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Rise of the smart device ECG and what it means for the general cardiologist
  1. Richard Bennett1,
  2. Antony French2
  1. 1 Cardiology, Bristol Heart Institute, Bristol, Bristol, UK
  2. 2 Cardiology, Royal United Hospital Bath NHS Trust, Bath, UK
  1. Correspondence to Dr Antony French, Royal United Hospital Bath NHS Trust, Bath, UK; antony.french{at}nhs.net

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Introduction

Diagnostic pathways for identification of clinically significant paroxysmal arrhythmia have historically relied on ambulatory ECG monitoring. While useful as a risk stratification tool in certain patient groups, in general, it has a limited yield for infrequent arrhythmia. This is inherently cost-inefficient, and time to diagnosis can be delayed. Smartphone-based ECG devices are now well established in the public market. However, their adoption into standard investigatory pathways is not yet widespread. Recently, the National Institute for Health and Care Excellence (NICE) published a diagnostics guidance document, which reviewed the smartphone-based devices, AliveCor Kardia and imPulse, with respect to atrial fibrillation (AF) detection. NICE concluded there was insufficient evidence to recommend routine adoption in primary care and recommended further research.1 Regardless, given the evidence that is available and their uptake by the general public, cardiologists are increasingly likely to encounter them. This article will focus on the AliveCor Kardia as the device is currently easily available to the general public.

How the AliveCor works

The AliveCor is a smartphone-based system which utilises a downloaded application and a battery powered pair of electrodes. It produces a single-lead rhythm strip, which is comparable to Lead 1 of a standard ECG. The device uses an algorithm with reported 98% sensitivity and 97% specificity for diagnosis of AF.2 More recently, a device capable of producing a six-lead ECG has been developed. The device is user friendly and easily transported. To record an ECG, a user should position the Kardia device close to the mobile phone, place a finger on each electrode for 30 s and, via ultrasonic audio, a single-lead ECG strip will appear on screen (figure 1). The application classifies the rhythm strip as normal sinus rhythm, possible AF, unclassified or unreadable. A monthly subscription can be paid, which allows the user to store multiple ECGs and send the image securely via email directly to a physician.

Figure 1

Image on the left shows the AliveCor Kardia; this can be used with an application on any smart device. The image on the right shows the Apple watch. Both devices record the ECG as a pdf file which can be sent to the physician. Both also indicate whether the ECG shows sinus rhythm, atrial fibrillation or cannot be determined.

Evidence base and clinical practice

Although its use in QT interval monitoring for patients deemed high risk of developing QT prolongation has been reported,3 the bulk of the evidence base behind the use of AliveCor in clinical practice primarily supports its use in detection of AF. There are, however, numerous case studies reporting the successful detection of other significant arrhythmias such as supraventricular tachycardia. The well-publicised 2017 REHEARSE-AF (Assessment of REmote HEArt Rhythm Sampling using the AliveCor heart monitor to scrEen for Atrial Fibrillation) trial studied patients ≥65 years of age with a CHA2DS2-VASc score of ≥2. One thousand and one patients were randomised equally to twice weekly ECG monitoring with the AliveCor device or routine clinical care over 12 months. Nineteen patients in the AliveCor group were diagnosed with AF compared with five in the routine care group, equating to a statistically significant outcome (p=0.007). Cost per AF diagnosis was calculated at £8255.2 The patient satisfaction scores with the device were very high. It appears likely that the cost of diagnosis and subsequent treatment would be outweighed by the reduction in thromboembolic events, but large-scale health economic evaluation would be required in the setting of randomised control trials in order to validate this. The Heart Rhythm Society and American College of Physicians recently completed a study designed to determine the feasibility of an AF screening programme using the AliveCor. The population was similar to that of the REHEARSE study, but all patients underwent a one-off AliveCor ECG assessment, with further confirmatory 12-lead ECG assessment by a physician if abnormal. They concluded that such a programme was feasible, but increased monitoring and targeting of high-risk groups would be required to increase diagnostic yield.4

Until recently, use of the AliveCor in detection of infrequent symptom driven arrhythmia such as supraventricular tachycardia has relied on self-purchase by the patient. However, the formal use of the device by cardiologists may offer an improvement on ambulatory ECG in this patient cohort in the future, being more patient friendly, and with a much-increased monitoring window. There is a need for a direct comparison study between standard care and the AliveCor in this setting.

Conclusion

Smart device ECG recording appears to represent a good diagnostic tool for patients with infrequent symptoms of palpitations, promoting patient-led care and may help relieve the increasing burden on ambulatory ECG use and analysis in today’s busy healthcare systems. There is growing evidence to support its use as a screening tool for the detection of subclinical AF in high-risk populations, but further studies are required in order to equate this benefit to stroke and mortality reduction. In summary, the AliveCor, along with the rise of other mobile ECG devices such as the imPulse, Apple watch and SnapECG seems likely to play a key role in the future of ambulatory ECG monitoring.

References

Footnotes

  • Contributors Both the authors have contributed to producing this article and are in agreement with submitting it for consideration of publication.

  • 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 for publication Not required.

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

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