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Original Article

Smartphone transmission of electrocardiography images to reduce time of cardiac catheterization laboratory activation

Chao, Chun-Chieha,b,c; Chen, Yi-Chunb; Shih, Chun-Mingd; Hou, Sen-Kuanga,b; Seethala, Raghu R.e; Aisiku, Imoigele P.e; Huang, Chuan-Chine; Hou, Peter C.e; Kao, Wei-Fonga,b,*

Author Information
Journal of the Chinese Medical Association: June 2018 - Volume 81 - Issue 6 - p 505-510
doi: 10.1016/j.jcma.2017.11.009


    1. Introduction

    The term ‘time is muscle’ is frequently used to emphasize the treatment for patients presenting with ST-segment elevation myocardial infarction (STEMI). Guidelines in adult advanced cardiac life support recommend that the door-to-balloon (D2B) time between initial presentation to the hospital and restoration of coronary flow to the ischemic myocardium should be within 90 min.1 Evidence has indicated that primary percutaneous coronary intervention (PCI) exhibits a greater benefit than fibrin-lytic therapy for treating patients with STEMI to restore myocardial reperfusion if performed less than 90 min after the initial presentation. Also, the guidelines state that electrocardiography (ECG) should be performed for patients presenting with chest pain and suspected acute coronary syndrome within 10 min upon arrival to the emergency department (ED). When STEMI is diagnosed, the emergency physician (EP) contacts the interventional cardiologist, and the most frequently used method of communication is verbal report by telephone. Telephone communication is rapid and convenient, but miscommunications may occur. Nowadays, images photographed on a smartphone can be transmitted to another smartphone easily, and there are many smartphone applications that can be used to transmit images.

    Many types of smartphone applications have recently been developed recently that have this function. The Line application (Line Corporation), which is an increasingly popular mobile messaging application, is available on all smartphone platforms. Like WhatsAPP, Line is a smartphone application used by more than 211 million people worldwide, and it allows users to send text messages and other types of media (such as images, voice messages, and videos) to their contacts. It is also easy to set up a group conference call that allows multiple users to participate in a conversation. For example, EPs have been using Line to transmit ECG images to interventional cardiologists when STEMIs are diagnosed in the ED (known as tele-ECG). After evaluating the patient's history and ECG, the cardiologist decides whether to activate the cardiac catheterization laboratory (CCL). This study evaluated the use of Line to facilitate communication between the EP and the interventional cardiologist in order to minimize the time from presentation to CCL activation.

    2. Methods

    Fifty-thousand patients visit the ED of this hospital annually, and patients can undergo emergent PCI. The hospital has six interventional cardiologists on call for consultation and emergent PCI (24/7). The decision to activate CCL was delegated to the interventional cardiologists after evaluation of the patient history and the ECG. For patients presenting with chest pain or angina-equivalent symptoms such as shortness of breath, ECGs were performed immediately upon the patient's arrival, and the EP was responsible for interpreting the findings immediately after it was completed. Mobile devices with a 12 megapixel camera were encrypted and provided by the hospital for the transmission of ECG images. Only personnel that participated in the program had access to the image transferred. Once STEMI had been diagnosed, the EP immediately consulted the interventional cardiologist by telephone. In the traditional group (group 1), the EP described the ECG pattern to the interventional cardiologist. In the tele-ECG group (group 2), the EP also transmitted the images of ECG to the interventional cardiologist through a smartphone application and as well as discussing the ECG images.

    We retrospectively evaluated patients diagnosed with STEMI who underwent PCI from January 1, 2014 to December 31, 2015. Patients were excluded if they were transferred from another hospital and if our hospital was informed of their arrival in advance. Group 1 included patient from the period January 1, 2014 to December 31, 2014 when traditional verbal (non-smartphone) communication was used. During this time period, hospital policy mandated adherence to the STEMI guidelines. In the ED, more technicians were hired to perform the initial ECG in the ED and steps in this process of care were enhanced to improve D2B time. In group 2, we included the use of Line for transmitting ECG that started on January 1, 2015, and we reviewed the charts of patients with STEMI through this method until December 31, 2015. To prepare for the use of smartphones to transmit ECGs, the smartphones of EPs and interventional cardiologists were encrypted. The images of ECG did not show any patient identifiers.

    We recorded chief complaints on arrival, and whether the patient's arrival was during regular hours or off-hours. Regular hours were defined as the time from 8:00 am to 5:00 pm Monday to Friday except for holidays, and off-hours represented all times other than regular hours. As demonstrated in Fig. 1, we recorded further time-points: (1) the time the ECG was performed from the initial time of ED arrival, (2) the time of ECG interpretation by the EP from the initial time of ED arrival, (3) the time of interventional cardiologist consultation from the initial time of ED arrival, (4) the CCL activation time by the interventional cardiologist from the initial time of ED arrival, and (5) D2B (time of balloon inflation after the initial time of ED arrival). We defined: (1) Time to ECG interpretation by EP = time from ED arrival to ECG interpretation by an EP; (2) Time to ECG interpretation by an EP = from initial time of ED arrival to ECG interpretation by an EP; (3) Activated CCL time = time from ED arrival to CCL activation; (4) Time of CCL activation = from initial time of ED arrival to CCL activation by the cardiologist.

    Fig. 1.:
    Timeline of the sequence on management of STEMI patients.

    Our primary outcome was the time from ECG interpretation to CCL activation. Secondary outcomes included D2B time ≤ 90 min, the proportion of patients reaching D2B time ≤ 90 min, and the 28-day mortality rate. Mortality is defined as death within 28 days after ED presentation.

    2.1. Statistical analysis

    Continuous variables were described as mean ± SE and compared using the Student t test, and the Wilcoxon rank-sum test was used for the D2B and CCL activation time because the times did not fit a normal distribution. Categorical variables were expressed as frequencies and compared using a χ2 tests and where appropriate, a Fisher exact test. We used a linear regression analysis to examine the association between two outcomes: ECG interpretation by EP to CCL activation time and ECG interpretation by EP to balloon inflation time, and three potential predictors: after Line usage, atypical presentation, and the effect of off-hour presentation. We first performed a univariate analysis, followed by a multivariate model including three potential predictors. p Values of <0.05 were considered to be statistically significant. A statistical analysis was performed using SPSS software version 14.0 (SPSS Inc, Chicago, IL).

    3. Results

    During this period, there were 329 transmissions with suspicions of abnormal ECG and clinical presentations of acute coronary syndrome. A total of 96 patients with STEMI were identified; however, 12 patients were excluded because they were transferred from another hospital and the study site hospital was notified in advance of their arrival. Hence, we enrolled and analyzed 84 patients with STEMI who were treated during the study period. Forty patients underwent ECG interpretation by EPs using traditional telephone communication with the cardiologist (group 1), and the ECG results of 44 patients were transmitted to the interventional cardiologist through Line (group 2).

    The baseline characteristics and results of both groups are detailed in Table 1: all 84 patients underwent successful PCI. Between groups 1 and 2, age and time of arrival exhibited no significant difference, and time of ECG performed was not significantly different. After the implementation of ECG image transmissions through Line, the time from ECG interpretation by an EP to CCL activation was significantly decreased from 28.3 ± 4.1 min in group 1 to 17.6 ± 2.3 min in group 2 (p = 0.03) as shown in Fig. 2. Balloon inflation time from time of ECG interpretation by EP also decreased from 93.1 to 73.4 min (p = 0.025). The D2B time was 119.3 ± 16.3 min in group 1 compared with 90.4 ± 9.8 min in group 2 (p = 0.23), and 52.5% of the patients in group 1 had a D2B time of ≦90 min compared with 70.5% in group 2 (p = 0.09). Mortality rate in group 1 was 12.5% compared with 2.2% in group 2 (p = 0.07).

    Table 1:
    The basic characteristics and time intervals of the study groups (group 1 using a telephone and group 2 with tele-ECG).
    Fig. 2.:
    Decrease in time of EP read ECG to CCL activation (p = 0.03). EP = emergency physician; CCL = cardiac catheterization laboratory.

    In the univariate analysis, patients had a shortened time from ECG interpretation by EP to CCL activation after the implementation of Line in the treatment procedure (−10.9 min; p = 0.02) or arrived during regular hours (−9.4 min; p = 0.046). D2B time was reduced by 28.9 min (p = 0.12) in patients with typical chest pain, while patients with atypical presentation had an increase of 109.5 min in D2B time (p < 0.001). In the multivariate analyses, the implementation of Line remained associated with a shortened time from ECG interpretation by EP to CCL activation (−9.3 min; p = 0.045), and atypical presentation was associated with a longer time D2B time (46 min; p < 0.001), as shown in Table 2. We intended to employ the same model for the mortality analysis; however the sample size was too small for the adjustment.

    Table 2:
    Univariate and multivariate analysis of ECG interpretation by EP to CCL activation time and door to balloon inflation time.

    4. Discussion

    In 2015, there were 1.91 billion users of smartphones worldwide. Smartphones can be used not only for communication in the general public, but also a tool to facilitate improved patient care. Many types of applications have been used for communication and the transmission of images such as WhatsApp, Skype, and Line. Line is very popular in eastern Asia, and its main functions include communication, and the sending of images and videos clips. Technological improvement in the speed of transmission and camera quality in mobile devices facilitates the sharing of medical information and assists medical personnel in making decision rapidly. A previous study demonstrated a significant reduction in D2B time when WhatsApp messenger was utilized to transmit the ECG images.2 Wireless mobile systems are useful and reliable for the transmission of ECG images through handheld computers and mobile phones.3 In our study, the implementation of Line to transmit ECG images reduced the time from ECG interpretation to CCL, and the time from ECG interpretation by EP to balloon inflation. Although the results were not statistically significant, our study indicated that the average D2B time was reduced after the implementation of Line from 119.3 to 90.4 min. Atypical presentations could have been a major confounding factor because ECG took longer to perform.

    Previous studies have indicated that PCI is more effective as a reperfusion strategy than thrombolytic therapy for the treatment of STEMI.4 Therefore, optimal outcomes with PCI will be obtained if the response time is reduced.5 Many strategies have been employed to reduce D2B time. Out-of-hospital ECG transmission from the emergency medical services (EMS) field has been shown to be associated with shorter D2B times and superior compliance with the 90-min benchmark.6,7 Activation of CCL by emergency physicians is another feasible method for time reduction from diagnosis to treatment.8,9 However, several studies have reported discordance in the interpretation of ECGs between EPs and cardiologists, resulting in errors that may have affected medical management in 3–4% of cases6 or a false-positive activation of cardiac catheterization that may have led to unnecessary resource utilization.10 The real-time transmission of ECGs to interventional cardiologists will minimize this discordance and reduce the number of false-positive activations. Bradley et al.11,12 identified six factors that improved D2B time: an EP being authorized to activate cardiac catheterization, a single call to a central page operator to activate cardiac catheterization, The ED activating the CCL equipment before patient arrival, the interventional cardiologist being notified and arriving in the CCL within 20 min of its equipment being activated, an attending cardiologist always being on duty on-site, and staff in the ED and the CCL using real-time data for feedback. From January 1, 2015 to December 31, 2015, we used Line for the transmission of ECG images to interventional cardiologists 194 times (82 times for arrhythmia, and 112 times for chest pain). There are 40 patients diagnosed with STEMI during this period. Adding the use of smartphone application to transmit the ECG of patient diagnosed with STEMI to the interventional cardiologist may reduce the errors from misinterpretation and miscommunication by telephone.

    In contrast, atypical presentations may delay the time that patients received their ECG after ED arrival. Several groups such as elderly patients, females, and patients with diabetes mellitus often present with atypical symptoms such as the painless onset of STEMI followed by various other symptoms.13

    In our study, the primary outcome of interest is the time from the initial ECG interpretation of the patient with STEMI to cardiac catheterization. Some factors may have affected the time that the patient received an ECG examination. If the ECG is not performed in a timely manner, the time of cardiac catheterization and D2B would definitely be affected. In this study, we use time interval from ECG to cardiac catheterization to minimize the confounding effect of the delay in the ECG being performed. Some factors relating to the patients themselves may have affected the time of ECG being performed, such as the chief complaint and the ED arrival time. In our study, the implementation of LINE to the reduce time between the ECG interpretation to CCL activation remained significant after adjustment for atypical presentation and arrival period. Previous studies have indicated that D2B time was reduced in the tele-ECG group compared with the control group (86 min vs 125 min, p < 0.0001),14 and a higher percentage of patients reached the D2B time goal (<90 min) (78% vs 55%; p < 0.001).15 In our study, we focused on the period after the ECG was performed to CCL activation. Due to many confounding factors such as decision time by patient or their family, the time when a patient arrived at the ED (during regular hours or off-hours), and the time that the ECG was performed may have affected the D2B time.

    Differences in the D2B time for patients with STEMI between regular hours and off-hours have been discussed in previous studies.16,17 Patients diagnosed with STEMI received PCI more promptly during regular hours. In our hospital, the interventional cardiologist was on call but not always on-site. During off-hours, interventional cardiologist are permitted to stay at home, and required to return to the hospital within 30 min of being contacted by telephone regarding a patient with STEMI. Early recognition of STEMI can facilitate and reduce the time required for the activation of the CLL.

    In conclusion, the implementation of Line for transmitting ECG images was associated with a reduction in the time from ECG interpretation by the EP to CCL activation, and the time from ECG interpretation by EP to balloon inflation in patients with STEMI. The use of Line in the ED for the transmission of ECG images to interventional cardiologists can facilitate communication and improve patient care. This study demonstrated the potential for integrating smartphones and their applications for clinical care and the improvement of patient outcomes.

    This is a retrospective, before-and-after study, in that resources were increased and hospital policy required adherence to STEMI guidelines before the implementation of Line for the transmission of ECG data. Hence, the results may have been influenced by the Hawthorn effect. Lastly, we could not determine the rate of discordance between EPs and interventional cardiologists in our study, and further research is required.


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    Cardiac catheterization laboratory; Electrocardiography; Percutaneous coronary intervention

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