The Signicance of Detective Arrhythmia by Using the Long- Term Ecg Monitoring in the Elderly “so Called” Healthy People: A Screening Study

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Introduction
Cardiac arrhythmias are often asymptomatic and associated with serious adverse outcomes [1]. Cardiac arrhythmias, such as atrial and ventricular arrhythmias and atrioventricular block, are associated with critical adverse outcomes, such as congestive heart failure, stroke and sudden cardiac death [2]. Atrial brillation (AF), which is the most common sustained cardiac arrhythmia, is highly associated with embolic stroke, leading to heavy economic burden to the patients [3]. In most countries, people choose to visit doctor for some symptoms. However, most people don't visit doctor if they do not have symptoms. This part of people are "so called" healthy people.
Electrocardiogram (ECG) and the Holter monitor are the most commonly used methods in routine medical checkups for screening arrhythmias in patients outpatient or inpatient. Although the traditional Holter records continuously for 24 hours, the equipment is expensive, resulting in a high procurement threshold for medical institutions and a limited diagnostic opportunities. The 24-hour 12-lead Holter monitor with many lead pathches usually has the shortness of discomfort and limiting patient activities, limiting its monitoring for a long period of time (seven or fourteen days) [4]. But the ECG also often misses to capture events due to short recording time. We have less few chances to monitor "so called" healthy people who never have the symptoms of palpitation or shortbreath or deny previous history of arrhythmia if they don't go to hospital. If the arrhythmia do not occur within 24 hours of the detection time, the arrhythmia of the culprit could not be detected by the 24-hour Holter monitor, leading to the miss of subclinical arrhythmia [5]. In addition, implantable loop recorders (ILR) can also be used to detect the cause of recurrent syncope, but its application is limited due to cost and surgical problems [6][7].
Some of the "so called" healthy people could be hospitalized for sudden acute events, such as syncope, stroke or heart attack due to the low rate of seeking medical care and diagnosis, resulting in serious consequences. Obviously, earlier use of noninvasive methods to detect arrhythmia, such as AF, ventricular tachycardia and atrioventricular block could reduce medical and nancial burdens, especially for the elderly. Adhesive patch monitor can detect more arrhythmias than traditional Holter monitor [8][9]. We aimed to evaluate the feasibility of using the adhesive patch monitor for diagnosing cardiac arrhythmias in the elderly "so called" healthy people.

Study design
The enrolled participants referred to be the elderly "so called" healthy people respectively from Heilongjiang Province Rong Yu Jun Ren Kang Fu Hospital, Rongshi Community Hospital and retired workers from the First A liated Hospital of Harbin Medical University between January 2017 to March 2019 who underwent health examination . After medical history inquiry and physical examtation, the participants were asked to wear the adhesive patch monitor (Shanghai Yueguang Medical Technology Co., LTD China Shanghai machinery note20162210201) for 7 days. The study was approved by the Institutional Review Board (IRB) of the First A liated Hospital of Harbin Medical University.
The inclusion and exclusion criteria of the study are as follows: all participants included in the study were more than 55 years old; asymptomatic or deny previous history of arrhythmia; informed consent to carry a long-term adhesive patch monitor for 7 days. We excluded participants having symptoms (shortness of breath and palpitation etc) and participants with a history of atrial brillation/ utter, supraventricular tachycardia (SVT), II type II atrioventricular block, three degree atrioventricular block, sinus arrest > 2.5 s, ventricular tachycardia, polymorphic ventricular tachycardia and ventricular brillation; history of cardiac electronic device implantation or skin allergic reaction.

Data collection
The Yueguang patch-based device ( Figure 1) can record up to 15-30 days of uninterrupted monitoring on a single vector. They were asked to wear the monitoring device for up to about 7 days and then sent it back to the hospital to analyse the data. The participant's medical records were summarized by investigators. The study was reviewed by the local government's approval consent and carried out as Helsinki declaration required. After they sent the monitor back for data analysis, a report was generated. Finally, we summarized the data, analyzed the incidence and characteristics of arrhythmia and detected the cumulative rate of arrhythmia. Baseline characteristics including demographics, medical history and health behaviors were abstracted from the patient medical record by 2 trained investigators (Table1). The study was approved to collect the data from the Rong Yu Jun Ren Kang Fu Hospital and Rongshi Community Hospital.

Statistical Analysis
Proportions and means were compared using the χ2 test and t test with unequal variance, respectively. P values <0.05 were considered signi cant. All analyses were performed using STATA software version 11.0 (StataCorp, College Station, TX).

Demographics
We enrolled 1087 participants, a total of 1056 participants (69.8±12.0 years, 620 males) to complete the monitoring. Among the subjects who did not complete the monitoring, 31 participants were disquali ed because of the allergy or discomfort of the patch and stopped wearing the device prior to the date ( Figure  2). The baseline characteristics of 1056 participants who completed the monitoring were shown in Table  1 Table 2. Overall, the adhesive patch monitor detected 61.08% (645/1056) arrhythmia events over the total wearing time of the devices, compared with 32.10% (339/1056) arrhythmia events over the rst 24 hours (P <0.001). We found that there were 276 subjects of supraventricular tachycardia recorded, 52 subject of atrial brillation/ utter, 1 subject of second degree type II atrioventricular block/ third degree atrioventricular block, 1 subject of sinus arrest, 9 subjects of ventricular tachycardia and ventricular brillation (0 subject of ventricular brillation) in the rst 24 hours. The diagnostic advantage in bradycardia (22% VS 78%, 24 hours VS after 24 hours, P<0.001) and ventricular arrhythmias (31% VS 69%, 24 hours VS after 24 hours, P<0.001) are more obvious in long-term adhesive patch monitor (APM) data ( Figure 3).The episode of AF was de ned as the lasting time ≥30 seconds of during monitoring.
All episodes of cardiac arrhythmias recorded were detected in 538 subjects of supraventricular tachycardia, 69 subjects of atrial brillation/ utter, 5 subject of second degree type II atrioventricular block/third degree atrioventricular block, 4 subjects of sinus arrest, 29 subjects of ventricular tachycardia/ventricular brillation (0 subject ventricular brillation) in the overall time. In addition to supraventricular tachycardia, the rest four types of arrhythmias (Atrial brillation, conduction block, sinus arrest, ventricular tachycardia) recorded in the rst 24 hours and the overall time were 5.97% 63/1056 and 10.13 % 107/1056 respectively ( Table 2).

Detection of AF
AF was detected in 69 subjects (6.53%) 52 of 69 subjects who were detected with AF had ≥1 episode in the rst 24 hours, and 17 of 69 subjects were detected after the rst 24 hours of monitoring. Moreover, 32 of 69 subjects experienced paroxysmal atrial brillation and 37 of 69 subjects experienced persistent atrial brillation ( Wearing the adhesive patch for an average 4.38±2.26 days, the time distribution of appeared arrhythmia is shown in Figure 5, the discovery of arrhythmia ratio is 33.21% in the rst 24 hours. As the extension of wearing time, the proportion of arrhythmia increased (44.88%, 49.01%, 51.89%, 53.50%, 53.68%, 54.04%), and until the seventh day, detection of arrhythmia events amount 20.83% increase from the previous 24 hours. The second day had the highest increase over the rst day, with an increase of 11.57%.

Discussion
Cardiac arrhythmias are often di cult to detect even though in most symptomatic patients, because patients are usually asymptomatic, leading to substantial mortality. The long-term adhesive patch ECG monitoring device is recently widely used for detecting AF, especially using in the screening of asymptomatic AF. Therefore, our study focused on the long-term ECG monitoring in asymptomatic patients in order to detect all kinds of arrhythmias in the elderly "so-called" healthy people and improve the screening and diagnostic rates [10][11].
We found that 6.53% participants had atrial brillation in the range of adhesive patch monitoring detection in our study. Furthermore, a high prevalence of 50.95% (538/1056) of participants with supraventricular tachycardia was monitored. These results con rme that targeted screening of asymptomatic atrial brillation and supraventricular tachycardia is feasible and has clinical diagnostic value. Since the asymptomatic arrhythmia is 30% [12], which is roughly consistent with our test data in the rst 24 hours (32.10%). The traditional screening approach is standard ECGs or Holter monitoring devices, but the adhesive patch device is more suitable for recording asymptomatic arrhythmias; the longer the monitoring time, the more morbidity will be found (61%). The di culty in screening for AF is that it is paroxysmal and asymptomatic, correlated with thromboembolic events. Therefore, it is quite important to initiate anticoagulant therapy considering the patients' risks, the duration and burden of AF and other factors [13]. SVT's therapy or intervention is also considered for its importance to select the suitable strategy. Because shorter episodes of atrial tachycardia can act as a precursor for atrial utter and atrial brillation, early treatment for atrial tachycardia may be bene cial in preventing atrial brillation. Therefore, it is necessary for patients with atrial arrhythmia to follow up or even hospitalized.
ECG and the 24-hour Holter monitor are common ways to screen outpatients or inpatients for arrhythmia, especially in those who have symptoms. 24-hour Holter extends the scope of detection beyond ECG but it may also miss events and limit patient activity [14][15][16]. A systematic review showed that undiagnosed AF has a rate of 1.0% in the general population (n=67,772) [17]. Therefore, our experiment focuses on the adhesive patch that can provide longer monitoring time and convenience. Moreover, it makes the patients nd the adhesive patch more comfortable to wear. It improves feasibility of wearing this device longer time, making us to obtain more data about arrhythmias.
Screening for atrial brillation is related to the age of enrollment, health status and detection time. The younger the age, the fewer risk factors in the medical history and the shorter the monitoring time, the lower the screening rate is [18][19]. Our baseline data included age, sex, heart failure, hypertension, diabetes and stroke. We found an increase in AF events as the duration of detection lengthened in Table  2, which has signi cant implications for screening atrial brillation. We told some patients that they had atrial brillation and might need anticoagulant therapy, but there was no follow-up. Further follow-up would be better for the treatment of these patients. The earlier the diagnosis of atrial brillation is, the more vital it is for patients to initiate anticoagulant therapy in order to prevent thromboembolic events. Previous studies have showed that patients with previous embolic events had a high rate of AF detection rates, showing that the stroke can be the rst clinical event of AF [20][21][22][23][24][25]. Therefore, we should focus on screening people with high risk factors in their medical history, who are the elderly "so called" healthy people and strengthen their follow-up in the future.
Our study demonstrated high diagnostic yield using the long-term ECG monitoring in arrhythmias. Many studies have found that long-term monitoring detected more arrhythmias than conventional Holter [8][9]. In our study, the rate of detected arrhythmias is 20.83% more than in the rst 24 hours, indicating that the clinically meaningful arrhythmia event rates detected increasingly by which could be found in using 24h Holter in the elderly "so called" healthy people in the rst 24h. Therefor there is also the need for longterm monitoring to detect more events of arrhythmias after the rst 24hrs. AF screening and stroke prevention are becoming more instructive through multi-center studies. In our study, 17 of 69 patients experienced the episode of AF after the rst 24 hours of monitoring (Table 2), so the advantages and necessity of the adhesive patch is obvious. If patients do not continue to wear the patch or use routine Holter, they will not be screened for atrial brillation or other arrhythmias, so some people may miss the opportunity to initiate anticoagulation and even may have embolism or other sudden cardiac death events. The next important step is that when detecting for atrial brillation, we need to contact patients and recommend outpatient or hospitalization. Then, according to the speci c situation, grasp the timing of anticoagulation and avoid the harm of stroke is one of the research signi cances of this experiment. In addition to anticoagulation and rhythm control treatment for atrial brillation, upstream treatment, such as blood pressure and blood lipid control, should not be ignored. Our experimental group is currently studying the screening for arrhythmia in the elderly to evaluate arrhythmia, which is conducive to early treatment and early intervention in anticoagulation, so as to reduce the future economics and mental burden of family and society.
For the patients with ventricular tachycardia or supraventricular tachycardia, it is necessary to recommend hospitalization for further diagnosis, and if con rmed, according to Guidelines and combining with patient's individual willingness, the pharmacological therapy or radiofrequency ablation can be recommended for treatment. If a high degree of conduction block is found, a pacemaker is recommended. In our study, one patient had completed pacemaker placement in our hospital after followup and recommended hospitalization. Also, another patient who was diagnosed sustained ventricular tachycardia had undergone radiofrequency ablation. In our study, the number of hypertensive patients was as high as 32.56%, indicating the necessity of screening for arrhythmia in hypertensive patients. Moreover, hypertension is a risk factor for AF and induces cardiac in ammation.

Conclusion
The long-term adhesive patch monitor can improve the diagnostic yield of undiagnosed arrhythmias in asymptomatic people who are the so-called healthy people, more arrhythmias could be detected with longer wearing time in our study, especially for bradycardia and ventricular arrhythmias. The patch monitor can accurately estimate rates of arrhythmias, contributing to early diagnosis, early interventions and avoiding harmful attained results.   The study flow chart shows detailed inclusion and exclusion criteria for study participation and completion. Abbreviations: AF, atrial fibrillation; SVT, supraventricular tachycardia; VT/VF, ventricular tachycardia and ventricular brillation.  Three sample ECG strips are shown, exhibiting episodes of AF (A), sustained SVT that was determined to be AT (B), and NSVT(C) detected in separate study participants.