Decremental properties of a concealed nodoventricular pathway.

INTRODUCTION: The decremental properties of the nodoventricular pathway (NVP) are uncertain. METHODS AND RESULTS: During short RP supraventricular tachycardia, a His-refractory premature ventricular contraction (PVC) consistently terminated the tachycardia without atrial capture immediately after the PVC. Whereas a slightly earlier PVC failed to reset the subsequent His but terminated the tachycardia without atrial capture one cycle later. CONCLUSION: These observations are diagnostic of slow-fast atrioventricular nodal reentrant tachycardia (AVNRT) with a bystander concealed-NVP and can be explained by decremental properties in the NVP itself; greater prematurity of the PVC resulted in more decremental conduction over the NVP, causing the AVNRT termination one cycle later.

Clinical characteristics and analysis of prognostic factors in methicillin-resistant Staphylococcus aureus endocarditis: A retrospective multicenter study in Japan.

BACKGROUND: Infective endocarditis (IE) caused by MRSA (methicillin-resistant Staphylococcus aureus) is associated with a high mortality rate. This study aimed to elucidate the characteristics of patients with MRSA-IE in Japan and identify the factors associated with prognosis. METHODS: This retrospective study included patients with a confirmed diagnosis of IE caused by MRSA, between January 2015 and April 2019. RESULTS: A total of 65 patients from 19 centers were included, with a mean age of 67 years and 26 % were female. Fifty percent of the patients with IE were had nosocomial infections and 25 % had prosthetic valve involvement. The most common comorbidities were hemodialysis (20 %) and diabetes (20 %). Congestive heart failure was present in 86 % of patients (NYHA class I, II: 48 %; III, IV: 38 %). The 30-day and in-hospital mortality rates were 29 % and 46 %, respectively. Multi-organ failure was the primary cause of death, accounting for 43 % of all causes of death. Prognostic factors for in-hospital mortality were age, disseminated intravascular coagulation, daptomycin and/or linezolid as initial antibiotic therapy, and surgery. Surgical treatment was associated with a lower mortality rate (odds ratio [OR], 0.026; 95 % confidence interval [CI], 0.002-0.382; p = 0.008 for 30-day mortality and OR, 0.130; 95 % CI; 0.029-0.584; p = 0.008 for in-hospital mortality). CONCLUSION: Mortality due to MRSA-IE remains high. Surgical treatment is a significant prognostic predictor of MRSA-IE.

Antimicrobial therapy and outcome of methicillin-resistant Staphylococcus aureus endocarditis: A retrospective multicenter study in Japan.

BACKGROUND: MRSA (methicillin-resistant Staphylococcus aureus)-infective endocarditis (IE) is associated with high morbidity and mortality. This study aimed to assess data from patients with MRSA-IE across multiple facilities in Japan, with a specific focus on antimicrobial therapy and prognosis. METHODS: This retrospective study enrolled patients with a confirmed diagnosis of IE attributed to MRSA, spanning the period from January 2015 to April 2019. RESULTS: Sixty-four patients from 19 centers were included, with a median age of 67 years. The overall mortality rate was 28.1% at 30 days, with an in-hospital mortality of 45.3%. The most frequently chosen initial anti-MRSA agents were glycopeptide in 67.2% of cases. Daptomycin and linezolid were selected as initial therapy in 23.4% and 17.2% of cases, respectively. Approximately 40% of all patients underwent medication changes due to difficulty in controlling infection or drug-related side effects. Significant prognostic factors by multivariable analysis were DIC for 30-day mortality and surgical treatment for 30-day and in-hospital mortality. For vancomycin as initial monotherapy, there was a trend toward a worse prognosis for 30-day and in-hospital mortality (OR, 6.29; 95%CI, 1.00-39.65; p = 0.050, OR, 3.61; 95%CI, 0.93-14.00; p = 0.064). Regarding the choice of initial antibiotic therapy, statistical analysis did not show significant differences in prognosis. CONCLUSION: Glycopeptide and daptomycin were the preferred antibiotics for the initial therapy of MRSA-IE. Antimicrobial regimens were changed for various reasons. Prognosis was not significantly affected by choice of antibiotic therapy (glycopeptide, daptomycin, linezolid), but further studies are needed to determine which antimicrobials are optimal as first-line agents.

A novel ablation strategy for recurrent atrial fibrillation: Fractionated signal area in the atrial muscle ablation 1-year follow-up.

INTRODUCTION: Treatment of recurrent atrial fibrillation (AF) is sometimes challenging due to non-pulmonary vein (PV) foci. Fractionated signal area in the atrial muscle (FAAM) is a valid predictor of the location of non-PV foci. FAAM ablation has the potential to decrease the recurrence rate of atrial tachyarrhythmia in patients with recurrent AF. We compared the clinical impact of FAAM ablation for recurrent AF, using 1 year follow up date. METHODS: A total of 230 consecutive patients with symptomatic recurrent AF who underwent catheter ablation specifically targeting non-PV foci as FAAM-guided ablation (n = 113) and non-FAAM-guided ablation (n = 117) were retrospectively analyzed. FAAM was assigned a parameter (peaks slider, which indicates the number of components of fractionated signals), ranging from 1 to 15, indicating the location of the FAAM (1: largest, 15: smallest). FAAM-guided ablation was performed by ablating FAAM until none inducibility of non-PV foci. On the other hand, non-FAAM-guided ablation was performed via linear ablation, complex fractionated atrial electrogram ablation, superior vena cava isolation, and focal ablation according to the location of the non-PV foci. The RHYTHMIA system was used to perform all the procedures. The primary endpoints were AF recurrence, atrial flutter, and/or atrial tachycardia. RESULTS: After a 1-year follow up, freedom from atrial tachyarrhythmia was achieved in 90.3% and 75.2% of patients in the FAAM and non-FAAM groups, respectively (hazard ratio = 0.438 [95% confidence interval: 0.243-0.788], p = .005). CONCLUSIONS: FAAM ablation showed a promising decrease in the recurrence rate of atrial tachyarrhythmia in patients with recurrent AF during a 1-year follow-up.

Zero-Contrast Left Atrial Appendage Closure in Patients With Chronic Kidney Disease.

BACKGROUND: Left atrial appendage closure (LAAC) usually requires contrast medium during the procedure. However, patients with chronic kidney disease (CKD) are at high risk of developing contrast nephropathy. This study aimed to assess the safety and feasibility of zero-contrast LAAC in patients with CKD.Methods and Results: Zero-contrast LAAC was attempted in 15 patients with CKD Stages 3b-5 who were not on hemodialysis. All procedures were performed successfully, without any periprocedural complications. At the 45-day follow-up, no device-related complications or acute kidney disease were observed. CONCLUSIONS: The strategy of zero-contrast LAAC in patients with CKD can be an acceptable option.

The hemodynamic effect of simulated atrial fibrillation on left ventricular function.

INTRODUCTION: Atrial fibrillation (AF) is the most common sustained arrhythmia in humans. The onset of the arrhythmia can significantly impair cardiac function. This hemodynamic deterioration has been explained by several mechanisms such as the loss of atrial contraction, shortening of ventricular filling, or heart rhythm irregularity. This study sought to evaluate the relative hemodynamic contribution of each of these components during in vivo simulated human AF. METHODS: Twelve patients undergoing catheter ablation for paroxysmal AF were paced simultaneously from the proximal coronary sinus and the His bundle region according to prescribed sequences of irregular R-R intervals with the average rate of 90 and 130 bpm, which were extracted from the database of digital ECG recordings of AF from other patients. The simulated AF was compared to regular atrial pacing with spontaneous atrioventricular conduction and regular simultaneous atrioventricular pacing at the same heart rate. Beat-by-beat left atrial and left ventricular pressures, including LV dP/dT and Tau index were assessed by direct invasive measurement; beat-by-beat stroke volume and cardiac output (index) were assessed by simultaneous pulse-wave doppler intracardiac echocardiography. RESULTS: Simulated AF led to significant impairment of left ventricular systolic and diastolic function. Both loss of atrial contraction and heart rate irregularity significantly contributed to hemodynamic impairment. This effect was pronounced with increasing heart rate. CONCLUSION: Our findings strengthen the rationale for therapeutic strategies aiming at rhythm control and heart rate regularization in patients with AF.

Clinical impact of eliminating nonpulmonary vein triggers of atrial fibrillation and nonpulmonary vein premature atrial contractions at initial ablation for persistent atrial fibrillation.

BACKGROUND: The role of nonpulmonary vein (PV) triggers ablation in persistent atrial fibrillation (PEAF) was suggested but it is still under debate. OBJECTIVES: We aimed to assess the effectiveness of non-PV trigger-targeted ablation for patients with PEAF. METHODS: Consecutive patients with PEAF undergoing catheter ablation (CA) between January 2015 and April 2017 were enrolled. Isoproterenol plus adenosine challenge was performed to provoke non-PV triggers. Non-PV triggers were defined as the trigger beats inducing AF (non-PV AF triggers) and/or frequent premature contractions (non-PV PACs) from other than PVs. Three groups were defined: Group 1 (n = 186) without non-PV triggers; Group 2 (n = 65) with non-PV triggers that could be completely eliminated with CA; Group 3 (n = 49) with non-PV triggers still inducible after CA. The primary endpoint was freedom from any atrial tachyarrhythmia (ATa) recurrence. RESULTS: A total of 300 patients (230 males, age 64 ± 10) were enrolled. The mean follow-up period was 27 ± 10 months. Freedom from ATa recurrence at 1 and 2 years were significantly lower in Group 3 compared to the other two groups (Group 1; 74.7%, 67.2% vs. Group 2; 75.8%, 68.3% vs. Group 3: 52.1%, 38.6%, p = .0005), irrespective of the type of non-PV triggers (non-PV AF triggers vs. non-PV PACs). On multivariate analysis, unsuccessful elimination of non-PV triggers was an independent predictor for ATa recurrence (hazard ratio = 1.80, 95% confidence interval = 1.07-2.95, p = .026). CONCLUSION: Successful non-PV triggers elimination can improve the ATa recurrence rate in PEAF ablation. ATa recurrence rate is higher, if non-PV AF triggers or even non-PV PACs remain in patients with PEAF.

Retrieval of a Micra transcatheter pacing system in a heart with a preexisting lead.

We report the case of a 74-year-old man with a previously implanted pacemaker lead. He had undergone Medtronic™ Micra Transcatheter Pacing System (TPS, Medtronic plc, MN, USA) implantation because of lead fracture. We implanted a new TPS and retrieved the dislodged one. We used a multiple-loop snare (EN snare®) and an 8.5F steerable sheath (Agilis NXT; St. Jude Medical, St Paul, MN, USA). The TPS was obstructed by the chordae tendineae of the tricuspid valve and the pacemaker lead. We pushed the TPS to the apex site; this enabled us to move the TPS away from the chordae tendineae and pacemaker lead. The TPS body was caught in the inferior vena cava and was successfully retrieved. To our knowledge, this is the first case reporting TPS retrieval in a heart with preexisting lead.

Differential effect of ganglionic plexi ablation in a patient with neurally mediated syncope and intermittent atrioventricular block.

AIMS: In patients with severe neurally mediated syncope (NMS), radiofrequency catheter ablation (RFA) of ganglionic plexi (GP) has been proposed as a new therapeutic approach. Cardio-inhibitory response during NMS is usually related to the sinoatrial (SA) and less frequently to atrioventricular (AV) node. Differential effect of GP ablation on SA and AV node is poorly understood. METHODS AND RESULTS: We report a case of a 35-year-old female with frequent symptomatic episodes of advanced AV block treated by anatomically guided RFA at empirical sites of GPs. After RFA at the septal portion of the right atrium-superior vena cava junction, heart rate accelerated from 62 to 91 beats/min and PR interval prolonged from 213 to 344 ms. Sustained first-degree AV block allowed to observe directly the effects of subsequent RFA on the AV nodal properties. Subsequent RFA at right- and left-sided aspects of the inter-atrial septum had no further effect on heart rate and PR interval. Ablation at the inferior left GP was critical for restoration of normal AV conduction (final PR interval of 187 ms). No bradycardia episodes were observed by implantable loop recorder during the follow-up of 10 months and the patient was symptomatically improved. CONCLUSION: This is the first clinical case showing the differential effect of GP ablation on SA and AV nodal function, and critical importance of targeting the GP at the postero-inferior left atrium. The successful procedure corroborates clinical utility of ablation treatment instead of pacemaker implantation in selected patients with cardio-inhibitory NMS.

Efficacy of Intensive Radiofrequency Energy Delivery to the Localized Dense Scar Area in Post-Infarction Ventricular Tachycardia Ablation　- A Comparative Study With Standard Strategy Targeting the Infarcted Border Zone.

BACKGROUND: Several reports have demonstrated the importance of severely low voltage areas as arrhythmogenic substrates of ventricular tachycardia (VT). However, a comparative study of dense scar-targeted and infarcted border zone-targeted strategies has not been reported.Methods and Results:We divided 109 consecutive patients with VT post-infarction from 6 centers into 2 groups according to the ablation strategy used: dense scar-targeted ablation (DS ablation, 48%) or border zone-targeted ablation (BZ ablation, 52%). During DS ablation, we attempted to identify VT isthmuses in the dense scar areas (≤0.6 mV) using detailed pace mapping, and linear ablation lesions were applied mainly to those areas. During BZ ablation, linear ablation of standard low voltage areas (0.5-1.5 mV) was performed along with good pace map sites of the clinical VT. Acute success was defined as complete success (no VTs inducible) or partial success (clinical VT was noninducible). The acute complete success rate was significantly higher for DS ablation than for BZ ablation (62% vs. 42%, P=0.043). During a median follow-up of 37 months, the VT-free survival rate was significantly higher for DS ablation than for BZ ablation (80% vs. 58% at 48 months; log-rank P=0.038). CONCLUSIONS: DS ablation may be a more effective therapy for post-infarction VT than BZ ablation in terms of the acute complete success rate and long-term follow-up.

Impact of Catheter Ablation for Paroxysmal Atrial Fibrillation in Patients With Sick Sinus Syndrome　- Important Role of Non-Pulmonary Vein Foci.

BACKGROUND: The clinical efficacy of catheter ablation (CA) for paroxysmal atrial fibrillation (PAF) in patients with sick sinus syndrome (SSS) and the mechanism and predictors of recurrence are not yet completely elucidated. METHODS AND RESULTS: Of 963 consecutive patients who underwent PAF ablation during the study period, a total of 108 patients with SSS (SSS group) and 108 matched controls without SSS (non-SSS group) were followed up. During the follow-up period (mean, 32.8±17.5 months), the SSS group had significantly higher AF recurrence rate since the last procedure than the non-SSS group (26.9% vs. 12.0%; P=0.02). The SSS group had significantly higher prevalence of non-pulmonary vein (non-PV) foci than the non-SSS group (25.9% vs. 13.9%; P=0.027). On multivariate analysis congestive heart failure (HR, 13.7; 95% CI: 1.57-119; P=0.02) and non-PV foci (HR, 5.75; 95% CI: 1.69-19.6; P=0.005) were independent predictors of recurrence following CA in the SSS group. In the SSS group, 88 patients had bradycardia-tachycardia syndrome without prior permanent pacemaker implantation. Of these, 6 required pacemaker implantation because of AF and sinus pause recurrence. CONCLUSIONS: Patients with SSS are at higher risk of AF recurrence after CA. Non-PV foci are associated with AF recurrence following PAF with SSS.

Implantable cardioverter defibrillator infection due to Mycobacterium mageritense.

Rapidly growing non-tuberculous mycobacteria (RGM) are usually detected in blood cultures after 4-5 days of incubation, so it is important to differentiate RGM from contamination of commensal organisms on human skin. We report an unusual case of Mycobacterium mageritense bacteremia and infection of an implantable cardioverter defibrillator originally misidentified as Corynebacterium spp. or Nocardia spp. in gram-stained smears. 16S rRNA gene sequencing had utility in the definitive identification of isolates. We should be aware that RGM infection may exist in repeated implantable device infections.

Outcomes of left bundle branch area pacing compared to His bundle pacing and right ventricular apical pacing in Japanese patients with bradycardia.

Background: His bundle pacing (HBP) and left bundle branch area pacing (LBBAP) emerge as better alternatives to right ventricular apical pacing (RVAP) in patients with bradycardia requiring permanent cardiac pacing. We aimed to compare the clinical outcomes of LBBAP, HBP, and RVAP in Japanese patients with bradycardia. Methods: A total of 424 patients who underwent successful pacemaker implantation (HBP, n = 53; LBBAP, n = 75; and RVAP, n = 296) were retrospectively enrolled in this study. The primary study endpoint was the cumulative incidence of heart failure hospitalization (HFH) during the follow-up. Results: The success rate for implantation was higher in the LBBAP group than in the HBP group (94.9% and 81.5%, respectively). Capture threshold increase >1V during the follow-up occurred in the HBP and RVAP groups (9.4% and 5.1%, respectively), while it did not in the LBBAP group. The cumulative incidence of HFH was significantly lower in the LBBAP group than the RVAP (adjusted hazard ratio, 0.12 [95% confidence interval: 0.02-0.86]; p = .034); it did not differ between the HBP and RVAP groups (adjusted hazard ratio, 0.48 [95% confidence interval: 0.17-1.34]; p = .16). Advanced age, mean percent right ventricular pacing (per 10% increase), left ventricular ejection fraction <50%, and RVAP were associated with HFH. Conclusions: Compared to RVAP and HBP, LBBAP appeared more feasible and effective in patients with bradycardia requiring permanent cardiac pacing.

Influence of the irrigation flow pattern and catheter tip design on the lesion formation: an ex vivo experimental model.

BACKGROUND: Lesion formation during catheter ablation is influenced by the power, contact force (CF), time, and catheter stability. However, the influence of the irrigation effects on lesion formation remains unknown. METHODS: An ex vivo experiment using conductive gel was performed. Using three different catheter designs (TactiFlex ™ SE [TF], IntellaNav MiFi ™ OI [MiFi], QDOT MICRO™ [QDOT]), a cross-sectional analysis of the lesion size and surface lesion type of 10g/40W lesions with a combination of various ablation times was performed in protocol 1. A longitudinal analysis (combination of various powers [30, 40, and 50W] and various ablation times with a 10g setting) was performed to investigate the influence of the auto-regulated irrigation system (QDOT) on lesion formation in protocol 2. RESULTS: The lesion formation with the QDOT catheter tended to create larger ablation lesions, while that with the TF catheter created smaller lesions than the other catheters. The lesion surface characteristics were divided into two patterns: ring (MiFi catheter and QDOT) and crescent (TF) patterns. The auto-regulated irrigation system did not influence the lesion formation, and the relationship between the lesion formation and RF energy exhibited similar changes regardless of the ablation power setting. CONCLUSION: The lesion formation and lesion surface characteristics differed among the different irrigation tip designs. An auto-regulated irrigation system did not affect the lesion creation or surface lesion characteristics. Care should be given to the inter-product differences in the lesion characteristics during RF catheter ablation, partly due to the irrigation flow control and tip design.

Initial results of transcatheter modification of left atrial appendage by obliteration with device in patients with nonvalvular atrial fibrillation: Real-world data from the TERMINATOR registry.

BACKGROUND: Percutaneous left atrial appendage closure (LAAC) has increased for those who need alternative to long-term anticoagulation with non-valvular atrial fibrillation (NVAF). METHODS AND RESULTS: From September 2019, after initiating WATCHMAN (Boston Scientific, Maple Grove, MN, USA) device implantation, we established Transcatheter Modification of Left Atrial Appendage by Obliteration with Device in Patients from the NVAF (TERMINATOR) registry. Utilizing 729 patients' data until January 2022, we analyzed percutaneous LAAC data regarding this real-world multicenter prospective registry. A total of 729 patients were enrolled. Average age was 74.9 years and 28.5 % were female. Paroxysmal AF was 37.9 % with average CHADS2 3.2, CHA2DS2-VASc 4.7, and HAS-BLED score of 3.4. WATCHMAN implantation was successful in 99.0 %. All-cause deaths were 3.2 %, and 1.2 % cardiovascular or unexplained deaths occurred during follow-up [median 222, interquartile range (IQR: 93-464) days]. Stroke occurred in 2.2 %, and the composite endpoint which included cardiovascular or unexplained death, stroke, and systemic embolism were counted as 3.4 % [median 221, (IQR: 93-464) days]. Major bleeding defined as BARC type 3 or 5 was seen in 3.7 %, and there was 8.6 % of all bleeding events in total [median 219, (IQR: 93-464) days]. CONCLUSIONS: These preliminary data demonstrated percutaneous LAAC with WATCHMAN device might have a potential to reduce stroke and bleeding events for patients with NVAF. Further investigation is mandatory to confirm the long-term results of this strategy using this transcatheter local therapy instead of life-long systemic anticoagulation.

Recurrent episodes of atrioventricular nodal reentrant tachycardia: Sites of ablation success, ablation endpoint, and primary culprits for recurrence.

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) sometimes recurs even after anatomical slow pathway (SP) ablation targeting the rightward inferior extension (RIE). This multicenter study aimed to determine the reasons for AVNRT recurrence. Methods and Results: Forty-six patients were treated successfully for recurrent AVNRT. Initial treatment was for 38 slow-fast AVNRTs, 3 fast-slow AVNRTs, 2 slow-slow AVNRTs, 2 slow-fast and fast-slow AVNRTs, and 1 noninducible AVNRT. All initial treatments were of RF application to the RIE; SP elimination was achieved in 11, dual AVN physiology was seen in 29, and AVNRT remained inducible in 5. The recurrent AVNRTs included 34 slow-fast AVNRTs, 6 fast-slow AVNRTs, 3 slow-slow AVNRTs, 2 slow-fast and fast-slow AVNRTs, and 1 slow-fast and slow-slow AVNRTs. Successful ablation site was within the RIE in 39 and left inferior extension in 7. In 30 of 39, the successful RIE site was in the same area or higher than that of the initial procedure. Conclusion: For a high majority (around 85%) of patients in whom AVNRT recurs after initial ablation success, the site of a second successful procedure will be within the RIE even though the RIE was originally targeted. Furthermore, a high majority (around 86%) of sites of successful ablation will be higher than those originally targeted.

Subcutaneous ICDs implantation following removal of normally functioning non-infected transvenous ICDs in two young patients.

In young patients with transvenous implantable cardioverter defibrillations (TV-ICDs), the possibility of device infection or lead fracture would be high in their long lifetimes. Furthermore, the risk of lead removal will gradually increase over the years. We reported two cases of subcutaneous ICDs implantation following removal of TV-ICDs. Patient 1, 35-year-old man, underwent TV-ICD implantation 9 years ago for idiopathic ventricular fibrillation, and Patient 2, 46-year-old man, underwent TV-ICD implantation 8 years ago for asymptomatic Brugada syndrome. In both cases, the electrical performance was stable, and there was no incidence of arrythmia or no pacing demand during the follow-up duration. Considering future risk of device infection or lead fracture, and difficulty in future lead removal, TV-ICDs were removed with sufficient informed consent, and then, subcutaneous ICDs (S-ICDs) implantation were performed as an alternative to them. Although indication of the TV-ICD removal should be carefully considered in individual cases, long-term risks leaving it in place should be also considered in the management of young patient. Learning objective: In young patient with TV-ICD, even for a normally functioning non-infected lead, S-ICD implantation following removal of the TV-ICD would represent a strategy associated with less long-term risks than leaving it in place.

Acute Effect of Atrial Fibrillation on Circulating Natriuretic Peptides: The Influence of Heart Rate, Rhythm Irregularity, and Left Atrial Pressure Overload.

Plasma natriuretic peptides (NPs) are increased in patients with atrial fibrillation (AF) compared with the patients with sinus rhythm. This study investigated whether this phenomenon is intrinsic to heart rhythm irregularity and independent of the heart rate and left atrial pressure (LAP) overload. We investigated 46 patients (age: 59 ± 10 years, male gender: 77%) with non-valvular paroxysmal AF who were scheduled for catheter ablation and had documented stable sinus rhythm for at least 18 hours before the procedure. All patients underwent direct measurement of right atrial pressure and LAP, simultaneously with assessment of plasma B-type NP, N-terminal pro-brain NP, and mid-regional pro-atrial NP. The baseline measurement was followed by induction of AF by rapid atrial pacing in the first 24 patients and by regular pacing from the coronary sinus at 100/min (corresponding to the mean heart rate during induced AF) in the latter 22 patients. Hemodynamic assessment and blood sampling were repeated after 20 min of the ongoing AF or fast regular paging. The baseline characteristics and hemodynamic measurements were comparable between study groups; however, patients in the regular atrial pacing group had a higher body mass index and a larger left atrial diameter compared with the induced AF group. Plasma levels of all 3 NPs increased significantly during induced AF but not during fast regular pacing, and the increase of NPs was independent of right atrial pressure and LAP. Baseline concentrations of NPs and heart rhythm irregularity were the only independent predictors of increased NPs.

Efficacy of SubcutAneous implantable cardioVErter-defibrillators in ≤18 year-old CHILDREN: SAVE-CHILDREN registry.

BACKGROUND: In adult patients, subcutaneous implantable cardioverter defibrillators (S-ICDs) have been reported to be non-inferior to transvenous ICDs with respect to the incidence of device-related complications and inappropriate shocks. Only a few reports have investigated the efficacy of S-ICDs in the pediatric field. This study aimed to investigate the utility and safety of S-ICDs in patients ≤18 years old. METHODS: This study was a multicenter, observational, retrospective study on S-ICD implantations. Patients <18 years old who underwent S-ICD implantations were enrolled. The detailed data on the device implantations and eligibility tests, incidence of appropriate- and inappropriate shocks, and follow-up data were assessed. RESULTS: A total of 62 patients were enrolled from 30 centers. The patients ranged in age from 3 to 18 (median 14 years old [IQR 11.0-16.0 years]). During a median follow up of 27 months (13.3-35.8), a total of 16 patients (26.2%) received appropriate shocks and 13 (21.3%) received inappropriate shocks. The common causes of the inappropriate shocks were sinus tachycardia (n = 4, 30.8%) and T-wave oversensing (n = 4, 30.8%). In spite of the physical growth, the number of suitable sensing vectors did not change during the follow up. No one had any lead fractures or device infections in the chronic phase. CONCLUSIONS: Our study suggested that S-ICDs can prevent sudden cardiac death in the pediatric population with a low incidence of lead complications or device infections. The number of suitable sensing vectors did not change during the patients' growth.