Incidence, implications, and management of sense-B-noise failure in subcutaneous cardioverter-defibrillator patients: insights from a large multicentre registry.

AIMS: Subcutaneous implantable cardioverter-defibrillators (S-ICDs) offer potentially distinct advantages over transvenous defibrillator systems. Recent randomized trials showed significantly lower lead failure rates than transvenous ICD. Still, S-ICDs remain associated with the risk of inappropriate shocks (IAS). While previous studies have reported varying causes of IAS, this study explores a rare cause of IAS, referred to as 'sense-B-noise.' It was recently described in case series, but its incidence has not been studied in a large cohort of S-ICD patients. METHODS AND RESULTS: We retrospectively reviewed data from patients implanted with S-ICD models 1010, A209, and A219 between October 2009 and July 2023 across nine centres in Europe and the USA. The analysis concentrated on determining the incidence and understanding the implications of sense-B-noise events. Sense-B-noise represents a rare manifestation of distinct electrogram abnormalities within the primary and alternate sensing vectors. Data were collected from medical records, device telemetry, and manufacturer reports for investigation. This registry is registered on clinicaltrials.gov (NCT05713708). Subcutaneous implantable cardioverter-defibrillator devices of the 1158 patients were analysed. The median follow-up time for all patients was 46 (IQR 23-64) months. In 107 patients (9.2%) ≥1 IAS was observed during follow-up. Sense-B-noise failure was diagnosed in six (0.5 and 5.6% of all IAS) patients, in all patients, the diagnosis was made after an IAS episode. Median lead dwell time in the affected patients was 23 (2-70) months. To resolve the sense-B-noise defect, in three patients reprogramming to the secondary vector was undertaken, and two patients underwent system removal with subsequent S-ICD reimplantation due to low amplitude in the secondary vector. In one patient, the secondary vector was initially programmed, and subsequently, an S-ICD system exchange was performed due to T-wave-oversensing IAS episodes. CONCLUSION: This multicentre analysis' findings shed light on a rare but clinically highly significant adverse event in S-ICD therapy. To our knowledge, we provide the first systematic multicentre analysis investigating the incidence of sense-B-noise. Due to being difficult to diagnose and limited options for resolution, management of sense-B-noise is challenging. Complete system exchange may be the only option for some patients. Educating healthcare providers involved in S-ICD patient care is crucial for ensuring accurate diagnosis and effective management of sense-B-noise issues.

Occurrence of premature battery depletion in a large multicentre registry of subcutaneous cardioverter-defibrillator patients.

AIMS: Subcutaneous implantable cardioverter-defibrillators (S-ICDs) have become established in preventing sudden cardiac death, with some advantages over transvenous defibrillator systems, including a lower incidence of lead failures. Despite technological advancements, S-ICD carriers may suffer from significant complications, such as premature battery depletion (PBD), that led to an advisory for nearly 40 000 patients. This multicentre study evaluated the incidence of PBD in a large set of S-ICD patients. METHODS AND RESULTS: Data from patients implanted with S-ICD models A209 and A219 between October 2012 and July 2023 across nine centres in Europe and the USA were reviewed. Incidence and implications of PBD, defined as clinically observed sudden drop in battery longevity, were analysed and compared to PBD with the definition of battery depletion within 60 months. Prospectively collected clinical data were obtained retrospectively from medical records, device telemetry, and manufacturer reports. This registry is listed on ClinicalTrials.gov (NCT05713708). Of the 1112 S-ICD devices analysed, 547 (49.2%) were equipped with a potentially affected capacitor linked to PBD occurrence, currently under Food and Drug Administration advisory. The median follow-up time for all patients was 46 [inter-quartile range (IQR) 24-63] months. Clinically suspected PBD was observed in 159 (29.1%) of cases, with a median time to generator removal or replacement of 65 (IQR 55-72) months, indicative of significant deviations from expected battery lifespan. Manufacturer confirmation of PBD was made in 91.7% of devices returned for analysis. No cases of PBD were observed in devices that were not under advisory. CONCLUSION: This manufacturer-independent analysis highlights a notable incidence of PBD in patients equipped with S-ICD models under advisory, and the rate of PBD in this study corresponds to the rate currently estimated by the manufacturer. To the best of our knowledge, this provides the largest contemporary peer-reviewed study cohort investigating the actual incidence of PBD in S-ICD patients. These findings emphasize the importance of post-market registries in collaboration between clinicians and the manufacturer to optimize safety and efficacy in S-ICD treatment.

Impact of implantation depth and calcium burden on infranodal conduction delay after transcatheter aortic valve replacement.

Background: Infranodal conduction disorders are common after transcatheter aortic valve replacement (TAVR). Risk factors are incompletely understood. Objective: The purpose of this study was to assess the impact of valve implantation depth and calcium burden of the device landing zone on infranodal conduction intraprocedure pre- and post-TAVR. Methods: In all patients undergoing TAVR between June 2020 and June 2021, the His-ventricle (HV) interval was measured pre- and post-valve deployment. The difference between the 2 measurements defined delta HV, whereas infranodal conduction delay was defined as HV interval >55 ms. Valve implantation depth was measured as the distance between the aortic annular plane and the ventricular prosthesis end. Calcium burden was quantified as the volume of calcium in 6 regions of interest: the non-, right, and left coronary cusps (NCC, RCC, and LCC, respectively) and the corresponding regions of the left ventricular outflow tract (LVOT) underlying each cusp (LVOTNCC, LVOTRCC, LVOTLCC, respectively). Results: Of 101 patients (mean age 81 ± 5.7 years; 47% women), 37 demonstrated infranodal conduction delay intraprocedure post-TAVR. Overall, mean implantation depth was 5 ± 3.1 mm, median calcium volume was 2080 mm3 [interquartile range 632-2400]. Delta HV showed no correlation with implantation depth or calcium burden (r = -0.08 and r = 0.12, respectively). However, LVOTNCC calcification was a significant predictor for infranodal conduction delay post-valve deployment in a multivariable logistic regression model (odds ratio 1.62 per 100-mm3 increase (95% confidence interval 1.06-2.69; P = .04). Conclusion: Assessment of LVOTNCC calcification may identify patients at risk for infranodal conduction delay after TAVR, whereas implantation depth did not predict infranodal conduction delay.

Accuracy in detecting atrial fibrillation in single-lead ECGs: an online survey comparing the influence of clinical expertise and smart devices.

BACKGROUND: Manual interpretation of single-lead ECGs (SL-ECGs) is often required to confirm a diagnosis of atrial fibrillation. However accuracy in detecting atrial fibrillation via SL-ECGs may vary according to clinical expertise and choice of smart device. AIMS: To compare the accuracy of cardiologists, internal medicine residents and medical students in detecting atrial fibrillation via SL-ECGs from five different smart devices (Apple Watch, Fitbit Sense, KardiaMobile, Samsung Galaxy Watch, Withings ScanWatch). Participants were also asked to assess the quality and readability of SL-ECGs. METHODS: In this prospective study (BaselWearableStudy, NCT04809922), electronic invitations to participate in an online survey were sent to physicians at major Swiss hospitals and to medical students at Swiss universities. Participants were asked to classify up to 50 SL-ECGs (from ten patients and five devices) into three categories: sinus rhythm, atrial fibrillation or inconclusive. This classification was compared to the diagnosis via a near-simultaneous 12-lead ECG recording interpreted by two independent cardiologists. In addition, participants were asked their preference of each manufacturer's SL-ECG. RESULTS: Overall, 450 participants interpreted 10,865 SL-ECGs. Sensitivity and specificity for the detection of atrial fibrillation via SL-ECG were 72% and 92% for cardiologists, 68% and 86% for internal medicine residents, 54% and 65% for medical students in year 4-6 and 44% and 58% for medical students in year 1-3; p <0.001. Participants who stated prior experience in interpreting SL-ECGs demonstrated a sensitivity and specificity of 63% and 81% compared to a sensitivity and specificity of 54% and 67% for participants with no prior experience in interpreting SL-ECGs (p <0.001). Of all participants, 107 interpreted all 50 SL-ECGs. Diagnostic accuracy for the first five interpreted SL-ECGs was 60% (IQR 40-80%) and diagnostic accuracy for the last five interpreted SL-ECGs was 80% (IQR 60-90%); p <0.001. No significant difference in the accuracy of atrial fibrillation detection was seen between the five smart devices; p = 0.33. SL-ECGs from the Apple Watch were considered as having the best quality and readability by 203 (45%) and 226 (50%) participants, respectively. CONCLUSION: SL-ECGs can be challenging to interpret. Accuracy in correctly identifying atrial fibrillation depends on clinical expertise, while the choice of smart device seems to have no impact.

Transvenous Lead Extraction during Cardiac Implantable Device Upgrade: Results from the Multicenter Swiss Lead Extraction Registry.

BACKGROUND: Device patients may require upgrade interventions from simpler to more complex cardiac implantable electronic devices. Prior to upgrading interventions, clinicians need to balance the risks and benefits of transvenous lead extraction (TLE), additional lead implantation or lead abandonment. However, evidence on procedural outcomes of TLE at the time of device upgrade is scarce. METHODS: This is a post hoc analysis of the investigator-initiated multicenter Swiss TLE registry. The objectives were to assess patient and procedural factors influencing TLE outcomes at the time of device upgrades. RESULTS: 941 patients were included, whereof 83 (8.8%) had TLE due to a device upgrade. Rotational mechanical sheaths were more often used in upgraded patients (59% vs. 42.7%, p = 0.015) and total median procedure time was longer in these patients (160 min vs. 105 min, p < 0.001). Clinical success rates of upgraded patients compared to those who received TLE due to other reasons were not different (97.6% vs. 93.0%, p = 0.569). Moreover, multivariable analysis showed that upgrade procedures were not associated with a greater risk for complications (HR 0.48, 95% confidence interval 0.14-1.57, p = 0.224; intraprocedural complication rate of upgraded patients 7.2% vs. 5.5%). Intraprocedural complications of upgraded patients were mostly associated with the implantation and not the extraction procedure (67% vs. 33% of complications). CONCLUSIONS: TLE during device upgrade is effective and does not attribute a disproportionate risk to the upgrade procedure.

Follow-up of CRT-D patients downgraded to CRT-P at the time of generator exchange.

Background: Some patients with cardiac resynchronisation therapy (CRT) experience super-response (LVEF improvements to ≥50%). At generator exchange (GE), downgrading (DG) from CRT-defibrillator (CRT-D) to CRT-pacemaker (CRT-P) could be an option for these patients on primary prevention ICD indication and no required ICD therapies. Long-term data on arrhythmic events in super-responders is scarce. Methods: CRT-D patients with LVEF improvement to ≥50% at GE were identified in four large centres for retrospective analysis. Mortality, significant ventricular tachyarrhythmia and appropriate ICD-therapy were determined, and patient analysis was split into two groups (downgraded to CRT-P or not). Results: Sixty-six patients (53% male, 26% coronary artery disease) on primary prevention were followed for a median of 129 months [IQR: 101-155] after implantation. 27 (41%) patients were downgraded to CRT-P at GE after a median of 68 [IQR: 58-98] months (LVEF 54% ± 4%). The other 39 (59%) continued with CRT-D therapy (LVEF 52% ± 6%). No cardiac death or significant arrhythmia occurred in the CRT-P group (median follow-up (FU) 38 months [IQR: 29-53]). Three appropriate ICD-therapies occurred in the CRT-D group [median FU 70 months (IQR: 39-97)]. Annualized event-rates after DG/GE were 1.5%/year and 1.0%/year in the CRT-D group and the whole cohort, respectively. Conclusions: No significant tachyarrhythmia were detected in the patients downgraded to CRT-P during follow-up. However, three events were observed in the CRT-D group. Whilst downgrading CRT-D patients is an option, a small residual risk for arrhythmic events remains and decisions regarding downgrade should be made on a case-by-case basis.

Atrial substrate characterization based on bipolar voltage electrograms acquired with multipolar, focal and mini-electrode catheters.

BACKGROUND: Bipolar voltage (BV) electrograms for left atrial (LA) substrate characterization depend on catheter design and electrode configuration. AIMS: The aim of the study was to investigate the relationship between the BV amplitude (BVA) using four catheters with different electrode design and to identify their specific LA cutoffs for scar and healthy tissue. METHODS AND RESULTS: Consecutive high-resolution electroanatomic mapping was performed using a multipolar-minielectrode Orion catheter (Orion-map), a duo-decapolar circular mapping catheter (Lasso-map), and an irrigated focal ablation catheter with minielectrodes (Mifi-map). Virtual remapping using the Mifi-map was performed with a 4.5 mm tip-size electrode configuration (Nav-map). BVAs were compared in voxels of 3 × 3 × 3 mm3. The equivalent BVA cutoff for every catheter was calculated for established reference cutoff values of 0.1, 0.2, 0.5, 1.0, and 1.5 mV. We analyzed 25 patients (72% men, age 68 ± 15 years). For scar tissue, a 0.5 mV cutoff using the Nav corresponds to a lower cutoff of 0.35 mV for the Orion and of 0.48 mV for the Lasso. Accordingly, a 0.2 mV cutoff corresponds to a cutoff of 0.09 mV for the Orion and of 0.14 mV for the Lasso. For healthy tissue cutoff at 1.5 mV, a larger BVA cutoff for the small electrodes of the Orion and the Lasso was determined of 1.68 and 2.21 mV, respectively. CONCLUSION: When measuring LA BVA, significant differences were seen between focal, multielectrode, and minielectrode catheters. Adapted cutoffs for scar and healthy tissue are required for different catheters.

Ventricular pacing burden in patients with left bundle branch block after transcatheter aortic valve replacement therapy.

INTRODUCTION: Electrophysiological testing has been proposed in the latest European Society of Cardiology (ESC) guidelines for cardiac pacing to identify left bundle branch block (LBBB) patients with infrahisian conduction delay (IHCD) after transcatheter aortic valve replacement (TAVR). While in general IHCD is defined by a His-ventricular (HV) interval of >55 ms, a cut-off of ≥70 ms to trigger pacemaker (PM) implantation has been proposed in the latest ESC guidelines. The ventricular pacing (VP) burden during follow-up in such patients is largely unknown. As such, we aimed to assess the VP burden during follow-up of patients receiving PM therapy for LBBB after TAVR based on an HV interval > 55 ms and ≥70 ms. METHODS: All patients with new-onset or pre-existing LBBB after undergoing TAVR at a tertiary referral center underwent EP testing the day after TAVR. In patients with a prolonged HV interval (>55 ms), PM implantation was performed by a trained electrophysiologist in a standardized fashion. All devices were programmed to avoid unnecessary VP by specific algorithms (e.g., AAI-DDD). RESULTS: 701 patients underwent TAVR at the University Hospital of Basel. One hundred seventy-seven patients presented with new-onset or pre-existing LBBB the day following TAVR and underwent EP testing. An HV interval > 55 ms was found in 58 patients (33%) and an HV interval ≥ 70 ms in 21 patients (12%). 51 patients (mean age 84 ± 6.2 years, 45% women) agreed to receive a PM, out of which 20 (39%) patients had an HV Interval over 70 ms. Atrial fibrillation was present in 53% of the patients. A dual chamber PM was implanted in 39 (77%), and a single chamber PC in 12 (23%) patients, respectively. Median follow-up was 21 months. The median VP burden overall was 3%. The median VP burden was not significantly different between patients with an HV ≥ 70 ms (6.5 [0.8-52]) and those with an HV between 55 and 69 ms (2 [0-17], p = .23). 31% of patients demonstrated a VP burden < 1%, 27% 1%-5% and 41% > 5%. The median HV intervals in patients with VP burdens < 1%, 1%-5% and >5% were 66 (IQR 62-70) ms, 66 (IQR 63-74) ms and 68 (IQR 60-72) ms, respectively, p = .52. When only assessing patients with an HV interval 55-69 ms, 36% demonstrated a VP burden of <1%, 29% of 1%-5% and 35% of >5%. In patients with an HV Interval ≥ 70 ms, 25% demonstrated a VP burden < 1%, 25% of 1%-5% and 50% of >5% %, p = .64 (Figure). CONCLUSION: In patients with LBBB after TAVR and IHCD defined by an HV interval > 55 ms, VP burden is relevant in a non-negligible amount of patients during follow-up. Further studies are warranted to define the optimal cut-off value for the HV interval or to develop risk models incorporating HV measurements and other risk factors to trigger PM implantation in patients with LBBB after TAVR.

Clinical Validation of 5 Direct-to-Consumer Wearable Smart Devices to Detect Atrial Fibrillation: BASEL Wearable Study.

BACKGROUND: Multiple smart devices capable to detect atrial fibrillation (AF) are presently available. Sensitivity and specificity for the detection of AF may differ between available smart devices, and this has not yet been adequately investigated. OBJECTIVES: The aim was to assess the accuracy of 5 smart devices in identifying AF compared with a physician-interpreted 12-lead electrocardiogram as the reference standard in a real-world cohort of patients. METHODS: We consecutively enrolled patients presenting to a cardiology service at a tertiary referral center in a prospective, diagnostic study. RESULTS: We prospectively analyzed 201 patients (31% women, median age 66.7 years). AF was present in 62 (31%) patients. Sensitivity and specificity for the detection of AF were comparable between devices: 85% and 75% for the Apple Watch 6, 85% and 75% for the Samsung Galaxy Watch 3, 58% and 75% for the Withings Scanwatch, 66% and 79% for the Fitbit Sense, and 79% and 69% for the AliveCor KardiaMobile, respectively. The rate of inconclusive tracings (the algorithm was unable to determine the heart rhythm) was 18%, 17%, 24%, 21%, and 26% for the Apple Watch 6, Samsung Galaxy Watch 3, Withings Scan Watch, Fitbit Sense, and AliveCor KardiaMobile (P < 0.01 for pairwise comparison), respectively. By manual review of inconclusive tracings, the rhythm could be determined in 955 (99%) of 969 single-lead electrocardiograms. Regarding patient acceptance, the Apple Watch was ranked first (39% of participants). CONCLUSIONS: In this clinical validation of 5 direct-to-consumer smart devices, we found differences in the amount of inconclusive tracings diminishing sensitivity and specificity of the smart devices. In a clinical setting, manual review of tracings is required in about one-fourth of cases.

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.

Sex-Related Differences in Patient Selection for and Outcomes after Pace and Ablate for Refractory Atrial Fibrillation: Insights from a Large Multicenter Cohort.

Background: A pace and ablate strategy may be performed in refractory atrial fibrillation with rapid ventricular response. Objective: We aimed to assess sex-related differences in patient selection and clinical outcomes after pace and ablate. Methods: In a retrospective multicentre study, patients undergoing AV junction ablation were studied. Sex-related differences in baseline characteristics, all-cause mortality, heart failure (HF) hospitalizations, and device-related complications were assessed. Results: Overall, 513 patients underwent AV junction ablation (median age 75 years, 50% men). At baseline, men were younger (72 vs. 78 years, p < 0.001), more frequently had non-paroxysmal AF (82% vs. 72%, p = 0.006), had a lower LVEF (35% vs. 55%, p < 0.001) and more frequently had cardiac resynchronization therapy (75% vs. 25%, p < 0.001). Interventional complications were rare in both groups (1.2% vs. 1.6%, p = 0.72). Patients were followed for a median of 42 months in survivors (IQR 22−62). After 4 years of follow-up, the combined endpoint of all-cause death or HF hospitalization occurred more often in men (38% vs. 27%, p = 0.008). The same was observed for HF hospitalizations (22% vs. 11%, p = 0.021) and all-cause death (28% vs. 21%, p = 0.017). Sex category remained an independent predictor of death or HF hospitalization after adjustment for age, LVEF and type of stimulation. Lead-related complications, infections, and upgrade to ICD or CRT occurred in 2.1%, 0.2% and 3.5% of patients, respectively. Conclusions: Pace and ablate is safe with a need for subsequent device-related re-interventions in 5.8% over 4 years. We found significant sex-related differences in patient selection, and women had a more favourable clinical course after AV junction ablation.

Clinical Validation of Automated Corrected QT-Interval Measurements From a Single Lead Electrocardiogram Using a Novel Smartwatch.

Introduction: The Withings Scanwatch (Withings SA, Issy les Moulineaux, France) offers automated analysis of the QTc. We aimed to compare automated QTc-measurements using a single lead ECG of a novel smartwatch (Withings Scanwatch, SW-ECG) with manual-measured QTc from a nearly simultaneously recorded 12-lead ECG. Methods: We enrolled consecutive patients referred to a tertiary hospital for cardiac workup in a prospective, observational study. The QT-interval of the 12-lead ECG was manually interpreted by two blinded, independent cardiologists through the tangent-method. Bazett's formula was used to calculate QTc. Results were compared using the Bland-Altman method. Results: A total of 317 patients (48% female, mean age 63 ± 17 years) were enrolled. HR-, QRS-, and QT-intervals were automatically calculated by the SW in 295 (93%), 249 (79%), and 177 patients (56%), respectively. Diagnostic accuracy of SW-ECG for detection of QTc-intervals ≥ 460 ms (women) and ≥ 440 ms (men) as quantified by the area under the curve was 0.91 and 0.89. The Bland-Altman analysis resulted in a bias of 6.6 ms [95% limit of agreement (LoA) -59 to 72 ms] comparing automated QTc-measurements (SW-ECG) with manual QTc-measurement (12-lead ECG). In 12 patients (6.9%) the difference between the two measurements was greater than the LoA. Conclusion: In this clinical validation of a direct-to-consumer smartwatch we found fair to good agreement between automated-SW-ECG QTc-measurements and manual 12-lead-QTc measurements. The SW-ECG was able to automatically calculate QTc-intervals in one half of all assessed patients. Our work shows, that the automated algorithm of the SW-ECG needs improvement to be useful in a clinical setting.

Value of Periprocedural Electrophysiology Testing During Transcatheter Aortic Valve Replacement for Risk Stratification of Patients With New-Onset Left Bundle-Branch Block.

Background Despite being the most frequent complication following transcatheter aortic valve replacement (TAVR), optimal management of left bundle-branch block (LBBB) remains unknown. Electrophysiology study has been proposed for risk stratification. However, the optimal timing of electrophysiology study remains unknown. We aimed to investigate the temporal dynamics of atrioventricular conduction in patients with new-onset LBBB after TAVR by performing serial electrophysiology study and to deduce a treatment strategy. Methods and Results We assessed consecutive patients undergoing TAVR via His-ventricular interval measurement prevalve and postvalve deployment and the day after TAVR. Infranodal conduction delay was defined as a His-ventricular interval >55 milliseconds. Among 107 patients undergoing TAVR, 53 patients (50%) experienced new-onset LBBB postvalve deployment and infranodal conduction delay was noted in 24 of 53 patients intraprocedurally (45%). LBBB resolved the day after TAVR in 35 patients (66%). In patients with new-onset LBBB postvalve deployment and no infrahisian conduction delay intraprocedurally, the His-ventricular interval did not prolong in any patient to >55 milliseconds the following day. Overall, 4 patients (7.5%) with new-onset LBBB after TAVR were found to have persistent infrahisian conduction delay 24 hours after TAVR. During 30-day follow-up, 1 patient (1.1%) with new LBBB and a normal His-ventricular interval after TAVR developed new high-grade atrioventricular block. Conclusions Among patients with new-onset LBBB postvalve deployment, infrahisian conduction delay can safely be excluded intraprocedurally, suggesting that early intracardiac intraprocedural conduction studies may be of value in these patients.

Simplified Integrated Clinical and Electrocardiographic Algorithm for Differentiation of Wide QRS Complex Tachycardia: The Basel Algorithm.

BACKGROUND: Prompt differential diagnosis of wide QRS complex tachycardia (WCT) is crucial to patient management. However, distinguishing ventricular tachycardia (VT) from supraventricular tachycardia (SVT) with wide QRS complexes remains problematic, especially for nonelectrophysiologists. OBJECTIVES: This study aimed to develop a simple-to-use algorithm with integration of clinical and electrocardiographic (ECG) parameters for the differential diagnosis of WCT. METHODS: The 12-lead ECGs of 206 monomorphic WCTs (153 VT, 53 SVT) with electrophysiology-confirmed diagnoses were analyzed. In the novel Basel algorithm, VT was diagnosed in the presence of at least 2 of the following criteria: 1) clinical high risk features; 2) lead II time to first peak >40 ms; and 3) lead aVR time to first peak >40 ms. The algorithm was externally validated in 203 consecutive WCT cases (151 VT, 52 SVT). Its' diagnostic performance and clinical applicability were compared with those of the Brugada and Vereckei algorithms. RESULTS: The Basel algorithm showed a sensitivity, specificity, and accuracy of 92%, 89%, and 91%, respectively, in the derivation cohort and 93%, 90%, and 93%, respectively, in the validation cohort. There were no significant differences in the performance characteristics between the 3 algorithms. The evaluation of the clinical applicability of the Basel algorithm showed similar diagnostic accuracy compared with the Brugada algorithm (80% vs 81%; P = 1.00), but superiority compared with the Vereckei algorithm (72%; P = 0.03). The Basel algorithm, however, enabled a faster diagnosis (median 36 seconds vs 105 seconds for the Brugada algorithm [P = 0.002] and 50 seconds for the Vereckei algorithm [P = 0.02]). CONCLUSIONS: The novel Basel algorithm based on simple clinical and ECG criteria allows for a rapid and accurate differential diagnosis of WCT.

High-power short-duration ablation index-guided pulmonary vein isolation protocol using a single catheter.

BACKGROUND: Catheter ablation for atrial fibrillation (AF) is the most commonly performed electrophysiological procedure. To improve healthcare utilization, we aimed to compare the efficacy, efficiency, and safety of a minimalistic, streamlined single catheter ablation approach using a high-power short-duration ablation index-guided protocol (HPSD) vs. a control single-catheter protocol (SP). METHODS: Pulmonary vein isolation (PVI) with a single transseptal puncture without a multipolar mapping catheter was performed in 91 patients. Left atrial mapping was performed with the ablation catheter, only. Pacing maneuvers were used to confirm exit block. Procedural characteristics and success rates were compared using HPSD (n = 34) vs. a control (n = 57) ablation protocol. Freedom from recurrence was defined as a 1-year absence of AF episodes > 30 s, beyond the 3-month blanking period. RESULTS: Using the HPSD protocol the median procedure and RF ablation time were significantly shorter compared to the SP, 84 (IQR 76-100) vs. 118 min (IQR 104-141) and 1036 (898-1184) vs. 1949s (IQR 1693-2261), respectively, p < .001 for all. First-pass PVI was achieved using the HPSD protocol in 88% and using the SP in 87% of patients, p = 1.0. No procedural complications were observed. High-sensitivity cardiac troponin levels were significantly higher in patients using the HPSD protocol compared to the SP. At 12 months follow-up, 87% patients remained free from AF with no differences between groups. CONCLUSIONS: A minimalistic, HPSD ablation index-guided PVI with a single-catheter approach is very efficient, safe, and associated with excellent clinical outcomes at 1 year.

High Incidence of Inappropriate Alarms in Patients with Wearable Cardioverter-Defibrillators: Findings from the Swiss WCD Registry.

BACKGROUND: The wearable cardioverter defibrillator (WCD) uses surface electrodes to detect arrhythmia before initiating a treatment sequence. However, it is also prone to inappropriate detection due to artefacts. OBJECTIVE: The aim of this study is to assess the alarm burden in patients and its impact on clinical outcomes. METHODS: Patients from the nationwide Swiss WCD Registry were included. Clinical characteristics and data were obtained from the WCDs. Arrhythmia recordings ≥30 s in length were analysed and categorized as VT/VF, atrial fibrillation (AF), supraventricular tachycardia (SVT) or artefact. RESULTS: A total of 10653 device alarms were documented in 324 of 456 patients (71.1%) over a mean WCD wear-time of 2.0 ± 1.6 months. Episode duration was 30 s or more in 2996 alarms (28.2%). One hundred and eleven (3.7%) were VT/VF episodes. The remaining recordings were inappropriate detections (2736 (91%) due to artefacts; 117 (3.7%) AF; 48 (1.6%) SVT). Two-hundred and seven patients (45%) had three or more alarms per month. Obesity was significantly associated with three or more alarms per month (p = 0.01, 27.7% vs. 15.9%). High alarm burden was not associated with a lower average daily wear time (20.8 h vs. 20.7 h, p = 0.785) or a decreased implantable cardioverter defibrillator implantation rate after stopping WCD use (48% vs. 47.3%, p = 0.156). CONCLUSIONS: In patients using WCDs, alarms emitted by the device and impending inappropriate shocks were frequent and most commonly caused by artefacts. A high alarm burden was associated with obesity but did not lead to a decreased adherence.

Cryoballoon Ablation of Atrial Fibrillation Without Demonstration of Pulmonary Vein Occlusion-The Simplify Cryo Study.

Background: The demonstration of pulmonary vein (PV) occlusion is routinely performed and considered a prerequisite for successful cryoballoon (CB) ablation of atrial fibrillation (AF). The purpose of this study was to assess the feasibility and impact on procedural parameters and outcome of a standardized procedural protocol without demonstrating PV occlusion. Methods and Results: Consecutive patients undergoing CB pulmonary vein isolation (PVI) were studied. After cMRI assessment, patients treated by PVI using a novel no-contrast (NC) protocol without routine contrast injections to demonstrate PV occlusion (NC group) were compared to patients undergoing PVI with contrast injections to demonstrate PV occlusion (standard group). One hundred patients with paroxysmal or persistent AF (age 61 ± 10 years, ejection fraction 59 ± 11%, left atrial volume index 37.2 ± 2.0 mL/m2) were studied. The NC protocol was feasible in 72 of 75 patients (96%). Total procedure time and fluoroscopy time were 64.0 ± 14.1 min and 11.0 ± 4.6 min in the NC group and 92.0 ± 25.3 min and 18.0 ± 6.0 min in the standard group, respectively (all p < 0.001). Dose area product was 368 ± 362 cGy*cm2 in the NC group compared to 1928 ± 1541 cGy*cm2 in the standard group (p < 0.001). Forty-five of 75 patients (60%) in the NC group and 16 of 25 patients (64%) in the standard group remained in stable sinus rhythm after a single PVI and a 1-year follow-up (p = 0.815). Conclusions: Performing CB ablation without using contrast injections to demonstrate PV occlusion was feasible, resulted in reduced radiation exposure, and increased the efficiency of the procedure.

Reassessment of clinical variables in cardiac resynchronization defibrillator patients at the time of first replacement: Death after replacement of CRT (DARC) score.

INTRODUCTION: Cardiac resynchronization defibrillator (CRT-D) as primary prevention is known to reduce mortality. At the time of replacement, higher age and comorbidities may attenuate the benefit of implantable cardioverter-defibrillator (ICD) therapy. The purpose of this study was to evaluate the progression of comorbidities after implantation and their association with mortality following CRT-D generator replacement. In addition, a risk score was developed to identify patients at high risk for mortality after replacement. METHODS AND RESULTS: We identified patients implanted with a primary prevention CRT-D (n = 648) who subsequently underwent elective generator replacement (n = 218) from two prospective ICD registries. The cohort consisted of 218 patients (median age: 70 years, male gender: 73%, mean left ventricular ejection fraction [LVEF]: 36 ± 11% at replacement). Median follow-up after the replacement was 4.2 years during which 64 patients (29%) died and 11 patients (5%) received appropriate ICD shocks. An increase in comorbidities was observed in 77 patients (35%). The 5-year mortality rate was 41% in patients with ≥2 comorbidities at the time of replacement. A risk score incorporating age, gender, LVEF, atrial fibrillation, anemia, chronic kidney disease, and history of appropriate ICD shocks at time of replacement accurately predicted 5-year mortality (C-statistic 0.829). Patients with a risk score of greater than 2.5 had excess mortality at 5-year postreplacement compared with patients with a risk score less than 1.5 (57% vs. 6%; p < .001). CONCLUSION: A simple risk score accurately predicts 5-year mortality after replacement in CRT-D patients, as patients with a risk score of greater than 2.5 are at high risk of dying despite ICD protection.

Application of the heart failure meta-score to predict prognosis in patients with cardiac resynchronization defibrillators.

BACKGROUND: The Heart Failure (HF) Meta-score may be useful in predicting prognosis in patients with primary prevention cardiac resynchronization defibrillators (CRT-D) considering the competing risk of appropriate defibrillator shock versus mortality. METHODS: Data from 648 consecutive patients from two centers were used for the evaluation of the performance of the HF Meta-score. The primary endpoint was mortality and the secondary endpoint was time to first appropriate implantable cardioverter-defibrillator (ICD) shock or death without prior appropriate ICD shock. Fine-Gray model was used for competing risk regression analysis. RESULTS: In the entire cohort, 237 patients died over a median follow-up of 5.2 years. Five-year cumulative incidence of mortality ranged from 12% to 53%, for quintiles 1 through 5 of the HF Meta-score, respectively (log-rank P < 0.001). Compared with the lowest quintile, mortality risk was higher in the highest quintile (HR 6.9; 95%CI 3.7-12.8). The HF Meta-score had excellent calibration, accuracy, and good discrimination in predicting mortality (C-statistic 0.76 at 1-year and 0.71 at 5-year). The risk of death without appropriate ICD shock was higher in risk quintile 5 compared to quintile 1 (sub HR 5.8; 95%CI 3.1-11.0, P < 0.001). CONCLUSIONS: Our study demonstrated a good ability of the HF Meta-score to predict survival in HF patients treated with CRT-D as primary prevention. The HF Meta-score proved to be useful in identifying a subgroup with a significantly poor prognosis despite a CRT-D.