Incidence of Inappropriate Subcutaneous Implantable Cardioverter Defibrillator Discharges Related to Electromagnetic Interferences View PDF

^*Maurizio Santomauro
Department Of Cardiovascular Emergency, Internal Medicine, Geriatric Medical School, University Of Naples Federico II, Naples, Italy

^*Corresponding Author:

Maurizio Santomauro
Department Of Cardiovascular Emergency, Internal Medicine, Geriatric Medical School, University Of Naples Federico II, Naples, Italy
Email:santomau@unina.it

Published on: 2020-06-29

Abstract

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) was approved for the prevention of sudden cardiac death among candidates to a transvenous implantable cardioverter-defibrillator (T- ICD) without indication for cardiac resynchronization therapy (CRT), recurrent monomorphic ventricular tachycardia (VT), or pre-existing unipolar pacemaker leads, or anti-bradycardia pacing. In the available S-ICD trials, the inappropriate shock (IAS) rate was reported to be between 5% to 25% and was mainly due to cardiac and extra cardiac over sensing.
Objective: The purpose of this study is to provide the rate of IAS related to electromagnetic interference (EMI) in patients with second- and third-generation of S-ICD. Consequently, we suggest recommendations that promote evidence-based best practices to avoid IAS in the Emergency Department.
Methods: Literature between January 2013 and May 2020 on IAS and S-ICD was identified by database search. We included studies assessing IAS rates due to electromagnetic over sensing. We identified 4 clinical studies and 28 case reports.
Results: The total population included 2286 patients. Of these, 54 patients received IAS due to extracardiac over sensing related to EMI (2.36%).
Conclusion: Extracardiac IAS related to EMI is detectable also in patients with second- and third-generation of S-ICD. In the Emergency Department in all the case of IAS related to EMI, in the absence of a suitable programmer, using a magnet is the first step to deactivate shocks and to avoid the painful and depletion of battery life.

Keywords

Subcutaneous defibrillator; Inappropriate shock; Electromagnetic interference; Deactivation shock therapy

Introduction

Electromagnetic Interference (EMI) is a disturbance that affects the electrical circuit of the S-ICD device due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt or otherwise limit the adequate performance of the circuit. For the normal functioning of S-ICD, appropriate detection of myocardial action potentials is needed. EMI resulting in S-ICD malfunction is a well-known phenomenon. The detection of these signals depends on various factors including the strength of the signal, the distance of the device from the source of EMI, path of the current through the body, and the size of the receiver [1-3]. Clinical scenarios in the Emergency Department, where EMI may interfere with the device functioning or where patients show IAS, warrant reprogramming of S-ICD. This review provides the incidence of IAS related to EMI in patients with the Model A209 EMBLEM S-ICD and the Model A219 EMBLEM MRI S-ICD (Boston Scientific), and the management in emergency situations.

Methods Search strategy

A systematic search was performed from January 2013 to May 2020 in the following database: PubMed, Embase.com (Elsevier), and the FDA Manufacturer and User Facility Device Experience (MAUDE) database were also queried for reports of S?ICD and EMI interactions. Articles with S- ICD IAS rates by 2 investigators were considered. The following Boolean search terms were utilized: “subcutaneous implantable defibrillator or S-ICD” and “shocks or therapy”, “inappropriate”, “cardiac oversensing” and “electromagnetic interference. 130 citations overall were identified by hand-search.

Study selection and data extraction

Overall, 110 citations were identified after the removal of duplicates. The references were screened by two independent researchers and, in case of disagreement, a third researcher was involved in resolving the differences. All authors have approved search criteria and methodology. Titles and abstracts retrieved in the search were reviewed, and observational and comparative studies and case report IAS rates by EMI in S-ICD were selected. For cardiac cause’s analysis, review articles, abstracts, meta-analysis, and editorials were excluded. If there were multiple publications from the same study, the latest study with the complete data available was selected, and the other publications were not used to avoid overlapping cohorts. Data were extracted by one author and were reviewed by additional authors.

Results

After excluding 98 articles for not meeting inclusion/exclusion criteria, 4 articles and 8 case-reports were assessed for eligibility. Years of enrolment for the studies ranged from 2013 to 2020. The total population included 2286 reported patients. Of these, 54 patients received extracardiac IAS related to EMI (2.36%) (Table 1). The sources of EMI were: household (63%), left ventricular assist device (LVAD) (29%), transcutaneous electrical nerve stimulation (TENS) (4%), bathroom (2%), drill (2%) (Figure 1).

Table 1: The select studies and case-reports that investigate the inappropriate shocks due to electromagnetic interference.

Authors	Time	Age (years)	Pt with IAS by EMI	Total pts	Actions
Weiss R, et al. (4)	2013	52±16	3	321	Device reprogramming
Burke MC, et al. (5)	2015	50±16	7	882	Reprogrammed device
Miller MA, et al. (6)	2015	24	1	1	Pt may still utilize TENS despite recommendations
Boesma L, et al. (7)	2017	48±12	22	985	Reprogramming device
Turner SL, et al. (8)	2018	41	1	1	Pt may still utilize TENS despite recommendations
Afzal MR, et al. (9)	2018	42,46	2	2	Pt 1: S-ICD was removed and T- ICD was implanted, Pt 2: Reprogrammed device
Ahmed AS, et al. (10)	2018	25	1	1	Reprogrammed device
Saini H, et al. (11)	2018	49	2	1	S-ICD was remouved and T- ICD was implanted
Khazen C, et al. (12)	2019	44±17	3	79	Pt 1: Recommendations, Pt 2: Reprogramming device, Pt 3: Reprogramming device
Lopez-Gil M (13)	2019	24	1		Reprogramming device
Ishida Y, et al. (14)	2020	33±4	10	10	3 Pts Reprogrammed device, 3 Pts S-ICD was removed and T- ICD was implanted, 3 Pts S-ICD turned OFF, 1 Pt Observation
Utkarsk K, et al. (15)	2020	34	1	1	Pt may still utilize drill
IAS: inappropriate Shocks; S-ICD: Subcutaneous Implanted Cardioverter Defibrillator; T-ICD: Transvenous Implanted Cardioverter Defibrillator; TENS: Transcutaneous electrical nerve stimulation; EMI: electromagnetic interference; Pt: patient.

Discussion

S-ICD is typically used to prevent sudden cardiac death in patients at risk for VT or ventricular fibrillation (VF). (Table 1) summarizes the S-ICD studies and case-reports that investigate the IAS due to oversensing of electromagnetic signals [4-15]. Weiss R, et al. (2013) showed in their work that the overall incidence of IAS was 13.1% (41 patients) over the 11-month average follow-up [4]. Supraventricular tachycardia (SVT) in the shock zone was the cause in 16 pts (5.1%); no patient experienced an IAS in the conditional zone due to a discrimination error. Oversensing produced IAS in 25 patients (8.0%); 22 patients experienced T-wave oversensing (TWO) or wide QRS complexes, whereas 3 patients experienced oversensing as a consequence of EMI. Thirty-two of the 41 patients who experienced an IAS were managed with device reprogramming or drug changes. In 9 patients an invasive procedure was needed to solve IAS. Burke MC, et al. (2015) noted by Kaplan-Meier analysis that the incidence of a first IAS was 13.1% at 3 years in patients with S-ICD [5]. With dual- zone programming at the index procedure, IAS incidence at 3 years was 11.7% compared with 20.5% with single-zone programming. The causes of IAS were SVT above the discrimination zone in 24%, SVT discrimination errors in 1%, TWO in 39%, low amplitude signal in 21%, noncardiac oversensing (EMI) in 8%, oversensing of VT/VF below the rate zone in 4%, other and/or combined types of cardiac oversensing in 2%, and committed shock for VT/VF in 1%. Boersma L, et al. (2017) reported data of the EFFORTLESS Registry with FU ≥1 year [7].

The primary endpoint for the EFFORTLESS Registry was the IAS rate for atrial fibrillation (AF) or SVT in the first year, which occurred in 15 (1.5%) patients. Over the average follow-up of the 3.1-year average, 23 (2.3%) patients received a shock for atrial fibrillation (AF) or SVT, 3 (0.3%) patients for SVT discrimination errors. In total, 8.1% of patients received an IAS in the first year, and 11.7% received 1 over the average 3.1-year follow-up. Seventy-six (7.7%) patients received a shock for cardiac oversensing, mainly due to TWO or low-amplitude signals (63%). Twenty-two (2.2%) patients received a shock for noncardiac oversensing, mainly EMI. At implantation, 850 (86%) patients had S-ICD programmed to dual-zone detection. By programmed setting at implantation, the rate of IAS in the first year was 7.5% for dual-zone and 11.8% for single-zone setting (p = 0.08), and 11.4% for dual-zone and 13.5% for single-zone setting at implantation (p = 0.36) over 3 years. Khazen C, et al. (2019) followed patients with S-ICD and seven of them experienced IAS due to TWO, SVT, EMI, and/or baseline over sensing due to lead movement [12]. However, the experience with concomitant use of S-ICD and EMI with pump speeds described discordant results in case-reports. In the case-reports of Gupta A, et al. (2015) and Raman AS, et al. (2016), the patient with LVAD was observed monthly and no adverse event was seen [16,17]. In contrast, Afzal MR, et al. (2018) and Ishida Y, et al. (2020) documented in LVAD patients with S?ICD, EMI in 12 patients [9,14]. In these cases, EMI may be falsely interpreted as a shockable rhythm and results in 65 Joule biphasic shock delivery. Recently, Black- Maier E, et al. (2020) performed a systematic review of studies involving patients with an S-ICD and LVAD [18]. Among 588 patients undergoing LVAD implant with a pre-existing ICD, 4 had an S-ICD following LVAD implantation. All 4 patients developed EMI in the primary/secondary vectors following LVAD implant, resulting in IAS in 2 patients. Sensing in the alternate vector was adequate immediately post-operatively in 1 patient. Post-operative under sensing was present in the alternate vector in 3 patients, but improved at first outpatient follow-up in 2 patients, allowing tachy-therapies to be re-enabled. EMI was common and frequently absent in the alternate vector. Source of EMI may be a normally functioning device including electronic article surveillance systems, hand-held radiofrequency remote controls, slot machines, abdominal muscle stimulators, etc. EMI may also be due to leakage of alternating electrical current from different devices such as a washing machine, refrigerator, swimming pool, and shower, among many others. The household items are generally safe to use with an S-ICD as long as they are in good working condition and used as intended (Table 2).

Table 2: Household electromagnetic interference sources to avoid.

Air purifiers

Blenders

CD/DVD Players

Clothes washing machines

Electric blankets

Electric can openers

Electric invisible fences

Electric toothbrushes

Fax/copy machines

Hair dryers

Heating pads

Hot tubs/whirlpool baths

Laser tag games

Microwave ovens

Ovens (electric, convection, or gas)

Personal computers

Personal digital assistants (PDAs)

Portable space heaters

Radios (AM and FM)

Remote controls (TV, garage door, stereo, camera/video equipment)

Stoves (electric or gas)

Tanning beds

Televisions

TV or radio towers (safe outside of restricted areas)

Vacuum cleaners

Video games

For the other items, it is important to keep them the recommended distance away from the implanted device to avoid interaction (Table 3).

Table 3: Electromagnetic interference sources to use with precautions.

Cordless (household) telephones

Electric razors

Handheld massagers

Electronic cigarettes

Portable MP3 and multimedia players (such as iPods )

Cellular phones, including PDAs and portable MP3 players with integrated cellular phones

Devices transmitting Bluetooth or WiFi signals (cellular phones, wireless Internet routers, etc.)

Headphones and ear buds

Magnetic wands used in the game of Bingo

Batterypowered cordless power tools

Chainsaws

Corded drills and power tools

Lawn mowers

Leaf blowersRemote controls with antennas

Shop tools (drills, table saws, etc.)

Slot machines

Snow blowers

Stereo speakers

Arc welders

CB and police radio antennas

Running motors and alternators, especially those found in vehicles

For reducing these complications, the Boston Scientific has listed the EMI Compatibility Table for S-ICD [19]. In this document, the manufacturer recommended not using the machines listed. Offline analysis of the EMI events was invaluable. Educate patients to avoid the device causing the EMI or additional device reprogramming or repositioning is needed to overcome these problems. The diagnosis of an IAS depends on history and device interrogation. These patients typically deny any symptoms such as dizziness, light-headedness, or syncope before the shock delivery. Interrogation of S-ICD reveals high-frequency background noise (resulting from EMI) superimposed on patients' baseline rhythm. Management of such IAS includes educating the patients about potential sources of EMI and their avoidance. At the same time, efforts should be made to improve the S-ICD, which includes better shielding the devices and improving the software algorithms to distinguish EMI from real cardiac dysrhythmias. In patients who experienced IAS, physicians have to reprogram the device to decrease the likelihood of inappropriate activation (Figure 2).

These shocks are painful and can potentially induce lethal arrhythmias and can be extremely distressful psychologically to the patient. In the case of repetitive IAS, prompt inactivation of therapy is necessary to prevent pain and psychological trauma. If the patient receives multiple shocks and VT/VF are not seen on the monitor before the device firing, placement of a donut magnet over the S-ICD will prevent subsequent shocks. In all the cases of malfunctions in the absence of a suitable programmer in emergencies, the first step is to use a magnet to deactivate shocks that can lead to myocardial injury and increased mortality. Magnets are readily available and do not require special training to use, making them an excellent option to reprogramme also S-ICD in emergencies. In general, magnet application switches pacemakers to an asynchronous pacing mode and suspends all anti-tachycardia therapies of T-ICD [20]. In S-ICD, magnet application suspends the shock therapy [21]. For the Model A209 EMBLEM S-ICD and the Model A219 EMBLEM MRI S-ICD, the magnet flat is applied against the skin over the device header or edge of the device (Figure 3).

The magnetic field effect of the clinical magnet is directly proportional to the strength of the magnet and inversely proportional to the distance of the magnet from the device [22-24]. If the magnet is correctly placed over the device, beeping tones (R-wave synchronous) will be heard approximately one second after the magnet is applied. Therapy is not suspended until beeping tones are heard. Arrhythmia detection is now suspended and shock therapy is inhibited. Shocks therapies are disabled for the least amount of time, since removing the magnet allows immediate reactivation of the device.

Conclusion

IAS by EMI is painful and stressful for S-ICD patients. Management of such IAS includes educating the patients about potential sources of EMI and their avoidance. Using a donut magnet allows Emergency Department providers to suspend the functionality of the devices. With the appropriate training, Emergency Department employees can help to prevent further discomfort for these patients through the use of any models donut magnet in the hospital setting.

Conflict of interest

The author has no conflict of interest to disclose.

Acknowledgments

The authors thank the engineers Luigi Campanile and Francesco Ricca (Boston Team) for their excellent technical support.