Feasibility and safety of left bundle branch area pacing in patients with septal hypertrophy.

INTRODUCTION: Left bundle branch area pacing (LBBAP) aims to provide physiological ventricular activation during pacing. Left ventricular septal hypertrophy (LVSH) might be challenging for LBBAP due to the thickness of the interventricular septum and potential presence of septal scar. This study assesses the feasibility, safety, and outcome of LBBAP in patients with LVSH using primarily stylet-driven leads (SDL). METHODS: Adult patients with LVSH who underwent LBBAP between March 2019 and November 2022 were enrolled. Baseline patient characteristics, procedural data and postprocedural results were collected. The feasibility of LBBAP in LVSH patients was compared to a cohort of LBBAP patients with normal septal wall thickness (NST). RESULTS: Seventeen LVSH and 133 NST patients underwent LBBAP with successful implantation achieved in 15 LVSH patients (88%). Mean implant depth was 17.2 ± 1.9 mm, with 53% proven left bundle branch (LBB) capture. Paced QRS duration (146 ± 14 ms) and V6 R-wave peak time (V6 RWPT; 79 ± 20 ms) were comparable between patients with and without septal hypertrophy, although patients with NST had higher rates of proven LBB capture (71% vs. 53%). In LVSH pacing thresholds (0.6 ± 0.3 V at 0.4 ms) and R-wave amplitude (13.9 ± 5.6 mV) were favorable and remained stable at follow-up. At 12 months, 87% of patients had stable or improved left ventricular ejection fraction. CONCLUSION: The results of the study indicate that LBBAP in patients with LVSH is safe and feasible and no lead-related complications were observed despite a mean implant depth exceeding 15 mm. LBBAP using SDL results in favorable pacing and electrocardiographic characteristics in LVSH patients, comparable to patients with NST.

Initial experience of left bundle branch area pacing using stylet-driven pacing leads: A multicenter study.

BACKGROUND: Left bundle branch area pacing (LBBAP) has been performed exclusively using lumen-less pacing leads (LLL) with fixed helix design. This registry study explores the safety and feasibility of LBBAP using stylet-driven leads (SDL) with extendable helix design in a multicenter patient population. METHODS: This study prospectively enrolled consecutive patients who underwent LBBAP for bradycardia pacing or heart failure indications at eight Belgian hospitals. LBBAP was attempted using SDL (Solia S60; Biotronik) delivered through dedicated delivery sheath (Selectra3D). Implant success, complications, procedural, and pacing characteristics were recorded at implant and follow-up. RESULTS: The study enrolled 353 patients (mean age 76 ± 39 years, 43% female). The mean number of implants per center was 25 (range: 5-162). Overall, LBBAP with SDL was successful in 334/353 (94%), varying from 93% to 100% among centers. Pacing response was labeled as left bundle branch pacing in 73%, whereas 27% were labeled as myocardial capture. Mean paced QRS duration and stimulus to left ventricular activation time measured 126 ± 21 ms and 74 ± 17. SDL-LBBAP resulted in low pacing thresholds (0.6 ± 0.4 V at 0.4 ms), which remained stable at 12 months follow-up (0.7 ± 0.3, p = .291). Lead revisions for SDL-LBBAP occurred in 5 (1.4%) patients occurred during a mean follow up of 9 ± 5 months. Five (1.4%) septal coronary artery fistulas and 8 (2%) septal perforations occurred, none of them causing persistent ventricular septal defects. CONCLUSION: The use of SDL to achieve LBBAP is safe and feasible, characterized by high implant success in low and high volume centers, low complication rates, and stable low pacing thresholds.

Left bundle branch area pacing using stylet-driven pacing leads with a new delivery sheath: A comparison with lumen-less leads.

INTRODUCTION: Left bundle branch area pacing (LBBAP) aims to achieve physiological pacing by capturing the conduction system in the area of the left bundle branch. LBBAP has exclusively been performed using lumen-less pacing leads (LLLs) with fixed helix design. This study explores the feasibility, safety, and pacing characteristics of LBBAP using stylet-driven leads (SDLs) with an extendable helix design. METHODS: Patients, in which LBBAP was attempted for bradycardia or heart failure pacing indications, were prospectively enrolled at the Ghent University Hospital. LBBAP was attempted with two different systems: 1/LLL with fixed helix (SelectSecure 3830, Medtronic Inc.) delivered through a preshaped sheath (C315His Medtronic Inc.) and 2/SDL with extendable helix (Solia S60, Biotronik, SE & CO) delivered through a new delivery sheath (Selectra 3D, Biotronik). RESULTS: The study enrolled 50 patients (mean age: 70 ± 14 years, 44% females). LBBAP with SDL was successful in 20/23 (87%) patients compared with 24/27 (89%) of patients in the LLL group (p = 0.834). Screw attempts, screw implant depth, procedural, and fluoroscopy times were comparable among both groups. Acute LBBAP thresholds were low and comparable between SDL and LLL (0.5 ± 0.15 V vs. 0.4 ± 0.17 V, p = 0.251). Pacing thresholds remained low at 3 ± 2.1 months of follow up in both groups and no lead revisions were necessary. Postprocedural echocardiography revealed a septal coronary artery fistula in one patient with SDLLBBAP. CONCLUSION: LBBAP using stylet-driven pacing leads is feasible and yields comparable implant success to LBBAP with LLLs. LBBAP thresholds are low and comparable with both types of leads.

Perimembranous ventricular septal defect following His bundle lead implantation.

His bundle pacing (HBP) offers physiologic pacing by placing the pacing lead directly to the His bundle. We present a case in which a HBP lead, implanted at the fragile membranous septum, resulted in a persistent restrictive perimembranous ventricular septal defect (VSD). This complication of HBP has not been reported before but brings new insights in the discussion regarding the optimal position of a pacing lead in the ventricular septum. The fragility of the membranous septum and low rate of spontaneous closure of membranous VSD, might favor lead placement in the muscular septum when aiming for physiologic pacing.

Feasibility of His-bundle pacing in patients with conduction disorders following transcatheter aortic valve replacement.

BACKGROUND: Conduction disorders requiring permanent pacemaker implantation occur frequently after transcatheter aortic valve replacement (TAVR). This multicenter study explored the feasibility and safety of His bundle pacing (HBP) in TAVR patients with a pacemaker indication to correct a TAVR-induced left bundle branch block (LBBB). METHODS: Patients qualifying for a permanent pacemaker implant after TAVR were planned for HBP implant. HBP was performed using the Select Secure (3830; Medtronic) pacing lead, delivered through a fixed curve or deflectable sheath (C315HIS or C304; Medtronic). Successful HBP was defined as selective or nonselective HBP, irrespective of LBB recruitment. Successful LBBB correction was defined as selective or nonselective HBP resulting in paced QRS morphology similar to pre-TAVR QRS and paced QRS duration (QRSd) less than 120 milliseconds with thresholds less than 3.0 V at 1.0-millisecond pulse width. RESULTS: The study enrolled 16 patients requiring a permanent pacemaker after TAVR (age 85 ± 4 years, 31% female, all LBBB; QRSd: 161 ± 14 milliseconds). Capture of the His bundle was achieved in 13 of 16 (81%) patients. HBP with LBBB correction was achieved in 11 of 16 (69%) and QRSd narrowed from 162 ± 14 to 99 ± 13 milliseconds and 134 ± 7 milliseconds during S-HBP and NS-HBP, respectively (P = .005). At implantation, mean threshold for LBBB correction was 1.9 ± 1.1 V at 1.0 millisecond. Thresholds remained stable at 11 ± 4 months follow-up (1.8 ± 0.9 V at 1.0 millisecond, P = .231 for comparison with implant thresholds). During HBP implant, one temporary complete atrioventricular block occurred. CONCLUSION: Permanent HBP is feasible in the majority of patients with TAVR requiring a permanent pacemaker with the potential to correct a TAVR-induced LBBB with acceptable pacing thresholds.

Diagnostic accuracy of R-wave detection by insertable cardiac monitors.

BACKGROUND: Insertable cardiac monitors (ICM) allow prolonged rhythm monitoring, but the diagnostic performance can be hampered by false positive arrhythmia alerts related to inadequate R-wave sensing. This study assesses the prevalence and predictors of inadequate R-wave sensing (both over- and undersensing) among different ICM types. METHODS: Patients implanted with an ICM at Ghent University Hospital between January 2017 and August 2018 were included. ICM tracings recorded at interrogation or transmitted by remote monitoring were reviewed for inadequate R-wave sensing leading to false arrhythmia alerts. Patient and implant characteristics were retrieved from the medical records and implant reports. RESULTS: The study screened 135 patients (age 59 ± 19 years, 44% female) implanted with different ICM types: Reveal LINQ™ and XT (Medtronic): n = 92 (68%), Confirm and Confirm Rx (Abbott): n = 35 (26%), and BioMonitor 2 (Biotronik): n = 8 (6%). ICM tracings were analyzed in 112 patients (83%). False arrhythmia alerts occurred in 22 (20%) patients, most frequently related to undersensing (77%). False diagnosis of bradycardia or pause was documented in 64%, false high ventricular rates in 14%, and false atrial fibrillation alerts in 22%. Occurrence of R-wave changes was not related to patient characteristics or implant R-wave sensing. A trend toward higher number of inadequate R-wave sensing seems to occur with nonparasternal implant sites (P = .074). CONCLUSIONS: False arrhythmia alerts due to inadequate R-wave sensing occurred in 20% of ICM patients independent of implant features and patient characteristics.

Different dynamics of new-onset electrocardiographic changes after balloon- and self-expandable transcatheter aortic valve replacement: Implications for prolonged heart rhythm monitoring.

BACKGROUND: New onset electrocardiographic (ECG) changes after transcatheter aortic valve replacement (TAVR) are used to assess the risk for late atrioventricular block. However, the time of ECG evaluation remains controversial. We aimed to compare the time course and dynamics of new onset ECG changes according to valve design in balloon- (BEV) and self-expandable (SEV) TAVR. METHODS AND RESULTS: This single center study enrolled 133 consecutive TAVR patients (28.6% SEV, 71.4% BEV). Patients with pre-existent permanent pacemaker implant (PPMI), procedural death or incomplete ECG registration were excluded. Standard 12­lead ECG was performed before the procedure, at 1, 24, 48 and 120 h and 1 month. In BEV patients, no significant PR prolongation occurred, whereas in SEV patients the PR interval prolonged significantly with 33.7 ± 22.0 ms (p < 0.001, compared to pre-TAVR) but only after 48 h after TAVR. Widening of QRS duration was comparable among both BEV and SEV patients (6.7 ± 21.5 versus 17.0 ± 26.9 ms, p = 0.061) and occurred immediately after TAVR. New-onset left bundle branch block was seen in 18.5% of BEV and 30.8% of SEV patients (p = 0.120) and occurred within 24 h after TAVR in both groups. Late PPMI (>24 h after TAVR) was higher in SEV compared to BEV patients (15.3% versus 1.5%, p = 0.008). CONCLUSION: Self-expandable valves cause more impairment in atrioventricular conduction with a delayed time course compared to balloon expandable valves. This might explain the higher pacemaker need beyond 24 h after TAVR. Our findings suggest that patients with self-expandable valves require at least 48 h ECG monitoring post TAVR.

How to deliver personalized cardiac resynchronization therapy through the precise measurement of the acute hemodynamic response: Insights from the iSpot trial.

INTRODUCTION: New pacing technologies offer a greater choice of left ventricular pacing sites and greater personalization of cardiac resynchronization therapy (CRT). The effects on cardiac function of novel pacing configurations are often compared using multi-beat averages of acute hemodynamic measurements. In this analysis of the iSpot trial, we explore whether this is sufficient. MATERIALS AND METHODS: The iSpot trial was an international, prospective, acute hemodynamic trial that assessed seven CRT configurations: standard CRT, MultiSpot (posterolateral vein), and MultiVein (anterior and posterior vein) pacing. Invasive and noninvasive blood pressure, and left ventricular (LV) dP/dtmax were recorded. Eight beats were recorded before and after an alternation from AAI to the tested pacing configuration and vice-versa. Eight alternations were performed for each configuration at each of the five atrioventricular delays. RESULTS: Twenty-five patients underwent the full protocol of eight alternations. Only four (16%) patients had a statistically significant >3 mm Hg improvement over conventional CRT configuration (posterolateral vein, distal electrode). However, if only one alternation was analyzed (standard multi-beat averaging protocol), 15 (60%) patients falsely appeared to have a superior nonconventional configuration. Responses to pacing were significantly correlated between the different hemodynamic measures: invasive systolic blood pressure (SBP) vs noninvasive SBP r = 0.82 (P < .001); invasive SBP vs LV dP/dt r = 0.57, r2 = 0.32 (P < .001). CONCLUSIONS: Current standard multibeat acquisition protocols are unfortunately unable to prevent false impressions of optimality arising in individual patients. Personalization processes need to include distinct repeated transitions to the tested pacing configuration in addition to averaging multiple beats. The need is not only during research stages but also during clinical implementation.

Failure to detect life-threatening arrhythmias in ICDs using single-chamber detection criteria.

BACKGROUND: There are anecdotal reports of sudden death despite a functional implantable cardioverter defibrillator (ICD). We sought to describe scenarios leading to fatal or near-fatal outcome due to inappropriately inhibited ICD therapy in devices programmed with single-chamber detection criteria. METHODS: Programmed settings, episode lists, and intracardiac electrograms from 24 patients with a life-threatening event (n = 12) or fatal outcome (n = 12) related to failed ventricular arrhythmia detection were used to clarify the underlying scenario. RESULTS: Fifty episodes of failed ventricular arrhythmia detection were identified and categorized into six scenarios: (1) spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) with a rate below the detection limits, (2) misclassification of polymorphic VT (PVT) or VF as supraventricular tachycardia (SVT), (3) misclassification of VT/VF as cluster of nonsustained VT episodes, (4) misclassification of monomorphic VT (MVT) as SVT, (5) inappropriate shock abortion, and (6) false termination detection. These scenarios occurred respectively 6, 9, 3, 9, 8, and 15 times. In 9/9 (100%) patients with PVT/VF classified as SVT, rate stability was active for rates ranging from 222 to 250 beats/min. MVT detected as SVT was due to the sudden onset criterion in 7/9 (78%) patients and twice a consequence of the rate stability criterion active for rates ranging from 200 to 250 beats/min. CONCLUSION: We describe six scenarios leading to failure of ventricular arrhythmia detection in a single-chamber detection setting withholding life-saving therapy. These scenarios are more likely to occur with high-rate programming and long detection times, especially if combined with rate stability and sudden onset.

Clinical assessment and comparison of annotation algorithms in high-density mapping of regular atrial tachycardias.

BACKGROUND: High-density automated mapping of regular atrial tachycardias (ATs) requires accurate assessment of local activation times (LATs). OBJECTIVE: To evaluate high-density mapping of ATs and compare the accuracy of different automated LAT annotation algorithms. METHODS: Fifteen patients underwent AT ablation guided by the automated ConfiDENSEۛ high-density mapping module (Carto 3 v4) allowing manual reannotation (edited maps). For each AT, unedited automated maps were reconstructed offline by three algorithms: maximum unipolar slope (LATSlope ), bipolar peak (LATPeak ), and a new hybrid annotation algorithm (LATHybrid ). Five blinded experts were asked to define the (1) tachycardia mechanism, (2) ablation target, and (3) level of difficulty of these unedited maps. RESULTS: Twenty-one ATs (cycle length 300 ± 46 ms, activation points 955 ± 421) were successfully ablated using LATHybrid guided ablation with manual editing in a small number of points. At 6 months, 14 (93%) of the patients were free of AT recurrences. Unedited LATHybrid maps showed the highest accuracy in defining the tachycardia mechanism (LATHybrid : 49% vs. LATPeak : 27% vs. LATSlope : 28%, P < 0.001) and ablation target (LATHybrid : 65% vs. LATPeak : 39% vs. LATSlope : 31%, P < 0.001). Overall, LATHybrid -annotated maps were graded as "easier to interpret" by the experts (difficulty score 2.3 ± 0.9) versus LATPeak (2.8 ± 1) and LATSlope (3.2 ± 0.8) (P < 0.001). Only 12% of the LATHybrid maps were annotated as uninterpretable compared to 31% of LATSlope and 45% of the LATPeak maps (P < 0.001). CONCLUSION: Automated LATHybrid annotation allows better and easier recognition of the tachycardia mechanism compared to automated LATPeak and LATSlope algorithms, although fully automated mapping still requires further improvements.

Biventricular Paced QRS Area Predicts Acute Hemodynamic CRT Response Better Than QRS Duration or QRS Amplitudes.

INTRODUCTION: Vectorcardiographic (VCG) QRS area of left bundle branch block (LBBB) predicts acute hemodynamic response in cardiac resynchronization therapy (CRT) patients. We hypothesized that changes in QRS area occurring with biventricular pacing (BV) might predict acute hemodynamic CRT response (AHR). METHODS AND RESULTS: VCGs of 624 BV paced electrocardiograms (25 LBBB patients with 35 different pacing configurations) were calculated according to Frank's orthogonal lead system. Maximum QRS vector amplitudes (XAmpl , YAmpl , ZAmpl , and 3DAmp ) and QRS areas (XArea , YArea , ZArea , and 3DArea ) in the orthogonal leads (X, Y, and Z) and in 3-dimensional projection were measured. Volume of the 3D vector loop and global QRS duration (QRSD) on the surface electrocardiogram were assessed. Differences (Δ) in VCG parameters between BV paced and LBBB QRS complexes were calculated. An increase of 10% in dP/dt max was considered as AHR. LBBB conduction is characterized by a large ZArea (109 µVs, interquartile range [IQR]:75;135), significantly larger than XArea (22 µVs, IQR:10;57) and YArea (44 µVs, IQR:32;62, P < 0.001). Overall, QRS duration, amplitudes, and areas decrease significantly with BV pacing (P < 0.001). Of all VCG parameters, 3DAmpl , Δ3DAmpl , ZArea, ΔZArea , Δ3DArea , and ΔQRSD differentiate AHR response from nonresponse (P < 0.05). ΔZArea predicted best positive AHR (area under the curve = 0.813) and outperformed any other VCG parameter or QRSD measurement. CONCLUSION: Of all VCG parameters, reduction in QRS area, calculated in Frank's Z lead, predicts acute hemodynamic response best. This method might be an easy, noninvasive tool to guide CRT implantation and optimization.

Automated verification of pulmonary vein isolation in radiofrequency- and cryoballoon-guided ablation.

BACKGROUND: Verification of pulmonary vein isolation (PVI) can be challenging due to the coexistence of pulmonary vein potentials and far-field potentials. This study aimed to prospectively validate a novel algorithm for automated verification of PVI in radiofrequency (RF)-guided and cryoballoon (CB)-guided ablation strategies. METHODS: A data set of 620 (RF: 516 EGMs and CB: 104 EGMs) bipolar electrograms (EGM), recorded by circular mapping catheter placed at the left atrium-pulmonary vein (PV) junction, were prospectively analyzed by a two-step algorithm. The algorithm differentiates isolated from nonisolated EGMs based on typology and specific parameters of the bipolar EGMs. EGMs were recorded at baseline and after proven isolation in RF- and CB-guided procedures. Additionally, in the RF group, EGMs during encircling of the PVs were analyzed. RESULTS: In the RF and CB group, the algorithm correctly identifies EGMs as isolated or nonisolated with respectively 93% and 96% sensitivity and 86% and 90% specificity. In the RF subgroups of (1) baseline and proven isolated EGMs, (2) EGMs during encircling, and (3) EGMs in redo procedures sensitivity was 96%, 88%, and 100%, respectively, with specificity of 81%, 91%, and 100%. Fourteen out of 14 (100%) reconnected PVs were correctly identified as containing PVPs. Eleven out of 12 (92%) failed freeze attempts were correctly identified as being nonisolated. CONCLUSION: We validated a two-step algorithm for automated PVI verification, applicable both for RF- and CB-guided PVI. The algorithm automatically differentiates isolated from nonisolated PVs with high accuracy and without the need for pacing maneuvers.

Dynamic filling parameters in patients with atrial fibrillation: differentiating rhythm induced from ventilation-induced variations in pulse pressure.

In patients with sinus rhythm, the magnitude of mechanical ventilation (MV)-induced changes in pulse pressure (PP) is known to predict the effect of fluid loading on cardiac output. This approach, however, is not applicable in patients with atrial fibrillation (AF). We propose a method to isolate this effect of MV from the rhythm-induced chaotic changes in PP in patients with AF. In 10 patients undergoing pulmonary vein ablation for treatment of AF under general anesthesia, ECG and PP waveforms were analyzed during apnea (T1) and during MV at tidal volumes of 8 ml/kg (T2) and 12 ml/kg (T3), respectively. In a first step, three mathematical models were compared in their ability to predict individual PP at T1. The best-fitting model was then selected as the reference to quantify the effects of MV on PP in these patients. A local polynomial regression model based on two preceding RR intervals (LOC2) was found to be superior over the quadratic models to predict PP. LOC2 was therefore selected to quantify variations in PP induced by MV. During T2 and T3, magnitude of PP deviations was related with the amplitude of tidal volume [mean bias error (SD) of -5 (6) and -8 (7) mmHg for T2 and T3, respectively; P = 0.003 repeated-measures ANOVA]. We conclude that LOC2 most accurately predicted rhythm-induced variations in PP. MV-induced deviations in PP can be quantified and may therefore provide a method to study cardiopulmonary interactions in the presence of arrhythmia.

Different Methods to Measure QRS Duration in CRT Patients: Impact on the Predictive Value of QRS Duration Parameters.

BACKGROUND: Measurements of QRS duration (QRSD) in patients undergoing cardiac resynchronization therapy (CRT) are not standardized. We hypothesized that both the measurement of QRSD and its predictive value on CRT response are sensitive to the method by which QRSD is measured. METHODS: Electrocardiograms (ECGs) pre- and post-CRT from 52 CRT patients (66 ± 12 years, 65% male) were retrospectively analyzed. Custom-made software was developed to measure global QRSD (QRSDglobal ) and lead-specific QRSD (QRSDI,II,III,aVR,aVL,aVF,V1,V2,V3,V4,V5,V6 ). QRSD was also assessed automatic by a routinely used ECG device. For each method we measured QRSD pre- and post-CRT and shortening of QRSD (∆QRSD). Response to CRT at 6 months was defined as an improvement of ≥1 class in New York Heart Association classification and an increase by >7.5% in left ventricular ejection fraction. RESULTS: The CRT response rate was 77% (n = 40). Different methods to measure QRSD show divergent nominal values before (median range 152-172 ms, P < 0.001) and after CRT (130-152 ms, P < 0.001). The predictive value of QRSD measurements for CRT response also varies significantly according to the method used (range AUC pre-CRT QRSD 0.400-0.580, P < 0.05; AUC post-CRT QRSD 0.447-0.768, P < 0.05; AUC ΔQRSD 0.540-0.858, P < 0.05). Global QRSD measurements revealed lower variability compared to lead-specific QRSD. CONCLUSION: Different methods to measure QRSD yield not only different nominal values but also influence the value of QRSD in predicting CRT response. Measuring QRSD by a global method can help to standardize QRSD measurements in future studies.

Variability in interpretation of the electrocardiogram in young athletes: an unrecognized obstacle for electrocardiogram-based screening protocols.

AIMS: To assess in young athletes (i) the variability in the percentage of abnormal electrocardiograms (ECGs) using different criteria and (ii) the variability in ECG interpretation among cardiologists and sport physicians. METHODS AND RESULTS: Electrocardiograms of 138 athletes were categorized by seven cardiologists according to the original European Society of Cardiology (ESC) criteria by Corrado (C), subsequently modified by Uberoi (U), Marek (M), and the Seattle criteria (S); seven sports physicians only used S criteria. The percentage of abnormal ECGs for each physician was calculated and the percentage of complete agreement was assessed. For cardiologists, the median percentage of abnormal ECGs was 14% [interquartile range (IQR) 12.5-20%] for C, 11% (IQR 9.5-12.5%) for U [not significant (NS) compared with C], 11% (IQR 10-13%) for M (NS compared with C), and 7% (IQR 5-8%) for S (P < 0.005 compared with C); complete agreement in interpretation was 64.5% for C, 76% for U (P < 0.05 compared with C), 74% for M (NS compared with C), and 84% for S (P < 0.0005 compared with C). Sport physicians classified a median of 7% (IQR 7-11%) of ECGs as abnormal by S (P = NS compared with cardiologists using S); complete agreement was 72% (P < 0.05 compared with cardiologists using S). CONCLUSION: Seattle criteria reduced the number of abnormal ECGs in athletes and increased agreement in classification. However, variability in ECG interpretation by cardiologists and sport physicians remains high and is a limitation for ECG-based screening programs.

Atrioventricular block precipitated by isoproterenol.

An isoproterenol infusion was administered during an electrophysiologic study (EPS) in a patient with a history of near syncope, left bundle branch block, and no documented atrioventricular (AV) block. Isoproterenol precipitated classic 2:1 Infra-Hisian AV block most probably proximal to the site of recording a His-Purkinje potential consistent with right bundle branch activity. Paroxysmal AV block also occurred during isoproterenol washout at a different site located distal to the presumed right bundle branch potential. Isoproterenol may be valuable diagnostically in an occasional patient suspected of AV block in whom an EPS is unrevealing and a drug challenge is negative.

Lead performance of stylet-driven leads in left bundle branch area pacing: Results from a large single-center cohort and insights from in vitro bench testing.

BACKGROUND: Left bundle branch area pacing (LBBAP) requires deep septal lead deployment for left-sided conduction stimulation. Advancing leads toward deep septal positions might add mechanical stress on these leads. Concerns about lead performance and reliability remain an unanswered question. OBJECTIVE: The purpose of this study was to analyze lead performance and integrity of stylet-driven pacing leads (SDLs) for LBBAP. METHODS: This study assessed lead fracture rates of SDL in a large single-center cohort of adult LBBAP patients. Fluoroscopic analysis of lead bending angulations at the septal insertion point and in vitro bench testing of lead preconditioning were performed to simulate clinical use conditions. Lead performance was compared between LBBAP and conventional right ventricular apical pacing (RVp) sites. RESULTS: The study included 325 LBBAP patients (66% male; age 71±15 years). During median follow-up of 18 months, 2 patients (0.6%) experienced conductor fracture between tip housing and ring electrode, whereas no such fractures occurred with RVp patients (n = 149; P = .22). X-ray analysis revealed that high lead bending angulations occurred in 1.3% of the patients. Accelerated bench testing of excessive preconditioned leads showcased a higher probability of early conductor fracture compared to standard preconditioned leads. CONCLUSION: The incidence of early conductor failure in LBBAP seems higher than with conventional RVp sites. The most vulnerable lead part seems to be the interelectrode space between the tip housing and ring electrode. Excessive angulation and preconditioning might contribute to early fatigue fracture.

Catheter ablation of atrial fibrillation in patients at low thrombo-embolic risk: efficacy and safety of a simplified periprocedural anticoagulation strategy.

BACKGROUND: To prevent thrombo-embolic (TE) events during ablation of atrial fibrillation (AF), warfarin is recommended in all patients irrespective of baseline TE risk. We evaluated the efficacy and safety of a simplified periprocedural anticoagulation strategy of aspirin (ASA) and low molecular weight heparin (LMWH) in patients at low TE risk. METHODS: We collected data from 214 low TE risk patients (CHADS2 score ≤1 and no warfarin at baseline) undergoing pulmonary vein isolation. After discontinuation of ASA, periprocedural antithrombotic therapy consisted of therapeutic subcutaneous LMWH injections (nadroparin 1 mL/kg once daily) from 10 days before until 10 days after the procedure, followed by ASA in all patients. At the time of procedure, transesophageal echocardiography (TEE) was not performed on a routine basis. During the procedure, unfractionated heparin was administered to achieve an ACT between 350 and 400 seconds. Data on TE events (stroke or transient ischemic attack), cardiac tamponade/perforation, and major vascular access complications within 3 months after the procedure were collected. RESULTS: Mean CHADS2 was 0.3 ± 0.5. TEE was performed in 3% of patients. No periprocedural TE events occurred. No cardiac tamponade/perforation was observed. Major vascular access complications occurred in 3 patients (1.4%). No permanent injury was observed (0%). CONCLUSION: In selected low TE risk patients undergoing ablation for AF, a short period of periprocedural therapeutic anticoagulation with LMWH together with aspirin is an effective and safe strategy to prevent TE events. If confirmed in a randomized trial, this approach might simplify periprocedural antithrombotic management in ablation of selected AF patients.