital 12-lead ECG and advance notification was associated with a 29% reduction in short-term mortality (1 study; n¼17,026; risk ratio 0.71; 95% confidence interval 0.54 to 0.93; P¼.01). First medical contact–to-balloon, door-to-balloon, and door-toneedle times were consistently reduced, though large heterogeneity generally precluded pooling. Conclusion: The present study adds to previous reviews by identifying and appraising the strength and quality of a larger body of evidence. Out-of-hospital identification with 12-lead ECG and aadvance notification was found to be associated with reductions in short-term mortality and first medical contact–to-balloon, door-to-balloon, and door-toneedle time. [Ann Emerg Med. 2013;-:1-20.] Please see page XX for the Editor’s Capsule Summary of this article. 0196-0644/$-see front matter Copyright © 2013 by the American College of Emergency Physicians. http://dx.doi.org/10.1016/j.annemergmed.2013.11.016
INTRODUCTION Background In patients with ST-segment elevation myocardial infarction (STEMI), ischemic time has been shown to be positively associated with mortality.1-6 In an effort to reduce ischemic time, many ambulances are now equipped to rapidly identify and triage a STEMI patient with the use of an out-of-hospital 12-lead ECG and advance notification. Out-of-hospital 12-lead ECG is a Class I recommendation from the American Heart Association/ American College of Cardiology and is similarly recommended by the Canadian Cardiovascular Society.7,8 These recommendations were largely based on historical studies and previous reviews of the utility of out-of-hospital 12lead ECG, but they had considerable imprecision in pooled mortality effectiveness estimates,9,10 perhaps owing to the limited number of included studies.11,12 Similarly, these reviews were primarily based on studies before the era of out-of-hospital triage of STEMI patients for percutaneous coronary intervention, which may enhance the effect of STEMI recognition. Finally,
Volume
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these reviews also included studies investigating out-of-hospital combination fibrinolysis with facilitated percutaneous coronary intervention. Current treatment guidelines, however, recommend against full-dose fibrinolytic therapy followed by routine, immediate percutaneous coronary intervention and recommend only selective use of facilitated strategies.13,14 When assessing interventions to reduce mortality in STEMI patients, previous reviews have focused on the surrogate time-toreperfusion outcomes of door-to-needle or door-to-balloon times.10,15 However, in recognition that emergency medical services (EMS) play an important role in the continuum of STEMI patient care, first medical contact–to-balloon or first medical contact–to-needle time—measured from the time EMS first assesses the patient—may be a preferred measure of system performance.3,4,8 Despite these limitations, the strong recommendations for out-of-hospital 12-lead ECG have had an influence on its implementation in the United States, Canada, and around the world. Although the use of out-of-hospital 12-lead ECG has
Annals of Emergency Medicine 1
Nam et al
Benefits of Out-of-Hospital 12-Lead ECG in STEMI Patients
Editor’s Capsule Summary
What is already known on this topic Rapid treatment of ST-elevation myocardial infarction decreases mortality and produces better outcomes. What question this study addressed This meta-analysis of 16 observational studies of outof-hospital 12-lead ECG compared with 3-lead or no monitoring was performed to refine the estimated mortality benefit in the percutaneous coronary intervention era and the temporal benefit from first (out-of-hospital) medical contact to reperfusion. What this study adds to our knowledge Out-of-hospital 12-lead ECG was associated with a 39% reduction in relative risk of 30-day mortality for percutaneous coronary intervention patients and a 21- to 78-minute reduction in first medical contact– to-balloon time. How this is relevant to clinical practice The existing literature confirms an important mortality benefit of out-of-hospital 12-lead ECG and advance emergency department notification in the percutaneous coronary intervention era, limited as in all meta-analyses by the validity of the individual studies and absence of publication bias.
expanded significantly in the last 10 years, not all ambulances have this capability and thus not all STEMI patients receive an out-of-hospital 12-lead ECG.16-18 The objective of the current review was to address the aforementioned issues and present an updated review of the literature related to out-of-hospital identification of STEMI patients transported by EMS with 12-lead ECG and advance notification compared with standard or no cardiac monitoring (no out-of-hospital identification and no advance notification).
MATERIALS AND METHODS Reporting of the present review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.19 A search strategy was constructed with controlled vocabulary (Medical Subject Headings or Emtree) and key words focusing on the concepts of “electrocardiogram,” “advance notification,” “emergency medical services,” and “myocardial infarction.” The search was limited to English-language publications and studies of humans. Search strategies are presented in Appendix E1 (available online at http://www.annemergmed.com). The 2 Annals of Emergency Medicine
following bibliographic databases were searched: EMBASE through OVID (1988 to 2013 week 10), PubMed (1988 to 2013 week 10), and Cochrane Central Register for Controlled Trials through Wiley (1988 to 2013 week 10). The search was restricted to 1988 onward because the landmark Second International Study of Infarct Survival–2 trial was published at this time, showing the benefits of streptokinase, aspirin, and combination streptokinase with aspirin in patients with acute myocardial infarction.20 Included studies of identified systematic reviews and meta-analyses were hand searched for inclusion. Studies were included if they had a comparative observational or randomized study design, if patients with STEMI were treated with primary percutaneous coronary intervention or fibrinolysis, if the intervention group included out-of-hospital identification with 12-lead ECG and advance notification, and if the control group included standard cardiac monitoring (3-lead ECG) or no monitoring. Outcomes of interest included short-term mortality (mortality within 30 days), first medical contact–to-balloon time (in minutes), first medical contact–to-needle time (in minutes), door-to-balloon time (in minutes), and door-to-needle time (in minutes). These outcomes were chosen after consideration of the intended effect of out-of-hospital management strategies on STEMI patients, as well as outcomes used in previous reviews. Inhospital mortality has been thought to closely approximate 30-day mortality and the 2 have been combined in a previous review.10 Mean values were abstracted where available. “First medical contact” was EMS contact, whereas “door” was the first hospital door. These definitions follow recommendations to address the larger system delay that is more relevant to the system than only a hospital delay metric. Studies were excluded if the control group included out-ofhospital identification, advance notification or activation protocols, or transportation to a destination other than the local emergency department (ED) (which may also have been a percutaneous coronary intervention center), either cohort group made use of out-of-hospital fibrinolysis, either cohort group included self-transported/walk-in patients, or the study enrolled fewer than 30 participants. A minimum sample size of 30 was chosen because a mean difference statistic relies on the samples behaving approximately normally; a general cutoff of 30 has been previously suggested.21 Titles and abstracts that met the inclusion criteria and were not excluded were selected for full-text screening. Afterward, citations that still met the inclusion criteria and were not excluded were included for final review. Title and abstract, as well as full-text screening, were assessed independently by 2 reviewers (J.N. and K.C.) in 2 stages, using predetermined screening forms. The reviewers were not blinded to authorship, journal, or year. Disagreements were resolved by consensus-based discussion. Data Collection and Processing The following study characteristics were abstracted by 1 reviewer: study design, country of origin, jurisdiction size, Volume
-,
no.
-
:
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2013
Nam et al
Benefits of Out-of-Hospital 12-Lead ECG in STEMI Patients
protocol for ECG interpretation, protocol for advance notification or activation, presence of bypass eligibility, protocol for transport destination, presence of interhospital transfer, and patient inclusion and exclusion criteria. The reported outcomes for mortality and time intervals were abstracted by 1 reviewer. To validate the abstracted outcomes, a second reviewer compared the abstracted values to the original full text. Disagreements were resolved by consensus-based discussion. Study authors were contacted by e-mail for unpublished data when an outcome was incompletely reported (eg, the mean was reported but not the measure of variation) or where conference abstracts were included but no corresponding full text could be identified. Study quality was assessed with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology,22 which assesses the strength and quality of evidence with standardized criteria such as risk of bias, inconsistency, indirectness, imprecision, and publication bias. Funnel plots and Egger’s tests, using R 2.15.2 (R Foundation for Statistical Computing, Vienna, Austria), were performed where appropriate. Primary Data Analysis Agreement was calculated with the k statistic. For outcomes with nonsignificant c2 values for heterogeneity, pooled estimates were completed. All estimates were pooled with Review Manager 5.1.6 (Cochrane Collaboration). Short-term mortality was assessed with random-effects Mantel-Haenszel risk ratios. Time differences were assessed with random-effects inverse variance mean differences. Where the mean and SD were not reported, they were estimated with a previously proposed method by Hozo et al.23 In trials reporting only the interquartiles, the minimum and maximum were estimated by extending the interquartiles by half the interquartile range. Subgroup analyses were conducted for jurisdiction type, activation protocol, and country.
RESULTS The literature search was completed December 2012, with updates until March 2013. A flow diagram of the literature search results is presented in Figure 1. After duplicates were removed, there were 1,338 unique citations. The full texts of 68 citations were screened,11,12,16,17,24-87 with 16 studies included in the review12,16,74-87 and 52 studies excluded.11,17,24-73 Two studies reported outcomes separately for patients who received primary percutaneous coronary intervention and fibrinolysis.16,75 Therefore, although there were 16 studies included for qualitative review, 2 included data on percutaneous coronary intervention and fibrinolysis. In addition, in 2 studies it was not clear whether advance notification occurred.16,75 These were included in the analysis for 2 reasons. First, no risk of bias was determined because any potential effect of no advance notification would work against the observed reductions in Volume
-,
no.
-
:
-
2013
Figure 1. Flow diagram of study inclusion. PCI, Percutaneous coronary intervention.
treatment delay. Second, in the more recent study conducted in 2007,16 it was likely that most, if not all, EMS that performed out-of-hospital identification also performed advance notification, which is indicative of EMS during the mid to late 2000s. In another study,75 sample sizes had to be inferred from the proportion of patients who received out-of-hospital ECG, stratified by primary intervention received (details in Appendix E1, available online at http://www.annemergmed.com). Although this practice had an effect on precision, it did not affect the point estimates themselves because they were reported directly. The k statistic for agreement was 0.81 for titles and abstracts screening and 0.80 for full-text screening. The raw agreement was 0.98 for titles and abstracts and 0.91 for full-text screening. Study characteristics of included studies are presented in Tables 1 and 2 for patients who received percutaneous coronary intervention and fibrinolysis, respectively. Generally, eligibility criteria were appropriately developed and applied in all studies. It was not clear whether the door-to-balloon time included the first hospital door for interhospital transfers in 1 study.16 This omission would favor the standard cardiac monitoring group. Finally, in one study, 1-year mortality was reported; authors provided 30-day estimates.83 In another, measures of dispersion were not available; authors provided the median and interquartile ranges.86 Annals of Emergency Medicine 3
Study
Type of Study/Setting
Intervention Group
Canto, 1997, n¼4,932, US75
Registry study; regional Diagnosis: source unclear; advance notification: jurisdiction of multiple PCI protocol unclear; bypass eligibility unclear; EMS centers transport protocol unclear
Diercks, 2009, n¼5,117, US16
Registry study; regional Diagnosis: source unclear; advance notification: jurisdiction of multiple PCI protocol unclear; bypass eligibility unclear; EMS transport protocol unclear. centers
Martinoni, 2011, n¼1,529, Italy81
Registry study; regional jurisdictions of multiple PCI centers
Carstensen, 2007, n¼301, Australia76
Volume -,
no. -
Unclear. Likely EMS direct to local ED (PCI or non-PCI center); interhospital transfer excluded. Unclear, likely EMS direct to local ED (PCI or non-PCI center); interhospital transfer protocol unclear
Other Incl/Exclusion Incl: STEMI transported by EMS Excl: interhospital transfer
Outcomes Inhospital mortality, DTB, DTN
Incl: STEMI transported by EMS to DTB, DTN an ACTION hospital. Excl: pts not evaluated first in ED or cath lab, pts transferred to nonACTION hospital Diagnosis: cardiologist by telemetry, advance EMS direct to ED of PCI center; Incl: STEMI/LBBB, SO 10 PCI in STEMI/year. Diagnosis: emergency physician by telemetry; EMS direct to local ED (PCI/ Incl: STEMI, SO
