Klinische studies

Lees meer over het wetenschappelijk onderzoek achter FibriCheck.

Klinische studies

Lees meer over het wetenschappelijk onderzoek achter FibriCheck.

Fundamentele principes

Clinical Validation of Heart Rate Apps: Mixed-Methods Evaluation Study

Objective: The aim of this paper was to investigate and describe the necessary elements in validating and comparing HR apps versus standard technology.
Methods: The FibriCheck (Qompium) app was used in two separate prospective nonrandomized studies. In the first study, the HR of the FibriCheck app was consecutively compared with 2 different Food and Drug Administration (FDA)-cleared HR devices: the Nonin oximeter and the AliveCor Mobile ECG. In the second study, a next step in validation was performed by comparing the beat-to-beat intervals of the FibriCheck app to a synchronized ECG recording.
Results: In the first study, the HR (BPM, beats per minute) of 88 random subjects consecutively measured with the 3 devices showed a correlation coefficient of .834 between FibriCheck and Nonin, .88 between FibriCheck and AliveCor, and .897 between Nonin and AliveCor. A single way analysis of variance (ANOVA; P=.61 was executed to test the hypothesis that there were no significant differences between the HRs as measured by the 3 devices. In the second study, 20,298 (ms) R-R intervals (RRI)–peak-to-peak intervals (PPI) from 229 subjects were analyzed. This resulted in a positive correlation (rs=.993, root mean square deviation [RMSE]=23.04 ms, and normalized root mean square error [NRMSE]=0.012) between the PPI from FibriCheck and the RRI from the wearable ECG. There was no significant difference (P=.92) between these intervals.
Conclusion: Our findings suggest that the most suitable method for the validation of an HR app is a simultaneous measurement of the HR by the smartphone app and an ECG system, compared on the basis of beat-to-beat analysis. This approach could lead to more correct assessments of the accuracy of HR apps.

Vandenberk T et al. Clinical Validation of Heart Rate Apps: Mixed-Methods Evaluation Study. JMIR 2018.

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Validation of a smartphone-based photoplethysmographic beat detection algorithm for normal and ectopic complexes

Objective: To develop and validate a smartphone based acquisition and processing algorithm based on photopletyhsmographic (PPG) data collected in a controlled hospital environment.
Methods: A smartphone camera application was developed to record PPG data in synchronization with a reference electrocardiogram. Subjects were recorded while undergoing an electrophysiological examination. The PPG data acquisition was validated on 28 volunteers with sinus rhythm. After signal analysis an algorithm was developed for detection of ectopic beats. To characterize arrhythmias, supraventricular extrasystoles were induced every 10, 5 or 3 beats after 500 ms by applying a pacing train to the right atrium. The coupling interval was also examined by altering the intermediary time by 400, 500 or 600 ms.
Results: After signal conditioning, an accurate ectopic beat detection was obtained from the PPG signal. Premature atrial ectopic beats could be differentiated based on the interpeak distance at different coupling intervals.
Conclusion: By acquiring a PPG signal with the camera, the smartphone is not only capable of determining a regular sinus rhythm, but it also has the power to identify ectopic beats.

Drijkoningen L et al. Validation of a smartphone-based photoplethysmographic beat detection algorithm for normal and ectopic complexes. Computing in Cardiology, 2014.

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Validatiestudies

Validation of a new smartphone application (“FibriCheck”) for the diagnosis of atrial fibrillation in primary care

Methods: A phase II diagnostic accuracy study in a convenience sample of 242 subjects recruited in primary care. The majority of the participants were patients with a known history of AF (n = 160). A PPG measurement was obtained while patients held their index finger on the smartphone camera during one minute. A synchronized single-lead ECG was taken on the chest. Both traces were interpreted by the FibriCheck AF algorithm. First, the results of the FibriCheck algorithm were compared with 12-lead electrocardiographic recordings. Secondly, beat-to- beat comparison was done between the PPG and the single-lead ECG measurements.
Results: The signal quality filter of the application defined 29 PPG’s and 10 single-lead traces as poor and unreliable signal quality. For the PPG measurement and interpretation by the FibriCheck app, a sensitivity of 98% (95% CI 92 – 100), a specificity of 88% (95% CI 80 – 94) and an accuracy of 93% (95% CI 89 – 96) were obtained. False positive results were caused by atrial (n = 7) or ventricular (n = 1) extrasystoles and by failure of the quality filter of the application in recognizing a poor and unreliable signal (n = 4). For the single-lead ECG interpretation by the FibriCheck app, a sensitivity of 98% (95% CI 93 – 100), a specificity of 90% (95% CI 83 – 95) and an accuracy of 94% (95% CI 91 – 97) was found. The 11 false positive results were due to atrial (n = 10) and ventricular (n = 1) extrasystoles. Beat-to-beat analysis of the synchronized PPG and singlelead ECG traces showed a small difference in performance (99% uniform diagnoses), due to the different measurement method.
Conclusion: The FibriCheck app is an accessible standalone smartphone application that showed promising results for AF detection in a primary care convenience sample. The app scored a high accuracy and sensitivity and a moderate to high specificity. The PPG measurement method nearly matched single-lead ECG performance. These findings make the app a possible candidate to implement in future screening or case-finding programs for AF.

Mortelmans C et al. Validation of a new smartphone application (“FibriCheck”) for the diagnosis of atrial fibrillation in primary case. EHRA conference, Vienna, 2017.

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PPG versus single lead ECG for the diagnose of Atrial Fibrillation

Objective: Diagnosis of Atrial Fibrillation based on the visual interpretation of a PPG signal results in a high clinical accuracy compared to single lead ECG and the current gold 12-lead ECG-standard.
Methods: A double-blind, randomized, prospective study was performed. The visual signal of simultaneous measured PPG and one-lead ECG were selected for diagnosis by a cardiologist. These files included AF, sinus rhythms, bad signal (bad quality of PPG or/and ECG signal) and other arrhythmia measurements. The PDF-files were randomly mixed and divided over two bundles. Four doctors (one cardiologist, one electrophysiologist and two assistant cardiologists) were asked to review one of the bundles. The diagnosis of the PPG and one-lead ECG signals were compared to the diagnosis of the 12-lead ECG.
Results: 344 pairs of PPG, one-lead ECG and 12-lead ECG signals were reviewed by cardiologists. Out of the 12-lead ECG files, 173 were diagnosed as AF. Averaged results showed a PPG sensitivity rate of 83.52% and a specificity rate of 92.39% compared to a sensitivity rate of 93.09% and a specificity rate of 95.89% for the one-lead ECG. After eliminating other arrhythmias and bad signals, further data-analysis was done. Sensitivity and specificity rates increased to 96.28% and 99.08% for PPG compared to 95.64% and 98.42% for one-lead ECG. Considerable differences between reviewers were found for sensitivity rates.
Conclusion: The use of a smartphone application for AF patients results in a good accuracy for the diagnose of this heart rhythm disorder. Although possible problems could arise round education and training for cardiologist. After enabling dataanalysis, sensitivity and specificity rates increase to very high accuracy corresponding 12-lead ECG. Algorithms could be important to process PPG measurements to adjust the quality of the data. This study concludes the potential to detect and
diagnose AF in patients by the use of a smartphone with FibriCheck.

Vandenberk T et al. PPG versus single lead ECG for the diagnose of Atrial Fibrillation. e-Cardiology, Berlin 2017.

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Smartphone-based use of the photoplethysmography technique to detect atrial fibrillation in primary care: a diagnostic accuracy study of the FibriCheck application

A convenience sample of patients, aged 65 and older, with and without a known history of AF, was recruited from 17 primary care facilities. Patients with an active pacemaker rhythm were excluded. A PPG signal was obtained with the backside camera of an iPhone 5S. Simultaneously, a single-lead ECG was registered using a dermal patch with a wireless connection to the same smartphone. PPG and single-lead ECG signals were analyzed using the FibriCheck AF algorithm. At the same time, a 12-lead ECG was obtained and interpreted off-line by independent cardiologists to determine the presence of AF. A total of 102/223 subjects (46%) were in AF. PPG signal quality was sufficient for analysis in 93%, and single-lead ECG quality was sufficient in 94% of the participants. After removing insufficient quality measurements, the sensitivity and specificity were 96% (95% CI 89-99%) and 97% (95% CI 91-99%) for the PPG signal versus 95% (95% CI 88-98%) and 97% (95% CI 91-99%) for the single-lead ECG, respectively. False-positive results were mainly due to premature ectopic beats. In 196 subjects where the signal quality of both techniques was adequate, PPG and single-lead ECG yielded a similar diagnosis in 192 subjects (98%).
Mortelmans C et al. Smartphone-based use of the photoplethysmography technique to detect atrial fibrillation in primary care: a diagnostic accuracy study of the FibriCheck application. JMIR, 2019.

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The diagnostic accuracy of a pulse-deriving smartphone application is device independent

This study evaluated the diagnostic accuracy of a PPG-based pulse-deriving smartphone application (FibriCheck) with respect to handheld single-lead ECG and the gold standard, 12-lead ECG. In addition, the device dependent nature of the performance of the application was assessed.
Patients who were scheduled for a regular consultation or procedure (i.e. ablation or cardioversion) were recruited from the cardiology ward. Additionally, patients hospitalized for continuous cardiac monitoring were recruited to enrich the database with atrial fibrillation (AF) measurements. After obtaining written informed consent, patients filled in a questionnaire collecting demographic and medical information. Patients were handed 6 Android and 2 iOS devices and were asked to perform one PPG-measurement per device. They also performed a single-lead ECG measurement with a handheld device (Kardia Mobile). Subsequently, a 12-lead ECG was taken to obtain a reference diagnosis.
A total of 150 patients participated in the study. The mean age of the study population was 64 (±19) years, 58% was male. The AF-prevalence was 37%. On average, patients in AF had a higher CHA2DS2-VASc score; 3.93 (±1.80) compared to 2.02 (±1.63) for non-AF patients.
The amount of insufficient quality measurements recorded with the pulse-deriving smartphone application ranged from 4% (iOS) to 13% (Android). Averaged for all the smartphone devices, the pulse-deriving application scored 87.7% (±3%) sensitivity, 96.6% (±3%) specificity, 77.2% (±5%) NPV, 98.3% (±1%) PPV, and 90.3% (±2%) accuracy. The handheld singlelead ECG device had 87.6% sensitivity, 91.5% specificity, 78.2% NPV, 95.5% PPV, and 88.9% accuracy.
The same calculations were preformed after excluding regular atrial flutter measurements. On average, the pulse-deriving application scored 94.8% (±1%) sensitivity, 96.1% (±3%) specificity, 88.1% (±3%) NPV, 98.3% (±1%) PPV, and 95.2% (±1%) accuracy. The handheld single-lead ECG device had 95.5% sensitivity, 90.2% specificity, 90.2% NPV, 95.5% PPV, and 93.9% accuracy.
The diagnostic accuracy of the pulse-deriving smartphone application and the handheld single-lead ECG device was strongly influenced by the presence of regular atrial flutters, stressing the importance of further thorough validation. For the pulsederiving smartphone application, there was no significant influence from device type in terms of diagnostic accuracy.

Proesmans T et al. The diagnostic accuracy of a pulse-deriving smartphone application is device independent. European Heart Rhythm Meeting, 2019.

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Patiënten met voorkamerfibrillatie behandelen

Post-ablation outcome monitoring using a pulse-deriving smartphone application

Objective: Despite improvements of outcome of ablation for AF, early arrhythmia recurrence is not uncommon up to 3 months post-ablation. Although these arrhythmias are transient and do not represent treatment failure, it is widely recognized as a risk factor for long-term recurrence. To date, a better understanding in the correlation between early and long-term recurrence is hindered by an inability to continuously monitor these patients. We hypothesize that the implementation of a pulse-deriving smartphone application in this population offers the potential to detect early as well as late recurrence in order to initiate proper treatment in a timely manner.
Methods: Four clinical centers included a total of 80 participants who underwent successful AF treatment using ablation therapy. All participants were instructed to measure twice daily with a pulse-deriving smartphone application (FibriCheck) and additionally when experiencing symptoms, for a monitoring period of 4 months post-ablation. The planned usual-care pathway was registered at study inclusion. All measurements were revised algorithmically and confirmed by the treating physicians and healthcare professionals from the FibriCheck monitoring center. At time of inclusion and study end a 12-lead ECG was performed.
Results: The mean age of the study population was 66 (±13) years from which 25 % was female. Using the CHA2DS2-VASc score, 61% of the participants had an increased stroke risk (i.e. a score of 2 or more). Overall compliance to conduct measurements was recorded at 91% with 2 measurements per day. The smartphone app was able to identify 29 AF-cases (36%) of which 27 paroxysmal and 2 persistent. Only 37% of the AF cases were symptomatic. In the usual care path only 3/29 (10%) cases were identified with 12-lead ECG at the next scheduled consult and 9 (31%) patients identified with AF would been monitored by Holter.
Conclusion: Pulse-deriving smartphone applications implemented in combination with a structured care path proved to be a promising methodology for short- and long-term outcome monitoring of post-ablation patients and are capable in the detection of silent intermittent atrial fibrillation episodes.

Proesmans T et al. Post-ablation outcome monitoring using a pulse-deriving smartphone application. European Society of Cardiology conference, Munich 2018.

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Implementation of a pulse-deriving smartphone application in highrisk populations for primary and secondary prevention of stroke

This multicenter national study addresses the implementation and evaluation of the FibriCheck application in high-risk patient populations as a solution for primary and secondary stroke prevention. This study was performed for the Cabinet of Minister of Health De Block and the National Institute for Health and Disability Insurance (RIZIV). The study was organized in 8 clinical centers in the Northern part of Belgium. Patients were included in the following groups: (1) patients with relevant comorbidities, (2) patients with structural heart disease, (3) patients with an increased CHARGE-AF score, (4) postcryptogenic stroke patients, (5) post-cardioversion, and (6) post-ablation patients. Patients with a pacemaker rhythm were excluded. To quantify the number of AF-patients identified with the application versus during usual care, the initially planned care-path of each patient was documented. Patients were requested to perform 2 measurements per day and log their symptoms with each recording. A 12-lead ECG was taken at inclusion and study end. In total, 460 patients were included, 168 were female (37%). The mean age was 66 ± 12 years. The mean CHA2DS2-VASc score was 2.2 ± 2.5, 97 patients (21%) were anticoagulated. On average, patients enrolled for 1.86 ± 1.1 months. 47,667 measurements were performed, 81% was normal and 2% indicative for AF. 34% of the AF-measurements was symptomatic. A 91% compliance in performing 2 measurements per day was observed. 61 AF-patients (13%) were identified by the algorithm and confirmed by physician interpretation, 25 were previously undiagnosed. The mean age of the AF-group was 66 ± 11 years. The mean CHA2DS2-VASc score was 2.4 ± 1.6. Following these findings, 49 therapeutic interventions were carried out. Of the 61 AF-patients, 11 (18%) were also identified on 12-lead ECG. When questioning the physicians concerning the planned usual care-path, it appeared that 37 AF-patients (61%) would have received 12-lead ECG checks during follow-up consultations. 6 AF-patients (10%) would have received 24-hour Holter monitoring. Patients with structural heart disease, post-cardioversion, and postablation patients had the greatest chance of being monitored during follow-up consultations.
This study presents the first results of prolonged PPG-monitoring in high-risk populations for AF detection. Considering the high number of asymptomatic registrations, repeated PPG spot-checks proved to be valuable for the detection of new or recurrent, (a)symptomatic, paroxysmal or persistent AF.

Proesmans T et al. Implementation of a pulse-deriving smartphone application in highrisk populations for primary and secondary prevention of stroke. Belgian Heart Rhythm Meeting, 2018.

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Screenen op voorkamerfibrillatie

Evaluating smartphone based photoplethysmography as a screening solution for atrial fibrillation: a digital tool to detect AF?

Methods: Participants presented themselves voluntarily at two screening sites. Screening was done using sequential measurements of a single lead ECG device (AliveCor) and a software only smartphone application based on PPG (FibriCheck). AliveCor measurements were performed by placing both hands on two electrodes while FibriCheck requires to place the finger on the smartphone camera. If one of the applications indicated an irregular rhythm a 12-lead ECG was taken for verification.
Results: In total 1056 participants were screened, 41% was male. The mean age was 59±15 years with a mean BMI of 26±10.
In total 31% had no risk factors for AF, 34% had 1 risk factor, 19% had 2 risk factors and 16% had +2 risk factors. The screening resulted in the identification of 8 AF cases, 1026 regular sinus rhythms and 22 other irregular rhythms. The AF cases had a CHADS2-VASc score of 3±1.18. AliveCor had a sensitivity of 100% and specificity of 99.6% for the detection of AF, while FibriCheck had a sensitivity of 100% and a specificity of 97.2%. Overall quality of the FibriCheck and AliveCor measurements was automatically determined and was unreadable in 2.9% and 3.8% of the cases respectively. No correlation was found between the cases with bad quality for both measurement techniques or demographics.
Conclusion: The obtained results indicate that detection of pulse intervals based on PPG is a feasible, sensitive and accurate screening tool for the detection of AF with a high level of agreement when compared to the results obtained using the single lead ECG. The use of a smartphone-only application could unlock the potential of digital screening and support case finding in selected population at risk for AF.

Grieten L et al. Evaluating smartphone based photoplethysmography as a screening solution for atrial fibrillation: a digital tool to detect AF? JACC, 2017.

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Screening for atrial fibrillation using only a smartphone application: a new tool to unlock digital screening?

Objective: Opportunistic screening for Atrial Fibrillation (AF) is proven to be important and effective in identifying cases of untreated, frequently asymptomatic AF. This work focuses on the performance evaluation of using a smartphone application FibriCheck as a screening tool during the week of the heart rhythm (WHR).
Methods: Participants presented themselves voluntarily at the screening sites (AZ Delta, Roeselare or Ziekenhuis Oost-Limburg, Genk) during the WHR. Screening was done using sequential measurements a single lead ECG device (AliveCor, 30 seconds) and a software only smartphone application based on photoplethysmography (PPG) (FibriCheck, 60 seconds). AliveCor measurements were performed by placing both hands on two electrodes while the FibriCheck requires to place the finger on the smartphone camera. Additionally, demographic and background questionnaires were obtained. If one of the screening technologies indicated an irregular rhythm a 12-lead ECG was taken for verification by the cardiologist on site.
Results: In total 1056 participants were screened, 41% was male. The overall mean age was 59±15 years with a mean BMI of 26±10. In total 31% had no risk factors for AF, 34% had 1 risk factor, 19% had 2 risk factors and 16% had two or more risk factors. The screening resulted in the identification of 8 AF cases, 1026 regular sinus rhythms and 22 irregular rhythms (bigeminy, trigeminy, supraventricular arrhythmia). The AF cases had a CHADS2-VASc score of 3±1.18. The AliveCor application had a sensitivity of 100% and specificity of 99.6% for the detection of atrial fibrillation, while the FibriCheck application had a sensitivity of 100% and a specificity of 95.8% for the detection of atrial fibrillation. Overall quality of the FibriCheck and AliveCor measurements was automatically determined and was unreadable/unusable in 2.9% and 3.8% of the cases respectively. These cases required an additional measurement to obtain a diagnosis. No correlation was found between the cases with bad quality measurements for both measurement techniques.
Conclusion: The obtained results indicate that detection of pulse intervals based on PPG is a sensitive and accurate screening tool for the detection of atrial fibrillation and has a high level of agreement with the results obtained using the single lead ECG. The use of a smartphone-only application could unlock the potential of digital screening and support case finding of atrial fibrillation in selected population at risk for atrial fibrillation.

Grieten G et al. Screening for atrial fibrillation using only a smartphone application: a new tool to unlock digital screening? Belgian Heart Rhythm Meeting, 2016.

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Evaluation of screening technologies and assessments in a voluntary screening program in the general Belgian population

Objective: This study was organized to assess the efficacy and feasibility of a nationwide voluntary screening program in the Belgian general population over 40 years of age.
Methods: Participants were ad-hoc invited for a complementary screening in 2 clinical centers in Belgium over a period of 5 consecutive days during the heart rhythm week. Participants filled in a questionnaire assessing eligibility and CHA2DS2-VASc parameters. A total of 1359 participants were screened, 1179 of whom were older than 40 years. From this general screening population, high quality measurements of 1095 participants captured by a PPG smartphone application (FibriCheck) and a single-lead ECG tool (KardiaMobile), evaluated by both an automatic algorithm and visual interpretation, were included for data analysis. Additionally, the accuracy of the algorithm-based tools with respect to manual rhythminterpretation was assessed.
Results: This study reports a prevalence of AF in the general screening population of 0.5% with a higher prevalence in men (0.9%) compared to in women (0.2%). The average age of the AF-group was 76 (±3) years. Using the CHA2DS2-VASc score, all participants with a positive AF-screening had a high risk score for stroke (i.e. a score of 2 or more). Although the intent of screening for AF is straightforward (either a positive or negative result), both screening tools have a subdivision to categorize irregular heart rhythms in AF, sinus rhythm or other arrhythmias. This extra category provides a clinical challenge on how to interpret screening results. Therefore, a dual assessment was made in this study: aiming for maximum sensitivity by combining the AF and the other arrhythmia categories versus maximum specificity by combining the normal and the other arrhythmia categories. When striving for maximal sensitivity, the algorithm-based interpretation of the PPG trace scored a sensitivity/specificity/accuracy (SSA) of 100%/97%/97%. Algorithm based interpretation of the single-lead ECG trace had an SSA of 100%/95%/95%. When striving for maximal specificity, the algorithm-based interpretation of the PPG trace scored SSA of 100%/98%/98%. Algorithm based interpretation of the single-lead ECG trace had a SSA of 100%/99%/99%.
Conclusion: AF was present in 0.5% of the participants. All participants with a positive AF-screening had an increased risk for thromboembolism. The present study shows that a voluntary screening program using high accuracy PPG-based and single-lead ECG tools was able to detect an important number of patients with previously undetected AF.

Grieten L et al. Evaluation of screening technologies and assessments in a voluntary screening program in the general Belgian population. Heart Rhythm Society, Boston 2018.

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Atrial fibrillation screening with photo-plethysmography through a smartphone camera

Objective: This cross-sectional study was set up to assess the feasibility of mass screening for atrial fibrillation (AF) with only the use of a smartphone.
Methods & results: A local newspaper published an article, allowing to subscribe for a 7-day screening period to detect AF. Screening was performed through an application that uses photo-plethysmography (PPG) technology by exploiting a smartphone camera. Participants received instructions on how to perform correct measurements twice daily, with notifications pushed through the application’s software. In case of heart rhythm irregularities, raw PPG signals underwent secondary offline analysis to confirm a final diagnosis. From 12 328 readers who voluntarily signed up for screening (49 ± 14 years; 58% men), 120 446 unique PPG traces were obtained. Photo-plethysmography signal quality was adequate for analysis in 92% of cases. Possible AF was detected in 136 individuals (1.1%). They were older (P < 0.001), more frequently men (P < 0.001), and had higher body mass index (P = 0.004). In addition, participants who strictly adhered to the recommended screening frequency (i.e. twice daily) were more often diagnosed with possible AF (1.9% vs. 1.0% in individuals who did not adhere; P = 0.008). Symptoms of palpitations, confusion, and shortness of breath were more frequent in case of AF (P < 0.001). The cumulative diagnostic yield for possible AF increased from 0.4% with a single heart rhythm assessment to 1.4% with screening during the entire 7-day screening period.
Conclusion: Mass screening for AF using only a smartphone with dedicated application based on PPG technology is feasible and attractive because of its low cost and logistic requirements.

Verbrugge F. et al. Atrial fibrillation screening with photo-plethysmography through a smartphone camera. Europace, 2019.

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Kwaliteitsstudies

Using smartphone enabled technologies for detection atrial fibrillation: is there a difference in signal quality between ECG and PPG?

Objective: This work focuses on comparing the performance between photoplethysmography (PPG) and single lead ECG based smartphone applications during a national incentivized screening initiative and evaluate the quality related issues between these technologies.
Methods: Participants presented themselves voluntarily during the screening initiative. Screening was done using sequential measurements. First the circumference of the index finger and temperature of the finger was recorded. Next a single lead ECG device (AliveCor, 30 seconds) and a software only smartphone application based on photoplethysmography (FibriCheck, 60 seconds). AliveCor measurements were performed by placing both hands on two electrodes while the FibriCheck requires to place the finger on the smartphone camera. Additionally, demographic and background questionnaires were obtained. If one of the screening technologies indicated an irregular rhythm a 12-lead ECG was taken for verification by the cardiologist on site.
Results: In total 1056 participants were screened, 41% was male. The overall mean age was 59±15 years with a mean BMI of 26±10. In total 31% had no risk factors for AF, 34% had 1 risk factor, 19% had 2 risk factors and 16% had two or more risk factors. The screening resulted in the identification of 8 AF cases, 1026 regular sinus rhythms and 22 irregular rhythms (bigeminy, trigeminy, supraventricular arrhythmia). The AF cases had a CHADS2-VASc score of 3±1.18. The AliveCor had a sensitivity of 100% and specificity of 99.6% for the detection of AF, while the FibriCheck application had a sensitivity of 100% and a specificity of 97.2. The proprietary quality algorithms of AliveCor and FibriCheck indicated if the quality of the signal was insufficient for analysis. The quality was unreadable in 2.9% and 3.8% of the cases respectively. The main indicator
were cold hands, tremor or callus formation at the hands of the users. Interestingly, no correlation was observed between both technologies. Only in 10% of the bad quality signals there was a correlation between both technologies. The other cases the majority of the findings favored normal recordings.
Conclusion: The obtained results indicate that detection of pulse intervals based on PPG is a sensitive and accurate screening tool for the detection of atrial fibrillation and has a high level of agreement with the results obtained using the single lead ECG. Despite the quality challenges of PPG signals, there is no correlation found in the cause nor the agreement between both technologies indicating that for the general population the quality parameters are properly tuned to prevent misdiagnosis as much as possible. These quality parameters will be a fundamental requirement further leverage PPG signals as a suitable signal for heart rhythm analysis.

Grieten L et al. Using smartphone enabled technologies for detection atrial fibrillation: is there a difference in signal quality between ECG and PPG? Heart Rhythm Society, Boston 2018.

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The quality of smartphone based heart rhythm monitoring using PPG technology in a large-scale free-living setting

This observational study evaluated the applicability and robustness of the FibriCheck smartphone application implemented in a broad population in a free-living setting.
A local newspaper published a free 7-day access code for a pulse-deriving smartphone application. Participants to this screening program received instructions on how to perform high quality measurements twice daily. To obtain a high quality signal, participants were instructed to adopt a sitting position with both arms resting on a firm surface, holding the smartphone in a vertical position with their dominant hand. Subsequently, the index finger of their non dominant hand should cover the flashlight and backside camera horizontally, without putting firm pressure. The FibriCheck application firstly checks acquired PPG signals for their quality. Compromised signals are not used for analysis to avoid inaccurate diagnostic results. Study participants with frequent poor quality PPG measurements received notifications through the application, guiding them on how to perform better measurements.
From 12,328 readers who voluntarily signed up for screening (49±14 years; 58% men), 120,446 unique PPG traces were obtained. AF was detected in 136 individuals (1.1%).
PPG signal quality was sufficient for analysis in 110,713 measurements (92%). The frequency of measurements with insufficient quality for analysis decreased significantly during the screening period, from 17% on day 1 to 2% on day 7 (Pvalue<0.001), indicating a steep learning curve. 8,683 participants only performed high quality PPG measurements. They were significantly younger compared to participants with at least one insufficient quality measurement (49 versus 51 years old, P-value<0.001).
This study demonstrates the applicability and robustness of a pulse-deriving smartphone application in a broad population in an unsupervised setting, provided that efforts are focused on training and education. Awaiting further validation studies, these results indicate the potential of a pulse-deriving smartphone application to detect atrial fibrillation.

Proesmans T et al. The quality of smartphone based heart rhythm monitoring using PPG technology in a large-scale free-living setting. European Heart Rhythm Meeting, 2019.

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Effect of age on the usability of a photoplethysmography based smartphone application

This work investigates the effect of age on the usability of the FibriCheck smartphone application. A usability test was performed on 95 participants divided in three age categories; young adults (18-29), adults (30-65) and pensioners (65+).
Participants were instructed to use the application and perform critical tasks with minimum supervision or assistance. The tasks included multiple functionalities of the app (e.g. downloading, create an account, perform a measurement, add context, log-in, etc.). The time to perform each task and amount of insufficient quality measurements were documented.
Subjective usability estimation was inquired via a survey.
Although significant differences were observed between the time required to perform each task, all the tasks were completed successfully. In general, the elderly required more time to perform a task and reported higher difficulty levels in the subjective usability estimation. No significant difference was found between the groups regarding the number of insufficient quality measurements.
Although there is a difference in time to perform tasks and in the difficulty experienced between age categories, it does not affect the usability of the smartphone application. These results demonstrate that the FibriCheck application can be implemented in the relevant target groups.

Elaâchiri A et al. Effect of age on the usability of a photoplethysmography based smartphone application. European Heart Rhythm Meeting, 2019.

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Gezondheidseconomie

Health economic assessment of smartphone implementation for atrial fibrillation monitoring in cryptogenic stroke patients

Objective: This study will address this by implementing a smartphone application for AF monitoring in post-cryptogenic stroke patients and assessing its cost-effectiveness.
Methods: In a multi-center prospective trial, 63 patients experiencing a cryptogenic stroke in the past year since the start of the study were enrolled. Patients were instructed to measure the heart rhythm twice daily with a pulse-deriving smartphone application (FibriCheck) and additionally when experiencing symptoms over a period of 3 months. At time of inclusion and study end, a 12-lead ECG was performed.
In addition, the cost-effectiveness of monitoring in patients after a recent cryptogenic stroke was assessed using a Markov model. The model simulated the health status of 1000 patients over a period of 35 years. Rates of AF detection and anticoagulation therapy from this study and published literature, together with epidemiological data from Belgium, were used to predict lifetime costs and effectiveness. The alternatives being investigated were opportunistic screening, usual care and screening with FibriCheck.
Results: This study reports 3 (5.2%) newly diagnosed AF cases and 1 (1.7%) recurrent AF case. None of these cases were identified with 12-lead ECG, neither at inclusion nor at the end of the study. Only 1 patient detected by FibriCheck during the monitoring period would been monitored by Holter as part of the usual care strategy.
The Markov model indicated that both opportunistic screening and usual care were inferior to FibriCheck in terms of costeffectiveness. Comparing FibriCheck as screening tool with usual care for patients post-cryptogenic stroke, the implementation of FibriCheck in a population of 1000 patients resulted in 26 quality adjusted life years (QALY) and substantial cost savings of -1.189 €/QALY.
Conclusion: After a cryptogenic stroke, 3-month FibriCheck monitoring proved to be cost-effective for preventing recurrent strokes. These results strengthen the evidence base for prolonged monitoring in secondary stroke prevention.

Proesmans T et al. Health economic assessment of smartphone implementation for atrial fibrillation monitoring in cryptogenic stroke patients. European Society of Cardiology Conference, Munich 2018.

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Draagbare sensoren

“Smart” solutions for paroxysmal atrial fibrillation?

Based on the review of Carpenter and Frontera, we present a case of a 66-year old female patient with a history of unexplained syncope, and symptoms of palpitations which was implanted with an Implantable Loop Recorder (ILR) (LinQ, Medtronic). After the procedure the patient was provided with a smartwatch device (E4, Empatica) able to measure the photoplethysmography (PPG) signal at the wrist and an iPhone 5S smartphone with a custom-made application (FibriCheck®), able to measure the PPG signal in the tip of the finger using the smartphone camera.
She was instructed to wear the smartwatch during the nights to perform at least 7 hours of continuous measurements. After waking and removing the watch for charging, she was instructed to perform spot-check measurements (60 seconds) using a smartphone application (FibriCheck®). In total 2 recordings standard recordings were obtained per day, and additional measurements upon presentation of symptoms.
All of these measurements were performed over a period of 4 months. After every recording the data was automatically sent to a secure database (in the cloud). All data are available and presented on a dashboard for over-reading by a clinical technician or cardiologist. Overall compliance rates for the smartwatch measurements were 98% and for the smartphone measurements 107%, indicating a good adherence for long term monitoring application. In total, the ILR detected 9 episodes of paroxysmal AF with episodes ranging between 40 minutes to 3 hours.
After synchronizing the data streams between the ILR, smartwatch and smartphone, all AF events that occurred while wearing or using one of the smart devices were picked-up and identified as AF. Our in-house developed algorithms identified episodes of AF based on RR variability, which is commonly accepted in literature.
To conclude, persuasive technologies such as smartphones and smartwatches can provide a new potential in the detection and management of patients with AF. Opening a unique way of long-term and cost-effective case-finding initiatives.

Grieten L et al. “Smart” solutions for paroxysmal atrial fibrillation? Europace, 2017.

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Patiënten op afstand behandelen

On-demand app-based rate and rhythm monitoring to manage atrial fibrillation through teleconsultations during COVID-19

During the coronavirus 2019 (COVID-19) pandemic, traditional face-to-face outpatient consultations in atrial fibrillation (AF) clinics were transformed into teleconsultations. Herein, we describe how we implemented a remote on-demand mobile health (mHealth) infrastructure, which was based on a mobile phone app using photoplethysmography (PPG) technology allowing rate and rhythm monitoring through teleconsultations.
Pluymaekers N et al. On-demand app-based rate and rhythm monitoring to manage atrial fibrillation through teleconsultations during COVID-19. IJC Heart & Vasculature, 2020, doi: 10.1016/j.ijcha.2020.100533.

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Delivering healthcare at distance to cardiac patients during the COVID-19 pandemic: Experiences from clinical practice

The COVID-19 pandemic has accelerated how healthcare providers are working to deliver healthcare at distance. Many cardiac patients are now relying on phone and videoconference to receive medical care from home. The situation is pushing healthcare towards the future, leading to a leap forward for cardiac telemedicine.
Klompstra L et al. Delivering healthcare at distance to cardiac patients during the COVID-19 pandemic: Experiences from clinical practice. European Journal of Cardiovascular Nursing, 2020, doi: 10.1177/1474515120930558.

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Coordination of a remote mHealth infrastructure for atrial fibrillation management during COVID-19 and beyond: TeleCheck-AF

During the coronavirus 2019 (COVID-19) pandemic, outpatient visits for patients with atrial fibrillation (AF), were converted into teleconsultations. As a response to this, a novel mobile health (mHealth) intervention was developed to support these teleconsultations with AF patients: TeleCheck-AF. This approach incorporates three fundamental components: 1) “Tele”: A structured teleconsultation. 2) “Check”: An app-based on-demand heart rate and rhythm monitoring infrastructure. 3) “AF”: comprehensive AF management.

This report highlights the significant importance of coordination of the TeleCheck-AF approach at multiple levels and underlines the importance of streamlining care processes provided by a multidisciplinary team, using an mHealth intervention, during the COVID-19 pandemic. Moreover, this report reflects on how the TeleCheck-AF approach has contributed to strengthening the health system in maintaining management of this prevalent sustained cardiac arrhythmia, whilst keeping patients out of hospital, during the pandemic and beyond.
MJ Van De Velden R et al. Coordination of a remote mHealth infrastructure for atrial fibrillation management during COVID-19 and beyond: TeleCheck-AF. SAGE Journals, 2020, doi: 10.1177/2053434520954619.

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