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The impact of pre-hospital 12-lead electrocardiogram and first contact by cardiologist in patients with ST-elevation myocardial infarction in Kanagawa, Japan
Division of Cardiology, Department of Internal Medicine, Showa University Fujigaoka Hospital, 1-30 Fujigaoka, Aoba-ku, Yokohama, Kanagawa 227-8501, Japan
Division of Cardiology, Department of Internal Medicine, Showa University Fujigaoka Hospital, 1-30 Fujigaoka, Aoba-ku, Yokohama, Kanagawa 227-8501, Japan
Division of Cardiology, Department of Internal Medicine, Showa University Fujigaoka Hospital, 1-30 Fujigaoka, Aoba-ku, Yokohama, Kanagawa 227-8501, Japan
Initial management of ST-elevation myocardial infarction (STEMI) is crucial.
•
Pre-hospital 12-lead electrocardiogram (ECG) is useful.
•
Fast care by cardiologists also plays an important role.
•
In STEMI registry, pre-hospital 12-lead ECG and initial physician both had impact.
Abstract
Background pre-hospital 12-lead electrocardiogram (ECG) by emergency medical service (EMS) personnel at the site of first medical contact (FMC) and the physician of first contact both play important roles in managing patients with ST-elevation myocardial infarction (STEMI). However, in Japan, pre-hospital 12-lead ECG is not routinely performed by EMS personnel at the site of FMC and the physician of first contact is not always a cardiologist.
Methods from October 2015 to October 2019, 2035 consecutive STEMI patients transported from the field by ambulance were analyzed from the K-ACTIVE registry. Based on the presence (+) or absence (-) of pre-hospital 12-lead ECG / first contact by cardiologist, patients were divided into 4 groups (+/+, +/-, -/+, -/-). Patient characteristics, FMC to door time, door to device time and in-hospital mortality were compared.
Results the numbers of patients in each group were as follows (+/+, n = 987; +/-, n = 211; -/+, n = 610; -/-, n = 227). For patient characteristics, there were significant differences in the prevalence of dyslipidemia and the presence of chest pain. The FMC to door time was similar (median value, +/+, 24 min; +/-, 25 min; -/+, 24 min; -/-, 24 min; p = 0.23). The door to device time was the shortest in the +/+ group (median value, +/+, 65 min; +/-, 80 min; -/+, 69 min; -/-, 88 min; p < 0.0001). Crude in-hospital mortality was the highest in the -/- group (+/+, 3.9%; +/-, 2.4%; -/+, 5.8%; -/-, 11.9%; p < 0.0001). After adjustment for age and sex, the adjusted odds ratios for in-hospital mortality were as follows [odds ratio (with 95% confidence interval) +/+, 0.33 [0.19-0.57]; +/-, 0.19 [0.07–0.52]; -/+, 0.49 [0.29–0.86]; -/-, 1 [reference)].
Conclusion pre-hospital 12-lead ECG and the physician of first contact had a significant impact on the door to device time and in-hospital mortality. Continuous efforts should be made to improve acute management of STEMI.
In patients with ST-elevation myocardial infarction (STEMI), shortening the interval from the onset to reperfusion with primary percutaneous coronary intervention (PCI) is crucial for improving the clinical outcome [
Relationship between delay in performing direct coronary angioplasty and early clinical outcome in patients with acute myocardial infarction: results from the global use of strategies to open occluded arteries in acute coronary syndromes (GUSTO-IIb) trial.
Relationship of symptom-onset-to-balloon time and door-to-balloon time with mortality in patients undergoing angioplasty for acute myocardial infarction.
]. Both European Society of Cardiology (ESC) and American College of Cardiology/American Heart Association (ACC/AHA) guidelines recommend primary PCI for reperfusion within 90 min after first medical contact [
2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines.
]. Pre-hospital 12-lead electrocardiogram (ECG) by emergency medical services (EMS) personnel at the site of first medical contact (FMC) is an effective tool for facilitating timely perfusion, which is also recommended in both the ESC and ACC/AHA guidelines [
Impact of pre-hospital electrocardiograms on time to treatment and one year outcome in a rural regional ST-segment elevation myocardial infarction network.
Impact of pre-hospital electrocardiograms on time to treatment and one year outcome in a rural regional ST-segment elevation myocardial infarction network.
Chest pain center accreditation is associated with improved in-hospital outcomes of acute myocardial infarction patients in China: findings from the CCC-ACS Project.
Current characteristics and management of ST elevation and non-ST elevation myocardial infarction in the Tokyo metropolitan area: from the Tokyo CCU network registered cohort.
]. Pre-hospital 12-lead ECG by EMS personnel at the site of FMC is infrequently performed. Few facilities have an established chest pain unit and the physician of first contact for patients complaining of chest pain varies depending on the area and hospital.
In Kanagawa prefecture, pre-hospital 12-lead ECG by EMS personnel at the site of FMC was introduced in 2004. Pre-hospital 12-lead ECG can be performed when the ambulance is equipped and when certified EMS personnel are present.
Using a multicenter acute myocardial infarction (AMI) registry in Kanagawa, we aimed to evaluate the impact of pre-hospital 12-lead ECG and first contact by a cardiologist on the FMC to door time, door to device time, and in-hospital mortality.
Methods
The K-ACTIVE (Kanagawa-ACuTe cardIoVascular rEgistry) is an observational multicenter registry of AMI that enrolled patients from 52 PCI-capable hospitals in Kanagawa prefecture, Japan beginning in October 2015, including large and small, urban and rural, educational and non-educational hospitals. This registry was approved by the local institutional review board and was registered in the University Hospital Medical Information Network (UMIN) in October 2015 (UMIN000019156). STEMI and non-STEMI (NSTEMI) were diagnosed based on the third universal definition of myocardial infarction consensus document [
]. All patients with STEMI or NSTEMI who presented to hospitals within 24 h from the onset of symptoms were registered. Each attending hospital was required to submit data to an online database from consecutive patients. From this registry, we included patients with STEMI who were transported from the field by ambulance. Patients with out-of-hospital cardiac arrest and missing data were excluded.
Based on the presence (+) or absence (-) of pre-hospital 12-lead ECG / first contact by cardiologist, patients with STEMI were divided into 4 groups (+/+, +/-, -/+, -/-). The pre-hospital 12-lead ECG was recorded and read by certified EMS personnel at the site of FMC when patients were suspected of acute coronary syndrome (ACS). In brief, EMS personnel called the hospital with their ECG finding, based on their judgment; however, ECG transmission was not performed due to a lack of such a system during this study period. Physicians were thus able to assess the raw pre-hospital 12-lead ECG only after the arrival of the EMS team. Pre-hospital ECG was not performed when the ambulance was not equipped to perform 12-lead ECG, when none of the EMS personnel was certified, or when patients were not suspected of having cardiovascular disease. During the study period, all EMS personnel used the same field protocol based on their capacity, and all hospital cardiologists treated STEMI patients according to the same Japanese Circulation Society (JCS) guidelines [
]. As chest pain units are scarce in Japan, first contact by a cardiologist in any circumstance was counted as the presence of first contact by a cardiologist.
The patient characteristics, AMI characteristics, FMC to door time, door to device time, FMC to device time, rate of achievement of FMC to device time within 90 min, rate of high-volume center, and in-hospital mortality were compared among the groups. A high-volume center was defined as one with ≥30 total STEMI patients during the study period based on the median value. Each risk factor (e.g. hypertension, diabetes mellitus, and dyslipidemia) was defined based on the JCS guidelines [
In-hospital outcome in patients presenting with acute coronary syndrome with left main coronary artery disease: a report from Japanese prospective multicenter percutaneous coronary intervention registry.
]. FMC was defined as the point at which the ambulance staff arrived to assist the patient. Door time was defined as the point at which the patient arrived at the hospital. Device time was defined as the point at which the first device (e.g. an aspiration device or balloon) was inserted. Off-hours were defined as 17:00 to 09:00 h the next day, regardless of the day of the week. In order to assess variability between institutes, the presence/absence of pre-hospital 12-lead ECG, physician of first contact, FMC to door time, door to device time, and FMC to device time were also stratified by each hospital.
The normality of data was tested with the Shapiro-Wilk test. Continuous variables were expressed as the mean ± standard deviation or median value (25th percentile - 75th percentile), as appropriate. Categorical variables were expressed as percentages. Variables with a normal distribution were compared by an analysis of variance (ANOVA) followed by a Tukey-Kramer post-hoc analysis. Variables with a non-normal distribution were compared by Wilcoxon's test followed by a Steel-Dwass post-hoc analysis. Categorical variables were analyzed by a chi-squared test, as appropriate. A multivariable logistic regression analysis adjusted for the age, sex, and Killip classification was performed to assess the difference in in-hospital mortality between the groups. JMP 15 (SAS institute, Cary, NC, USA) was used to perform the statistical analyses. Values of p < 0.05 were considered statistically significant.
Results
A total of 5648 patients with AMI were registered in the K-ACTIVE registry database from October 2015 to October 2019. After excluding patients with NSTEMI (n==1026), direct visits (n==626), transfers from other hospitals (n==920), in-hospital onset (n==84), out of hospital cardiac arrest (n==226), door to device time >24 h (n==155), and cases with insufficient data (n==576), a total of 2035 patients (+/+, n==987; +/-, n==211; -/+, n==610; -/-, n==227) were analyzed in this study.
Table 1 shows the patient characteristics. The median age was approximately 70 years in all groups. The prevalence of male patients, dyslipidemia, and previous history of myocardial infarction tended to be greater in the +/+ group. No significant differences were observed among the groups in other risk factors (including hypertension, diabetes, and smoking). Patients who did not complain of chest pain had less chance of receiving pre-hospital ECG or first contact by a cardiologist. Among the laboratory data, the low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and hemoglobin A1c values did not differ among the groups; significant differences were observed in the serum creatinine and albumin levels.
Table 1Patient Characteristics.
Pre-hospital ECG (+)
Pre-hospital ECG (-)
p-value
Cardiologist
Non-cardiologist
Cardiologist
Non-cardiologist
Number
987
211
610
227
Age, years
68 (58–77)
70 (59–78)
69 (57–78)
71 (60–81)
0.15
Male, n (%)
793 (80.3%)
164 (77.7%)
457 (74.9%)
171 (75.3%)
0.06
Hypertension, n (%)
637 (64.5%)
134 (63.5%)
365 (59.8%)
140 (61.7%)
0.29
Diabetes, n (%)
319 (32.3%)
74 (35.1%)
182 (29.8%)
73 (32.2%)
0.52
Dyslipidemia, n (%)
588 (59.6%)
126 (59.7%)
333 (54.6%)
109 (48.0%)
<0.01
Smoking, n (%)
374 (37.9%)
69 (32.7%)
220 (36.1%)
71 (31.3%)
0.19
Previous MI, n (%)
103 (10.4%)
16 (7.6%)
46 (7.5%)
14 (6.2%)
0.08
Chest pain, n (%)
852 (86.3%)
165 (78.2%)
537 (88.0%)
169 (74.5%)
<0.01
Cre, mg/dl
0.89 (0.76–1.07)
0.90 (0.73–1.05)
0.86 (0.71–1.06)
0.93 (0.77–1.20)
<0.01
LDL, mg/dl
123 (101–148)
122 (96–151)
124 (99–152)
121 (91–148)
0.64
HDL, mg/dl
47 (40–57)
49 (38–59)
48 (40–58)
46 (36–58)
0.57
HbA1C, %
5.9 (5.6–6.6)
6.0 (5.7–6.4)
5.8 (5.5–6.4)
5.9 (5.6–6.8)
0.08
Alb, g/dl
4.1 (3.7–4.4)
3.9 (3.6–4.2)
3.9 (3.6–4.3)
3.9 (3.7–4.2)
<0.01
Data are expressed as median (interquartile) or number (%).
Table 2 shows the characteristics of AMI. Patients first contacted by a non-cardiologist were more likely to have cardiogenic shock (Killip 4). The onset to the FMC time was similar, whereas the rate of ‘onset to FMC time’ >6 h was significantly greater in the -/+ group than in the others. Final TIMI flow grades and peak creatine kinase tended to be worse in the -/+ group and -/- group than in the others. The rate of arrival in off-hours, culprit vessel, initial TIMI flow, peak creatine kinase level, use of intra-aortic balloon pump, and use of extracorporeal membrane oxygenation did not differ markedly among the groups. The prevalence of multi-vessel disease and coronary artery bypass graft (CABG) tended to be greater in the -/- group.
Table 2Characteristics of acute myocardial infarction.
Pre-hospital ECG (+)
Pre-hospital ECG (-)
p-value
Cardiologist
Non-cardiologist
Cardiologist
Non-cardiologist
N
987
211
610
227
SBP, mmHg
141 (118–163)
134 (113–162)
136 (114–160)
132 (110–158)
0.02
HR, n/min
75 (61–89)
71 (60–90)
74 (60–88)
76 (59–93)
0.64
Onset to FMC, min
52 (26–126)
57 (27–142)
50 (23–138)
60 (28–152)
0.43
Rate of onset to FMC >6 h, n (%)
39 (4.0%)
8 (3.8%)
44 (7.2%)
8 (3.5%)
0.02
Arrival in off hours, n (%)
565 (57%)
133 (63%)
373 (62%)
143 (63%)
0.17
Killip, n (%)
<0.01
1
772 (78.2%)
153 (72.5%)
480 (78.7%)
154 (67.8%)
2
47 (4.8%)
27 (12.8%)
47 (7.7%)
30 (13.2%)
3
75 (7.6%)
4 (1.9%)
22 (3.6%)
12 (5.3%)
4
93 (9.4%)
27 (12.8%)
61 (10.0%)
31 (13.7%)
Culprit Vessel, n (%)
0.56
LMT
26 (2.6%)
6 (2.8%)
14 (2.3%)
3 (1.3%)
LAD
484 (49.0%)
99 (46.9%)
283 (46.4%)
102 (44.9%)
RCA
389 (39.4%)
84 (39.8%)
250 (41.0%)
105 (46.3%)
LCX
87 (8.8%)
22 (10.4%)
63 (10.3%)
16 (7.1%)
Bypass graft
1 (0.1%)
0 (0%)
0 (0%)
1 (0.4%)
TIMI (pre PCI), n (%)
0.11
0
675 (68.4%)
138 (65.4%)
416 (68.2%)
148 (65.2%)
1
109 (11.0%)
16 (7.6%)
74 (12.1%)
26 (11.5%)
2
156 (15.8%)
45 (21.3%)
92 (15.1%)
33 (14.5%)
3
47 (4.8%)
12 (5.7%)
28 (4.6%)
20 (8.8%)
TIMI (post PCI), n (%)
0.02
0
1 (0.1%)
2 (1.0%)
2 (0.3%)
2 (0.9%)
1
7 (0.7%)
1 (0.5%)
8 (1.3%)
2 (0.9%)
2
51 (5.2%)
6 (2.8%)
51 (8.4%)
15 (6.6%)
3
927 (94.0%)
202 (95.7%)
549 (90.0%)
208 (91.6%)
Peak CK, IU/ml
2139 (932–4104)
2012 (976–3362)
2308 (977–4317)
2348 (1067–4504)
0.37
IABP, n (%)
139 (14.1%)
40 (19.0%)
105 (17.2%)
39 (17.2%)
0.17
ECMO, n (%)
19 (1.9%)
3 (1.4%)
12 (2.0%)
9 (4.0%)
0.21
Multi-vessel disease, n (%)
466 (47.2%)
103 (48.8%)
266 (43.6%)
122 (53.7%)
0.06
PCI, n (%)
987 (100%)
211 (100%)
610 (100%)
227 (100%)
NA
CABG, n (%)
4 (0.4%)
4 (1.9%)
4 (0.7%)
4 (1.8%)
0.04
Data are expressed as median (interquartile) or number (%).
ECG, electrocardiogram; SBP, systolic blood pressure; HR, heart rate; FMC, first medical contact; LMT, left main trunk; LAD, left anterior descending artery; RCA, right coronary artery; LCX, left circumflex artery; TIMI, thrombolysis in myocardial infarction; PCI, percutaneous coronary intervention; CK, creatine kinase; IABP, intra-aortic balloon pumping; ECMO, extracorporeal membrane oxygenation; CABG, coronary artery bypass grafting.
The FMC to door time (min) (Fig. 1A) was comparable in all groups (median value: +/+, 24 min; +/-, 25 min; -/+, 24 min; -/-:24 min; p = 0.23). However, the door to device time (min) was the shortest in the +/+ group followed by the -/+ group (median value: +/+, 65 min; +/-, 80 min; -/+, 69 min; -/-, 88 min, p < 0.0001) (Fig. 1B). Accordingly, the FMC to device time (min) was the shortest in the +/+ group followed by the -/+ group (median value: +/+, 91 min; +/-, 105 min; -/+, 95 min; -/-, 112 min; p < 0.0001) (Fig. 1C). In terms of the door to device time (min) and FMC to device time (min), a post-hoc analysis showed that there were no significant differences not only between the +/+ and -/+ groups but also between the +/- and -/- groups. The rate of achievement of an FMC to device time of within 90 min (%) was also greatest in the +/+ group followed by the -/+ group (+/+, 48.6%; +/-, 29.9%; -/+, 45.4%; -/-, 27.8%; p < 0.0001) (Fig. 1D). The rates of high-volume center were significantly greater in the +/+ and -/+ groups than in the +/- and -/- groups (+/+, 83.8%; +/-, 73.9%; -/+, 85.1%; -/-, 75.8%; p < 0.0001) (Fig. 1E).
Fig. 1The first medical contact (FMC) to door time, door to device time, and FMC to device time are shown in A, B, and C, respectively, while rates of achievement of FMC to device time within 90 min and rates of high-volume center are shown in D and E, respectively. The numbers of patients in each group were as follows: +/+, n = 987; +/-, n = 211; -/+, n = 610; -/-, n = 227. The tables under B and C show the p-values between each pair in the post-hoc analysis.
Fig. 1The first medical contact (FMC) to door time, door to device time, and FMC to device time are shown in A, B, and C, respectively, while rates of achievement of FMC to device time within 90 min and rates of high-volume center are shown in D and E, respectively. The numbers of patients in each group were as follows: +/+, n = 987; +/-, n = 211; -/+, n = 610; -/-, n = 227. The tables under B and C show the p-values between each pair in the post-hoc analysis.
Fig. 2A–E shows the presence/absence of pre-hospital 12-lead ECG, physician of first contact, FMC to door time, door to device time and FMC to device, which were also stratified by each hospital. The hospitals were ordered by the number of patients with STEMI that they accepted. All variables showed significant variability, irrespective of the number of patients with STEMI.
Fig. 2A and B show the presence or absence of a pre-hospital 12-lead ECG and physician stratified by each hospital and ordered by the number of STEMI patients. C, D, and E show the first medical contact (FMC) to door time, door to device time, and FMC to device time, respectively, stratified by each hospital and ordered by the number of STEMI patients.
Fig. 2A and B show the presence or absence of a pre-hospital 12-lead ECG and physician stratified by each hospital and ordered by the number of STEMI patients. C, D, and E show the first medical contact (FMC) to door time, door to device time, and FMC to device time, respectively, stratified by each hospital and ordered by the number of STEMI patients.
Fig. 2A and B show the presence or absence of a pre-hospital 12-lead ECG and physician stratified by each hospital and ordered by the number of STEMI patients. C, D, and E show the first medical contact (FMC) to door time, door to device time, and FMC to device time, respectively, stratified by each hospital and ordered by the number of STEMI patients.
Crude in-hospital mortality was the highest in the -/- group (+/+, 3.9%; +/-, 2.4%; -/+, 5.8%; -/-, 11.9%; p < 0.0001) (Fig. 3A). The majority showed cardiac death (77%) while non-cardiac death was reported in 23%. A significant difference in the adjusted odds ratios for in-hospital mortality, after adjusting for the age, sex, and Killip classification, was observed between the -/- group and the other groups [odds ratio (95% confidence interval): +/+, 0.33 (0.19–0.57); +/-, 0.19 (0.07–0.52); -/+, 0.49 (0.29–0.86); -/-:1 (reference)] (Fig. 3B).
Fig. 3A shows the crude in-hospital mortality, while B shows the adjusted risk for in-hospital mortality. The numbers of patients in each group were as follows: +/+, n = 987; +/-, n = 211; -/+, n = 610; -/-, n = 227.
Our study assessed the impact of pre-hospital 12-lead ECG by EMS personnel at the site of FMC and first contact by a cardiologist on patients with STEMI using a multicenter ACS registry in Japan. The FMC to door time was equivalent among the groups. The door to device time was the shortest when both factors were present. On the other hand, the door to device time was the longest when both factors were absent. The door to device time was somewhat shortened when either of the factors was present. Accordingly, in-hospital mortality was the worst when neither of the factors were present.
Pre-hospital 12-lead ECG by EMS personnel at the site of FMC was introduced in late 20th century. In 1990, two groups reported on the utility of myocardial infarction triage using pre-hospital ECG transmitted by cellular telephone [
Myocardial infarction triage and intervention project—phase I: patient characteristics and feasibility of prehospital initiation of thrombolytic therapy.
]. A study from the USA reported that during 2000–2002, pre-hospital 12-lead ECG was performed in 4.5% of the fibrinolytic therapy cohort and in 8.0% of the PCI cohort, resulting in significantly shorter door to drug time (mean value, 24.6 min vs. 34.7 min, p < 0.0001) or door to balloon time (mean value, 94.0 min vs. 110.3 min, p < 0.0001) [
The pre-hospital electrocardiogram and time to reperfusion in patients with acute myocardial infarction, 2000-2002. Findings from the National Registry of Myocardial Infarction-4.
]. In 2007, nearly a quarter of patients received a pre-hospital 12-lead ECG showing further shorter door to balloon time (mean value, 61 min vs. 75 min, p < 0.0001) [
Utilization and impact of pre-hospital electrocardiograms for patients with acute ST-segment elevation myocardial infarction. Data from the NCDR (National Cardiovascular Data Registry) ACTION (Acute Coronary Treatment and Intervention outcomes Network) registry.
Association between prehospital electrocardiogram use and patient home distance from the percutaneous coronary intervention center on total reperfusion time in ST-segment-elevation myocardial infarction patients: a retrospective analysis from the national cardiovascular data registry.
Predictive ability and efficacy for shortening door-to-balloon time of a new prehospital electrocardiogram-transmission flow chart in patients with ST-elevation myocardial infarction – results of the CASSIOPEIA study.
]. Both Takeuchi et al. and Fujita et al. evaluated a mobile cloud ECG system; however, the studies were limited by their relatively small study populations [
]. Kawakami et al. compared reperfusion delay in patients managed with and without the use of mobile telemedicine in a single center (mobile telemedicine group, n==37 vs. field transfer group, n==125 vs. interhospital transfer group, n==139) [
Time to reperfusion in ST-segment elevation myocardial infarction patients with vs. without pre-hospital mobile telemedicine 12-lead electrocardiogram transmission.
Time to reperfusion in ST-segment elevation myocardial infarction patients with vs. without pre-hospital mobile telemedicine 12-lead electrocardiogram transmission.
], which was also similar in our study. This may have been because pre-hospital 12-lead ECG can be performed within a few minutes by well-trained EMS teams, or because the presence of a pre-hospital 12-lead ECG may have facilitated hospital selection, thereby helping to reduce the selection time. In their study, the door to device time was significantly shorter in the mobile telemedicine group (median value, mobile telemedicine group, 58 min vs. field transfer group, 72 min vs. interhospital group, 70 min, p = 0.002) [
Time to reperfusion in ST-segment elevation myocardial infarction patients with vs. without pre-hospital mobile telemedicine 12-lead electrocardiogram transmission.
]. These times were slightly shorter in comparison to our study, ranging from 65 to 88 min in each group, presumably due to the variation in the institutional capacity of our study group. Sakai et al. also reported the successful introduction of ECG-transmission using a new flow chart in a single center located in a rural area [
Predictive ability and efficacy for shortening door-to-balloon time of a new prehospital electrocardiogram-transmission flow chart in patients with ST-elevation myocardial infarction – results of the CASSIOPEIA study.
]. The introduction of pre-hospital ECG could be simpler in an area with a high-volume center or a rural area with a single PCI-capable hospital.
The interpretation of 12-lead ECG by EMS personnel is another important point in our study because previous reports from Japan required a physician's judgment with the use of mobile telemedicine [
Predictive ability and efficacy for shortening door-to-balloon time of a new prehospital electrocardiogram-transmission flow chart in patients with ST-elevation myocardial infarction – results of the CASSIOPEIA study.
2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines.
]. A “false-positive” could be a concern when EMS personnel make a decision. However, transfer to non-PCI capable hospitals can be an even greater concern as inter-hospital transfer can lead to a significant delay in primary PCI [
Outcome of inter-hospital transfer versus direct admission for primary percutaneous coronary intervention: an observational study of 25,315 patients with ST-elevation myocardial infarction from the London Heart Attack Group.
]. It is also reported that the rate of false activation is relatively low (approximately 15%) and is more than balanced by earlier treatment times for the majority of STEMI patients for whom the notification is appropriate [
]. To date, there has been no specific statement about the interpretation of 12-lead ECG by EMS personnel in the Japanese Circulation Society guidelines [
]. The EMS in Kanagawa prefecture is still unique, in comparison to other prefectures in Japan, in its implementation of 12-lead ECG interpretation by trained EMS personnel. As more than 1000 PCI capable hospitals exist in this small area (377,900 km2), fibrinolytic therapy is rarely performed. This geographic feature allows for the EMS system to focus on fast transportation rather than a fast diagnosis.
Despite the important role of cardiologists in managing STEMI patients [
The metamorphosis of ST-segment elevation myocardial infarction programs: the changing role of the interventional cardiologist and its manpower implications.
], the physician of first contact varies due to the variable size of hospitals that accept urgent patients in the Japanese emergency medical system. STEMI patients may initially be cared for by a cardiologist or well-trained emergency room specialists in a large hospital. However, in a small hospital that is still capable of performing PCI with a limited number of cardiologists, a general internal medicine doctor of another specialty will often be the physician who initially manages a patient with chest pain during the night shift. If possible, a dedicated system, such as a chest pain unit—a concept that has been introduced in other countries—would be ideal [
Chest pain center accreditation is associated with improved in-hospital outcomes of acute myocardial infarction patients in China: findings from the CCC-ACS Project.
]. It would be ideal for a cardiologist to participate from the very beginning of STEMI management as our study revealed that—in the absence of pre-hospital ECG—the door to device time and in-hospital mortality rate were both lower when a cardiologist was involved in the initial management. In this setting, skipping the emergency room department and direct transfer to the catheter laboratory would be smoother [
2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines.
Central and local governmental support would be necessary for further improvement in the management of STEMI patients. In our study, the rate of a prehospital 12-lead ECG being performed was 59%; the remaining 41% patients did not receive a prehospital 12-lead ECG either because the EMS teams were incapable of performing this or misjudged the need for it. However, the penetration of a pre-hospital 12-lead ECG is still very low, and it is infrequently performed throughout Japan compared with other developed countries. For example, chest pain patients transported from Tokyo Prefecture to Kanagawa Prefecture by EMS do not usually receive a pre-hospital 12-lead ECG because Tokyo EMS teams are not capable of performing a pre-hospital ECG; this situation should be improved through education and/or investment. Beyond Kanagawa Prefecture, considerable variability in the initial management of STEMI exists all over Japan.
Limitations
The present study was associated with some limitations. Our study included various hospitals in a prefecture with a population of approximately 9 million people and high population density (3806/km2). The implementation of pre-hospital 12-lead ECG is highly dependent on the capacity of local EMS personnel and equipment. Similarly, the physician of first contact is often a non-cardiologist. Thus, in the present study, patients who fortunately had the chance to receive pre-hospital 12-lead ECG and/or first contact with a cardiologist were compared with those who did not have these opportunities. Nevertheless, this is the largest multicenter study to assess the impact of pre-hospital 12-lead ECG and first contact by a cardiologist in STEMI patients in Japan, and therefore we believe that the findings of this study are significant.
Conclusion
Both pre-hospital 12-lead ECG and first contact by a cardiologist significantly reduced the door to device time. In-hospital mortality was the worst when both factors were absent. Continuous efforts should be made from multiple angles in order to establish an appropriate acute management system for STEMI.
Funding
This work was supported in part by a Grant-in-Aid for Scientific Research (15K09101) from the Ministry of Education, Science, and Culture, Japan.
Disclosure
The authors declare no conflict of interest in association with the present study.
Acknowledgments
We thank all of the investigators, clinical research coordinators, and data managers involved in the K-ACTIVE study for their contributions.
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