RM of lead parameters is fundamental for the early detection of lead dislodgments and fractures. Thanks to the automation of the measurement of the technical parameters of the leads and device, values can be regularly transmitted; this is the case for the values of sensing of the intracardiac signals collected in the atrium and in the ventricles, of thresholds and impedances of stimulation and of shock impedance, which make it possible to control the functionality of the leads. Compared to scheduled controls, especially on an outpatient basis, RM can involve the daily transmission of the values of the measured parameters, with an alert system in the event of an out-of-range value. The abundance of data brought to the electrophysiologists’ knowledge may cause a difficulty of interpretation and also requires an adequate adjustment of the alert thresholds. Let us take an example with the pacing impedance. In some patients, the impedance has a constant value very close to the standard threshold for triggering an alert because of an out-of-range value. This case is relatively frequent and requires a modification of the threshold of the alert so as not to multiply identical and irrelevant alerts. Moreover, daily monitoring of lead parameters leads to regular questioning in the case of out-of-range value(s) of when to intervene in a patient; indeed, the multiplicity of measurements made by the device has shown us that the trends of the pacing impedance can take different aspects, as we can see in Figure 2.1. If a first out-of-range value generates an alert, the electrophysiologist should avoid reacting instantly, of course if the lead is not recalled, so as not to cause a patient to be transported unnecessarily to the hospital while later values will be normal (Figure 2.1A). On the other hand, a single out-of-range value associated with oversensing episodes (Figure 2.1B) will certainly give rise to suspicion of lead fracture and will necessitate the transport of the patient to the rhythmologic center. If the increase of impedance is progressive (Figure 2.1C), before intervening, the electrophysiologist will wait for the occurrence of other signs, such as changes in the sensing or pacing thresholds or, of course, occurrence of episodes of oversensing. Indeed, a gradual increase in impedance can sometimes be attributed to change in the electrode-myocardium interface that is compatible with normal sensing and pacing functions of the lead.⁴

The transmitted values of the device-related parameters include battery voltage and capacitor charge time. In addition, the RM system makes it possible to transmit any abnormal working of the device, such as transition to backup mode, deactivation of therapies, electrical reset, maintenance in magnetic resonance imaging (MRI) mode, and failure of the high-voltage circuit or of the system integrity. The alerts related to these device issues are much less frequent than those for leads. Indeed, the alert about the elective replacement index (ERI) of the battery obviously occurs only once during the life of the device and the alert about the end of service should not occur. But the ERI alert is particularly useful because it does not allow patients to be transported to the rhythmic center quarterly during the device’s last year of life only for controlling the battery charge. Moreover, sometimes the battery can discharge prematurely, because of malfunction or of multiple shocks, which requires the electrophysiologist to be alerted. Regarding the duration of the battery, RM and RIs have a relatively negative impact by the electrical consumption they generate. The intensity of this impact varies by brand. On the contrary, remote management has a positive impact on the longevity of the battery, in particular, by limiting the number of capacitor charges of ICDs by the early identification of conditions likely to trigger shocks (mainly atrial fibrillation and oversensing that are responsible for inappropriate shocks, and electrical storms responsible for appropriate shocks), enabling to prevent these shocks
(Figure 2.2). Indeed, the randomized Effectiveness and Cost Of ICD follow-up Schedule with Telecardiology (ECOST) study showed that RM compared with IPE was associated with a reduction of capacitor charges, exerting a favorable impact on battery longevity.⁵ For PM, the more sustained follow-up because of RM may lead to greater responsiveness in the adaptation of the device’s programming and may
allow an extension of the life of the battery by decreasing the percentage of pacing.⁶ RM also brings a very clear added value by alerting immediately when the device is programmed in a very unusual mode. In fact, it is most often involuntary programming that, in the absence of RM, is only detected at the time of interrogation of the device using a programmer. But in the meantime, the programming in question may be at risk for the patient. This is the case, for example, of the automatic switch of programming in backup mode that can occur during radiotherapy, a mode that induces a high risk of inappropriate ICD shocks. Other examples that may be mentioned are the inadvertent absence of activation of defibrillator therapies, or more frequently the inadvertent absence of reactivation of defibrillator therapies when they were deactivated for a surgical intervention in order to avoid potential shocks during surgery, or the maintenance in MRI mode when a device is wrongly not controlled by the electrophysiologist after the MRI evaluation.

In addition to the monitoring of the technical parameters of the device/lead system, RM makes it possible to transmit events related to the occurrence of ICD therapies, completely documenting them (date and time of onset, duration of the ventricular arrhythmia, and modalities of the delivered therapies) and accompanying this information with corresponding intracardiac electrograms (IEGM).⁷ It also makes it possible to transmit information on the percentage of pacing in the different chambers. Why would one like to be alerted if appropriate therapies for ventricular arrhythmia occur? The very first reason is that only the electrophysiologist can diagnose whether therapy is appropriate, and we will come back to this point later. The second reason is that if the therapy consists of an appropriate shock, the circumstances of occurrence and the IEGM must be quickly analyzed in order to prevent possible recurrence of shocks, events most often symptomatic and therefore undesirable for the patient. For example, if a shock occurs under relative hyperadrenergic conditions, as the rapid underlying heart rate before the start of the arrhythmia testifies, then one will tend to contact the patient, if they have not already made contact themselves because they may not have felt the shock (in the case of a shock during the night or loss of consciousness before the shock), in order to ensure that the therapeutic observance of pharmacologic treatment is good, especially the observance of beta-blocker treatment, and that its regimen is adapted. Also, it is useful to check if the shock was not induced by ischemic conditions. In some cases, the needed further evaluation can be done by the general practitioner or the cardiologist who is in proximity, avoiding a transportation. Furthermore, medical treatment can be carried out remotely or by the general practitioner to the extent that the programming of the device does not need to be changed. In the case of a shock, especially single without any favoring circumstance, which in any case could not have been avoided, RM allows, thanks to the remote analysis of the data, to remotely reassure the patient, while their therapeutic strategy has no reason to be modified. The third reason lies in the early detection of electrical storms, especially those that are asymptomatic, thus preventing any solicitation of the electrophysiologist emanating directly from the patient. This is the occurrence of multiple episodes treated with antitachycardia pacing, whose transmission arouses the attention of the electrophysiologist. These electrical storms, even asymptomatic, always require a review of patient management to avoid the occurrence of much more serious adverse events. Indeed, electrical storms are the consequence or the cause of the deterioration of the patient’s cardiac condition. Early detection of all electrical storms requires that any episode that triggers antitachycardia pacing does alert the electrophysiologist (Figure 2.3).

More rarely, some alerts not initially intended to bring attention on ventricular arrhythmias allowed their detection (Figure 2.4). This is the case of supraventricular arrhythmia-related alerts in inappropriate diagnosis. Exceptionally, an alert indicating a biventricular pacing rate to 0% could reveal an undersensed unceasing ventricular tachycardia (VT) because of cardiac frequency slower than the threshold of the first VT zone.