Subcutaneous air entrapment after subcutaneous implantable cardioverter defibrillator implantation evaluated by computed tomography.

BACKGROUND: Inappropriate shock (IAS) caused by subcutaneous air entrapment (AE) in an early period after subcutaneous implantable cardioverter defibrillator (S-ICD) implantation has been reported, however, no detailed data on air volume are available. We evaluated the subcutaneous air volume after implantation and its absorption rate one week after implantation. METHODS: Patients who underwent S-ICD implantation in our hospital received chest CT scans immediately after implantation and followed up 1 week later. The total subcutaneous air volume, air around the generator, the distal electrode, and the proximal electrode within 3 cm were calculated using a three-dimensional workstation. Fat areas at the level of the lower edge of the generator were also analyzed. RESULT: Fifteen patients received CT immediately after implantation. The mean age was 45.6 ± 17.9 (66.7% of men), and the mean body mass index was 24.3 ± 3.3. The three-incision technique was applied in seven patients and two-incision technique was in the latter eight patients. The mean total subcutaneous air volume was 18.54 ± 7.50 mL. Air volume around the generator, the distal electrode, and the proximal electrode were 11.05 ± 5.12, 0.72 ± 0.72, and 0.88 ± 0.87 mL, respectively. Twelve patients received a follow-up CT 1 week later. The mean total subcutaneous air was 0.25 ± 0.45 mL, showing a 98.7% absorption rate. CONCLUSION: Although subcutaneous air was observed in all patients after S-ICD implantation, most of the air was absorbed within 1 week, suggesting a low occurrence of AE-related IAS after a week postoperation.

Inappropriate shock incidence in patients with subcutaneous implantable cardioverter-defibrillators with concomitant cardiac implantable electronic devices: A single-center cohort study.

BACKGROUND: Subcutaneous implantable cardioverter defibrillators (S-ICDs) are occasionally used in combination with other cardiac implantable electronic devices (CIEDs). However, whether the incidence of inappropriate shock increases in patients with S-ICDs and concomitant CIEDs remains unclear. This study aimed to investigate the association between the concomitant use of CIEDs and the incidence of inappropriate shock in patients with current-generation S-ICDs. METHODS: A total of 127 consecutive patients received an S-ICD. Patients were assigned to two groups depending on concomitant use of CIEDs at the time of S-ICD implantation: patients without other CIEDs (non-combined group, 106 patients) and patients with other CIEDs (combined group, 21 patients). CIEDs included pacemakers, implantable cardioverter defibrillators, cardiac resynchronization therapy pacemakers, and cardiac resynchronization therapy defibrillators. The primary outcome was inappropriate shock, defined as a shock other than ventricular arrhythmia. Hazard ratios and 95% confidence intervals were calculated using a time-varying Cox proportional hazards model which was adjusted for age because age differed between the groups and could be a confounder. RESULTS: During a median follow-up period of 2.2 years (interquartile range, 1.0-3.4 years), inappropriate shock events occurred in 17 (16%) and five (19%) patients of the non-combined and combined groups, respectively. While the age-adjusted hazard ratio for inappropriate shock was 24% higher in the combined than in the non-combined group (hazard ratio = 1.24, 95% confidence interval, 0.39-3.97), this difference was insignificant (p = .71). CONCLUSION: The incidence of inappropriate shock did not differ between patients with and without concomitant use of CIEDs, suggesting that S-ICDs could potentially be combined with other CIEDs without increasing the number of inappropriate shocks. Further studies are warranted to confirm the safety and feasibility of concomitant use of S-ICDs and CIEDs.

Device programing and SMART pass algorithm activation in subcutaneous implantable defibrillator patients: Data from a remote monitoring database.

BACKGROUND: The programing of subcutaneous implantable cardioverter-defibrillators (S-ICD) in clinical practice has been little studied, as the activation status of the SMART Pass filter, which was implemented to reduce inappropriate shocks. PURPOSE: We assessed device programing during follow-up and the rate of detected arrhythmias in consecutive S-ICD recipients. METHODS: We analyzed data from 670 S-ICD patients followed on the remote network at 17 Italian centers for a median of 31 months (25th-75th percentile: 16-51). The enhanced SMART Pass version, introduced in October 2022, was expected to reduce the unintentional deactivation rate. RESULTS: At the latest remote data transmission, the median conditional zone cut-off was set to 210 bpm (25th-75th percentile: 200-220), the shock zone cutoff was 250 bpm (25th-75th percentile: 240-250), and the SMART Pass was enabled in 586 (87%) patients. During follow-up, 194 automatic deactivation events were reported in 118 (18%) patients. Shocks were delivered in 129 (19%) patients, and untreated arrhythmias were recorded in 136 (20%) patients. The rate of shocks was lower when SMART Pass was enabled -0.12/patient-year (95% CI: 0.10-0.14) versus 0.20 (95% CI: 0.15-0.26) (p = .002), as it was the rate of untreated arrhythmias -0.12/patient-year (95% CI: 0.11-0.14) versus 0.23 (95% CI: 0.18-0.30) (p = .001). The enhanced SMART Pass version was associated with a lower rate of deactivations -0.04/patient-year (95% CI: 0.02-0.05) versus 0.14 (95% CI: 0.12-0.16) (p < .001), and with a reduction in treated and untreated arrhythmias (Incidence rate ratios: 0.40 (95% CI: 0.28-0.53) and 0.40 (95% CI: 0.30-0.55), respectively (p < .001)). CONCLUSIONS: Centers tend to program devices to detect high ventricular rates for arrhythmia detection, to minimize inappropriate shock occurrences. SMART Pass activation is associated with lower rates of detected and treated arrhythmias. The enhanced SMART Pass version seems associated with a lower deactivation rate and with a further decrease in treated arrhythmias.

Reduction in inappropriate therapies through device programming in subcutaneous implantable defibrillator patients: data from clinical practice.

AIMS: In subcutaneous implantable cardioverter defibrillator (S-ICD) recipients, the UNTOUCHED study demonstrated a very low inappropriate shock rate on programming a conditional zone between 200 and 250 bpm and a shock zone for arrhythmias >250 bpm. The extent to which this programming approach is adopted in clinical practice is still unknown, as is its impact on the rates of inappropriate and appropriate therapies. METHODS AND RESULTS: We assessed ICD programming on implantation and during follow-up in a cohort of 1468 consecutive S-ICD recipients in 56 Italian centres. We also measured the occurrence of inappropriate and appropriate shocks during follow-up. On implantation, the median programmed conditional zone cut-off was set to 200 bpm (IQR: 200-220) and the shock zone cut-off was 230 bpm (IQR: 210-250). During follow-up, the conditional zone cut-off rate was not significantly changed, while the shock zone cut-off was changed in 622 (42%) patients and the median value increased to 250 bpm (IQR: 230-250) (P < 0.001). UNTOUCHED-like programming of detection cut-offs was adopted in 426 (29%) patients immediately after device implantation, and in 714 (49%, P < 0.001) at the last follow-up. UNTOUCHED-like programming was independently associated with fewer inappropriate shocks (hazard ratio 0.50, 95%CI 0.25-0.98, P = 0.044), and had no impact on appropriate and ineffective shocks. CONCLUSIONS: In recent years, S-ICD implanting centres have increasingly programmed high arrhythmia detection cut-off rates, at the time of implantation in the case of new S-ICD recipients, and during follow-up in the case of pre-existing implants. This has contributed significantly to reducing the incidence of inappropriate shocks in clinical practice. Rordorf: Programming of the S-ICD. CLINICAL TRIAL REGISTRATION: URL: http://clinicaltrials.gov/Identifier: NCT02275637.

Intermuscular technique for implantation of the subcutaneous implantable defibrillator: a propensity-matched case-control study.

AIMS: A previous randomized study demonstrated that the subcutaneous implantable cardioverter defibrillator (S-ICD) was noninferior to transvenous ICD with respect to device-related complications and inappropriate shocks. However, that was performed prior to the widespread adoption of pulse generator implantation in the intermuscular (IM) space instead of the traditional subcutaneous (SC) pocket. The aim of this analysis was to compare survival from device-related complications and inappropriate shocks between patients who underwent S-ICD implantation with the generator positioned in an IM position in comparison with an SC pocket. METHODS AND RESULTS: We analysed 1577 consecutive patients who had undergone S-ICD implantation from 2013 to 2021 and were followed up until December 2021. Subcutaneous patients (n = 290) were propensity matched with patients of the IM group (n = 290), and their outcomes were compared. : During a median follow-up of 28 months, device-related complications were reported in 28 (4.8%) patients and inappropriate shocks were reported in 37 (6.4%) patients. The risk of complication was lower in the matched IM group than in the SC group [hazard ratio 0.41, 95% confidence interval (CI) 0.17-0.99, P = 0.041], as well as the composite of complications and inappropriate shocks (hazard ratio 0.50, 95% CI 0.30-0.86, P = 0.013). The risk of appropriate shocks was similar between groups (hazard ratio 0.90, 95% CI 0.50-1.61, P = 0.721). There was no significant interaction between generator positioning and variables such as gender, age, body mass index, and ejection fraction. CONCLUSION: Our data showed the superiority of the IM S-ICD generator positioning in reducing device-related complications and inappropriate shocks. CLINICAL TRIAL REGISTRATION: Clinical Trial Registration: ClinicalTrials.gov; NCT02275637.

Modern subcutaneous implantable defibrillator therapy in patients with cardiomyopathies and channelopathies: data from a large multicentre registry.

AIMS: Patients with cardiomyopathies and channelopathies are usually younger and have a predominantly arrhythmia-related prognosis; they have nearly normal life expectancy thanks to the protection against sudden cardiac death provided by the implantable cardioverter defibrillator (ICD). The subcutaneous ICD (S-ICD) is an effective alternative to the transvenous ICD and has evolved over the years. This study aimed to evaluate the rate of inappropriate shocks (IS), appropriate therapies, and device-related complications in patients with cardiomyopathies and channelopathies who underwent modern S-ICD implantation. METHODS AND RESULTS: We enrolled consecutive patients with cardiomyopathies and channelopathies who had undergone implantation of a modern S-ICD from January 2016 to December 2020 and who were followed up until December 2022. A total of 1338 S-ICD implantations were performed within the observation period. Of these patients, 628 had cardiomyopathies or channelopathies. The rate of IS at 12 months was 4.6% [95% confidence interval (CI): 2.8-6.9] in patients with cardiomyopathies and 1.1% (95% CI: 0.1-3.8) in patients with channelopathies (P = 0.032). No significant differences were noted over a median follow-up of 43 months [hazard ratio (HR): 0.76; 95% CI: 0.45-1.31; P = 0.351]. The rate of appropriate shocks at 12 months was 2.3% (95% CI: 1.1-4.1) in patients with cardiomyopathies and 2.1% (95% CI: 0.6-5.3) in patients with channelopathies (P = 1.0). The rate of device-related complications was 0.9% (95% CI: 0.3-2.3) and 3.2% (95% CI: 1.2-6.8), respectively (P = 0.074). No significant differences were noted over the entire follow-up. The need for pacing was low, occurring in 0.8% of patients. CONCLUSION: Modern S-ICDs may be a valuable alternative to transvenous ICDs in patients with cardiomyopathies and channelopathies. Our findings suggest that modern S-ICD therapy carries a low rate of IS. CLINICAL TRIAL REGISTRATION: URL: http://clinicaltrials.gov/Identifier: NCT02275637.

Sense-B-noise: an enigmatic cause for inappropriate shocks in subcutaneous implantable cardioverter defibrillators.

AIMS: Subcutaneous implantable cardioverter defibrillators (S-ICDs) are well established. However, inappropriate shocks (IAS) remain a source of concern since S-ICDs offer very limited troubleshooting options. In our multicentre case series, we describe several patients who experienced IAS due to a previously unknown S-ICD system issue. METHODS AND RESULTS: We observed six patients suffering from this novel IAS entity. The IAS occurred exclusively in primary or alternate S-ICD sensing vector configuration (therefore called 'Sense-B-noise'). IAS were caused by non-physiologic oversensing episodes characterized by intermittent signal saturation, diminished QRS amplitudes, and disappearance of the artefacts after the IAS. Noise/oversensing could not be provoked by manipulation, X-ray did not show evidence for lead/header issues and impedance measurements were within normal limits. The pooled experience of our centres implies that up to ∼5% of S-ICDs may be affected. The underlying root cause was discussed extensively with the manufacturer but remains unknown and is under further investigation. CONCLUSION: Sense-B-noise is a novel cause for IAS due to non-physiologic signal oversensing, arising from a previously unknown S-ICD system issue. Sense-B-noise may be suspected if episodes of signal saturation in primary or alternate vector configuration are present, oversensing cannot be provoked, and X-ray and electrical measurements appear normal. The issue can be resolved by reprogramming the device to secondary sensing vector.

Laser Doppler flow for the hemodynamic differentiation of tachycardia.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) offer effective therapy for the prevention of sudden cardiac death (SCD) due to ventricular arrhythmias. However, inappropriate shocks have detrimental effects on survival and quality of life. The addition of hemodynamic monitoring may be useful in discriminating clinically important ventricular arrhythmias. OBJECTIVE: In this study, we assess the ability of laser Doppler flowmetry to assess the hemodynamic effect of paced atrial and ventricular arrhythmias using mean arterial blood pressure as the reference. METHODS: In this acute human study in patients undergoing an elective electrophysiological study, laser Doppler flowmetry, arterial blood pressure, and surface ECG were acquired during high-rate atrial and ventricular pacing to simulate supraventricular and ventricular tachycardias. RESULTS: Arterial blood pressure and laser Doppler flow signals correlated well during atrial and ventricular pacing (rho = 0.694, p < .001). The hemodynamic impairment detected by both methods was greater during ventricular pacing than atrial pacing (-1.0% vs. 19.0%, p < .001). Laser Doppler flowmetry performed better than rate alone to identify hemodynamic impairments. CONCLUSION: In this acute study, laser Doppler flowmetry tissue perfusion served as a good surrogate measure for arterial pressure, which could be incorporated into future ICDs.

How likely is the sense-B-noise to affect patients with subcutaneous implantable cardioverter-defibrillators and can we solve that problem in every case?

BACKGROUND: Sense-B-noise is a newly reported possible cause of inappropriate shocks in patients with subcutaneous implantable cardioverter-defibrillators (S-ICDs). The nature of that noise is unknown, it is not related to mechanical failure of the S-ICD system. Reprogramming to the secondary sensing vector is suggested by the producer as a possible solution. METHODS: We analyzed the medical records of S-ICD recipients from two university clinical centers (Gdansk and Szczecin, Poland). Our aim was to determine the rate of sense-B-noise, and whether the secondary sensing vector would be available for reprogramming if such a problem occurred in our patients. RESULTS: The sense-B-noise issue affected three patients in our cohort (3%), which corresponds to the incidence of 0.012 events per patient-year of follow-up. The primary vector was permanently used in 47 patients (52%), secondary in 28 (31%), and alternate in 16 (17%), respectively. Therefore, the total number of patients potentially vulnerable to sense-B noise (with the primary or alternate vector programmed permanently) was 63 (69%). Among those 63 patients, 51 individuals (81%) had also the secondary vector available for permanent use. CONCLUSION: The sense-B-noise affected 3% of patients in our cohort, with an incidence of 0.012 per patient-year of follow-up. Most patients potentially vulnerable to sense-B noise could be reprogrammed to the secondary sensing vector, if necessary. Further investigation of the sense-B-noise issue is needed.

Subcutaneous versus transvenous implantable cardioverter-defibrillator among drug-induced type-1 ECG pattern Brugada syndrome: a propensity score matching analysis from IBRYD study.

No real-world data are available about the complications rate in drug-induced type 1 Brugada Syndrome (BrS) patients with an implantable cardioverter-defibrillator (ICD). Aim of our study is to compare the device-related complications, infections, and inappropriate therapies among drug-induced type 1 BrS patients with transvenous- ICD (TV-ICD) versus subcutaneous-ICD (S-ICD). Data for this study were sourced from the IBRYD (Italian BRugada sYnDrome) registry which includes 619 drug-induced type-1 BrS patients followed at 20 Italian tertiary referral hospitals. For the present analysis, we selected 258 consecutive BrS patients implanted with ICD. 198 patients (76.7%) received a TV-ICD, while 60 a S-ICD (23.4%). And were followed-up for a median time of 84.3 [46.5-147] months. ICD inappropriate therapies were experienced by 16 patients (6.2%). 14 patients (7.1%) in the TVICD group and 2 patients (3.3%) in S-ICD group (log-rank P = 0.64). ICD-related complications occurred in 31 patients (12%); 29 (14.6%) in TV-ICD group and 2 (3.3%) in S-ICD group (log-rank P = 0.41). ICD-related infections occurred in 10 patients (3.88%); 9 (4.5%) in TV-ICD group and 1 (1.8%) in S-ICD group (log-rank P = 0.80). After balancing for potential confounders using the propensity score matching technique, no differences were found in terms of clinical outcomes between the two groups. In a real-world setting of drug-induced type-1 BrS patients with ICD, no significant differences in inappropriate ICD therapies, device-related complications, and infections were shown among S-ICD vs TV-ICD. However, a reduction in lead-related complications was observed in the S-ICD group. In conclusion, our evidence suggests that S-ICD is at least non-inferior to TV-ICD in this population and may also reduce the risk of lead-related complications which can expose the patients to the necessity of lead extractions.

Low Risk of Inappropriate Shock Among Pediatric Patients With an Implantable Cardioverter Defibrillator: A Single Center Experience.

Implantable cardioverter-defibrillators (ICD) are increasingly being used among the pediatric population for indications of both primary and secondary prevention. There is limited long-term data on the outcomes of pediatric patients following ICD implantation. The aim of this study was to investigate the characteristics of this population, burden of appropriate and inappropriate shock and complication rate in a large tertiary pediatric medical center. Included were children under the age of 18 years who underwent ICD implantation and had clinical follow up at our center. Data were retrospectively collected between study period 2005-2020. Primary outcome was the incidence of ICD shock appropriate and inappropriate. Secondary outcome was defining our patient population characteristics. Our cohort included 51 patients who underwent ICD implantation. Mean age at implantation was 10.9 ± 4.7 years and average follow-up time was 67 months. Diagnoses of implanted patients were: 28 (55%) patients with syndromes with risk for sudden death, cardiomyopathy in 14 patients (27%) and congenital heart disease (CHD) in 9 patients (18%). Forty-two (82%) patients had an ICD implanted for secondary prevention after experiencing a life-threatening arrhythmia and 9 (18%) for primary prevention. An endocardial system was implanted in 39 (76%) patients and an epicardial systems in 12 (24%) patients. A total of 20 (39%) patients received appropriate shocks for ventricular fibrillation(VF). 5 patients received inappropriate shocks, 4 due to sinus tachycardia and 1 due to rapidly conducted atrial fibrillation. Those who received an inappropriate shock had a significantly shorter ICD-programmed VF detection cycle length compared to those who did not receive an inappropriate shock (320 ms versus 270 ms, p = 0.062). This single center study demonstrates a high rate of appropriate ICD shocks (39%) and a low rate of inappropriate ICD shocks. Accurate programming of ICD devices in the pediatric population is paramount to avoid inappropriate ICD shocks.

Air entrapment as a cause of early inappropriate shocks after subcutaneous defibrillator implant: A case series.

Inappropriate shock (IAS) is the most frequent device-related complication among patients with subcutaneous implantable cardioverter-defibrillator (S-ICD). Air entrapment (AE) has been described as an underdiagnosed cause of early postimplant IAS. We report 6 consecutive cases of early IAS after S-ICD implant, in whom the electrogram analysis (EGM) and/or chest radiography (CXR) were consistent with AE.

Air entrapment as a potential cause of early subcutaneous implantable cardioverter defibrillator malfunction: a systematic review of the literature.

AIMS: Air entrapment (AE) has been reported as a potential cause of early inappropriate shocks (ISs) following subcutaneous implantable cardioverter defibrillator (S-ICD) implantation, but a cause-effect relationship is not always evident. This systematic review aims to analyse this phenomenon concerning implantation techniques, electrogram (EGM) features, radiologic findings, and patient management. METHODS AND RESULTS: A systematic search was conducted using PubMed, Embase, and Google Scholar databases following the PRISMA guidelines to obtain all available literature data since 2010 on S-ICD malfunctions possibly due to AE. The final analysis included 54 patients with AE as a potential cause of S-ICD malfunction. Overall, the aggregate incidence of this condition was 1.2%. Of ICD malfunctions possibly due to AE, 93% were ISs, and 95% were recorded within the first week following implantation. Radiologic diagnosis of AE was confirmed in 28% of the entire study cohort and in 68% of patients in whom this diagnostic examination was reported. At the time of device malfunction, EGMs showed artefacts, baseline drift, and QRS voltage reduction in 95, 76, and 67% of episodes, respectively. Management included ICD reprogramming or testing, no action (observation), and invasive implant revision in 57, 33, and 10% of patients, respectively. No recurrences occurred during follow-up, irrespective of management performed. CONCLUSIONS: Device malfunction possibly due to AE may occur in ∼1% of S-ICD recipients. Diagnosis is strongly suggested by early occurrence, characteristic EGM features, and radiologic findings. Non-invasive management, principally device reprogramming, appears to be effective in most patients.

Inappropriate shocks due to air entrapment in patients with subcutaneous implantable cardioverter-defibrillator: A meta-summary of case reports.

BACKGROUND: Air entrapment has been recently described as a cause of inappropriate shock (IAS) among patients who underwent subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation. Data about this complication are lacking in the literature. METHODS: In this meta-summary 14 case reports describing IAS due to air entrapment were included. Patients' characteristics, S-ICD implant technique and air entrapment properties were collected. RESULTS: All patients experienced IAS within 4 days following S-ICD implant. The subcutaneous air was demonstrated by chest x-ray in 11 cases (73.3%). The sensing vector was reprogrammed in 11 cases (73.3%), and ICD was switched off in 2 cases (1.3%). CONCLUSIONS: IAS due to air entrapment is an early complication of S-ICD implant. No association was observed between the implant technique and air retention. Diagnosis is confirmed by chest x-ray and device interrogation. Management includes switching off the device or, preferably, changing the sensing vector.

Subcutaneous versus transvenous implantable cardioverter defibrillators in children and young adults: A meta-analysis.

INTRODUCTION: The implantable cardioverter defibrillator (ICD) has been demonstrated to successfully prevent sudden cardiac death (SCD) in children and young adults. A wide range of device-related complications/malfunctions have been described, which depend on the intrinsic design of the defibrillation system (transvenous-implantable cardioverter defibrillator [TV-ICD] vs. subcutaneous-implantable cardioverter defibrillator [S-ICD]). OBJECTIVE: To compare the device-related complications and inappropriate shocks with TV-ICD versus S-ICD. METHODS AND RESULTS: Electronic databases were queried for studies focusing on the prevention of SCD in children and young adults with TV-ICD or S-ICD. The effect size was estimated using a random-effect model as odds ratio (OR) and relative 95% confidence interval (CI). The primary endpoint was a composite of any device-related complications and inappropriate shocks. We identified a total of five studies including 236 patients (Group S-ICD: 76 patients; Group TV-ICD: 160 patients) with a mean follow-up time of 54.2 ± 24.9 months. S-ICD implantation contributed to a significant reduction in the risk of the primary endpoint of any device-related complications and inappropriate shocks (OR: 0.18; 95% CI: 0.05-0.73; p = .02). S-ICD was also associated with a significantly lower incidence of inappropriate shocks (OR: 0.28; 95% CI: 0.11-0.74; p = .01) and lead-related complications (OR: 0.18; 95% CI: 0.05-0.66; p = .01). A trend toward a higher risk of pocket complications (OR: 5.91; 95% CI: 0.98-35.63; p = .05) was recorded in patients with S-ICD. CONCLUSION: Children and young adults undergoing S-ICD implantation may have a lower risk of a composite of device-related complications and inappropriate shocks, compared to TV-ICD patients.

Inappropriate shock delivery as a result of electromagnetic interference originating from the faulty electrical installation.

We present a case report of a 74-year-old male patient with an implantable cardioverter defibrillator who suffered an inappropriate defibrillation shock while bathing in the tub. Insight in the ICD stored electrogram episodes revealed electromagnetic interferences, with a typical 50 Hz electrical artifact mimicking fast ventricular tachycardia as a device misinterpreted. After this event, the maintenance workers investigated the electrical installation in the bathroom and revealed that there was voltage leaking between electrical installation and metal pipes. After the repair was completed without any additional programming, the patient has had no subsequent shocks.

Inappropriate defibrillator shock due to EMI despite noise reversion and SecureSense - What is the mechanism?

Implantable cardioverter defibrillator (ICD) shocks are always a matter of anxiety and concern for both patient and clinician. We report a case of ischemic cardiomyopathy who reported to us after receiving two shocks within 48 hours. The therapy was inappropriate as noted from device logs. EMI was identified as the incriminating cause. We discuss the reasons why he received the therapy despite active 'Noise reversion' and 'SecureSense' algorithms to avoid noise /EMI related oversensing.

Predictors of inappropriate shock in Brugada syndrome patients with a subcutaneous implantable cardiac defibrillator.

BACKGROUND: Subcutaneous implantable cardioverter defibrillators (S-ICDs) avoid complications secondary to transvenous leads, but inappropriate shocks (ISs) are frequent. Furthermore, IS data from patients with Brugada syndrome (BrS) with an S-ICD are scarce. OBJECTIVE: We aimed to establish the frequency and predictors of IS in this population. METHODS: We analyzed the clinical and electrocardiographic characteristics, automated screening test data, device programming, and IS occurrence in adult patients with BrS with an S-ICD. RESULTS: Thirty-nine patients were enrolled (69% male, mean age at diagnosis 46 ± 13 years, mean age at implantation 48 ± 13 years). During a mean follow-up of 26 ± 21 months, 18% patients experienced IS. Patients with IS were younger at the time of diagnosis (36 ± 8 vs. 48 ± 13 years, p = .018) and S-ICD implantation (38 ± 9 vs. 50 ± 23 years, p = .019) and presented with spontaneous type 1 Brugada electrocardiogram pattern more frequently at diagnosis or during follow-up (71% vs. 25%, p = .018). During automated screening tests, patients with IS showed lower QRS voltage in the primary vector in the supine position (0.58 ± 0.26 vs. 1.10 ± 0.35 mV, p = .011) and lower defibrillator automated screening score in the primary vector in the supine (123 ± 165 vs. 554 ± 390 mV, p = .005) and standing (162 ± 179 vs. 486 ± 388 mV, p = .038) positions. Age at diagnosis was the only independent predictor of IS (hazard ratio = 0.873, 95% confidence interval: 0.767-0.992, p = .037). CONCLUSION: IS was a frequent complication in patients with BrS with an S-ICD. Younger age was independently associated with IS. A more thorough screening process might help prevent IS in this population.

Usefulness of subcutaneous implantable cardioverter-defibrillator therapy in patients with Brugada syndrome.

Implantable cardioverter-defibrillators (ICDs) are the main therapy to prevent sudden cardiac death in patients with Brugada syndrome (BrS). The subcutaneous ICD (S-ICD) can eliminate lead-associated complications compared with transvenous ICD (TV-ICD). However, S-ICD is susceptible to T-wave oversensing (TWOS) and may result in more frequent inappropriate shocks in patients with BrS. This study aimed to compare inappropriate shocks between TV-ICD and S-ICD in patients with BrS. We enrolled 32 patients with BrS (including one woman; mean age 52 ± 18 years) who were implanted with ICD (23 TV-ICDs and 9 S-ICDs) between January 2002 and November 2018 in Oita University Hospital. We carried out a standard surface electrocardiogram (ECG) screening tests in both supine and standing positions prior to S-ICD implantation. The patients received routine clinical review every month and device monitoring every 4 months. The period of follow-up was 129 ± 51 months. Six patients with BrS and TV-ICDs experienced inappropriate shocks (26%) with their ICD therapy. In contrast, two patients with BrS and S-ICDs experienced inappropriate shocks (22%). There was no significant difference between the two groups (P = 0.82). Although one case in the S-ICD group experienced TWOS-induced inappropriate shock, SMART Pass (new high-pass filter) prevented the subsequent recurrence of inappropriate shocks during ICD therapy. Our results suggest that S-ICD is not inferior to TV-ICD in the incidence of inappropriate shocks. SMART Pass may be a useful tool to prevent inappropriate ICD shocks by TWOS in patients with BrS.

Inappropriate shock delivery by an implantable cardioverter-defibrillator due to electrical interference with a refrigerator in a 4-year-old child.

We report a patient with long QT syndrome who received an inappropriate implantable cardioverter-defibrillator shock due to electrical interference from a refrigerator. This electrical interference was mistakenly detected as an episode of ventricular fibrillation and ended with an inappropriate delivery of shock without any warning symptoms before.