The implantation of electronic cardiac devices has increased exponentially over the last decade in response to widening indications. Subsequent monitoring is an integral part of both device and patient care, but remains unguided by any prospectively derived data. A consensus suggests that patients with implantable cardioverter– defibrillators (ICDs) should report for routine face-to-face clinic checks every three to six months, generating a huge clinical burden.1 Symptomatic events such as shock therapy prompt additional encounters including unscheduled office/emergency room (ER) visits or even hospitalisation. The volume of unscheduled encounters periodically increases, for example when a device reaches its elective replacement indicator (ERI) or in response to product advisories and recalls. A major limitation of this conventional follow-up method based on patient presentation is that no monitoring takes place between hospital visits, which is the majority of the time. Hence, important diagnostic data, such as system problems or the onset of atrial fibrillation (AF), may remain concealed indefinitely until the next device check. Remote monitoring may be a mechanism for performing intensive device surveillance without overburdening device clinics.
The available technologies have different capabilities and modes of operation. Wand-based systems require patient-driven downloads relayed via telephone connections to hospital/clinic facilities.2,3 This time-consuming process may be cumbersome to use and challenge compliance, and remains vulnerable to overlooking asymptomatic events. Also, this technology may fail to reduce cardiac-related resource utilisation.4 By contrast, an automatic transmission mechanism fully independent of patient or physician interaction has considerable advantages. It implements the use of automatic (wireless or landline-based) data transmissions, which can be reviewed securely via the Internet (see Figures 1 and 2). This form of technology was pioneered by Biotronik (Home Monitoring [HM] and approved by the US Food and Drug Administration [FDA] in 2002). The reliability and early notification ability of this communication system are excellent,5 and operation of the system is not costly in terms of energy consumption. HM, with instantaneous event transmission with no need for any patient or nurse involvement, has the ability to maintain surveillance and rapidly bring to attention significant data, enabling clinically appropriate intervention. This was tested in the Lumos-T Safely Reduces Routine Office Device Follow-up Study (TRUST).
Lumos-T Reduces Routine Office Device Follow-up Study
TRUST has been the only prospective multicentre clinical study to assess follow-up both conventionally and with remote monitoring using HM.6,7 In this study, 1,450 patients were enrolled at 102 US sites and were randomised to conventional care (HM off) or to remote monitoring (HM on) (see Figure 3). The results demonstrated the following:
- HM reduced healthcare utilisation by approximately 50% as measured by the total of scheduled and unscheduled (ER visits, patient- or physician-initiated checks) hospital evaluations. This resulted predominantly from the reduction in the number of scheduled encounters, the bulk of which involve collection of routine measurements only (e.g. battery status, lead impedance, sensing function) and require no clinical intervention (e.g. re-programming, alteration of antiarrhythmic medications) and which can be performed by online data review.
- Importantly, the reduction in the number of face-to-face visits was accomplished safely, as there was no difference between the two study arms in terms of death, incidence of strokes and events requiring surgical interventions (e.g. device explants or lead revision).
- HM permitted earlier detection and physician evaluation of cardiac and/or device problems despite fewer face-to-face encounters. For example, arrhythmia detection (combined AF, VT, and VF events) in HM patients occurred in a median period of one day compared to more than one month with conventional care.
- HM secured greater follow-up adherence to every-three-months calendar-based checks. This was presumably because patient data can be monitored remotely any time and from anywhere, as opposed to the situation in the conventional arm, which relies on patients to present themselves physically to their physician’s office.
These results indicate that remote monitoring can be adopted as an instrument for device management, performing intensive surveillance and substituting for in-office follow-up, but also fulfilling the important role of a mechanism for early detection. Management of unscheduled checks may be also facilitated. For example, with patient enquiries, shock data and online electrograms are available and can be used to determine best management confidently. An appropriate shock may require reassurance only without the need for a hospital visit. By contrast, a series of inappropriate shocks may be rapidly evaluated online and the patient asked to come in to the hospital promptly.
The capacity for early detection is exceptionally valuable for detection of silent events. Potentially dangerous asymptomatic events that typically remain concealed in diagnostic memory and manifest only at formal interrogation may be revealed within hours by automatic HM and direct clinical intervention (see Figures 4 and 5).5,8,9
Several claims for HM based on the TRUST study results received FDA approval in May 2009, and the TRUST management protocol has been adopted by several large-volume centres in the US. It should be noted that the follow-up scheme described is for device management and is not intended to replace consultations with internists, cardiologists or heart failure specialists. Reimbursement guidelines were instituted in January 2009 in the US. Checks performed remotely every three months are reimbursed; between these checks, additional remote interrogations performed within the 90-day ‘global period’ are reimbursed only if the evaluation prompted an in-office evaluation and device re-programming.
Lead and Device Performance
The assessment of post-implantation system performance is an important responsibility, but is challenging in view of the increasing volume of cases, device complexity and advisory notices. Management of components under advisory notice poses several daunting challenges. Intensive monitoring by increasing office visits (e.g. monthly) is impractical, onerous and inefficient (since the incidence of any problems is very low) and is likely to fail to detect potentially catastrophic problems occurring between interrogations.10,11 Remote monitoring systems relying on patient-driven communication may have similar limitations in the detection of asymptomatic failure. By contrast, HM technology, which provides constant surveillance of system integrity with automatic alerts, eliminates the burden of patients having to monitor their own devices frequently and co-ordinate with the clinic’s services. TRUST demonstrated that conventional monitoring methods under-reported device-related problems.13 By contrast, HM enhanced the discovery of system issues (even when asymptomatic) and enabled prompt clinical decisions in terms of conservative versus surgical management. Performance problems were often asymptomatic. Figure 5 illustrates the benefit of HM in the management of recalled components.9,12
Thus, the call for intensive and comprehensive monitoring of implantable devices may be met by remote monitoring technology, as exemplified by HM.12,14 The ability to collect detailed device-specific data, with component function assessed daily and automatic archiving, sets a precedent for longitudinal evaluation of lead and generator performance.
Monitoring Disease Progression
Recipients of ICD therapy commonly have heart failure, which is a dynamic condition. Factors that may potentially cause morbidity or decompensation can be detected early with HM and treated.15 For example, AF in heart failure patients may be associated with increased morbidity and mortality.16,17 This is likely to be multifactorial, involving an increased risk of heart failure and stroke and, possibly, facilitation of ventricular arrhythmias. AF may precipitate acute heart failure decompensation by adversely affecting ventricular haemodynamics. AF may be associated with periods of rapid conduction. This is important because the beneficial effect of cardiac resynchronisation therapy (CRT) may be reduced when pacing is diminished to <92%.18 Withdrawal of ventricular pacing in CRT defibrillators (CRT-Ds) is notified by HM (see Figure 4).
Clearly, a daily patient-monitoring system generating trend analysis automatically has the ability to notify clinicians to deviations from the baseline. Action taken on the basis of these notifications may have the ability to prevent hospitalisations.15,19 In the future, incorporation of sensor technology may provide sentinel notification of conditions, leading to decompensation and prompt pre-emptive therapy. This may form the basis of stand-alone implantable cardiac monitors.20–22 Remote monitoring provides the mechanism for accessing and delivering prioritised data collected by these increasingly sophisticated implantable units.
In summary, automatic remote home monitoring fulfils the aims of post-implantation device management. TRUST presents a device-management model in which near continuous remote surveillance maintains the continuity of follow-up and combines with automatic self-declaration of problems, identifying the exceptional group of patients requiring in-clinic attention. Thus, unnecessary in-office follow-up is avoided and necessary face-to-face encounters facilitated. This reduces the clinic load for the physician, but permits earlier attention to actionable events. Patient safety and convenience are improved. Automatic data archiving provides a resource for monitoring system performance and disease progression. These characteristics have significant ramifications for implantable cardiac electronic devices in general, as well as for patient safety.