Abstract
Background: Mobile cloud electrocardiography (C-ECG) can reduce the door-to-balloon time of acute coronary syndrome (ACS) patients, so we hypothesized it would also assist in transporting ACS-suspected patients to the optimal institutes.
Methods and Results: Initially, 10 fire departments in Oita had 10 ambulances equipped with C-ECG. Ambulance crews recorded a 12-lead ECG from the patient at the first point of contact and transmitted them to 18 hospitals (13 institutions (PCII) with 24-h availability for percutaneous coronary intervention (PCI) and 5 regional core hospitals (RCH) without 24-h PCI) for analysis by a cardiologist. During 41 months, 476 ECGs suspected to be ACS were transmitted and analyzed. Of these, 24 ECGs transmitted to PCII were judged as not requiring PCI, and the patients were directly transported to a RCH (PCII-RCH); 35 ECGs sent to a RCH were judged as requiring PCI, and the patients were directly transported to a PCII (RCH-PCII). The prevalence of cardiovascular disease was significantly higher in the RCH-PCII group than in the PCII-RCH group (P<0.01). There was no significant difference in the door-to-balloon time between the RCH-PCII and the group in which the C-ECG was sent to a PCII and the patients were transported directly to PCII (PCII-PCII) (49±14 vs. 59±20 min, P=0.14).
Conclusions: Prehospital 12-lead ECG can assist in transporting ACS-suspect patients to the optimal treatment facility.
The recording of a prehospital 12-lead electrocardiogram (ECG), and its transmission to the hospital has been shown to reduce the time from first medical contact to reperfusion and from arrival at the hospital to catheterization.1–4 A 32% reduction in death at 30 days was reported in the group in whom a prehospital 12-lead ECG was recorded and the hospital was notified, compared with the group in whom the ECG was not recorded among patients with ST-segment elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI).5 We used a mobile cloud electrocardiography system (C-ECG) as the prehospital 12-lead ECG and measured its effect on door-to-balloon times in Oita Prefecture.6 Transmitting the prehospital 12-lead ECG by emergency teams to the hospital improve outcomes by enabling preparation of the cardiac catheterization room before patient arrival, early convening of the catheterization team, and thus shortening the time to coronary reperfusion.
Editorial p 1488
The transmission of a prehospital 12-lead ECG before transport may also contribute to more efficient patient transport, such as transporting true STEMI patients directly to a PCI facility even if it is further away, or transporting nonurgent, noncardiogenic patients to a nearby non-PCI facility instead of a distant PCI facility. We therefore evaluated the hypothesis that prehospital 12-lead ECG can assist in the transport of suspected acute coronary syndrome (ACS) to the optimal institute for treatment.
Methods
Prehospital ECG System in Oita
The C-ECG (Cloud Cardiology®, Labtech Co., Debrecen, Hungary) system was started on April 17, 2017, in 18 hospitals and 10 ambulances of the 10 respective fire departments in Oita Prefecture, which has a total of 14 fire departments. In March 2022, this system has spread to 23 hospitals, and 41 ambulances of 13 respective fire departments across the whole prefecture. Emergency medical service (EMS) personnel were educated on the symptoms of ACS being frequently atypical and nonlocalized, including in the upper extremities and jaw, and might be accompanied by nonspecific symptoms, including dyspnea, cold sweats, discomfort, and nausea. The ambulance crew recorded a 12-lead ECG and transmitted it to a secure cloud server (SCUNA®, Mehergen, Japan), using an existing image transmission system. The ECG in the cloud server can be accessed simultaneously from personal computers, smartphones, and tablets anywhere after access key authentication. Cardiologists in the 18 hospitals participating in the C-ECG system analyzed the ECG and immediately after the diagnosis of suspicious ACS made the decision to perform emergency cardiac catheterization before the patient’s arrival at the hospital. Figure 1 shows the location of ambulances equipped with C-ECG and the fire departments and hospitals participating in the C-ECG system in Oita Prefecture. The 5 regional core hospitals (RCH) were unable to perform PCI with 24 h availability, but the 13 PCI institutions could (PCII).
Patients were transported to PCII or RCH following C-ECG judgment. Over 41 months, 476 ECGs with suspicion of ACS were transmitted to hospitals by the ambulances equipped with a C-ECG system.
The patients were divided into four groups: PCII-PCII (ECGs transmitted to PCII, and patients directly transported to PCII); RCH-RCH group (ECGs transmitted to RCH, and patients directly transported to RCH); PCII-RCH group (ECGs transmitted to PCII, judged as not requiring primary PCI, and patients directly transported to RCH); and RCH-PCII group (ECGs transmitted to RCH, judged as requiring primary PCI, and patients directly transported to PCII) (Figure 2).
This study was conducted according to the principles expressed in the Declaration of Helsinki and the protocol was approved by the Oita University Research Ethics Committee (No. 1262).
Definitions
Door-to-balloon time (DTBT) is defined as the time from arrival at the emergency department where emergency catheterization is performed to the first device use or balloon inflation. Door-to-catheterization laboratory time is defined as the interval from the door time to arrival at the emergency catheterization laboratory. The time from the first medical contact to reperfusion is defined as the interval from the arrival of EMS on the scene to the first device use or balloon inflation. All of these times were measured for primary PCI in STEMI patients.
Statistical Analysis
Data are presented as the mean±SD. A chi-square test was used for categorical variables, and an analysis of variance was used for continuous variables. The differences between groups were analyzed using Student’s t-test. P<0.05 was considered significant. All analyses were performed using JMP (version 13.2.0; SAS, Cary, NC, USA) running under Windows 10 (Microsoft, Redmond, WA, USA).
Results
Baseline Characteristics
The Table presents the baseline characteristics of the PCII-PCII, PCII-RCH, RCH-PCII, and RCH-RCH groups. Age and sex had no observable significant difference. One patient in the PCII-PCII group and 1 patient in the PCII-RCH group were of indeterminate age. The prevalence of cardiovascular disease was significantly higher in the PCII-PCII group than in the RCH-RCH and PCII-RCH groups. It was also higher in the RCH-PCII group than in the RCH-RCH and PCII-RCH groups.
Table. Baseline Clinical Characteristics of the 4 Groups of Transported Patients
| |
PCII-PCII
(n=310) |
RCH-RCH
(n=107) |
PCII-RCH
(n=24) |
RCH-PCII
(n=35) |
P value |
| Age (years) |
72±14 |
76±12 |
73±12 |
72±13 |
0.17 |
| Sex (female/male) |
117/193 |
42/65 |
12/12 |
12/23 |
0.64 |
| Final diagnosis |
|
|
|
|
0.0004 |
| Cardiovascular (%) |
147 (47)*,##,$ |
37 (35)#,$$ |
4 (17)$$ |
21 (60) |
|
| Noncardiovascular (%) |
163 (53) |
70 (65) |
20 (83) |
14 (40) |
|
*<0.05 vs. RCH-RCH, **<0.01 vs. RCH-RCH, #<0.05 vs. PCII-RCH, ##<0.01 vs. PCII-RCH, $<0.05 vs. RCH-PCII, $$<0.01 vs. RCH-PCII. PCII, institution with 24-h percutaneous coronary intervention; RCH, regional core hospital without 24-h percutaneous coronary intervention; PCII-PCII, ECG transmitted to PCII, and patients directly transported to PCII; PCII-RCH, ECG transmitted to PCII, and patients directly transported to RCH; RCH-PCII, ECGs transmitted to RCH, and patients directly transported to PCII; RCH-RCH, ECGs transmitted to RCH, and patients directly transported to RCH.
Transmission of ECGs via the C-ECG system was successfully achieved in 97% of cases. ECG transmission was not achieved successfully in 16 cases due to human error in 5 cases, failure of Bluetooth connection due to insufficient battery charge in 2, malfunction of the application software in 7, and unknown cause in 2 cases. The C-ECG was transmitted in 0.82% of the total 59,878 transportations of patients with sudden illnesses in the participating areas during the study period. Figure 3 shows the final diagnosis of the transported patients: acute myocardial infarction was the most frequent diagnosis, followed by heart failure.
Figure 4A shows details of the transport of patients in the 4 groups except for Oita City. The use of the system varied greatly among the various EMS areas: the Usuki fire department was operating the C-ECG system most frequently.
Figure 5 shows the final diagnosis among the 4 groups. Cardiovascular disease was significantly more common in the PCII-PCII and RCH-PCII groups than in the other 2 groups.
Analysis of Patients Who Underwent PCI <24 h From Onset
Figure 6 shows the rates of patients who underwent PCI <24 h from onset among the 4 groups. There was no PCI in the PCII-RCH group. PCI was performed in the PCII-PCII, RCH-RCH, and RCH-PCII groups. The patients who underwent PCI <24 h from onset in the PCII-PCII group consisted of 47 with STEMI (87%), 4 with non-STEMI (7%), and 3 with unstable angina pectoris (6%). One patient who underwent PCI <24 h from onset in the RCH-RCH group had STEMI. All of the patients who underwent PCI <24 h from onset in the RCH-PCII group had STEMI.
Figure 4B shows the details of the transport in 2 groups of patients who underwent PCI <24 h from onset from areas outside Oita City. The Usuki fire department transported many patients who underwent emergency PCI in the RCH-PCII group.
Time Intervals
DTBT, door-to-catheterization laboratory time, and first medical contact to reperfusion time were investigated in 47 patients with STEMI in the PCII-PCII group (13 females, 69±12 years) and 10 patients with STEMI in the RCH-PCII group (2 females, 70±13 years). DTBT within 90 min was achieved in 87% in the PCII-PCII group and in 100% in the RCH-PCII group (P=0.26).
No significant difference was observed in DTBT (59±20 vs. 49±14 min), door-to-catheterization laboratory time (29±12 vs. 24±9 min), and first medical contact to reperfusion time (93±35 vs. 109±12 min) between the PCII-PCII and RCH-PCII groups (Figure 7A–C).
The 1 patient in the RCH-RCH group who underwent PCI <24 h from onset was temporarily admitted to a nearby RCH after reperfusion at the nearest PCII. He was transported to another PCII and eventually underwent primary PCI 2 h later. The DTBT of this patient was 55 min, the door-to-catheterization laboratory time was 40 min, the first medical contact to reperfusion time was 206 min, and the door-in door-out time was 94 min.
Discussion
There are 2 core findings of the present study. (1) C-ECG can assist in transporting ACS-suspicious patients to the optimal treatment facility, reducing unnecessary ambulance transport within a provincial prefecture, Oita, in Japan, and (2) DTBT (61±22 vs. 50±13 min, P=0.10) and door-to-catheterization laboratory time (31±15 vs. 26±10 min, P=0.28) did not show significant differences between the PCII-PCII and RCH-PCII groups.
DTBT and Prehospital 12-Lead ECG System and Prognosis
Among patients with STEMI who underwent primary PCI, a 32% reduction in death at 30 days was reported in the group in which a prehospital 12-lead ECG was recorded and the hospital was notified, compared with the group in which no such ECG was recorded.5 We recently reported that usage of C-ECG across a wide area of Oita, Japan, significantly reduced DTBT by 26 min and door-to-catheterization laboratory time by 20 min.6 It is important to reduce the time from onset to reperfusion for a better outcome for patients with STEMI. The goal of treatment in STEMI is to achieve reperfusion within 120 min from onset, which means initiating therapy within 30 min from first contact with medical personnel for fibrinolysis in emergency department at hospital and catheter treatment to within 90 min from the first contact with medical personnel for PCI. It is desirable to establish an integrated system of STEMI treatment through the cooperation of local medical administration, medical control, emergency transport system by fire departments, medical associations, and specialized medical institutions to achieve this goal.7
Prehospital ECG System for Transporting ACS-Suspicious Patients to Optimal Institutes
Our results showed that the prevalence of cardiovascular diseases was significantly more common in the PCII-PCII and RCH-PCII groups, especially in the RCH-PCII group (Figure 5), and the same trend was observed in the frequency of PCI <24 h from onset (Figure 6). The prehospital ECG system assisted in deciding to change the destination of patients with suspected ACS to PCII instead of a RCH, and the destination of patients in the RCH-PCII group was especially changed. The prehospital ECG system helped ensure cardiogenic patients requiring primary PCI were transported to an appropriate PCII.
We found no significant difference in DTBT between the PCII-PCII and RCH-PCII groups, and changing the EMS destination via the prehospital ECG system did not prolong the DTBT.
The PCII-RCH group had less prevalence of cardiovascular disease and no cases of PCI <24 h from onset (Figures 5,6). This was a result of the prehospital ECG changing the transport destination of patients with noncardiovascular diseases to a nearby RCH rather than toa distant PCII.
Both prehospital 12-lead ECG and first contact with a cardiologist significantly reduced the door-to-device time in a previous study.8 In-hospital mortality rates were worse when both factors were absent. The authors ascribed the results to a prehospital 12-lead ECG being performed within a few minutes by well-trained EMS and the prehospital 12-lead ECG facilitating hospital selection.8
Further Benefit of the Prehospital ECG System for ACS Patients
The prehospital 12-lead ECG can alert the cardiologist to the arrival of a patient in need of primary PCI. Without this foreknowledge, a hospital without a cardiologist on duty will have to contact the cardiologist on patient arrival and preparations for primary PCI will only then begin. However, direct transmission of prehospital ECGs to the cardiologist will enable preparations for primary PCI to begin immediately befoe the patient’s arrival.
Future Issues for Prehospital ECG Systems
Patients who underwent PCI <24 h from onset were very common in the PCII-PCII group as well as the RCH-PCII group (Figure 4), possibly because when the EMS crew recorded the 12-lead ECG in the ambulance, they inferred that the patient had ACS based on ECG findings, symptoms, vitals, etc. and requested a PCII to read the ECG and accept the patient with a single call. Automated ECG interpretation algorithms were introduced in the 1960s,9 and their performance has greatly improved since then, solidifying their role as a routine tool in cardiac care. The automatic interpretation statement for ACS on a prehospital ECG is very specific but not sensitive enough to exclude symptomatic coronary artery disease.10 If there is a system in the future using artificial intelligence that can infer ACS based on ECG findings, symptoms, vitals, etc. and determine the need for primary PCI correctly when the EMS team arrives at the patient, it will increase the probability of correct diagnosis, which will further assist in transporting ACS-suspicious patients to the optimal institute.
Many patients were transported to a distant PCII even though they did not require primary PCI, possibly because the number of cardiologists at RCHs is limited, and often ECG transmission and patient transport to a RCH are not available. There may be generally many cases in which a patient was not diagnosed with ACS but was transferred to thea PCII because the ECG alone was not sufficient to make a decision. Progree in prehospital ECG systems that can overcome these issues will be important for appropriate patient transport in the future.
In conclusion, our results demonstrated that a prehospital 12-lead ECG system in Oita was helpful in transporting ACS-suspicious patients to the optimal treatment facility, with a reduction in unnecessary ambulance transport. To achieve 100% success, further progress in prehospital ECG systems is important.
Acknowledgments
We thank Masae Hayashi and Tomomi Syuto for their assistance with the manuscript.
Sources of Funding
This research received no grant from any funding agency in the public, commercial or not-for-profit sectors.
Disclosures
There was no financial support for the present study. N.T. is a member of Circulation Journal’s Editorial Team.
Statement of Ethics
The authors have no ethical conflicts to disclose.
IRB Information
The Oita University Research Ethics Committee (No. 1262) approved this study.
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