European Journal of Cardiovascular Medicine

The digital revolution and the rapid development of smart phones, mobile connections and social media has changed the way we live. The digital revolution has transformed virtually every industry and every facet of our lives, but healthcare networks and physicians have been slow to adopt technology. However novel solutions for wireless monitoring have emerged and begun to be integrated with the care of the cardiac patient. The evolution of these wireless cardiac monitoring solutions will help in individualized care of the patients who are equipped with advanced bio sensor and have their data processed through sophisticated algorithms to predict events before they occur. (1,2)

Ambulatory electrocardiogram (ECG) monitoring is a useful and essential test to detect paroxysmal arrhythmias in patients with intermittent symptoms (3). Cardiac arrythmias are aberrant rhythm disorders such as atrial fibrillation which is common and often asymptomatic and can lead to adverse outcomes such as embolic stroke. Less common but more malignant rhythm disorders such as ventricular tachycardia can herald sudden cardiac death. (4) The identification and management of arrythmias in a patient with palpitations, syncope, history of arrythmia or high risk of sudden cardiac death often rely on conventional Holter monitoring which is cumbersome in design with multiple wire tangles attached to the body and in turn produce more noise and less analysable data.  Innovative engineering and advanced manufacturing have hastened development of several new generation ECG monitoring devices viz., wearable wireless ECG patches, event recorders, external loop recorders, smart tech. ECG with advanced technologies and are under validation.

These new devices have several advantages including light weight, small and water-proof design, efficient energy use, longer duration of monitoring, wireless data transfer, interactive mobile apps and no interruption in daily life compared to conventional Holter recorders. These newer solutions can improve quality of life of patients and elongate ECG monitoring duration. However, diagnostic accuracy and safety of the devices need to be evaluated/validated. The safety and diagnostic accuracy of these modern technologies, which can increase patient quality of life and lengthen the time of ECG monitoring, should be assessed. (5)

The aim of the present study is to compare and validate 24 hours ECG monitoring between an adhesive single lead ECG device-based solution (Vigo Heart) and conventional Holter monitoring among patients admitted with cardiac diseases.

This was a prospective, non-randomized, observational, comparative, single-center cohort study conducted at a tertiary hospital. The study consecutively enrolled 128 participants who were admitted to the cardiology department of ESIC Hospital from April 2023 to August 2023. Patients with indications for 24-hour ECG monitoring were enrolled or excluded according to the criteria listed below. Out of the 128 participants enrolled in the study, nine participants were excluded from the study due to connectivity issues, lead off or low analyzable data. Hence only 119 patients were included in the study for 24 hours ECG monitoring.

Inclusion criteria

• Age more than 18 years
• Patient intended to use ECG monitors.
• Capable of giving informed consent
• Able to comply with long term continuous monitoring with Vigo Heart patch
• Suspected arrhythmia related signs
• Symptoms as judged by the Investigators.
• Presyncope of uncertain etiology
• Palpitations of uncertain etiology
• Cryptogenic transient ischemic stroke or minor stroke syncope of uncertain etiology
• Clinical diagnosis of acute ischemic stroke

Exclusion Criteria

• Age less than 18years
• Have known skin allergies to adhesives or psoriasis.
• Patients with any dermatitis or infected skin or skin with burns on chest area
• A sternal or thoracic incision that extends under the patch within 3 months from date of enrolment.
• Patients with chest injuries
• Intra cerebral bleed in medical history.
• End stage renal disease.
• Pregnant and lactating women
• Infective endocarditis
• Anticipated to be exposed to high frequency equipment or MRI and CT-Scans
• Stroke induced by trauma, infection, surgery procedures.
• Dementia, mental disorders, suspected non-compliance of the study.
• Enrolled patients with connectivity issues, lead off, data loss or analyzable data <60% are excluded from the study

Ethical Procedure

The study was approved by the Institutional Ethics Committee (IEC) of ESIC Medical College and Hospital (ESICMC/SNR/IEC-F521/03-2023, version no. V01) and was conducted in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. All participants were educated about the study objectives before signing an informed consent form. The trial was registered prospectively with the "Clinical Trial Registry in India" (registry number: CTRI/2023/04/051734).

Ambulatory ECG Monitoring Using an Adhesive Single-Lead ECG and Holter Monitoring

Patients with a confirmed diagnosis of coronary artery disease, rhythm disorders or symptoms of palpitations, giddiness, skipped heartbeat, or chest pain who were stable on medication were selected for the study. All study participants who met the defined inclusion criteria were simultaneously onboarded with both the Vigo Heart and traditional Holter devices for 24 hours under direct, continuous physician supervision aiming to:

• Compare the arrhythmia detection of conventional ambulatory Holters vs. Vigo Heart single lead systems (corresponding to ECG lead 2).
• Evaluate patient compliance and usability of the Vigo Heart solution during the monitoring period.
• Assess the accuracy of the clinical report generated by the traditional Holter vs Vigo Heart by the physicians.

All the enrolled participants were educated about the usage of both, the single-lead ECG monitoring device (Vigo Heart VV330 patch, Vigocare pvt. Ltd., Hyderabad) and the Holter ECG monitoring device (Schiller, USA). For Holter monitoring, the study participants attached three sticky electrodes to the chest to record leads I, II, and III. They were also required to carry the handheld recording device for 24 hours.

Initial patient demographic details including the age, gender, weight, height, chest circumference were recorded, as well as any history of prior heart disease. Additional comorbidities and the indication for ambulatory ECG monitoring were documented.

Patients having smart phones were asked to download Vigo life app. Vigo Heart solution is paired using Bluetooth connectivity and similarly conventional ECG Holter device is connected to the patient simultaneously for 24hours. After the completion of the study, patients were asked to give feedback on the ease of usability, comfort, intervention of daily activities and adverse events if noted between both the devices.  The physicians were requested to give feedback on efficiency, clarity of the recorded signals, accuracy of the reports, clinical analysis and ease of usability of both the solutions.

Device description- Vigo Heart:

Vigo Heart is a solution kit comprising of VV330 Patch, Vigo platform and AI engine for ECG analysis. VV330 amongst the world’s smallest re-usable, rechargeable medical grade cardiac patches available and wearable ECG monitor is an FDA cleared Device, 21CFR 870.2910 (see Figure 1).  It is a continuous ECG bio sensor patch for ECG acquisition, storage and transmission patch that utilizes disposable adhesive to maintain contact with patient skin and hydrogel to promote electrical activity. Vigo Life is a mobile app that works as a conduit between the patch and the Vigocare system. Patients would apply ECG patch on their chest and use Vigo Life app to connect to the patch. Vigo Life app collects ECG waves from patch and streams the same to the Vigo Care’s backend engine Scaena running in the cloud.

Figure 1: Vigo Heart Wireless Patch and its Operation

The Vigo Life App is compatible with Android and iOS system applications. Data from the Vigo life gets transmitted to the Vigo platform running on the cloud and then analysed by the FDA approved AI engine 21 CFR 870.1425. Vigocare Multi Vital Monitoring (MVM) Platform enables care providers to monitor their patients’ physiological data (vitals) and receive timely insights, allowing for proactive diagnostics and disease management. The technology can be leveraged across various disease conditions and a variety of clinical situations irrespective of where the patient is within or outside of a care setting. Analyzed reports are further verified by certified ECG technicians.  Digital Reports are delivered in a fast manner to the clinician and the patient.

When Vigo Heart is attached to the patient, several pre-defined methods are applied to prevent the occurrence of noise or signal loss. First skin is disinfected with 70% ethanol solution (alcohol swab) skin hair is removed if required, the device is placed at the left 3^rdics at 45^o tilted inside. The device is paired to an android or iOS mobile device via Bluetooth, which records ECG signals for 24 hours via a specific Vigo life application.

ISO-13485/2016 13485/201Figure 2: A Sketch of Vigo Platform

Conventional Ambulatory ECG Monitoring

The conventional Holter device was attached to patients with gel electrodes. The intertwined wires are connected to the device and the device is kept in the patient pocket during the monitoring period of 24 hours, patients are asked to move gently and not to take showers or have any vigorous activity. After the monitoring period is completed, patients were required to handover the devices to the technician, who manually downloads the recorded ECG data. The recorded ECG data is then analyzed, and the report is generated within 24 hours. There were no pre-defined methods to reduce and prevent the occurrence of noise or signal loss. There was no provision to record the events perceived by the patient during the monitoring period and correlate them during the report generation. A detailed comparison of Vigo Heart patch and Holter monitoring is provided in Table 1.

Table 1: Comparison between Holter ECG and Vigo Heart

 Onboarding the patient with Vigo Heart

 The mobile application Vigo Life will be downloaded from the play store, log in with the credentials provided to initiate the monitoring. The fully charged ambulatory ECG patch is connected to the mobile application (Vigo life) by Bluetooth and continuously acquires data after applying the patch to the patient’s left chest below the clavicle. The data is continuously acquired and uploaded to cloud during the monitoring period. The live ECG and HR can be seen in the patient mobile application. After completion of the monitoring the data is analysed by Artificial Intelligence based ECG Analysis Engine. Heart rhythm abnormalities that occurred during the monitoring period are included in the report. The AI-generated ECG report is then verified by an expert ECG analyst and transmitted to the doctor for clinical correlation and/or intervention(s).

The Cardiac rhythm was monitored simultaneously using both devices for 24 h. If a participant had symptoms associated with arrhythmia during monitoring, the participant recorded the event using vigo life application only.  In the case of Vigo Heart patch, the event could be recorded with the preinstalled smartphone application. The ECG data acquired with the Vigo Heart biosensors were collected from the user’s smartphone and then wirelessly transferred to a designated server for research and analysis purposes. All data stored in the server were anonymized to protect the participants’ privacy. The ECG data from Holter monitoring device were stored within the device’s memory bank and transferred to the physician’s computer via a network cable. After the 24 hours monitoring was finished, the participants devices were removed and a self-report questionnaire about use of the Vigo Heart patch was completed. All the study participants, research associates, clinicians were asked to give feedback on the usage of Vigo Heart wireless ECG patch in comparison to the Holter ECG monitoring method on various aspects as described in Table 5 and Table 6.

The primary efficacy end point compared the incidence and type of arrhythmias recorded by the Vigo Heart patch and Holter ECG monitoring method. The secondary efficacy end point of the study assesses the accuracy, efficiency, clarity of recorded signals, comfort and usability of the Vigo Heart. Accuracy in the detection of arrhythmias is measured with sensitivity, specificity, positive and negative predictive values. The primary safety end point was the incidence of contact dermatitis, discomfort or pain, infection or allergic reactions at the site of device application. The secondary safety end point was to assess any device dislodgement, false positives or negative arrhythmia detection and battery related issues. The difference between the primary and secondary end points is evaluation of performance and safety objectives respectively.

Parameters of ECG Monitoring

To compare the diagnostic performance between single-lead ECG and Holter monitoring devices, we measured the following ECG parameters and compared them between the devices: the proportion of noise (i.e., non-analyzable noisy signals or loss of Bluetooth connection for the Vigo Heart patch), number of total ventricular ectopic beats (VEBs)/supraventricular ectopic beats (SVEBs), minimum/ average/maximum heart rates. The Holter monitoring device (Schiller, USA) and the Vigo Heart patch VV330 recorded 24 h raw ECG data with their own software. All the raw ECG data obtained from both the devices were subjected to double blinded review and validation by expert cardiologists. The clinical diagnoses made with each device were compared for each of the 119 study participants. The cardiologist independently evaluated these diagnoses.

Statistical analysis

Demographic data was expressed as Mean ± SD wherever applicable.  The feedback on patient compliance and convenience was collected through a structured questionnaire. Physician satisfaction levels with the overall performance of each system was evaluated by another structured questionnaire. All statistical analyses were performed using the SPSS software.

From April 2023 to August 2023, 119 patients enrolled in the study. Table 2 shows the baseline characteristics of the study population. All the patients were successfully on-boarded with both the devices for ECG monitoring. The study population had a mean age of 56.14±13.38 years and a male proportion of 68%. The most frequent comorbidities were hypertension (34.4%), coronary artery disease (52.9%), CAG (21%), PTCA (23.5%) and diabetes mellitus (16.8%). The most frequent ECG monitoring indications were suspicious arrhythmia-related symptoms (47.8%), that mostly included chest pain (25.2%) and shortness of breath (16.8%).

Table 2: Baseline characteristics of the study participants

Table 3: Primary Efficacy Endpoints - ECG Monitoring comparison between Holter ECG and Vigo Heart for the study Population

*The total wear time is the duration between the attachment and the detachment of each device.

Comparison of ECG Monitoring Parameters between the Vigo Heart patch and Holter:

All the study participants completed both Holter and single-lead ECG monitoring. Comparisons of ECG monitoring between the Vigo Heart patch and Holter devices are presented in Table 3. We performed Holter and single-lead ECG monitoring during the routine daily activities of the patient. In this study, the noise included various signal artifacts originating from body motions or poor electrode contact to the skin. The Vigo Heart ECG showed a negligible amount of mean noise percentage (1.94 ± 6.68%) when compared with the traditional Holter 17.84 ± 23.95% of the total recording time. Total recording time or wear time for an ECG patch refers to the duration during which the patch is continuously worn by the patient to record their cardiac activity. ECG patches are typically adhesive patches equipped with electrodes that continuously monitor and record the electrical activity of the heart over an extended period. In addition, the total ventricular and supraventricular ectopic beats showed strong statistical correlation between both the ECG monitoring methods. For the maximum heart rate, there was significant difference between the Holter monitoring and Vigo Heart patch (129.69 ± 22.5 vs. 113.31 ± 23.6 beats/min, p = 0.02). The results also showed significant correlation for the average heart rates (74.85 ± 10.8 vs. 76 ± 10.3 beats/min, p = 0.02) and minimum heart rates (47.94 ± 9.5 vs. 59.21 ± 8.9 beats/min, p = 0.02), for the Vigo Heart ECG and Holter monitoring, respectively.

Table 4: Comparison of diagnosis between Holter and Vigo Heart ECG monitoring

The cardiologist independently read the ECG recordings from both the Vigo Heart device and Holter monitoring and provided diagnoses for all 119 participants. He opined that VEB and SEB are more clearly differentiated in Vigo Heart than with traditional Holter. The type of arrhythmias that were detected individually with only traditional Holter ECG and only with Vigo Heart ECG are presented in Table 4.  The study findings revealed that the clinical diagnoses of arrhythmias detected by Vigo Heart are comparable with that of traditional Holter ECGs.

Table 5: Accuracy data of Holter and Vigo Heart Monitoring

The performance of Vigo Heart and Holter ECG in this study are presented in Table 5. At the end of the study, the study participants were asked to fill out a self-reported questionnaire about using the Vigo Heart patch. The majority of the participants were satisfied with using the Vigo heart device and application (102 (85.7%) and 99 (83.19%) participants expressed it was better than the Holter ECG. Very few study participants felt discomfort during sleep (4 (3.36%) and while doing their daily chores 6 (5.04%). Sixteen (13.44%) participants received the alarms due to disconnection episodes between the Vigo Heart patch device and the smartphone. In contrary none of the patients received alarms about the disconnection of Holter ECG leads. The observations in the self-reported questionnaire are described in Table 6.

Table 6: Self-reported Questionnaire on Vigo Heart

Table 7: Secondary Efficacy end points: Questionnaire to Patients/guardians/ research associates/clinicians

Also, all the patients or their guardians, clinicians and research associates were requested to analyze, compare and give scores to both the devices as presented in Table 7. ECG patches are known to cause a few adverse skin reactions like skin discomfort, pruritis or minor vesicles around the patch. (7) Out of 119 participants, only 3 (2.52%) people reported mild itching at the beginning of the study which later subsided. None of the participants reported dermatitis, unbearable pain or persistent discomfort or infection at the site of device application. There was no permanent device dislodgement and battery breakdown issues throughout the duration of the study. There were no considerable cases of false positives or negatives for evaluation during the complete course of the study.

In this study, individuals with suspected arrhythmias underwent 24 h ECG monitoring using a Holter device vs an adhesive single-lead patch-type device. Our findings on noise burden, total wear time, ventricular ectopics, supraventricular ectopics, minimum/average/maximum heart rates, showed comparable excellent results with that of the traditional Holter ECG monitoring method.  The Vigo Heart patch recorded less noise than the traditional Holter ECG monitoring method. The majority of participants felt at ease using the adhesive single-lead ECG monitoring device for 24 hours, and clinical diagnoses were coherently independent of the monitoring techniques.

Wearable devices and smartphone technology have enabled the emergence of a variety of portable ECG monitoring systems in recent years. (8,9) Out of the 12 leads in the conventional ECG, standard limb lead II represents the best lead for detecting arrhythmias. (10)

Therefore, single-lead monitoring has been the most widely used method of measuring ECG.  (11) A prolonged recording from one lead is used to provide a rhythm strip for accurate cardiac rhythm assessment. Lead II, which usually gives a good view of the P wave, is most commonly used to record the rhythm strip. Vigo Heart’s single lead biosensors are used to detect limb lead II of ECG with (ICC 0.97) with standard 3 lead ECG patch. (12) Adhesive patch-type systems have been developed by attaching electrodes to pre-programmed or handheld devices that can be easily self-worn by patients. (13,14). Patch-type systems offer the advantage of being able to continuously monitor ECG signals for up to 72 hours. Depending on the product and type of patch, ECG measurement can be recorded for up to two weeks and are capable of transferring ECG data to a patient's smartphone (e.g. the Vigo app) or storing it in the device’s memory (15,16,17). Many patch-style ECG devices are noted for a limitation compared to the traditional Holter test: they typically monitor only one ECG lead (lead II). Nevertheless, it has been proposed that patients are more likely to favor these devices due to their greater comfort when worn for extended periods. Furthermore, many studies have indicated that these devices may be able to detect irregular heartbeats more accurately than the Holter (18,19,20). Studies have shown that ECG measurements with patch type wearable devices would be more cost-effective to screen arrhythmias than to use traditional Holter methodology. (21) Thus, patch type wearable device has gained attention and become increasingly popular as a means of detecting as well as diagnosing cardiac arrhythmias.

Single lead ECG monitoring with Vigo Heart wearable patch has acceptable accuracy and is more convenient to use by both patients and clinicians when compared with traditional Holter method. Our results showed that there was a substantial concordance in the ECG parameters, data analysis and diagnoses between the Vigo Heart patch and traditional Holter monitoring. Continued research in a large population is warranted to validate this device for detecting carious types of arrhythmias in clinical practice.