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Comparison of a smartphone-based ECG recording system with a standard cardiac event monitor in the investigation of palpitations in children
  1. Mairi Macinnes,
  2. Nicholas Martin,
  3. Helen Fulton,
  4. Karen A McLeod
  1. Royal Hospital for Children, Glasgow, UK
  1. Correspondence to Dr Karen A McLeod, Department of Cardiology, Royal Hospital for Children, Glasgow G51 4TF, UK; karen.mcleod{at}ggc.scot.nhs.uk

Abstract

Background The AliveCor (Kardia) monitor attaches to a smartphone and allows a single-lead ECG to be recorded during symptoms. In 2016, we introduced the use of this smartphone device for investigating palpitations, without syncope, in children. The aim of our study was to review our experience with the smartphone device, comparing it with our previous standard conventional approach to cardiac event monitoring using the Cardiocall monitor, which uses skin electrodes and is given for a finite period.

Methods Over a period of 24 months, 80 smartphone monitors were issued and compared with the most recent 100 conventional event monitors. The number of ECG recordings received, arrhythmias documented, quality of ECG recordings and patient satisfaction were evaluated.

Results Median patient age was 11 years in the smartphone monitor group compared with 10 years in the conventional group. Seventy-nine of 80 (98%) patients with a smartphone monitor sent an ECG recorded during symptoms, compared with 62/100 (62%) from the conventional group. A total of 836 ECG recordings were sent from the smartphone monitors compared with 752 from the conventional group. Eight per cent of ECG recordings in each group were of inadequate quality for analysis. Twenty of 80 (25%) patients with a smartphone monitor had documented tachyarrhythmia compared with 6/100 (6%) patients with the conventional monitor (p<0.001). On comparison with the conventional approach, the smartphone monitor outperformed with respect to diagnostic yield and patient satisfaction.

Conclusions A smartphone-based event monitor allows simple, effective, long-term ECG event monitoring in children that is highly acceptable to the patient and parent.

  • cardiology
  • monitoring
  • paediatric practice

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What is already known on this topic?

  • Palpitations in children can be difficult to diagnose due to their paroxysmal nature and unwillingness of children to wear a cardiac event monitor.

  • A smartphone cardiac event monitor and mobile phone app may be useful in the diagnosis of arrhythmias in adults and children.

What this study adds?

  • A smartphone event monitor is a simple, effective way to diagnose symptomatic arrhythmia in children that is associated with high levels of patient satisfaction.

Introduction

Palpitations in children can be difficult to investigate because arrhythmias are typically paroxysmal and an ECG trace is required at the time of symptoms. Our standard approach to diagnosis has relied on cardiac event monitors with skin electrodes to record an ECG during symptoms.1 These are associated with a number of problems in children, including irritation of the skin by electrodes and failure to capture the ECG because of infrequent symptoms, coupled with relatively short duration of wearing the monitor or not wearing it when symptoms occur. As a result, repeated uses may be required to record transient arrhythmias. Other issues include failure or delay of parents to return the monitor, high costs of repairs and servicing and waiting times to receive an event monitor. As a result of these problems, in January 2016 at the Royal Hospital for Children in Glasgow, we introduced the use of a smartphone event monitor for the investigation of children with palpitations. The AliveCor monitor (Kardia) attaches to a mobile device running the AliveECG application. It has mostly been used for diagnosing atrial fibrillation (AF) in adults but has been shown to be successful in recording supraventricular tachycardia (SVT) in children.2–5

In our institution, children are eligible for the smartphone event monitor if they are aged 2 years or older, have symptoms of palpitations less frequently than once per week and they, or their parents, have a device compatible with the monitor. Children with frequent symptoms of once a week or more either are issued a conventional cardiac event monitor with skin electrodes, in our institution the Cardiocall (Spacelabs Healthcare) for up to 4 weeks or ambulatory continuous ECG monitor for up to 7 days with analysis of ECG during events only.

To record an ECG with the smartphone monitor, the user places two fingers from each hand onto the electrodes and a single-lead rhythm strip is obtained. Children under the age of 2 years and children with syncope during symptoms are not eligible for using the device as they are not expected to be able to place their fingers adequately on the electrodes. Artefact can be reduced by encouraging the child to rest their forearms on a flat surface with the event monitor resting in their hands. It is also possible to record an ECG trace by placing the left knee in contact with one electrode and the right hand on the other electrode or by placing the device on the lower left side of the chest with the bottom of the device pointing towards the centre of the body. Families are issued an information leaflet on how to use the device and download the App. They also attend a brief appointment with a cardiac physiologist (previously known as cardiac technician) to set up the device. A National Health Service email account has been set up for use by the cardiac physiologists, exclusively to accept email ECG recordings sent from the patient’s phone or other device. This email account is checked by a cardiac physiologist twice daily. All ECG recordings are analysed by the cardiac physiologist and then forwarded by email to the patient’s consultant paediatric cardiologist. If any ECG shows an arrhythmia, the patient’s cardiologist or, if not available, the on-call cardiology team is contacted immediately to prompt consultant review of the arrhythmia. All patients are issued the smartphone device to keep unless they, or their cardiologist, arrange for it to be returned.

After 24 months, we undertook a retrospective review of diagnostic yield and patient satisfaction, comparing the results with the last 100 Cardiocall monitors issued for investigation of palpitations.

The number of ECG recordings from each type of device, number of arrhythmias documented and quality of ECG recordings were analysed. Patient satisfaction questionnaires were sent out to 50 patients in each group.

This study was a retrospective review of an aspect of routine medical care and did not involve human or animal experimentation. The study was reviewed by the local Research and Development and Ethical Services, who concluded that formal ethical approval was not required.

Results

There were 80 smartphone monitors issued for palpitations over a period of 24 months. Patient age varied from 4 to 17 years (median 11 years) and 51 patients were female (63%). Of the 100 patients issued with the conventional event monitor, their ages ranged from 2 to 17 years (median10 years) and 55 were female (55%).

A total of 836 ECG recordings had been received at the time of analysis from the smartphone monitor group compared with 752 ECG recordings from the conventional group. Seventy-nine (98%) of the 80 patients in the smartphone monitor group sent at least one recording compared with 69/100 (69%) patients in the conventional group (p<0.05). In the smartphone event monitor group, the number of ECG traces received from the 79 patients who sent recordings ranged from 1 to 138, with a median of four recordings per patient. In the conventional group, of the 69 patients who sent a recording, there were 1–111 ECG traces received per patient, with a median of three recordings per patient. In the smartphone event monitor group, 69 traces (8.3%) were uninterpretable due to artefact, similar to that in the conventional group in which 60 traces (8%) were uninterpretable. In the smartphone monitor group, 100 ECG traces from 20 (25%) of the 80 patients showed an arrhythmia, compared with 19 ECG traces from 6 (6%) of the 100 patients in the conventional group (p<0.0001). A narrow complex tachycardia was diagnosed in 19/20 smartphone event monitor patients with arrhythmia. The remaining patient had broad complex tachycardia (figure 1), which was diagnosed as atrioventricular nodal re-entry tachycardia with aberrant conduction at subsequent electrophysiology study. Narrow complex regular tachycardia was found in five of the six patients with arrhythmia in the conventional group and the remaining patient had AF. A comparison of traces received from the two devices can be seen in figures 2 and 3.

Figure 1

Rhythm strip from smartphone event monitor showing broad complex tachycardia.

Figure 2

Rhythm strip from AliveCor monitor showing narrow complex tachycardia. Spontaneous termination of tachycardia is captured on the recording.

Figure 3

Rhythm strip from Cardiocall monitor showing narrow complex tachycardia.

Of the anonymous patient satisfaction questionnaires sent out to 50 families in both groups, there was a return rate of 38% (19/50) in the smartphone monitor group and 26% (13/50) in the conventional group. At the time of returning the questionnaire the median age was 13 years for both the smartphone monitor group and the conventional group. Overall satisfaction was higher in the smartphone monitor group with 89% of responders giving a rating of ‘satisfied’ or ‘very satisfied’ compared with 38% in the conventional group (p<0.01). In terms of ease to set up the device and use of the device at time of symptoms, responses were similar between the two groups. A higher proportion in the conventional group found it difficult to upload and send the ECG trace (38%) compared with the smartphone monitor group (5%). In terms of how helpful the device was at identifying a cause for the patient’s symptoms, 13/19 (68%) found the smartphone monitor device and 7/13 (54%) found the conventional device helpful or very helpful.

Discussion

Smartphone use is becoming increasingly common in medicine and is omnipresent in society as a whole.6 Children of increasingly younger ages have access to mobile devices and are familiar with their use. This technology can be harnessed when trying to detect paediatric arrhythmias. Previous studies have looked at the ability of apps, which use the camera flashlight, to detect heart rate and found that the reliability and accuracy of the app reduced at higher heart rates.7 8 This limits their use in paediatric practice as tachyarrhythmias will typically be associated with heart rates >200/min.9 Ferdman et al conducted a study to determine the utility of the smartphone device to record SVT and distinguish atrioventricular nodal re-entry tachycardia from atrioventricular re-entry tachycardia.3 They found that the single ECG tracing from the smartphone device could correctly identify SVT in all cases and was able to predict the mechanism of SVT as accurately as published reports of Holter monitors. Nguyen et al investigated the use of the smartphone device in 35 children with documented paroxysmal arrhythmia and concluded that the smartphone device can generate tracings of diagnostic and therapeutic quality in children with a diagnosis of SVT or AF.4 Patient satisfaction surveys indicated that the device was easy to use in terms of obtaining and transmitting the ECG trace.

At present, the smartphone device is in clinical use in adult practice for the detection of paroxysmal AF.10 11 A number of studies have validated the detection of AF on traces obtained from the smartphone device in comparison to a standard 12-lead ECG and a traditional cardiac event monitor.2 12 Patient satisfaction has been reported higher in the smartphone group when compared with standard cardiac event recorders.12

This study is the first to review the use of the smartphone event monitor in routine clinical practice for the investigation of palpitations in children. The data concur that the smartphone device generates ECG tracings of sufficient quality to make a diagnosis of arrhythmia in children. The diagnostic quality of traces obtained was comparable to our previous standard approach to cardiac event monitoring. The majority of arrhythmias detected were SVT, this being the most common arrhythmia seen in the paediatric population.1 The arrhythmia yield was significantly higher in the smartphone monitor group, largely due to them being issued for the child to keep rather than for a finite period of time, although for those who sent recordings, the number of ECG traces submitted per patient was similar between the two groups. Paediatric cardiology is a relatively small subspecialty and patients with possible arrhythmias may be geographically distant from a tertiary paediatric cardiology centre. The relatively low initial outlay costs, simplicity and availability of the device make it ideal for use by paediatricians with expertise in cardiology in smaller centres. The ECG traces can easily be sent by email and thus review of traces by a paediatric cardiologist can easily be facilitated.

There are virtually no maintenance or retrieval costs associated with the smartphone event monitor in comparison to conventional cardiac event monitors. Healthcare costs can also be reduced by ongoing remote ECG monitoring, potentially reducing the need for outpatient clinic and emergency department attendances. In selected patients, it may avoid the need for an implantable loop recorder. It has been our experience that issuing the smartphone monitors to keep can help reduce patient and parental anxiety as the patient can simply record and send an ECG whenever there are further symptoms rather than wait for a further medical review. When this is taken into account the smartphone event monitors can be considered to ‘pay for themselves’ over time. User satisfaction in our study was extremely positive in the smartphone monitor group with reported overall satisfaction levels significantly higher than the conventional monitor group. However, the return rate of the questionnaires was low in both groups, so this may not be truly representative.

The smartphone event monitor has several limitations. Patients can only use it if they have access to a compatible smartphone or tablet. It is unsuitable for those presenting with palpitations associated with syncope or for detecting initiation of arrhythmia.

Conclusions

A smartphone event monitor can generate ECG traces of diagnostic quality in children and has a greater diagnostic arrhythmia yield when compared with a standard approach of using a cardiac event recorder with skin electrodes. It is a simple, effective way to diagnose symptomatic arrhythmia in children, associated with high levels of patient satisfaction. It may avoid the need for an implantable loop recorder in selected patients.

References

Footnotes

  • Contributors MM was involved in data collection, creating the patient satisfaction questionnaires, analysing the data and was the main author in writing the paper. NM and HF did most of the data collection and analysis. KAM had the idea of reviewing our institution’s experience of issuing a smartphone cardiac even to investigate children with palpitations. KAM was involved in data analysis and had a major contribution to writing the paper.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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