Smart detection of atrial fibrillation†

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Abstract

Aims

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice, and its paroxysmal nature makes its detection challenging. In this trial, we evaluated a novel App for its accuracy to differentiate between patients in AF and patients in sinus rhythm (SR) using the plethysmographic sensor of an iPhone 4S and the integrated LED only.

Methods and results

For signal acquisition, we used an iPhone 4S, positioned with the camera lens and LED light on the index fingertip. A 5 min video file was recorded with the pulse wave extracted from the green light spectrum of the signal. RR intervals were automatically identified. For discrimination between AF and SR, we tested three different statistical methods. Normalized root mean square of successive difference of RR intervals (nRMSSD), Shannon entropy (ShE), and SD1/SD2 index extracted from a Poincaré plot. Eighty patients were included in the study (40 patients in AF and 40 patients in SR at the time of examination). For discrimination between AF and SR, ShE yielded the highest sensitivity and specificity with 85 and 95%, respectively. Applying a tachogram filter resulted in an improved sensitivity of 87.5%, when combining ShE and nRMSSD, while specificity remained stable at 95%. A combination of SD1/SD2 index and nRMSSD led to further improvement and resulted in a sensitivity and specificity of 95%.

Conclusion

The algorithm tested reliably discriminated between SR and AF based on pulse wave signals from a smartphone camera only. Implementation of this algorithm into a smartwatch is the next logical step.

Related collections

Most cited references 4

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Incidence of newly detected atrial arrhythmias via implantable devices in patients with a history of thromboembolic events.

Ehab Daoud, Michael Ezekowitz, E Hilker … (2010)

Evidence of atrial tachycardia/atrial fibrillation (AT/AF) is often sought in patients with ischemic stroke or transient ischemic attack. We studied patients with previous thromboembolic events (TE) who were implanted with devices capable of continuous arrhythmia monitoring to comprehensively quantify the incidence and duration of newly detected AT/AF. This study represents a subgroup analysis of the TRENDS trial, which included patients with clinical indications for pacemakers or defibrillators and >or=1 stroke risk factors (heart failure, hypertension, age 65 or older, diabetes, or previous TE). A history of AF was not required. All implanted devices were capable of continuously monitoring the cumulative time spent in AT/AF each day. This analysis focuses primarily on the incidence and duration of newly detected AT/AF (defined as >or=5 minutes of AT/AF on any day) in patients with previous TE, no documented history of AF, and no warfarin or antiarrhythmic drug use. A total of 319 patients had a history of TE and >or=1 day of device data. Patients with a documented history of AF (n=80), warfarin use (n=56), or antiarrhythmic drug use (n=20) were excluded from analysis. Of the remaining 163 patients, newly detected AT/AF was identified via the device in 45 patients (28%) over a mean follow-up of 1.1+/-0.7 years. AT/AF recurred infrequently, with only 12 patients experiencing AT/AF on >10% of follow-up days. Newly detected episodes of AT/AF were found via continuous monitoring in 28% of patients with previous TE. Most episodes would not have been detected by standard intermittent monitoring techniques.

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Application of the Poincaré plot to heart rate variability: a new measure of functional status in heart failure.

James A. Tonkin, P W Kamen (1995)

Conventional methods of quantifying heart rate variability using summary statistics have shown that decreased variability is associated with increased mortality in heart failure. However, many patients with heart failure have arrhythmias which make the 'raw' heart rate variability data less suitable for the use of summary statistical measures. To examine the clinical potential of a new measure of heart rate variability data, presented by the Poincaré plot pattern, as an adjunct to the summary statistical measures of R-R interval variability. We used the Poincaré plot pattern to display beat-to-beat heart rate variability data from a group of 23 patients with heart failure and compared them with data collected from 20 healthy age-matched control subjects. The data, which consists of 2000 consecutive R-R intervals, were gathered over 20-40 minutes while the subjects rested supine in a quiet darkened room. The morphological classification scheme proposed reflected the functional status of patients in heart failure. There was a significant difference (chi-square = 27.5, p < 0.0001) in the different pattern types between patients with NYHA Class I and II compared to patients with NYHA Class II and IV. All healthy subjects displayed a 'cluster' type of pattern characterised by normally distributed data. Sixteen of the 23 patients in heart failure also produced data which were normally distributed but the remaining seven produced data which required careful filtering to make them suitable for analysis using summary statistics, but which could be analysed by the Poincaré plot. The Poincaré plot pattern is a semi-quantitative tool which can be applied to the analysis of R-R interval data. It has potential advantages in that it allows assessment of data which are grossly non-Gaussian in distribution, and is a simple and easily implemented method which can be used in a clinical setting to augment the standard electrocardiogram to provide 'real time' visualisation of data.

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Short-term heart rate variability--age dependence in healthy subjects.

A Heitmann, Darrell Schroeder, S Perz … (2012)

Heart rate variability (HRV) analysis is an established method to characterize the autonomic regulation and is based mostly on 24h Holter recordings. The importance of short-term HRV (less than 30 min) for various applications is growing consistently. Major reasons for this are the suitability for ambulatory care and patient monitoring and the ability to provide an almost immediate test result. So far, there have been only a few studies that provided statistically relevant reference values for short-term HRV. In our study, 5 min short-term HRV indices were determined from 1906 healthy subjects. From these records, linear and nonlinear indices were extracted. To determine general age-related influences, HRV indices were compared from subjects aged 25-49 years with subjects aged 50-74 years. In a second approach, we examined the development of HRV indices by age in terms of age decades (25-34, 35-44, 45-54, 55-64 and 65-74 years). Our results showed significant variations of HRV indices by age in almost all domains. While marked dynamics in terms of parameter change (variability reduction) were observed in the first age decades, in particular the last two age decades showed certain constancy with respect to the HRV indices examined.

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Author and article information

Journal

Journal ID (nlm-ta): Europace

Journal ID (iso-abbrev): Europace

Journal ID (publisher-id): europace

Title: Europace

Publisher: Oxford University Press

ISSN (Print): 1099-5129

ISSN (Electronic): 1532-2092

Publication date (Print): May 2017

Publication date (Electronic): 01 July 2016

Publication date PMC-release: 01 July 2016

Volume: 19

Issue: 5

Pages: 753-757

Affiliations

[1 ]Department of Internal Medicine, Basel University Hospital, Petersgraben 4, Basel 4031, Switzerland

[2 ]Department of Internal Medicine, University Hospital Regensburg, Franz-Josef-Strauß-Allee 11, Regensburg 93053, Germany

[3 ]Medical Outpatient Clinic, Basel University Hospital, Petersgraben 4, Basel 4031, Switzerland

[4 ]Department of Cardiology, Bern University Hospital, Freiburgstrasse 10, Bern 3010, Switzerland

[5 ]Department of Cardiology, Basel University Hospital, Petersgraben 4, Basel 4031, Switzerland

[6 ]Preventicus GmbH, Tatzendpromenade 2, Jena 07745, Germany

Author notes

[* ]Corresponding author. Tel: +41 61 32 87689; fax: +41 61 265 5353. E-mail address: jens.eckstein@ 123456usb.ch

[†]

Trial was performed at the University Hospital Basel.

[‡]

Both authors contributed equally to this work.

Article

Publisher ID: euw125

DOI: 10.1093/europace/euw125

PMC ID: 5437701

PubMed ID: 27371660

SO-VID: c97868e0-c457-4038-8569-2ca35e1a8bc3

License:

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

History

Date received : 23 February 2016

Date accepted : 10 April 2016

Page count

Pages: 5

Funding

Funded by: University Hospital Basel

Funded by: Preventicus

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