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REVIEWS
Remote monitoring and follow-up of pacemakers and implantable cardioverter defibrillators
Cardiology service, University Hospital of Geneva, 23, rue Micheli-du-Crest, 1211 Geneva, Switzerland
Manuscript submitted 30 December 2008. Accepted after revision 12 April 2009.
* Corresponding author. Tel: +41 22 372 72 00, Fax: +41 22 372 72 29, Email: haran.burri{at}hcuge.ch
| Abstract |
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In the era of communication technology, new options are now available for following-up patients implanted with pacemakers (PMs) and defibrillators (ICDs). Most major companies offer devices with wireless capabilities that communicate automatically with home transmitters, which then relay data to the physician, thereby allowing remote patient follow-up and monitoring. These systems are being widely used in the USA for remote follow-up, and have been more recently introduced in Europe, where their adoption is increasing. In this article, we describe the currently existing systems, review the available evidence in the literature regarding remote follow-up and monitoring of PMs and ICDs, and finally discuss some unresolved issues.
Key Words: Pacemaker, Implantable cardioverter defibrillator, Telemedicine, Remote monitoring, Remote follow-up
| Introduction |
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With increasing awareness of indications for pacemakers (PMs) and especially implantable cardioverter defibrillators (ICDs), the number of patients with implantable devices has been growing steadily. According to the recent ACC/AHA/HRS guidelines,1
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| Existing remote monitoring systems |
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Most major PM/ICD manufacturers have introduced their version of remote monitoring system (Figure 1 and Table 2):
- Home MonitoringTM (Biotronik, Berlin, Germany)
- CareLink NetworkTM (Medtronic, Inc., MN, USA)
- Latitude Patient Management systemTM (Boston Scientific, St Paul, USA)
- Merlin.netTM (St Jude Medical, Sylmar, USA).
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All current models of PMs and ICDs from these manufacturers are able to be manually interrogated by the patient using a telemetry wand incorporated in the home transmitter and are thus able to perform remote follow-ups. However, automatic wireless interrogation of the device is preferable, as it depends less on patient compliance and allows frequent transmissions, which is mandatory for effective remote monitoring. Automatic wireless interrogation requires that the implanted device is equipped with a micro-antenna for communication with the transmitter located close to the patient. Data are then sent to a central database using either the analogue landline phone system and a toll-free number (Boston Scientific, Medtronic and St-Jude Medical systems) or via the GSM network (Biotronik). The data are processed and made accessible to the physician on a secured webpage. The physician is informed by e-mail, SMS, fax, or phone messages whenever critical data are available for consultation. The types of events which trigger an alert can be customized for each patient. None of the systems currently allows remote device programming (although this is technically feasible), essentially for safety issues.
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Biotronik (Home Monitoring®)
This company is the pioneer in the field of remote PM/ICD follow-up and monitoring, with FDA approval of their first system in 2001. The transmitter (CardioMessenger®) is a little bigger than a cell phone and communicates wirelessly with the implanted device within a radius of 2 m. It sends the retrieved data to a centre in Germany using the GSM network, which is the main advantage of the system. This is an important issue today, as the patient may not have a landline phone connection (due to increased use of cell phones) or may have a digital landline connection (currently incompatible with all device systems) or a DSL/VOIP connection that requires special filters and converters. It also means that the patient can be monitored continuously around the clock, as the CardioMessenger has a rechargeable battery that allows it to be carried around by the patient. Furthermore, the patient can continue to be monitored while travelling abroad with the CardioMessenger, as the system is compatible with most available GSM networks throughout the world. Parameters for the alerts can be fully configured on the secured webpage, without having to bring the patient into the clinic for a manual transmission (Figure 2). EGMs of 30 s duration are sent periodically that may assist with data interpretation (Figure 3). Biotronik is the only company today that offers PMs with wireless technology for remote monitoring (other manufacturers are also going to offer wireless PMs in the future).
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Medtronic (Carelink NetworkTM)
The system has been introduced in Europe in a pilot study in 2005.3
Boston Scientific (Latitude Patient Management systemTM)
This system is to be introduced in Europe in 2009. The transmitter also uses an analogue landline for data transmission, which may be configured for use in various countries (but may require plug adapters). A unique feature of the system is the possibility to connect wireless weight scales and blood pressure cuffs for remote monitoring of heart failure status (Figure 1). Also, the patient can self-report heart failure symptoms into the system on a weekly basis (such as fatigue, ankle swelling, orthopnea etc.). Event notifications can be configured individually in each patient based upon red and yellow alerts. Furthermore, the system allows customizable data transmission to different physicians (for example to the general practitioner or general cardiologist in addition to the heart rhythm specialist), which improves networking of heart failure management.
St Jude Medical (Merlin.netTM)
The wireless transmitter (Merlin{at}home) has been introduced in Europe in 2008 at pilot centres. The system communicates automatically by radiofrequency with the implantable device and sends data to the physician using the analogue landline system (a cellular adapter card is planned for 2009). As with the other available systems, remote monitoring is possible with alerts being sent by e-mail, fax, or SMS to notify the physician of events. A useful feature is the ability for the physician to indicate alerts or reminders of scheduled in-office visits on the patient's transmitter, and to send automated phone calls to patients indicating the results of the remote follow-up (e.g. that everything is normal). The next generation of ICDs will also have capture thresholds for all leads, which will facilitate full remote follow-up.
| Potential benefits and existing evidence of utility |
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Reduction of in-clinic visits
In a study by Brugada,4
More recently Heidbuchel et al.5
retrospectively analysed data from 1739 in-clinic ICD visits in 169 patients. The authors found that only 6% of scheduled in-clinic visits resulted in device reprogramming or patient hospitalization. Thus, in 94% of all scheduled visits, remote follow-up would have sufficed. Furthermore, they estimated that ICD remote monitoring could potentially diagnose > 99% of arrhythmia- or device-related problems, if combined with clinical follow-up by the local general practitioner and/or the referring cardiologist.
Preliminary results of the TRUST (Lumax-T/Lumos-T safely RedUceS rouTine office device follow-up) study were recently presented.6
Data on 1312 patients with a Biotronik VR/DR ICD were randomized to standard (3 months) in-office visits vs. remote monitoring (with in-office visits at 3 and 15 months). Remote monitoring and follow-up resulted in a 43% relative reduction in visits (from 3.0 to 2.5 visits/patient-year, P < 0.001) with a better adherence to the scheduled follow-up timetable. The trial demonstrated also similar safety (death, stroke, or event-related surgery) by remote monitoring compared with in-clinic control group.
In addition to reducing scheduled in-clinic visits, remote follow-up may avoid unscheduled visits following an ICD shock.7
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After such an event, the patient may perform manual interrogation to upload data to the physician for determining if the shock was appropriate or not, and it may then be decided whether the patient should be seen for device reprogramming or modification of drug therapy.
Patients with cardiac resynchronization therapy (CRT) may require special consideration, as they are usually sicker and have more complex devices with specific issues (e.g. requirement for atrio-ventricular interval optimization, greater variations in left ventricular thresholds, phrenic nerve capture etc.). Thus frequency of follow-up and requirement for in-office device reprogramming may be greater than in patients with standard PMs or ICDs. In a report from the Insync ICD Italian Registry,9
there was a marked reduction in number of interrogations requiring reprogramming between the first 6 months of follow-up and subsequent periods, as pacing and CRT delivery parameters were usually optimized relatively quickly after implantation and maintained unmodified thereafter. This means that remote follow-up is an acceptable alternative in these patients, especially with the advent of algorithms that automatically adjust device settings such as left ventricular pacing output based upon daily threshold measurements.10
Even though remote device monitoring and interrogation has the potential to reduce numbers of in-clinic visits, it does not entirely replace direct contact (that is valued by many patients). According to current guidelines, in-office visits need to take place at least yearly (Table 1), but this may change in the future for subsets of patients (e.g. primary prevention ICD patients without clinical events or elderly/disabled patients etc.).
Improved patient safety
Figure 4 shows an example of a patient in whom remote follow-up proved to be life-saving.
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In a recent study by Nielsen et al.,11
3% of patients. The temporal distribution of home monitoring events is interesting, as over 60% occurred during the first month following the last visit. In another report using the Biotronik Home Monitoring system with over 3 million transmissions in > 11 000 patients,12
Remote monitoring may be particularly useful in patients with CRT, as they are most likely to have transmissions of medically related events.12
A number of different randomized trials are currently underway to assess the utility of monitoring lung fluid overload in patients with heart failure (Table 3).
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Failure of ICD leads is a major issue and has been highlighted by the Fidelis lead recall. The Medtronic lead integrity alert algorithm has been shown to give a warning of impending inappropriate shocks by at least 3 days advance in 76% of patients,15
Remote follow-up and monitoring can also be used for tracking product performance in a large number of patients, and may allow earlier identification of issues with specific models. The large amount of data gathered in a consistent manner also has the potential to facilitate medical research.
Increased patient satisfaction
The first studies evaluating patient satisfaction by remote follow-up of ICDs were published in 2004 using the Medtronic Carelink system20
and the St Jude Medical HouseCall IITM.21
Patient satisfaction with the systems was high in both studies. In an Italian study, 67 patients implanted with a Medtronic CRT-D were followed remotely using the CareLinkTM system.8
,22
Remote follow-ups were preferred to in-clinic visits by 78% of the patients. Satisfaction by the physicians was also very favourable. Likewise, in another study using the Medtronic CareLinkTM conducted in Finland,23
the patients and physicians level of satisfaction with the system was high. Our own experience is that most patients readily accept remote monitoring, and feel secured by the use of this technology to improve their healthcare.
Potential cost savings
There are a few studies that assess the potential cost/benefit of remote monitoring-assisted care compared with conventional follow-up, and all are based on the fact that remote data access may decrease the rate of inhospital patient visits. Using a French database of 502 ICD-patients followed in tertiary care hospitals, Fauchier et al.24
estimated a decrease in costs for follow-up visits of as much as $2149 over a 5 years device lifespan. However, savings were closely related to the distance between home and medical facilities. It is noteworthy that this study did not include reimbursement for the time spent reviewing remote monitoring data.
Recently, an interesting Finnish study23
replaced standard ICD follow-up at 3 and 6 months after implantation, by remote data transmission using the Medtronic CareLinkTM system. This was safe, reduced time burden for patient and inhospital staff, and was also cost-effective. However, one should note that the economic impact of remote follow-up may not be the same in all countries, due to the fact that indirect costs (such as travel expenses and sickness allowance) played a major role.
| Specific issues |
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Optimal workflow
Even though reports suggest that the physician is unlikely to be submerged by incoming data from his patients (for example, the mean numbers of events per patient per month reported in the largest study to date12
Several companies are working on compatibility of their systems with electronic medical records for exporting remote follow-up data. This will considerably alleviate the clinic's workload and help streamline workflow.
Legal aspects
The patient needs to be informed of the purpose and limitations of remote monitoring, such as the fact that it does not replace an emergency service or absence of dealing with alert events outside office hours. Before initiating remote monitoring and follow-up, the patient may be requested to sign a written informed consent stating these points and authorizing transmission of personal data to third parties, respect of privacy, and confidentiality of patient data by device companies should be subjected to strict rules, described in contracts.
Patient privacy and security
In order to test the vulnerability of security breaches by hackers accessing devices with wireless capability, Halperin et al.26
performed laboratory tests on a Medtronic Maximo DR ICD. After having partially reversed the ICD's communications protocol with an oscilloscope and a software radio, they performed several software radio-based attacks that were able to retrieve uncrypted personal patient data, as well as change device settings (including commanded shocks). This report triggered considerable media coverage, although it is believed that the risk of unauthorized access to an ICD is unlikely, given the considerable technical expertise required.27
There have been no reports to date of hacking of implantable devices. Another consideration, however, is hacking of the internet server database.
Reimbursement
In the USA, Medicare and Medicaid have expanded reimbursement for remote device monitoring for all states since 2006. Reimbursement rates vary from state to state, and in some instances are the same as an in-office visit without device programming. In the UK, Germany, and Portugal, reimbursement for remote monitoring is similar to that offered for standard follow-up visits.
| Conclusions |
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Remote monitoring and follow-up are likely to become the standard of care for patients with PMs and ICDs, as they have the potential to improve patient safety and satisfaction, to support efficient use of resources, and to reduce costs. Existing data show that current technology for remote monitoring is reliable and that it is readily accepted by patients and their physicians. Large randomized trials are underway that will hopefully prove that remote monitoring improves patient outcome. Specific issues such as reimbursement need to be dealt with by the authorities, in order to ensure that this solution is a viable one.
Conflicts of interest: D.S. is a member of the Boston Scientific fellowship program. H.B. receives research grants from Medtronic, Boston Scientific, and St Jude Medical, has been on the speakers bureau for Medtronic and Boston Scientific, and is a member of the Latitude advisory board.
| Funding |
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H.B. was supported in part by a research grant from the Foundation for Cardiovascular Research of the Hôpital de la Tour, Meyrin, Switzerland. Funding to pay the Open Access publication charges for this article was provided equally by Biotronik, Boston Scientific, Medtronic and St. Jude Medical.
| Acknowledgements |
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The authors would like to thank Mr Tim Montgomery (Biotronik), Mr Matthias Wollenstein (Boston Scientific), Mr Bertjo Frick (Medtronic), Mrs Severine Pradere (Sorin), and Mr Blaise Sahli (St Jude Medical) for their kind assistance and technical review of the manuscript.
| References |
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