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Introduction: We investigated whether pacing-induced electrical dyssynchrony at the time of cardiac resynchronization therapy (CRT) device implantation was associated with chronic CRT response. Methods and Results: We included a total of 69 consecutive heart failure patients who received a CRT device. Left (LVp-RVs) and right (RVp-LVs) pacing-induced interlead delays were measured intraoperatively and used to determine if there was paced left ventricular (LV) dyssynchrony, defined as present when LVp-RVs is larger than RVp-LVs. CRT response was defined as a reduction in LV end-systolic volume ≥15%, 6 months after implantation. Paced left ventricular dyssynchrony (PLVD) was associated with ischemic cardiomyopathy (ICM) (χ 2: 8; P =.005) but not with QRS morphology nor with pacing lead positions. In a univariate analysis, PLVD (odds ratio [OR], 6.53; 95% confidence interval [CI], 2.2-18.9; P =.001), atypical left bundle branch block (LBBB) (OR, 3.3; 95% CI, 1.2-9.4; P =.022), and ICM (OR, 5.2; 95% CI, 1.6-17; P =.006) were associated with nonresponse. In a multivariate analysis, both PLVD (OR, 9.74; 95% CI, 2.8-33.9; P 2 to enter: 8; P

Background: Optimal timing of the atrioventricular delay in cardiac resynchronization therapy (CRT) can improve synchrony in patients suffering from heart failure. The purpose of this study was to evaluate the impact of SyncAV™ on electrical synchrony as measured by vectorcardiography (VCG) derived QRS metrics during bi-ventricular (BiV) pacing. Methods: Patients implanted with a cardiac resynchronization therapy (CRT) device and quadripolar left ventricular (LV) lead underwent 12‑lead ECG recordings. VCG metrics, including QRS duration (QRSd) and area, were derived from the ECG by a blinded observer during: intrinsic conduction, BiV with nominal atrioventricular delays (BiV Nominal), and BiV with SyncAV programmed to the optimal offset achieving maximal synchronization (BiV + SyncAV Opt). Results: One hundred patients (71% male, 40% ischemic, 65% LBBB, 32 ± 9% ejection fraction) completed VCG assessment. QRSd during intrinsic conduction (166 ± 25 ms) was narrowed successively by BiV Nominal (137 ± 23 ms, p

Background Temporary transvenous pacing in critically ill patients requiring prolonged cardiac pacing is associated with a high risk of complications. We sought to evaluate the safety and efficacy of self-contained intracardiac leadless pacemaker (LPM) implantation in this population. Methods and results Consecutive patients implanted with a Micra LPM during the hospitalization in an intensive care unit were retrospectively included. Inclusion criteria were: ≥1 supracaval central venous, or a ventilation tube, or intravenous antibiotic therapy for ongoing sepsis or bacteremia. Patients with a history of previous implantation of a pacemaker were excluded. Out of 1,016 patients implanted with an LPM, 99 met the inclusion criteria. Mean age was 75 years and Charlson comorbidity index 7. LPM implantation was successfully performed in 98% of cases, with a peri-operative complication rate of 5%, mainly cardiac injuries. In-hospital mortality rate was 6%. No late (>30 days) device-related complication occurred, especially no infection. Conclusions LPM appears as an acceptable alternative to conventional temporary transvenous pacing in selected critically ill patients requiring prolonged cardiac pacing, especially regarding the risk of infection. This article is protected by copyright. All rights reserved.

INTRODUCTION: MARVEL 2 assessed the efficacy of mechanical atrial sensing by a ventricular leadless pacemaker, enabling a VDD pacing mode. The behavior of the enhanced MARVEL 2 algorithm during variable atrio-ventricular conduction (AVC) and/or arrhythmias has not been characterized and is the focus of this study. METHODS: Of the 75 patients enrolled in the MARVEL 2 study, 73 had a rhythm assessment and were included in the analysis. The enhanced MARVEL 2 algorithm included a mode-switching algorithm that automatically switches between VDD and ventricular only antibradycardia pacing (VVI)-40 depending upon AVC status. RESULTS: Forty-two patients (58%) had persistent third degree AV block (AVB), 18 (25%) had 1:1 AVC, 5 (7%) had variable AVC status, and 8 (11%) had atrial arrhythmias. Among the 42 patients with persistent third degree AVB, the median ventricular pacing (VP) percentage was 99.9% compared to 0.2% among those with 1:1 AVC. As AVC status changed, the algorithm switched to VDD when the ventricular rate dropped less than 40 bpm. During atrial fibrillation (AF) with ventricular response greater than 40 bpm, VVI-40 mode was maintained. No pauses longer than 1500 ms were observed. Frequent ventricular premature beats reduced the percentage of AV synchrony. During AF, the atrial signal was of low amplitude and there was infrequent sensing. CONCLUSION: The mode switching algorithm reduced VP in patients with 1:1 AVC and appropriately switched to VDD during AV block. No pacing safety issues were observed during arrhythmias. ispartof: JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY vol:32 issue:7 pages:1947-1957 ispartof: location:United States status: published

International audience; Background:Frequency and distribution of left ventricular (LV) venous collaterals were studied in vivo to evaluate the ease and feasibility of implanting a new ultra-thin LV quadripolar microlead for cardiac resynchronization therapy (CRT).Methods and Results:Evaluable venograms were analyzed to define the prevalence of venous collaterals (>0.5 mm diameter) between: (1) different LV segments; and (2) different major LV veins in: unselected patients who underwent CRT from 2008 to 2012 at Rouen Hospital, France (retrospective); and CRT patients from the Axone Acute pilot study in 2018 (prospective). In prospective patients with evaluable venograms, LV microlead implantation was attempted. Thirty-six (21/65 retrospective, 15/20 prospective) patients had evaluable venograms with ≥1 visible venous collaterals. Collaterals were found between LV veins in all CRT patients with evaluable venograms. Regionally, prevalence was highest between: the apical inferior and apical lateral (42%); and mid inferior and mid inferolateral (42%) segments. Collateral connections were most prevalent between: the inferior interventricular vein (IIV) and lateral vein (64% [23/36]); and IIV and infero-lateral vein (36% [13/36]). Cross-vein microlead implantation was possible in 18 patients (90%), and single-vein implantation was conducted in the other 2 patients (10%).Conclusions:Venous collaterals were found in vivo between LV veins in all CRT patients with evaluable venograms, making this network an option for accessing multiple LV sites using a single LV microlead.

BACKGROUND: The MARVEL (Micra Atrial TRacking Using a Ventricular AccELerometer) 2 study assessed the efficacy of atrioventricular (AV) synchronous pacing with a Micra leadless pacemaker. Average atrioventricular synchrony (AVS) was 89.2%. Previously, low amplitude of the Micra-sensed atrial signal (A4) was observed to be a factor of low AVS. OBJECTIVE: The purpose of this study was to identify predictors of A4 amplitude and high AVS. METHODS: We analyzed 64 patients enrolled in MARVEL 2 who had visible P waves on electrocardiogram for assessing A4 amplitude and 40 patients with third-degree AV block for assessing AVS at rest. High AVS was defined as >90% correct atrial-triggered ventricular pacing. The association between clinical factors and echocardiographic parameters with A4 amplitude was investigated using a multivariable model with lasso variable selection. Variables associated with A4 amplitude together with premature ventricular contraction burden, sinus rate, and sinus rate variability (standard deviation of successive differences of P-P intervals [SDSD]) were assessed for association with AVS. RESULTS: In univariate analysis, low A4 amplitude was inversely related to atrial function assessed by E/A ratio and e'/a' ratio, and was directly related to atrial contraction excursion (ACE) and atrial strain (Ɛa) on echocardiography (all P ≤.05). The multivariable lasso regression model found coronary artery bypass graft history, E/A ratio, ACE, and Ɛa were associated with low A4 amplitude. E/A ratio and SDSD were multivariable predictors of high AVS, with >90% probability if E/A

Contains fulltext : 220908.pdf (Publisher’s version ) (Closed access) BACKGROUND: Morphology algorithms are currently recommended as a standalone discriminator in single-chamber implantable cardioverter defibrillators (ICDs). However, these proprietary algorithms differ in both design and nominal programming. OBJECTIVE: To compare three different algorithms with nominal versus advanced programming in their ability to discriminate between ventricular (VT) and supraventricular tachycardia (SVT). METHODS: In nine European centers, VT and SVTs were collected from Abbott, Boston Scientific, and Medtronic dual- and triple-chamber ICDs via their respective remote monitoring portals. Percentage morphology matches were recorded for selected episodes which were classified as VT or SVT by means of atrioventricular comparison. The sensitivity and related specificity of each manufacturer discriminator was determined at various values of template match percentage from receiving operating characteristics (ROC) curve analysis. RESULTS: A total of 534 episodes were retained for the analysis. In ROC analyses, Abbott Far Field MD (area under the curve [AUC]: 0.91; P < .001) and Boston Scientific RhythmID (AUC: 0.95; P < .001) show higher AUC than Medtronic Wavelet (AUC: 0.81; P < .001) when tested for their ability to discriminate VT from SVT. At nominal % match threshold all devices provided high sensitivity in VT identification, (91%, 100%, and 90%, respectively, for Abbott, Boston Scientific, and Medtronic) but contrasted specificities in SVT discrimination (85%, 41%, and 62%, respectively). Abbott and Medtronic's nominal thresholds were similar to the optimal thresholds. Optimization of the % match threshold improved the Boston Scientific specificity to 79% without compromising the sensitivity. CONCLUSION: Proprietary morphology discriminators show important differences in their ability to discriminate SVT. How much this impact the overall discrimination process remains to be investigated.

Aims To identify independent electrocardiogram (ECG) predictors of long-term clinical outcome based on standardized analysis of the surface ECG in a large multicentre cohort of patients with sarcomeric hypertrophic cardiomyopathy (HCM). Methods and results Retrospective observational study from the REMY French HCM clinical research observatory. Primary endpoint was a composite of all-cause mortality, major non-fatal arrhythmic events, hospitalization for heart failure (HF), and stroke. Secondary endpoints were components of the primary endpoint. Uni- and multivariable Cox proportional hazard regression analysis was performed to identify independent predictors. Among 994 patients with HCM, only 1.8% had a strictly normal baseline ECG. The most prevalent abnormalities were inverted T waves (63.7%), P-wave abnormalities (30.4%), and abnormal Q waves (25.5%). During a mean follow-up of 4.0 ± 2.0 years, a total of 272 major cardiovascular events occurred in 217 patients (21.8%): death or heart transplant in 98 (9.8%), major arrhythmic events in 40 (4.0%), HF hospitalization in 115 (11.6%), and stroke in 23 (2.3%). At multivariable analysis using ECG covariates, prolonged QTc interval, low QRS voltage, and PVCs of right bundle branch block pattern predicted worse outcome, but none remained independently associated with the primary endpoint after adjustment on main demographic and clinical variables. For secondary endpoints, abnormal Q waves independently predicted all-cause death [hazard ratio (HR) 2.35, 95% confidence interval (CI) 1.23–4.47; P = 0.009] and prolonged QTc the risk of HF hospitalization (HR 1.006, 95% CI 1.001–1.011; P = 0.024). Conclusion The 12-lead surface ECG has no independent value to predict the primary outcome measure in patients with HCM. The 12-lead surface ECG has been widely used as a screening tool in HCM but its prognostic value remains poorly known. The value of baseline surface ECG to predict long-term clinical outcomes was studied in a cohort of 994 patients with sarcomeric HCM. The surface ECG has no significant additional value to predict outcome in this patient population

BACKGROUND Subcutaneous implantable cardioverter-defibrillator (S-ICD) implantations are rapidly expanding. However, the subcutaneous detection and interpretation of cardiac signals in S-ICDs is much more challenging than by conventional devices. There is a complete paradigm shift in cardiac signal sensing with subcutaneous signal detection, leading in some cases to oversensing with restricted programming options.OBJECTIVES The aim of this single-center study was to quantify and describe cases where recurring oversensing made the extraction of the device necessary.METHODS Consecutive patients (n = 108) implanted with an S-ICD in our tertiary referral hospital were considered for analysis. Clinical and remote monitoring data were analyzed.RESULTS The S-ICD had to be explanted in 6 of 108 implanted patients (5.6%) because of refractory oversensing issues: myopotential oversensing, P- or T-wave oversensing, rate-dependent left bundle branch block aberrancy during exercise with R-wave double counting, and R-wave amplitude decrease after ventricular tachycardia ablation leading to noise detection. Seventeen of 108 patients experienced oversensing (15.7%): 9 patients had at least 1 inappropriate charge without a shock (8.3%), 3 patients had at least 1 inappropriate shock (2.8%), and 5 patients had both episodes (4.6%).CONCLUSION So far, cardiologists have had to deal with transvenous ICD lead fractures, but signal oversensing without correcting programming option could be the equivalent weakness of S-ICDs, despite an adequate screening.

BACKGROUND The subcutaneous implantable cardioverter-defibrillator (S-ICD) remains a new technology requiring accurate assessment of the various aspects of its functioning. Isolated cases of delayed sensing of ventricular arrhythmia have been described. OBJECTIVE The purpose of this multicenter study was to assess the quality of sensing during induced ventricular fibrillation (VF). METHODS One hundred thirty-seven patients underwent induction of VF at the end of the S-ICD implantation. RESULTS VF induction was successful in 133 patients (97%). Mean time to first therapy was 16.2 +/- 3.1 seconds, with a substantial range from 12.5 to 27.0 seconds. Four different detection profiles were arbitrarily defined: (1) optimal detection (n = 39 [29%]); (2) undersensing with moderate prolongation of time to therapy (18 seconds; n = 19 [14%]); and (4) absence of therapy or prolonged time to therapy related to noise oversensing (n = 7 [6%]). In some of the patients in the last group, despite induction of VF the initial counter was never filled, the device did not charge the capacitors, and the shock was not delivered because of a sustained diagnosis of noise (n = 5). A manual shock by the device or an external shock had to be delivered to restore the sinus rhythm. CONCLUSION Our study demonstrated a marked sensing delay leading to prolonged time to therapy in a large number of S-ICD patients. A few worrisome cases of noise oversensing inhibiting the therapies were detected. These results support the need for systematic intraoperative defibrillation testing.

Background The natural history and long‐term outcome in pediatric patients with idiopathic ventricular fibrillation ( IVF ) are poorly characterized. We sought to define the clinical characteristics and long‐term outcomes of a pediatric cohort with an initial diagnosis of IVF . Methods and Results Patients were included from an International Registry of IVF (consisting of 496 patients). Inclusion criteria were: (1) VF with no identifiable cause following comprehensive analysis for ischemic, electrical or structural heart disease and (2) age ≤16 years. These included 54 pediatric IVF cases (age 12.7±3.7 years, 59% male) among whom 28 (52%) had a previous history of syncope (median 2 syncopal episodes [interquartile range 1]). Thirty‐six (67%) had VF in situations associated with high adrenergic tone. During a median 109±12 months of follow‐up, 31 patients (57%) had recurrence of ventricular arrhythmias, mainly VF . Two patients developed phenotypic expression of an inherited arrhythmia syndrome during follow‐up (hypertrophic cardiomyopathy and long QT syndrome, respectively). A total of 15 patients had positive genetic testing for inherited arrhythmia syndromes. Ten patients (18%) experienced device‐related complications. Three patients (6%) died, 2 due to VF storm. Conclusions In pediatric patients with IVF , a minority develop a definite clinical phenotype during long‐term follow‐up. Recurrent VF is common in this patient group.

Aims Implantable cardioverter-defibrillators (ICDs) reduce sudden cardiac death in selected patients but inappropriate ICD shocks have been associated with increased mortality. The THORN registry aims to describe the rate of inappropriate ventricular arrhythmia diagnoses and therapies in patients followed by remote monitoring, as well as the following delay to next patient contact (DNPC). Methods and results One thousand eight hundred and eighty-two patients issued from a large remote monitoring database first implanted with an ICD for primary or secondary prevention in 110 French hospitals from 2007 to 2014 constitute the THORN population. Among them, 504 patients were additionally followed prospectively for evaluation of the DNPC. Eight hundred and ninety-five out of 1551 (58%) patients had ischaemic heart disease and 358/771 (46%) were implanted for secondary prevention. During 13.7 ± 3.4 months of follow-up, the prevalence of first inappropriate diagnosis in a ventricular arrhythmia zone with enabled therapy was 162/1882 (9%). Among those patients, 122/162 (75%) suffered at least one inappropriate therapy and 58/162 (36%) at least one inappropriate shock. Eighty-three out of 162 (51%) of first inappropriate diagnosis occurred during the first 4 months following implantation. The median DNPC was 8 days (interquartile range 1–26). At least one other day with recording of an inappropriate diagnosis of the same cause occurred in 13/43 (30%) of available DNPC periods, with an inappropriate therapy in 7/13 (54%). Conclusion Inappropriate diagnoses occurred in 9% of patients implanted with an ICD during the first 14 months. The DNPC after inadequate ventricular arrhythmia diagnoses remains long in daily practice and should be optimized. ClinicalTrials.gov Identifier NCT01594112.

Introduction Some cardiac resynchronization therapy (CRT) device manufacturers (Biotronik, Germany; Boston Scientific, United States) have implemented left ventricular (LV) sensing functionality to prevent pacing into the vulnerable phase. Physicians are only partially aware of programming pitfalls related to LV sensing and general programming advice is lacking. Methods and results We provide an illustrative case-series-based review of the variety of potential problems with LV sensing. LV sensing may inappropriately impair CRT delivery due to LV-sensing issues or improper device programming. This can cause beat-wise loss of resynchronization but also ongoing desynchronization. On the other hand, LV sensing provides additional diagnostic information, which may reveal intermittent problems of the LV lead such as capture loss. We summarize the available evidence to provide manufacturer-specific recommendations on device programming and troubleshooting for daily clinical practice. Conclusion CRT devices with LV sensing may suffer from impaired resynchronization due to programming pitfalls. If LV sensing is active (nominal setting in Biotronik and Boston Scientific devices), careful lookout for related problems and resynchronization percentage is required. Optimization is mandatory and even deactivation of LV sensing may have to be considered.

Background Patient-specific programming of cardiac resynchronization therapy (CRT) is often neglected, despite significant nonresponse rates. The device-based SyncAV CRT algorithm dynamically adjusts atrioventricular delays to the intrinsic AV interval, reduced by a programmable offset, to accommodate each patient's changing needs. Objective The purpose of this study was to evaluate the acute effect of biventricular (BiV) pacing enhanced by SyncAV on electrical synchrony in a broad patient population. Methods Patients with existing CRT implants were prospectively evaluated at 5 international centers. Blinded 12-lead electrocardiographic QRS duration (QRSd) measurements were used to compare intrinsic conduction with nominal BiV pacing, BiV + SyncAV (default 50 ms offset), and BiV + SyncAV (optimized, patient-specific offset). BiV configurations were tested twice using the latest activating and earliest activating left ventricular (LV) electrodes as cathodes. Results Ninety patients (mean age 67.1 ± 9.5 years; 67 (74%) men; 55 (63%) with left bundle branch block; 37 (43%) with ischemic cardiomyopathy; LV ejection fraction 32% ± 9%) with intact atrioventricular conduction (PR interval 195 ± 45 ms) were enrolled. With BiV pacing from the latest activating LV electrode, the intrinsic QRSd of 155 ± 29 ms was reduced by 9% ± 20% to 138 ± 27 ms using traditional BiV pacing and by 13% ± 14% to 133 ± 25 ms using BiV + SyncAV (50 ms offset). The maximal QRSd reduction by 20% ± 10% to 123 ± 22 ms was achieved by BiV + SyncAV with an optimized offset. Similar QRSd reductions were observed with BiV pacing from the earliest activating LV electrode across all settings. Of all baseline characteristics, intrinsic QRSd was the only significant predictor of QRSd reduction magnitude. Conclusion SyncAV improved acute electrical synchrony beyond conventional CRT, particularly with patient-specific optimization. The degree of synchrony restored was contingent on intrinsic QRSd, but not limited by other baseline characteristics or by the LV pacing electrode used.

Key Teaching Points • Current pacing guidelines recognize VDD pacing systems as an alternative to DDD pacemakers among patients with high-degree atrioventricular (AV) block. • The Micra Atrial TRacking Using a Ventricular AccELerometer (MARVEL) study has recently shown that an AV synchronous pacing mode is feasible using a single-chamber ventricular leadless pacemaker. • We present a first-in-human description of an episode of paroxysmal atrial fibrillation in an “AV synchronous ventricular leadless pacemaker.”

BACKGROUND: Early results of the Micra Investigational Device Exemption (IDE) study and Micra Post-Approval Registry (PAR) demonstrated excellent safety and efficacy performance; however, intermediate-term results across a large patient population in the real-world setting have not been evaluated. OBJECTIVES: We report updated performance of the Micra transcatheter pacemaker from a worldwide PAR and compare it with the IDE study as well as a transvenous historical control. METHODS: The safety objective of the analysis was system- or procedure-related major complications through 12 months postimplantation. We compared the major complication rate with that of the 726 patients from the IDE and with a reference data set of 2667 patients with transvenous pacemakers by using a Fine-Gray competing risk model. RESULTS: The Micra device was successfully implanted in 1801 of 1817 patients (99.1%). The mean follow-up period was 6.8 ± 6.9 months. Through 12 months, the major complication rate was 2.7% (95% confidence interval [CI] 2.0%-3.7%). The risk of major complications for Micra PAR patients was 63% lower than that for patients with transvenous pacemakers through 12 months postimplantation (hazard ratio 0.37; 95% CI 0.27-0.52; P < .001). The major complication rate trended lower in the PAR than in the IDE study (hazard ratio 0.71; 95% CI 0.44-1.1; P = .160), driven by the lower pericardial effusion rate in the PAR. There were 3 cases of infection associated with the procedure, but none required device removal and there were no battery or telemetry issues. Pacing thresholds were low and stable through 12 months postimplantation. CONCLUSION: Performance of the Micra transcatheter pacemaker in international clinical practice remains consistent with previously reported data. Major complications were infrequent and occurred 63% less often compared to transvenous systems. CLINICAL TRIAL REGISTRATION: Micra Transcatheter Pacing System Post-Approval Registry ClinicalTrials.gov identifier: NCT02536118; Micra Transcatheter Pacing Study ClinicalTrials.gov identifier: NCT02004873. ispartof: HEART RHYTHM vol:15 issue:12 pages:1800-1807 ispartof: location:United States status: published

Background In Boston Scientific dual-chamber devices, the RYTHMIQ algorithm aims to minimize right ventricular pacing. Objective We evaluated the performance of this algorithm determining (1) the appropriateness of the switch from the AAI(R) mode with backup VVI pacing to the DDD(R) mode in case of suspected loss of atrioventricular (AV) conduction and (2) the rate of recorded pacemaker-mediated tachycardia (PMT) when AV hysteresis searches for restored AV conduction. Methods In this multicenter study, we included 157 patients with a Boston Scientific dual-chamber device (40 pacemakers and 117 implantable cardioverter-defibrillators) without permanent AV conduction disorder and with the RYTHMIQ algorithm activated. We reviewed the last 10 remote monitoring–transmitted RYTHMIQ and PMT episodes. Results We analyzed 1266 episodes of switch in 142 patients (90%): 207 (16%) were appropriate and corresponded to loss of AV conduction, and 1059 (84%) were inappropriate, of which 701 (66%) were related to compensatory pause (premature atrial contraction, 7%; premature ventricular contraction, 597 (56%); or both, 27 (3%)) or to a premature ventricular contraction falling in the post-atrial pacing ventricular refractory period interval (219, 21%) and 94 (10%) were related to pacemaker dysfunction. One hundred fifty-four PMT episodes were diagnosed in 27 patients (17%). In 85 (69%) of correctly diagnosed episodes, the onset of PMT was directly related to the algorithm-related prolongation of the AV delay, promoting AV dissociation and retrograde conduction. Conclusion This study highlights some of the limitations of the RYTHMIQ algorithm: high rate of inappropriate switch and high rate of induction of PMT. This may have clinical implications in terms of selection of patients and may suggest required changes in the algorithm architecture.

Supplemental Digital Content is available in the text., Background: Sudden cardiac death because of ventricular fibrillation (VF) is commonly unexplained in younger victims. Detailed electrophysiological mapping in such patients has not been reported. Methods: We evaluated 24 patients (29±13 years) who survived idiopathic VF. First, we used multielectrode body surface recordings to identify the drivers maintaining VF. Then, we analyzed electrograms in the driver regions using endocardial and epicardial catheter mapping during sinus rhythm. Established electrogram criteria were used to identify the presence of structural alterations. Results: VF occurred spontaneously in 3 patients and was induced in 16, whereas VF was noninducible in 5. VF mapping demonstrated reentrant and focal activities (87% versus 13%, respectively) in all. The activities were dominant in one ventricle in 9 patients, whereas they had biventricular distribution in others. During sinus rhythm areas of abnormal electrograms were identified in 15/24 patients (62.5%) revealing localized structural alterations: in the right ventricle in 11, the left ventricle in 1, and both in 3. They covered a limited surface (13±6 cm2) representing 5±3% of the total surface and were recorded predominantly on the epicardium. Seventy-six percent of these areas were colocated with VF drivers (P

Background: The predictive value of interventricular versus intraventricular dyssynchrony for response to cardiac resynchronization therapy (CRT) remains unclear. We investigated the relative importance of both ventricular electrical substrate components for left ventricular (LV) hemodynamic function. Methods and Results: First, we used the cardiovascular computational model CircAdapt to characterize the isolated effect of intrinsic interventricular and intraventricular activation on CRT response (ΔLVdP/dt max ). Simulated ΔLVdP/dt max (range: 1.3%–26.5%) increased considerably with increasing interventricular dyssynchrony. In contrast, the isolated effect of intraventricular dyssynchrony in either the LV or right ventricle was limited (ΔLVdP/dt max range: 12.3%–18.3% and 14.1%–15.7%, respectively). Effects of activation during biventricular pacing on ΔLVdP/dt max were small. Second, electrocardiographic imaging–derived activation characteristics of 51 CRT candidates were used to personalize ventricular activation in CircAdapt. The individualized models were subsequently used to assess the accuracy of ΔLVdP/dt max prediction based on the electrical data. The model-predicted ΔLVdP/dt max was close to the actual value in patients with left bundle branch block (measured−simulated: 2.7±9.0%) when only intrinsic interventricular dyssynchrony was personalized. Among patients without left bundle branch block, ΔLVdP/dt max was systematically overpredicted by CircAdapt (measured−simulated: 9.2±7.1%). Adding intraventricular activation to the model did not improve the accuracy of the response prediction. Conclusions: Computer simulations revealed that intrinsic interventricular dyssynchrony is the dominant component of the electrical substrate driving the response to CRT. Intrinsic intraventricular dyssynchrony and any dyssynchrony during biventricular pacing play a minor role in this respect. This may facilitate patient-specific modeling for prediction of CRT response. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01270646.

International audience; Objectives - The aim of this study was to identify using implantable loop recorder (ILR) monitoring the mechanisms leading to sudden death (SD) in patients undergoing hemodialysis (HD). Background - SD accounts for 11% to 25% of death in HD patients. Methods - Continuous rhythm monitoring was performed using the remote monitoring capability of the ILR device in patients undergoing HD at 8 centers. Clinical, biological, and technical HD parameters were recorded and analyzed. Results - Seventy-one patients (mean age 65 ± 9 years, 73% men) were included. Left ventricular ejection fraction was 5.0 mmol/l, bicarbonate 11.5 g/dl, pre-HD systolic blood pressure >140 mm Hg, the longer interdialytic period, history of coronary artery disease, previous other arrhythmias, and diabetes mellitus. A higher risk for ventricular arrhythmia was associated with potassium

Background The SecureSense right ventricular (RV) lead noise discrimination algorithm is designed to detect lead fracture and other types of oversensing in order to decrease inappropriate therapy. Objective We studied the real-life accuracy of the SecureSense algorithm in implantable cardioverter-defibrillator (ICD) patients followed by remote monitoring across multiple centers. Methods Across 3 French centers, we studied 486 patients with a St Jude Medical device who were followed by remote monitoring and who had the SecureSense algorithm activated. We reviewed ≤10 of the most recent remote monitoring–transmitted electrograms of nonsustained oversensing, RV lead noise, and ventricular tachycardia/ventricular fibrillation that received therapy. Results SecureSense inhibited 22 inappropriate therapies (lead dysfunction in 10 cases, P-wave oversensing in 12 cases). A total of 57 patients (12%) sent ≥1 nonsustained oversensing episode (total of 393 episodes) with multiple etiologies: noise on the near-field channel (38%), oversensing of T waves during ventricular pacing (33%), oversensing of the sinus P wave (12%), and oversensing of the paced P wave (6%). Two episodes (0.5%) of nonsustained VT were undersensed by the far-field channel. Of 336 analyzed episodes of ventricular tachyarrhythmia, 15 episodes (4%) in 4 patients were related to oversensing of intrinsic P waves in 11 episodes or oversensing of external noise due to electrical cautery for the remaining 4 episodes. Conclusion Of ICD patients equipped with SecureSense, 12% developed episodes of oversensing. The SecureSense algorithm prevented inappropriate ICD therapies with accurate diagnosis of oversensing (caused by lead dysfunction or oversensing of physiological signals). P-wave oversensing in integrated bipolar leads, electrical cautery, and electromagnetic interference are prone to be missed by SecureSense.

International audience; T he deleterious impact of abnormal left ventricular (LV) activation in heart failure (HF) is well established. 1 Cardiac resynchronization therapy (CRT) represents a highly effective intervention in selected patients with HF and abnormal LV activation. The QRS pattern emerged as a more specific selection criterion in the latest American Heart Association (AHA)/European Heart Rhythm Association guidelines. These recommendations are based on multiple subgroup analyses demonstrating a clear benefit to CRT depending on the preim-plantation QRS pattern. 2-4 Therefore, patients with baseline left bundle branch block (LBBB) have a class I indication for CRT implantation and represent the best responders to CRT. Patients with narrow QRS currently have a class III indication for CRT as a result of large trial, demonstrating that CRT has a neutral or deleterious effect in this group of patients. 5-8 In patients with nonspecific intraventricular conduction delay (NICD), the guidelines are less clear, with a class IIa or IIb indication depending on the QRS duration. These patients represent a more heterogeneous group that is not clearly characterized. Its definition wide QRS without the appearance of left or right bundle block corresponds to a definition by default. Results obtained after CRT include only small numbers of patients, with no dedicated randomized studies. 9-11 The electrophysiological mechanisms of lack of response in narrow QRS and NICD are not well understood. The use of a more detailed electric activation map rather than QRS analysis could significantly enhance our understanding of the electric activation sequence in HF patients, especially in narrow QRS and NICD patients and, therefore, refine selection criteria for CRT. Original Article Background-In contrast to patients with left bundle branch block (LBBB), heart failure patients with narrow QRS and nonspecific intraventricular conduction delay (NICD) display a relatively limited response to cardiac resynchronization therapy. We sought to compare left ventricular (LV) activation patterns in heart failure patients with narrow QRS and NICD to patients with LBBB using high-density electroanatomic activation maps. Methods and Results-Fifty-two heart failure patients (narrow QRS [n=18], LBBB [n=11], NICD [n=23]) underwent 3-dimensional electroanatomic mapping with a high density of mapping points (387±349 LV). Adjunctive scar imaging was available in 37 (71%) patients and was analyzed in relation to activation maps. LBBB patients typically demonstrated (1) a single LV breakthrough at the septum (38±15 ms post-QRS onset); (2) prolonged right-to-left transseptal activation with absence of direct LV Purkinje activity; (3) homogeneous propagation within the LV cavity; and (4) latest activation at the basal lateral LV. In comparison, both NICD and narrow QRS patients demonstrated (1) multiple LV breakthroughs along the posterior or anterior fascicles: narrow QRS versus LBBB, 5±2 versus 1±1; P=0.0004; NICD versus LBBB, 4±2 versus 1±1; P=0.001); (2) evidence of early/pre-QRS LV electrograms with Purkinje potentials; (3) rapid propagation in narrow QRS patients and more heterogeneous propagation in NICD patients; and (4) presence of limited areas of late activation associated with LV scar with high interindividual heterogeneity. Conclusions-In contrast to LBBB patients, narrow QRS and NICD patients are characterized by distinct mechanisms of LV activation, which may predict poor response to cardiac resynchronization therapy.

The efficacy of biventricular (BiV) pacing in patients with a narrow or moderately prolonged QRS duration remains questionable.To assess the hypothesis that electrical dyssynchrony is required to obtain hemodynamic benefit from BiV pacing by investigating the relationship between intrinsic QRS duration and hemodynamic response to BiV pacing in a patient population covering a broad spectrum of QRS duration.Eighty-two consecutive heart failure patients underwent cardiac resynchronization therapy implantation irrespective of their QRS duration. Thirty-four patients had a narrow QRS duration (120 ms), whereas 11 patients had a moderately prolonged QRS duration (≥120 to150 ms) and 37 patients had a severely prolonged QRS duration (≥150 ms). After implantation, invasive left ventricular (LV) dP/dt measurements were compared between intrinsic rhythm and simultaneous BiV pacing with an optimized atrioventricular delay.A high correlation (r = .65; P.001) was observed between baseline QRS duration and changes in LV dP/dt(max) induced by BiV pacing. BiV pacing was ineffective in patients with a narrow QRS duration (+0.4% ± 6.1%; P = ns). No significant increase in LV dP/dt(max) was observed in patients with a QRS duration of ≥120 to150 ms (+4.4% ± 6.9%; P = .06), whereas patients with a QRS duration of ≥150 ms exhibited a significant increase in LV dP/dt(max) (+17.1% ± 13.4%; P.001). Only 9% of the patients with a narrow QRS duration exhibited a ≥10% increase in LV dP/dt(max).Baseline QRS duration is linearly related to acute hemodynamic response to BiV pacing. Patients with a narrow QRS duration do not derive hemodynamic improvement. This improvement is also limited in patients with a moderately prolonged QRS duration, raising questions about the potential clinical benefit of this therapy in these patients.

International audience; Background - The early repolarization (ER) pattern is associated with an increased risk of arrhythmogenic sudden death. However, strategies for risk stratification of patients with the ER pattern are not fully defined. Objectives - This study sought to determine the role of electrophysiology studies (EPS) in risk stratification of patients with ER syndrome. Methods - In a multicenter study, 81 patients with ER syndrome (age 36 ± 13 years, 60 males) and aborted sudden death due to ventricular fibrillation (VF) were included. EPS were performed following the index VF episode using a standard protocol. Inducibility was defined by the provocation of sustained VF. Patients were followed up by serial implantable cardioverter-defibrillator interrogations. Results - Despite a recent history of aborted sudden death, VF was inducible in only 18 of 81 (22%) patients. During follow-up of 7.0 ± 4.9 years, 6 of 18 (33%) patients with inducible VF during EPS experienced VF recurrences, whereas 21 of 63 (33%) patients who were noninducible experienced recurrent VF (p = 0.93). VF storm occurred in 3 patients from the inducible VF group and in 4 patients in the noninducible group. VF inducibility was not associated with maximum J-wave amplitude (VF inducible vs. VF noninducible; 0.23 ± 0.11 mV vs. 0.21 ± 0.11 mV; p = 0.42) or J-wave distribution (inferior, odds ratio [OR]: 0.96 [95% confidence interval (CI): 0.33 to 2.81]; p = 0.95; lateral, OR: 1.57 [95% CI: 0.35 to 7.04]; p = 0.56; inferior and lateral, OR: 0.83 [95% CI: 0.27 to 2.55]; p = 0.74), which have previously been demonstrated to predict outcome in patients with an ER pattern. Conclusions - Our findings indicate that current programmed stimulation protocols do not enhance risk stratification in ER syndrome.

BACKGROUND Left bundle branch block (LBBB) leads to prolonged left ventricular (LV) total activation time (TAT) and ventricular electrical uncoupling (VEU; mean LV activation time minus mean right ventricular [RV] activation time); both have been shown to be preferential targets for cardiac resynchronization therapy (CRT). Whether right ventricular apical pacing (RVAP) produces similar ventricular activation patterns has not been well studied. OBJECTIVE The purpose of this study was to compare electrical ventricular activation patterns during RVAP and LBBB. METHODS We performed ECG mapping during sinus rhythm, RVAP, and CRT in 24 patients with LBBB. RESULTS We observed differences in the electrical activation pattern with RVAP compared to LBBB. During LBBB, RV activation occurred rapidly; in contrast, RV activation was prolonged during RVAP (46 +/- 21 ms vs 69 +/- 17 ms, P

Aims Permanent cardiac pacing is the only effective treatment for symptomatic bradycardia, but complications associated with conventional transvenous pacing systems are commonly related to the pacing lead and pocket. We describe the early performance of a novel self-contained miniaturized pacemaker. Methods and results Patients having Class I or II indication for VVI pacing underwent implantation of a Micra transcatheter pacing system, from the femoral vein and fixated in the right ventricle using four protractible nitinol tines. Prespecified objectives were >85% freedom from unanticipated serious adverse device events (safety) and

Cardiac resynchronization therapy (CRT) is a proven treatment for heart failure but ∼30% of patients appear to not benefit from the therapy. Left ventricular (LV) endocardial and multisite epicardial [triventricular (TriV)] pacing have been proposed as alternatives to traditional LV transvenous epicardial pacing, but no study has directly compared the hemodynamic effects of these approaches. Left bundle branch block ablation and repeated microembolizations were performed in dogs to induce electrical dysynchrony and to reduce LV ejection fraction to max and other hemodynamic indexes were measured with a conductance catheter during LV epicardial, LV endocardial, biventricular (BiV) epicardial, BiV endocardial, and TriV pacing performed at three atrioventricular delays. LV endocardial pacing was obtained with a clinically available pacing system. The optimal site was defined as the site that increased dP/d tmax by the largest percentage. Implantation of the endocardial lead was feasible in all canines ( n = 8) without increased mitral regurgitation seen with transesophageal echocardiography and with full access to the different LV endocardial pacing sites. BiV endocardial pacing increased dP/d tmax more than BiV epicardial and TriV pacing on average ( P < 0.01) and at the optimal site ( P < 0.01). There were no significant differences between BiV epicardial and TriV pacing. BiV endocardial pacing was superior to BiV epicardial and to TriV pacing in terms of acute hemodynamic response. Further investigation is needed to confirm the chronic benefit of this approach in humans.

International audience; The growing interest in dyssynchrony and cardiac resynchronization therapy has opened the field of cardiac stimulation to new haemodynamic indications. French investigators have played a key role in the formulation of new concepts, all arising from clinical observations, and the development (in collaboration with industry) and clinical evaluation of resynchronization devices. This review summarizes recent knowledge and perspectives pertaining to atrial, atrioventricular and ventricular dyssynchrony and resynchronization. Some of these concepts have been validated by robust clinical evidence, on the basis of which scientific recommendations have been formulated. Other concepts have been less successful but probably merit further attention.

International audience; AIMS: Little is known about the incidence of paroxysmal atrial tachycardias (PAT) in patients with heart failure (HF). The availability of cardiac resynchronization therapy (CRT) devices with extended diagnostics for AT enables continuous monitoring of PAT episodes. The aim of the study was to assess the incidence over time of PAT in HF patients treated with CRT. METHODS AND RESULTS: Consecutive patients in NYHA functional class III or IV despite optimal drug therapy, QRS duration > or = 130 ms, left ventricular ejection fraction < or = 35%, and left ventricular end-diastolic dimension > or = 55 mm were eligible for enrolment. Patients with permanent or persistent atrial fibrillation (AF) were not included in the study. The first follow-up examination was performed 2 weeks after implantation, to optimize atrial sensing and CRT. Subsequent follow-up examinations were carried out 15 and 28 weeks after implantation, to collect the telemetric data. A total of 173 patients (67 +/- 11 years, M 116) were enrolled. Complete arrhythmia monitoring data were available from 120 patients over a mean follow-up of 183 +/- 23 days. Atrial tachycardia episodes were detected through telemetry in 25 of 120 patients (21%) during at least one follow-up examination. Atrial tachycardia episodes were recorded in 29 and 17% (P = NS) of patients with and without previous history of AF, respectively. CONCLUSION: More than 20% of the overall HF patient population treated with CRT suffer PAT episodes. Paroxysmal atrial tachycardia may interfere with response to CRT. Therefore, telemetric data may be relevant to drive the appropriate therapy in each patient.

International audience; BACKGROUND: The important role played by peak endocardial acceleration (PEA or sonR) in hemodynamic monitoring of cardiac resynchronization therapy (CRT) was recently highlighted in several studies with the sensor embedded in a right ventricular (RV) lead tip. This study examined the short- and long-term reliability of a right atrial (RA) sonR sensor. METHODS: RA and RV sonR signals were measured from RA and RV leads respectively, at implant and up to 12 months of follow-up, in 19 recipients of either single chamber pacemakers or CRT systems. At 1 month of follow up, RA sonR signals and heart rate were simultaneously recorded during exercise. RESULTS: A reliable RA sonR signal amplitude was measured at implant, proportional to the RV amplitude. We observed in both the right atrium and right ventricle (1) a similar signal noise ratio at implant, (2) a similar evolution of the sonR signal amplitude up to 12 months of follow-up, and (3) a high correlation between heart rate and RA sonR signal amplitude during exercise. CONCLUSIONS: The RA sonR signal was reliable and proportional to the RV signal on the short and long term, and reflected changes in activity. These observations suggest that the sonR sensor could be placed in the atrium for the hemodynamic monitoring of CRT system recipients.

Background— Brugada syndrome is an arrhythmogenic disease characterized by an increased risk of sudden cardiac death (SCD) by ventricular fibrillation. At present, an implantable cardioverter-defibrillator (ICD) is the recommended therapy in high-risk patients. This multicenter study reports the outcome of a large series of patients implanted with an ICD for Brugada syndrome. Methods and Results— All patients (n=220, 46±12 years, 183 male) with a type 1 Brugada ECG pattern implanted with an ICD in 14 centers between 1993 and 2005 were investigated. ICD indication was based on resuscitated SCD (18 patients, 8%), syncope (88 patients, 40%), or positive electrophysiological study in asymptomatic patients (99 patients, 45%). The remaining 15 patients received an ICD because of a family history of SCD or nonsustained ventricular arrhythmia. During a mean follow-up of 38±27 months, no patient died and 18 patients (8%) had appropriate device therapy (10±15 shocks/patient, 26±33 months after implantation). The complication rate was 28%, including inappropriate shocks, which occurred in 45 patients (20%, 4±3 shocks/patient, 21±20 months after implantation). The reasons for inappropriate therapy were lead failure (19 patients), T-wave oversensing (10 patients), sinus tachycardia (10 patients), and supraventricular tachycardia (9 patients). Among implantation parameters, high defibrillation threshold, high pacing threshold, and low R-wave amplitude occurred, respectively, in 12%, 27%, and 15% of cases. Conclusion— In this large Brugada syndrome population, a low incidence of arrhythmic events was found, with an annual event rate of 2.6% during a follow-up of >3 years, in addition to a significant risk of device-related complications (8.9%/year). Inappropriate shocks were 2.5 times more frequent than appropriate ones.

Cardiac electrical stimulation as primary or adjunctive treatment of congestive heart failure is entering its second decade of existence. Initial trials of conventional DDD pacing1-5 were followed by bifocal right ventricular stimulation.6 The concept of multisite stimulation for haemodynamic support was introduced in 1994.7 8 Various studies have already reported the benefits of this method,9 10 or are in progress.11 The transition from conventional DDD pacing to multisite stimulation was not fortuitous. Successive “advances” in the design of cardiac pacing systems have aimed at correcting anomalies in the sequence of cardiac chamber activation, as well as in the synchronisation of the various phases of myocardial contraction and relaxation. The phenomenon of asynchrony is a consequence of progressive, global or focal degradation of the myocardium. One can easily visualise interstitial fibrosis gradually replacing areas of normal myocardium, and causing heterogeneous propagation of cardiac electrical activity. Such heterogeneity combines, to various degrees, three consecutive atrioventricular, interventricular, and intraventricular asynchrony levels. Among various analytical and modelling methods, Doppler echocardiography is preferred for its ease of application in day to day practice.12 The oldest concept, that of desynchronised atrioventricular sequential activation, applies only to sinus rhythm. It is the product of a mismatch between end of atrial systole and onset of ventricular systole, sometimes facilitated by a disorder of atrioventricular conduction or QRS prolongation. It may be simply described as an abbreviated ventricular filling time with respect to the complete cardiac cycle, and, on occasion, by early passive ventricular filling flow superimposed on atrial systole dependent flow. Dual chamber pacing, by linking ventricular to atrial activation, normalises flow patterns of ventricular filling, provided atrial contraction …

Objectives Management of pacemaker infection in pacing-dependent patients is often challenging. Typically, temporary pacing is used while antibiotic therapy is given for a number of days before reimplantation of a new endocardial system. This results in a prolonged hospital stay and complications associated with temporary pacing. In this study, we examine the feasibility of performing a single combined procedure of epicardial pacemaker implantation followed by system extraction. Methods One hundred consecutive infected pacemaker-dependent patients underwent implantation of 2 epicardial ventricular leads and were converted to a ventricular demand pacing system. The infected pacing system was then extracted during the same procedure. Patients were followed up for 12 months. Results Significant pericardial bleeding developed during the procedure in 3 patients. The presence of the pericardial drain positioned during the implantation of the epicardial pacing system meant that cardiac tamponade did not occur, allowing surgical repair with sternotomy to be carried out under stable hemodynamic conditions. Two of these 100 patients died in the 30-day postoperative period; 1 death was due to septic shock and 1 to pulmonary distress. Median 1-year epicardial pacing thresholds were stable and excellent (1.4 ± 0.9 volts). However, 1 of the 2 leads developed increased thresholds in 6 patients, which led to the exclusive use of other ventricular lead. Conclusions A single combined procedure of surgical epicardial pacemaker implantation and pacemaker system extraction appears to be a safe and effective method for managing pacemaker-dependent patients with infected pacemakers.

Biventricular resynchronization, a therapy recommended for patients presenting with left ventricular (LV) dysfunction and ventricular dyssynchrony, requires the implantation of an LV lead, usually placed in a lateral or posterolateral tributary of the coronary sinus. Despite important progress made in the development of dedicated instrumentation, the procedure remains sometimes challenging and unsuccessful in a minority of patients. In the rare instances of unsuccessful transvenous implantations occurring in the presence of major surgical contraindications, a few operators have implanted the LV lead transseptally, an approach limited by technical difficulties and by the thromboembolic risk associated with the presence of a lead inside the LV cavity. The interest in this approach was recently renewed by 2 studies in an animal model and in humans, respectively, which both found a distinctly superior hemodynamic performance associated with endocardial compared with epicardial stimulation. This review discusses the advantages and disadvantages of LV endocardial stimulation, examines the various techniques of LV endocardial stimulation, and projects their future applications in light of these highly promising recent results. The implementation of endocardial stimulation will ultimately depend on: 1) the development of safe, effective, and durable instrumentation, and reliable and reproducible intraprocedural methods to identify the optimal site of stimulation; and 2) the completion of controlled trials confirming the superiority of this technique compared with standard cardiac resynchronization therapy.

Objectives The purpose of this study was to enhance understanding of the working mechanism of cardiac resynchronization therapy by comparing animal experimental, clinical, and computational data on the hemodynamic and electromechanical consequences of left ventricular pacing (LVP) and biventricular pacing (BiVP). Background It is unclear why LVP and BiVP have comparative positive effects on hemodynamic function of patients with dyssynchronous heart failure. Methods Hemodynamic response to LVP and BiVP (% change in maximal rate of left ventricular pressure rise [LVdP/dt(max)]) was measured in 6 dogs and 24 patients with heart failure and left bundle branch block followed by computer simulations of local myofiber mechanics during LVP and BiVP in the failing heart with left bundle branch block. Pacing-induced changes of electrical activation were measured in dogs using contact mapping and in patients using a noninvasive multielectrode electrocardiographic mapping technique. Results LVP and BiVP similarly increased LVdP/dt(max) in dogs and in patients, but only BiVP significantly decreased electrical dyssynchrony. In the simulations, LVP and BiVP increased total ventricular myofiber work to the same extent. While the LVP-induced increase was entirely due to enhanced right ventricular (RV) myofiber work, the BiVP-induced increase was due to enhanced myofiber work of both the left ventricle (LV) and RV. Overall, LVdP/dt(max) correlated better with total ventricular myofiber work than with LV or RV myofiber work alone. Conclusions Animal experimental, clinical, and computational data support the similarity of hemodynamic response to LVP and BiVP, despite differences in electrical dyssynchrony. The simulations provide the novel insight that, through ventricular interaction, the RV myocardium importantly contributes to the improvement in LV pump function induced by cardiac resynchronization therapy.

Evaluation of Syncope in Brugada Syndrome The Effect on Outcome Risk stratification in pts with Brugada syndrome (BS) is difficult. The report from the 2 nd Consensus Committee on BS suggests that all pts with syncope without a “clear extracardiac cause” should have an implantable cardioverter-defibrillator (ICD). However a clear cause for syncope may be difficult to prove. Methods All pts diagnosed with BS at Bordeaux CHU between 1999 and 2009 have been enrolled in a prospective registry. All patients with syncope were enrolled in the present study (Group 1 without and Group 2 with a “clear extracardiac cause” of syncope). Patients were followed in the clinic or by phone annually unless there was an event. Results Of 185 pts with BS, 49 (39 male, 47 ±12yo) had at least one syncope. All 27 pts in group 1 received an ICD. Of the 22 pts in group 2, 4 received an implantable loop recorder [MJW1] (ILR) and 1 patient received an ICD after positive EP study. With a mean follow-up of 53 ±38 months, 19 pts were asymptomatic, 5 had appropriate ICD therapy, 2 patients had further syncopal events not associated with cardiac arrhythmia and 1 pt died of a non cardiac cause in group 1. In group 2, 14pts were asymptomatic, 5 had recurrent atypical syncopal events (without arrhythmia shown by ILR in 3 pts), 2 experienced atypical chest pain and 1 died of drug abuse. Conclusions Diagnosis of syncope is difficult, and 7% of BS pts presenting with syncope without a clear cardiac cause will have further events without cardiac arrhythmia. Better evaluation of syncope is required to spare pts unnecessary ICDs. group 1 27 patients syncope without a clear extracardiac cause group 2 22 patients syncope with a clear extracardiac cause p gender (male) 21 (80.8%) 18 (78.3%) 0.83 age (years old) 48 (+/- 12.2) 45 (+/- 11) 0.39 follow-up (months) 53 (+/- 36.1) 52 (+/- 42.3) 0.90 spontaneous type 1 ECG 21 (80.8%) 13 (56.5%) 0.07 EP Study: – positive 8 (29.7%) 1 (4.5%) 0.06 – negative 13 (48%) 17 (77.3%) – not done 6 (22.3%) 4 (18.2%) circunstances of diagnosis: – unexpected finding 4 (14.8%) 7 (31.8%) 0.43 – familial assessment 2 (7.4%) 2 (9.1%) – syncope 21 (77.8%) 13 (59.1%)