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1 Introduction

With the increasing awareness of indications for cardiac devices, especially related to the clinical benefits of implantable cardioverter-defibrillators (ICD) and cardiac resynchronization therapy (CRT), the number of patients with implanted electronic devices (CIED) has been growing steadily [1–3]. Recent data from the country members of the European Heart Rhythm Association (EHRA) have shown a general trend to increase in the number of centers implanting CIED, and, despite great differences in implanting rates among EHRA members, a steadily increase in the number of implants in almost all countries [4]. Consequently, more patients require regular follow-up to ascertain technical integrity. In 2007, over 1.6 million CIED were implanted in the United States and Europe, which would translate to over 5.5 million patient-encounters per year [5]. In view of these numbers, facilitated methods for follow-up are required. This growth, primarily resulting from more complex devices, in a population that most of the times present heart failure (HF) symptoms with significant underlying comorbidities, has led to difficulties in providing the specialized follow-up. Current suggestions regarding in-office visits for patients with an ICD or a CRT recommend a minimum frequency of 2 to 4 scheduled appointments per year [6, 7]. In fact, considerable human and logistical resources are needed to provide appropriate care, particularly for regular interrogation of the technical parameters of different CIED, detection and resolution of problems, identification and treatment of arrhythmias via the ICD, ensuring biventricular stimulation to optimize CRT, and specialized clinical care. These services can only be provided by hospital teams that are trained and able to perform tasks that are complex and challenging. Therefore, remoe monitoring (RM) has gained significant attention regarding the potential impact on CIED management, particularly in order to perform face-to-face visits less frequently, while maintaining safety and effectiveness, allowing health team to check the device between follow-ups in a more comprehensive care for heart health.

The advent of RM systems for CIED, which provides an access to complete information on device performance, as an alternative to the traditional outpatient visits, offers many options and, at the same time, raises many questions with regard to its implementation, organization of the obtained wealth of data, safety, legal issues and reimbursement [8].

In the last ten years, telemedicine systems for RM of these devices have become a reality and are increasingly used in clinical practice, enabling changes in the specialized follow-up of this population, with well documented benefits and levels of safety [9–11]. Today, the broad application of RM systems supports the capability to improve the care of CIED recipients, contributing to the optimization of healthcare resources. The ability of the device follow-up clinic personnel to review data has expanded and has challenged the traditional model of patient care after CIED implantation. Undoubtedly, this technology is becoming an integral part of the future treatment for many of these patients.

2 Remote Monitoring of Cardiac Electronic Implantable Devices

CIED require long-term regular follow-up interrogation in dedicated clinics. However, due to the increasing population referred for implantation and the resources required, routine in-clinic follow-up contribute with a significant burden to the already over-strained electrophysiology teams and hospital services. Also, time spent in patient’s travelling to the hospital and waiting time in the outpatient clinic may be an important issue in optimal care.

RM is expanding rapidly for chronic follow-up. Therefore, issues ranging from clinical and technological aspects (particularly concerning the long-term performance of the devices) to implementation, management and organization, legal questions, data protection, and funding still a matter of debate. All major CIED manufacturers have developed systems to allow patients to have their devices interrogated remotely, using standard phone lines but also wireless cellular technology to extend telemetry links into the patient’s location.

How does RM work? RM allows you to send comprehensive device information over a standard phone line or a mobile phone (GSM) network to a central computer (server), which can be reviewed by your hospital team on a secure website, allowing routine device follow-up or a special situation to be reviewed quickly and efficiently. It may represent a safe and effective alternative to conventional follow-up programmes, and contribute to cost savings in health care. This technology has been proven to be reliable, allowing early identification of device malfunction and minimizing the risk of underreporting. All RM systems are slightly different and use slightly different technology. The different cardiac implantable devices currently available are listed in Table 1 and Fig. 1.

Fig. 1.
figure 1

Remote Monitoring Systems for follow-up of cardiac implantable devices. A – SmartView (Sorin, Italy); B – CareLink (Medtronic, USA); C – Home Monitoring (Biotronik, Germany); D – Merlin (S. Jude Medical, USA); E – Latitude (Boston Scientifgic, USA).

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The device can be interrogated manually using a wand linked to the monitor in the patient’s home (usually by the patient’s bedside), or automatically using wireless systems, in which data are sent regularly without the patient’s involvement at intervals set by the hospital team. All systems allow data to be sent when scheduled and according to clinical circumstances, as agreed between the patient and the team. Data are transmitted to a central (internet-based) data repository. The information is formatted and transmitted to a central information service, through the internet fixed telephone lines at standard call cost in the CareLinkTM, LatitudeTM and MerlinTM systems, and through the GSM cell network for the Home MonitoringTM and SmartViewTM systems (Table 1). Each center has access limited to its patient’s using a password code in a web page in order to analyze the dynamic parameters of various devices, including stored and measured information about the lead(s), sensor(s), battery and the implanted pulse generator function, as well as data collected about the patient’s heart rhythm, detection of arrhythmia episodes recorded on intracavitary electrograms, therapies delivered by the device, the percentage of different pacing modes and tachyarrhythmias treated. These parameters can be configured individually to define alert levels according to the potential clinical impact of the alterations detected.

Table 1. Remote monitoring systems for cardiac implantable electronic devices.
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Yellow alerts may be remotely selected and re-configured according to each patient’s clinical indications through the secure website without bringing the patient into the hospital, while red alerts (clinical event notification) will always appear on the secure website (Table 2). Thus, not all yellow alerts are enabled for all patients. Patients may trigger more than one alert simultaneously and may also trigger the same type of alert several times.

Who deal with the telemonitoring information? The patient’s healthcare team, that has access to the clinical and device status. The device managing team, while working in a multidisciplinary approach, may communicate these data to the health following team in a collaborative patient management. This can be very important in clinical conditions, such as arrhythmic events or HF (Fig. 2).

Table 2. Remote yellow alert configuration (A) and red alert notifications (B) A - Yellow alert configuration B -Red alert notifications
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Receive all the diagnostic data remotely that we would normally get with the patient in front of us has a role in the surveillance of the device function, but has also the potential to improve quality of care and improve patient outcome, and, in addition, to reduce the number of out-patient clinic visits and healthcare costs [11–13].

Fig. 2.
figure 2

Device based monitoring features in heart failure. BIV = biventricular pacing; CRT = cardiac resynchronization therapy; RV = right ventricle; ICD = implantable cardioverter-defibrillator; VT = ventricular tachycardia; VF = ventricular fibrillation; NSVT = non-sustained ventricular tachycardia; AF = atrial fibrillation; AT = atrial tachycardia.

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3 Advantages of Remote Monitoring Systems

Telemedicine, in general, is recognized by governmental and medical agencies as an innovation for improving the access to healthcare services, with a potential reduction in patient hospital stays related to cardiac events [2].

One of the main functions of systems for monitoring CIED is to detect malfunctions as early as possible. Failure to apply therapies when required and problems of lead and/or generator malfunction may only occur between scheduled hospital visits. Therefore, a rapid detection of technical failures followed by a fast response to alerts by the cardiologist or allied professional can prevent potential harm to the device patient. Electronic malfunctions in these devices are unpredictable, with ICD leads representing the most common cause of complications, with an incidence ranging between 2 % and 15 % at five years [14]. Recalls, although uncommon, are an important factor in decisions concerning the frequency of consultations, clinical management and inappropriate detections. RM systems provide regular assessment of the function of the various components of implanted devices, as well as detection and characterization of arrhythmias, therapies applied, and even identification of factors that could indicate risk of hospitalization for decompensated HF [11].

RM capabilities are associated with patient’s convenience, better device surveillance, clinic efficiency, and a potential improvement in monitoring arrhythmias and HF. Scheduled remote CIED follow-up can save the time and efforts of the cardiologist and allied professional, and of the patient and the accompanying family by avoiding in-hospital visits for CIED follow-up. It has been suggested that RM can substantially reduce the number of hospital visits, freeing up hospital staff to attend other patients and to perform other tasks [2].

If RM is applied, accessibility increases due to the networking of patient data, but also because patient-initiated interrogations (non scheduled follow-ups initiated manually by the patient as a result of a clinical event) allow information analysis avoiding unnecessary in-clinic visits. By using RM with an individualized approach, the team’s decision is based on better health care, with a positive impact in quality of life, less time spent by the patient and caregivers, quicker follow-ups, with more efficient use of hospital resources contributing to costs savings [2, 15]. Finally, it is expected that RM can counteract the pending imbalance between the annually increasing load of CIED population.

4 Cardiac Implantable Device Based Monitoring in Heart Failure

Patients with chronic HF are prone to frequent exacerbation of symptoms that can substantially increase hospital admissions carrying a heavy economic burden. The current guidelines for the management of chronic HF include the use of ICDs and CRT-Ds as the standard care in selected patients [16]. A multidisciplinary approach, which requires specialized knowledge as well as frequent monitoring, may contribute to improve clinical outcome and keep HF patients in an optimized healthcare program.

The use of RM has emerged as a possible way to improve the management of these patients by providing more frequent assessment of the function of the various components of CIED, as well as detection and characterization of arrhythmias, therapies applied, and even identification of factors that could indicate risk of hospitalization for decompensated HF [9]. The ability of CIED to continuously monitor variables such as mean heart rate (and heart rate variability), episodes of arrhythmias, patient’s daily activity, changes in intrathoracic impedance (for the detection of fluid accumulation), and the integrity of the CIED system appears very attractive and may provide early warning of changes in cardiac status or of safety issues, and allow adequate clinical management. It has been suggested that blood pressure, atrial fibrillation episodes, intrathoracic impedance (a surrogate marker of pulmonary congestion), heart rate variability (giving information about autonomic nervous system activity), percentage of time in biventricular pacing and appropriate ICD shocks can predict HF events and change outcomes [17, 18]. This important subject remains under active investigation. Until now, and despite the potential impact on the healthcare system of different follow-up RM strategies for HF management, published data are conflicting. In the ALTITUDE study, patients followed remotely showed higher survival rates than those followed in-clinic [19]. Also, survival outcomes were better than those observed previously in clinical trials, suggesting that closer management with RM allows to clinicians to intervene more effectively with impact on survival.

Management adapted in response to monitoring intrathoracic impedance presented low sensivity and low positive predictive values, and, in previous studies, has not been shown to improve outcomes [20–22]. However, recent findings indicate that the sensitivity of intrathoracic impedance monitoring is superior to daily weight monitoring for predicting worsening HF events [23]. Also, device-based RM has been shown to identify patients in increased risk of HF hospitalization and improve prognosis by allowing timely detection of HF decompensation and therapeutic intervention, while reducing the number of total clinical visits and visits for HF [17, 24, 25]. More recently, early physical activity levels, measured by an accelerometer on implanted CRT and ICD devices, showed a strong value in the prediction of outcome in patients with chronic HF [26]. Newly unpublished studies showed that at one-year, significantly more patients with an ICD or a CRT and chronic HF with reduced left ventricular ejection fraction, randomized to home monitoring scored better on a composite endpoint that included all-cause mortality and specific cardiac measures [27], and that patients with high adherence to RM, measured as weekly transmission of data at least 75 % of the time, had a 58 % reduced likelihood of mortality, compared to patients not using RM, and a 35 % reduced likelihood of mortality, compared to those with low adherence to RM [28].

These studies reflect the importance of a potential role for the use of RM device–based diagnostics in the ever-growing population of HF patients with an implanted CIED. Further data are required to validate the use of device-based algorithms in HF. Current investigation efforts are ongoing in this area in order to provide physicians with technology support to improve management of cardiac status. Meanwhile, the general applicability of this RM approach is uncertain and a guideline recommendation about the positive impact of CIED algorithms in chronic HF patients is not yet possible.

5 Cost-Benefit Ratio of Remote Monitoring

The increasing number of patients referred for CIED implantation and the resources required for routine in-clinic CIED follow-up causes a significant burden to the electrophysiology departments and hospital services contributing to increasing health care costs. In-person hospital visits usually entail transportation to the hospital, time spent waiting and loss of productivity, which represent additional costs for patients and for the health system.

RM is a safe technology, widely accepted by patients and physicians, for its convenience, reassurance, and diagnostic potential. It has been associated with a significant reduction of hospital visits while maintaining levels of safety, but also with a reduction of the number of patients lost to follow-up, and a shorter interval between detection of actionable events and a clinical decision when compared with conventional follow-up [29, 30]. In the CONNECT trial, the mean length of hospital stays were significantly shorter in the RM group, representing a potential advantage in cost-saving for both hospital care and patients [30].

Analysis of quality of life showed that 93–97 % of patients were satisfied with the convenience and feasibility of RM, with high levels of satisfaction among both ICD or CRT-D patients and physicians [31, 32].

Prospective health-economic studies are important to determine the clinical and economic benefits of systematic RM in patients with ICD and CRT-D. In the EVOLVO study, the authors aimed to measure the benefits and economic evaluation of RM in chronic HF patients with an ICD or a CRT-D. The results showed cost savings of €888.10 per patient over the 16-month follow-up period [12]. In a recent meta-analysis, regarding the economic impact of RM in patients with HF, there was a significantly lower number of hospitalizations for HF (p < 0.001) and for any cause (p = 0.003) compared to conventional follow-up [33]. The difference in costs between RM and usual care ranged from €300 to €1000, favouring a RM strategy. A recent single-center prospective randomized study showed that the time spent by the hospital staff was significantly reduced in the RM group, with costs savings for both patients and the hospital [34]. The ECOST trial, designed to compare prospectively the safety and the costs of remote ICD monitoring with standard ambulatory follow-up, showed that the direct non-hospital-related costs of RM were 26 % lower than the costs of ambulatory follow-up over a period of 27 months after ICD implantation [35]. The savings observed in this study were particularly significant in view of the greater efficacy of RM (fewer shocks delivered) with equivalent safety (no increase in major adverse events) when compared with ambulatory visits. Increasing the time interval between in-office follow-up visits may be safe if adequate RM is performed.

These cost savings, combined with a quality-adjusted life years gain, suggest that adoption of a RM program will be a progressive dominant technology over existing standard care, particularly in centers performing a large amount of CIED implants.

Overall, the cost–benefit analysis seems to be clearly in favor of RM. A RM network enabling technology and medical information, promptly providing physicians with data comparable to an in-clinic follow-up visit, and offering patients a reduction in the time spent during routine follow-up, may contribute to a closer monitoring of CIED functions, with a favourable impact in costs, irrespective of the patient location, while offering practitioners ability to proactively respond to changes in the device status.

6 Legal Aspects and Data Protection

Despite its potential to reduce the number of visits, RM cannot replace direct contact with the physician, which is important to many patients. The consensus document of the Heart Rhythm Society and the European Heart Rhythm Association on the follow-up of CIED recommends an in-person visit at least once a year and that RM should take place every 3–6 months [9]. When RM is proposed, the patient must be told clearly how this complex system works, its potential benefits and limitations, and that it cannot replace the emergency department since the data transmitted are not analyzed immediately.

Regarding medico legal implications, questions related to the use of RM have been raised. A recent review of publications on RM of CIED revealed that 38 % of the studies included legal and technical issues among the disadvantages of remote follow-up [36]. Standardization and consensus are essential concerning the requirement and ability of the follow-up team to respond to alerts, to deal with information arriving outside the hospital’s normal working hours, to manage the human resources required and to allocate responsibility. Data obtained by RM should be reviewed within reasonable time and frequency during office hours and immediate action should be undertaken when problems are identified.

The informed consent must cover the authorization for transmission of data, recording, and its use for clinical and scientific purposes, respecting privacy and confidentiality. There is also the question of whether to inform all patients of the option of RM. These and other issues must be discussed thoroughly from a multidisciplinary perspective, taking into account that active communication between the treating physicians provide comprehensive information about the findings.

The implementation of a RM program will require a reorganization of the duties of the health team, who will require access to the servers hosting the data repository and will need to manage the large quantity of data transmitted. Clinical decisions will need to be taken regarding the management of alerts, telephone contact with patients and type of information provided, requests for unscheduled visits, measures to increase monitoring if necessary, and reprogramming and maintenance of equipment.

The involvement of data protection commissions is also of considerable importance to ensure that all the components of the system respect legal requirements and confidentiality. Although there have been no reports of security breaches by software attacks to date, the servers that contain patient data are potentially vulnerable to hackers. Therefore, powerful security software must be installed and constant vigilance is required to ensure that the systems are able to resist possible intrusions.

Legal and safety aspects and cost-effectiveness are subject of much debate justifying further studies focusing on how to best allocate this new technology in clinical practice, regarding the use of RM as the new standard of care for follow-up of patients with CIED.

7 Future Directions in Remote Monitoring Technologies

As RM becomes accepted by patients, physicians, and health systems, it may play an increased role in the care of patients with CIED. Integration of the growing amount of RM information in a multidisciplinary approach, the increase of complex workload and compatibility of the relevant data with hospital electronic medical records represent a challenge in optimizing the clinical management of this population. Also, reimbursement issues still need to be addressed in several countries.

The proliferation of CIED and the expanding of HF population raise the question of HF monitoring. This complex task, combining multiple features that provide additional information to HF specialists, requires a well trained team, a detailed analysis and integration of all data received, and an adequate strategy to allow early intervention. This will certainly involve new dedicated devices to monitor cardiac rhythm and hemodynamic parameters to improve patients management. Additional studies in this area are needed to evaluate whether advances in HF monitoring will result in outcomes improvement and reduction in health care costs to justify the widespread indications for these technologies.