Modified positioning of a smartphone based single-lead electrocardiogram device improves detection of atrial flutter

Validation of a novel smartphone-based photoplethysmographic method for ambulatory heart rhythm diagnostics: the SMARTBEATS study

AIMS

In the current guidelines, smartphone photoplethysmography (PPG) is not recommended for diagnosis of atrial fibrillation (AF), without a confirmatory electrocardiogram (ECG) recording. Previous validation studies have been performed under supervision in healthcare settings, with limited generalizability of the results. We aim to investigate the diagnostic performance of a smartphone-PPG method in a real-world setting, with ambulatory unsupervised smartphone-PPG recordings, compared with simultaneous ECG recordings and including patients with atrial flutter (AFL).

METHODS AND RESULTS

Unselected patients undergoing direct current cardioversion for treatment of AF or AFL were asked to perform 1-min heart rhythm recordings post-treatment, at least twice daily for 30 days at home, using an iPhone 7 smartphone running the CORAI Heart Monitor PPG application simultaneously with a single-lead ECG recording (KardiaMobile). Photoplethysmography and ECG recordings were read independently by two experienced readers. In total, 280 patients recorded 18 005 simultaneous PPG and ECG recordings. Sufficient quality for diagnosis was seen in 96.9% (PPG) vs. 95.1% (ECG) of the recordings (P < 0.001). Manual reading of the PPG recordings, compared with manually interpreted ECG recordings, had a sensitivity, specificity, and overall accuracy of 97.7%, 99.4%, and 98.9% with AFL recordings included and 99.0%, 99.7%, and 99.5%, respectively, with AFL recordings excluded.

CONCLUSION

A novel smartphone-PPG method can be used by patients unsupervised at home to achieve accurate heart rhythm diagnostics of AF and AFL with very high sensitivity and specificity. This smartphone-PPG device can be used as an independent heart rhythm diagnostic device following cardioversion, without the requirement of confirmation with ECG.

Consumer-Led Screening for Atrial Fibrillation: Frontier Review of the AF-SCREEN International Collaboration

The technological evolution and widespread availability of wearables and handheld ECG devices capable of screening for atrial fibrillation (AF), and their promotion directly to consumers, has focused attention of health care professionals and patient organizations on consumer-led AF screening. In this Frontiers review, members of the AF-SCREEN International Collaboration provide a critical appraisal of this rapidly evolving field to increase awareness of the complexities and uncertainties surrounding consumer-led AF screening. Although there are numerous commercially available devices directly marketed to consumers for AF monitoring and identification of unrecognized AF, health care professional-led randomized controlled studies using multiple ECG recordings or continuous ECG monitoring to detect AF have failed to demonstrate a significant reduction in stroke. Although it remains uncertain if consumer-led AF screening reduces stroke, it could increase early diagnosis of AF and facilitate an integrated approach, including appropriate anticoagulation, rate or rhythm management, and risk factor modification to reduce complications. Companies marketing AF screening devices should report the accuracy and performance of their products in high- and low-risk populations and avoid claims about clinical outcomes unless improvement is demonstrated in randomized clinical trials. Generally, the diagnostic yield of AF screening increases with the number, duration, and temporal dispersion of screening sessions, but the prognostic importance may be less than for AF detected by single-time point screening, which is largely permanent, persistent, or high-burden paroxysmal AF. Consumer-initiated ECG recordings suggesting possible AF always require confirmation by a health care professional experienced in ECG reading, whereas suspicion of AF on the basis of photoplethysmography must be confirmed with an ECG. Consumer-led AF screening is unlikely to be cost-effective for stroke prevention in the predominantly young, early adopters of this technology. Studies in older people at higher stroke risk are required to demonstrate both effectiveness and cost-effectiveness. The direct interaction between companies and consumers creates new regulatory gaps in relation to data privacy and the registration of consumer apps and devices. Although several barriers for optimal use of consumer-led screening exist, results of large, ongoing trials, powered to detect clinical outcomes, are required before health care professionals should support widespread adoption of consumer-led AF screening.

Atrial fibrillation detection using ambulatory smartwatch photoplethysmography and validation with simultaneous holter recording

BACKGROUND

Atrial fibrillation (AF)-associated embolic stroke is preventable, and AF detection may help to prevent stroke in subjects with paroxysmal AF. We aimed to evaluate the AF detection performance of smartwatch photoplethysmography (PPG) and the feasibility of ambulatory monitoring for AF detection in the daily life.

DESIGN AND METHODS

Consecutive subjects who underwent ambulatory Holter electrocardiogram (ECG) monitoring for AF detection or AF burden evaluation were enrolled. The participants underwent 24 hours of simultaneous Holter ECG monitoring and continuous PPG recording using a Garmin smartwatch. The PPG signals were processed for noise rejection, beat detection, beat labeling, and rhythm labeling for each 5-minute segment. The accuracy of the PPG AF detection was calculated using the corresponding simultaneous Holter ECG as the AF diagnostic standard.

RESULTS

Among the 200 available participants, 112 participants (56%) developed AF (the AF group). The sensitivity, specificity, and positive predicted value of AF detection in participants were 97.3%, 88.6%, and 91.6%, respectively. The area under the receiver operating characteristic curve was 0.90. When the performance was analyzed in these 5-minute segments, the sensitivity, specificity, and positive predicted values of AF detection were 97.1%, 86.8%, and 89.7%, respectively.

CONCLUSIONS

This study demonstrated the feasibility of ambulatory monitoring for AF detection using a commercial smartwatch in daily life. A smartwatch may be an alternative screening tool to standard ambulatory Holter monitoring.

Beyond the wrist: Using a smartwatch electrocardiogram to detect electrocardiographic abnormalities

BACKGROUND

When worn on the wrist, smartwatch electrocardiograms may provide important but incomplete information.

AIMS

We sought to evaluate the added benefit of placing the smartwatch on the ankle and on the chest to diagnose various electrocardiographic abnormalities compared with 12-lead electrocardiograms.

METHODS

Two hundred and sixty patients with (n=189) or without (n=71) known cardiac disorders underwent 12-lead electrocardiogram and smartwatch electrocardiogram recordings of lead I (AW-I) and of leads I and II and pseudo chest leads V1 and V6 (AW-4). AW-I and AW-4 diagnoses (three-cardiologist consensus) were compared with 12-lead electrocardiogram diagnoses (three-cardiologist consensus) to calculate sensitivity and specificity.

RESULTS

AW-I showed high accuracy for the diagnoses of atrial fibrillation (96% sensitivity, 91% specificity) and complete bundle branch block (85% sensitivity, 98% specificity). Compared with AW-I, AW-4 improved detection of an abnormal 12-lead electrocardiogram (91% vs. 80% sensitivity; P<0.01), atrial flutter/tachycardia (69% vs. 25% sensitivity; P=0.04), T-wave abnormalities (77% vs. 34% sensitivity; P<0.01), pathological Q-waves (41% vs. 7% sensitivity; P<0.01) and left anterior hemiblock (70% vs. 0% sensitivity; P=0.02). AW-4 also enabled better differentiation between atrioventricular block and sinus bradycardia (from 81% to 95% correct; P=0.03) and between atrial fibrillation and atrial flutter/tachycardia (from 71% to 89% correct; P=0.02), but not between bundle branch blocks (from 82% to 87% correct; P=0.57).

CONCLUSIONS

A smartwatch electrocardiogram on the wrist accurately diagnoses atrial fibrillation and bundle branch block. Recording additional leads significantly improves the accuracy of detecting an abnormal electrocardiogram and repolarization changes, and also allows for better differentiation of brady- and tachyarrhythmias.

Single limb electrocardiogram using vector mapping: Evaluation and validation of a novel medical device

INTRODUCTION

The Tiger Tech Warfighter Monitor (WFM) is a novel single-limb device for ECG acquisition. The WFM provides true (not derived) single limb Electrocardiogram monitoring (ECG) to provide heart rate and R-R interval monitoring between QRS complexes. Herein, we evaluate the diagnostic accuracy of the WFM heart rate, R-R interval monitoring, and heart rate variability monitoring in comparison to a 2‑lead chest ECG.

METHODS

Data was collected under Institutional Review Board (IRB) approval. Patients available within our institution's pre-operative holding unit were randomly selected to undergo simultaneous chest and WFM ECG monitoring. 3-5-min measurements were taken depending on the patient's availability. Data was saved to two separate mobile phones and time-stamped for synchronization. A proprietary Tiger Tech extraction algorithm was used to tag proper features on both the WFM 1-Limb ECG and Chest ECG data files. A separate algorithm was then used to compare the beat-to-beat variations between the ECGs.

RESULTS

Data was extracted and analyzed on 26 subjects. Linear regression of heart rate analysis revealed excellent correlations with an R² of 0.99 (p < 0.05). Similar linear regression evaluation of R-R interval correlation demonstrated a mean R² value of 0.95 (p < 0.05). Statistically significant correlation was achieved in all 26 included study participants. Heart rate variability also achieved excellent correlation (SDNN R² = 0.997, RMSSD R² = 0.995, LnRMSSD R² = 0.992, p << 0.05).

CONCLUSION

Results demonstrate that the WFM achieves excellent correlation with chest ECG for heart rate, R-R internals, and heart rate variability.

Prospective blinded evaluation of smartphone-based ECG for differentiation of supraventricular tachycardia from inappropriate sinus tachycardia

Introduction

Supraventricular tachycardias (SVT) are often difficult to document due to their intermittent, short-lasting nature. Smartphone-based one-lead ECG monitors (sECG) were initially developed for the diagnosis of atrial fibrillation. No data have been published regarding their potential role in differentiating inappropiate sinus tachycardia (IST) from regular SVT. If cardiologists could distinguish IST from SVT in sECG, economic health care burden might be significantly reduced.

Methods

We prospectively recruited 75 consecutive patients with known SVT undergoing an EP study. In all patients, four ECG were recorded: a sECG during SVT and during sinus tachycardia and respective 12-lead ECG. Two experienced electrophysiologists were blinded to the diagnoses and separately evaluated all ECG.

Results

Three hundred individual ECG were recorded in 75 patients (47 female, age 50 ± 18 years, BMI 26 ± 5 kg/m², 60 AVNRT, 15 AVRT). The electrophysiologists’ blinded interpretation of sECG recordings showed a sensitivity of 89% and a specificity of 91% for the detection of SVT (interobserver agreement κ = 0.76). In high-quality sECG recordings (68%), sensitivity rose to 95% with a specificity of 92% (interobserver agreement of κ = 0.91). Specificity increased to 96% when both electrophysiologists agreed on the diagnosis. Respective 12-lead ECG had a sensitivity of 100% and specificity of 98% for the detection of SVT.

Conclusion

A smartphone-based one-lead ECG monitor allows for differentiation of SVT from IST in about 90% of cases. These results should encourage cardiologists to integrate wearables into clinical practice, possibly reducing time to definitive diagnosis of an arrhythmia and unnecessary EP procedures.

Graphical abstract

A smartphone-based one lead ECG device (panel A) can be used reliably to differentiate supraventricular tachycardia (panel B) from inappropriate sinus tachycardia when compared to a simultaneously conducted gold-standard electrophysiology study (panels C, D).

Feasibility and Reliability of SmartWatch to Obtain 3-Lead Electrocardiogram Recordings

Some of the recently released smartwatch products feature a single-lead electrocardiogram (ECG) recording capability. The reliability of obtaining 3-lead ECG with smartwatches is yet to be confirmed in a large study. This study aimed to assess the feasibility and reliability of smartwatch to obtain 3-lead ECG recordings, the classical Einthoven ECG leads I-III compared to standard ECG. To record lead I, the watch was worn on the left wrist and the right index finger was placed on the digital crown for 30 s. For lead II, the watch was placed on the lower abdomen and the right index finger was placed on the digital crown for 30 s. For lead III, the same process was repeated with the left index finger. Spearman correlation and Bland-Altman tests were used for data analysis. A total of 300 smartwatch ECG tracings were successfully obtained. ECG waves' characteristics of all three leads obtained from the smartwatch had a similar duration, amplitude, and polarity compared to standard ECG. The results of this study suggested that the examined smartwatch (Apple Watch Series 4) could obtain 3-lead ECG tracings, including Einthoven leads I, II, and III by placing the smartwatch on the described positions.