Emerging Technologies in Cardiac Pacing.

Cardiac pacing to treat bradyarrhythmias has evolved in recent decades. Recognition that a substantial proportion of pacemaker-dependent patients can develop heart failure due to electrical and mechanical dyssynchrony from traditional right ventricular apical pacing has led to development of more physiologic pacing methods that better mimic normal cardiac conduction and provide synchronized ventricular contraction. Conventional biventricular pacing has been shown to benefit patients with heart failure and conduction system disease but can be limited by scarring and fibrosis. His bundle pacing and left bundle branch area pacing are novel techniques that can provide more physiologic ventricular activation as an alternative to conventional or biventricular pacing. Leadless pacing has emerged as another alternative pacing technique to overcome limitations in conventional transvenous pacemaker systems. Our objective is to review the evolution of cardiac pacing and explore these new advances in pacing strategies.

Early Experience of Left Bundle Branch Pacing with Lumenless Lead in a Single Center: A Case Series.

Left bundle branch pacing (LBBP) has been subject to increasing interest over the last few years due to its capacity for physiological conduction and its advantages compared to His bundle pacing. His bundle pacing has certain limitations, such as a small pacing area for the His bundle, a high threshold that leads to battery depletion, a low R-wave amplitude that may result in atrial or His oversensing, and ventricular signal undersensing. In this case series, four patients (two female and two male) aged 62.2 ± 8.4 years old with symptomatic sick sinus disease and no scar tissue in the interventricular septum underwent LBBP. All LBBPs were done with standard LBBP using a lumenless SelectSecure 3830 lead (Medtronic®, Minneapolis, USA) with a fixed helix. The lead parameters showed a good R-wave amplitudes (13 ± 7.4 mV) and a low threshold  (0.77 ± 0.17 V @ 0.4 ms). All patients were discharged on the next day. During follow-up period of 13.3 ± 12.9 months, all patients were well and no complications were noted. In conclusion, LBBP may be as an alternative of novel conduction pacing techniques and can be done relatively easy and safe, even with limited experience center.

Effect of scar and His-Purkinje and myocardium conduction on response to conduction system pacing.

INTRODUCTION: Conduction system pacing (CSP), in the form of His bundle pacing (HBP) or left bundle branch pacing (LBBP), is emerging as a valuable cardiac resynchronization therapy (CRT) delivery method. However, patient selection and therapy personalization for CSP delivery remain poorly characterized. We aim to compare pacing-induced electrical synchrony during CRT, HBP, LBBP, HBP with left ventricular (LV) epicardial lead (His-optimized CRT [HOT-CRT]), and LBBP with LV epicardial lead (LBBP-optimized CRT [LOT-CRT]) in patients with different conduction disease presentations using computational modeling. METHODS: We simulated ventricular activation on 24 four-chamber heart geometries, including His-Purkinje systems with proximal left bundle branch block (LBBB). We simulated septal scar, LV lateral wall scar, and mild and severe myocardium and LV His-Purkinje system conduction disease by decreasing the conduction velocity (CV) down to 70% and 35% of the healthy CV. Electrical synchrony was measured by the shortest interval to activate 90% of the ventricles (90% of biventricular activation time [BIVAT-90]). RESULTS: Severe LV His-Purkinje conduction disease favored CRT (BIVAT-90: HBP 101.5 ± 7.8 ms vs. CRT 93.0 ± 8.9 ms, p < .05), with additional electrical synchrony induced by HOT-CRT (87.6 ± 6.7 ms, p < .05) and LOT-CRT (73.9 ± 7.6 ms, p < .05). Patients with slow myocardium CV benefit more from CSP compared to CRT (BIVAT-90: CRT 134.5 ± 24.1 ms; HBP 97.1 ± 9.9 ms, p < .01; LBBP: 101.5 ± 10.7 ms, p < .01). Septal but not lateral wall scar made CSP ineffective, while CRT was able to resynchronize the ventricles in the presence of septal scar (BIVAT-90: baseline 119.1 ± 10.8 ms vs. CRT 85.1 ± 14.9 ms, p < .01). CONCLUSION: Severe LV His-Purkinje conduction disease attenuates the benefits of CSP, with additional improvements achieved with HOT-CRT and LOT-CRT. Septal but not lateral wall scars make CSP ineffective.

Comparison of automated subcutaneous defibrillator screening between different pacing sites in cardiac pacing device carriers.

AIMS: The compatibility of cardiac pacing with the presence of a subcutaneous implantable cardioverter-defibrillator (S-ICD) has been investigated, but S-ICD screening test results have not been compared among different pacing sites. The objective was to compare S-ICD screening results among different cardiac pacing sites and to assess the electrocardiographic predictors of success. METHODS AND RESULTS: This prospective single-centre study conducted automated S-ICD screening in 102 carriers of cardiac pacing devices in conduction system (CSP), biventricular (BVP), right ventricular outflow tract (RVOT), or right ventricular apex (RVA) pacing sites. The study included 102 patients: 40 with CSP (20 left bundle pacing and 20 His bundle pacing), 21 with BVP, and 20 and 21 with RVOT and RVA pacing, respectively. The percentage of positive screenings was significantly higher for CSP (97.5%) than for the other patient groups (BVP 71.4%, RVOT 70%, and RVA 19%). In multivariate analysis, positive screening was associated with a narrower QRS (OR 0.95 [0.92-0.98] P = 0.001) and higher R/T ratio in precordial leads (1.76 [1.18-2.61]). CONCLUSION: A higher S-ICD eligibility rate of cardiac pacing device carriers was obtained in CSP than in conventional pacing (RVA or RVOT) or BVP. The presence of narrower paced QRS width and paced corrected QT interval and of higher R/T ratio in precordial and limb leads are electrocardiographic predictors of a positive response to screening.

Left bundle branch area pacing in congenital heart disease.

AIMS: Left bundle branch area pacing (LBBAP) has been shown to be effective and safe. Limited data are available on LBBAP in the congenital heart disease (CHD) population. This study aims to describe the feasibility and safety of LBBAP in CHD patients compared with non-CHD patients. METHODS AND RESULTS: This is a single-centre, non-randomized observational study recruiting consecutive patients with bradycardia indication. Demographic data, ECGs, imaging, and procedural data including lead parameters were recorded. A total of 39 patients were included: CHD group (n = 13) and non-CHD group (n = 26). Congenital heart disease patients were younger (55 ± 14.5 years vs. 73.2 ± 13.1, P < 0.001). Acute success was achieved in all CHD patients and 96% (25/26) of non-CHD patients. No complications were encountered in either group. The procedural time for CHD patients was comparable (96.4 ± 54 vs. 82.1 ± 37.9 min, P = 0.356). Sheath reshaping was required in 7 of 13 CHD patients but only in 1 of 26 non-CHD patients, reflecting the complex and distorted anatomy of the patients in this group. Lead parameters were similar in both groups; R wave (11 ± 7 mV vs. 11.5 ± 7.5, P = 0.881) and pacing threshold (0.6 ± 0.3 V vs. 0.7 ± 0.3, P = 0.392). Baseline QRS duration was longer in the CHD group (150 ± 28.2 vs. 118.6 ± 26.6 ms, P = 0.002). Despite a numerically greater reduction in QRS and a similar left ventricular activation time (65.9 ± 6.2 vs. 67 ± 16.8 ms, P = 0.840), the QRS remained longer in the CHD group (135.5 ± 22.4 vs. 106.9 ± 24.7 ms, P = 0.005). CONCLUSION: Left bundle branch area pacing is feasible and safe in CHD patients as compared to that in non-CHD patients. Procedural and fluoroscopy times did not differ between both groups. Lead parameters were satisfactory and stable over a short-term follow-up.

The year in cardiovascular medicine 2020: arrhythmias.

of the progress in arrhythmias in 2020. RACE4 and ALL-IN indicated that integrated nurse-led care improves outcomes in AF patients.3,4 The same was reported for early rhythm control therapy15 and cryoablation as initial AF treatment.25,26 Subcutaneous ICD was non-inferior to classical transvenous ICD therapy in PRAETORIAN.54 One mechanistic study showed that autoantibodies against misexpressed actin, keratin, and connexin-43 proteins create a blood-borne biomarker profile enhancing diagnosis of Brugada syndrome.50 Another mechanistic study indicated that transseptal LV pacing yields similar improvement in contractility as His bundle pacing whilst being more easy to execute.44 In PRE-DETERMINE a simple-to-use ECG risk score improved risk prediction in patients with ischemic heart disease possibly enhancing appropriate ICD therapy in high risk patients.58.

Left bundle branch pacing: A comprehensive review.

Cardiac pacing is the only effective therapy for patients with symptomatic bradyarrhythmia. Traditional right ventricular apical pacing causes electrical and mechanical dyssynchrony resulting in left ventricular dysfunction, recurrent heart failure, and atrial arrhythmias. Physiological pacing activates the normal cardiac conduction, thereby providing synchronized contraction of ventricles. Though His bundle pacing (HBP) acts as an ideal physiological pacing modality, it is technically challenging and associated with troubleshooting issues during follow-up. Left bundle branch pacing (LBBP) has been suggested as an effective alternative to overcome the limitations of HBP as it provides low and stable pacing threshold, lead stability, and correction of distal conduction system disease. This paper will focus on the implantation technique, troubleshooting, clinical implications, and a review of published literature of LBBP.

Selective left bundle branch pacing for pediatric complete heart block.

Traditionally Right Ventricle has been the preferred site of pacing for the management of symptomatic brady-arrhythmias. The deleterious effect of chronic RV pacing has been shown by several studies. This has generated interest into a novel pacing strategy called physiological pacing wherein the His bundle or the left bundle is paced directly with 4.1 F pacing lead. Herewith we are reporting a case of congenital complete heart block in a 13-year-old child for whom selective left bundle branch pacing was done. This physiological pacing will ensure a synchronized contraction of the ventricles thereby avoiding the deleterious effect of RV pacing.

Impacts of Left Bundle/Peri-Left Bundle Pacing on Left Ventricular Contraction.

BACKGROUND: His-bundle pacing is an emerging routine technique that avoids pacing-dependent side effects. However, the success rate of His-bundle pacing is not 100%.Methods and Results:Left bundle pacing or peri-left bundle pacing (LBP/peri-LBP) are recently developed techniques that directly capture the left bundle or ventricular tissue near the left bundle. We evaluated the success rate of LBP/peri-LBP in patients whose treatment with His-bundle pacing failed. In addition, we evaluated left ventricular contraction and desynchrony after LBP/peri-LBP. CONCLUSIONS: LBP/peri-LBP is an alternative ventricular pacing method in atrioventricular block in patients with failure of His-bundle pacing.

Conduction system pacing learning curve: Left bundle pacing compared to His bundle pacing.

Introduction: Conduction system pacing (CSP), consisting of His bundle pacing (HBP) or left bundle branch area pacing (LBBAP) is a rapidly developing field. These pacing techniques result in single lead left ventricular resynchronisation. Understanding of the associated learning curve of the two techniques is an important consideration for new implanters/implanting centres. Methods: We conducted a review of the first 30 cases of both HBP and LBBAP at The Royal Brompton Hospital. The procedural duration and fluoroscopy time were used as surrogates for the learning curve of each technique. Results: Patient characteristics were similar in HBP and LBBAP groups; LV ejection fraction (46% vs 54%, p = 0.08), pre-procedural QRS duration (119 ms vs 128 ms, p = 0.32).Mean procedural duration was shorter for LBBAP than for HBP (87 vs 107mins, p = 0.04) and the drop in procedural duration was more marked in LBBAP, plateauing and remaining low at 80mins after the initial 10 cases. Fluoroscopic screening time mirrored procedural duration (8 min vs 16 min, p < 0.01). Discussion/Conclusion: Our data suggest that the CSP learning curve was shorter for LBBAP than for HBP and appears to plateaux after the first 10 cases, however the HBP learning curve is longer with continued improvement over the first 30 cases. The shorter learning curve of LBBAP in conjunction with the superior electrical parameters and simplified programming mean the establishment of a CSP program is potentially easier with LBBAP compared to with HBP.

Comparison of methods for delivering cardiac resynchronization therapy: electrical treatment targets and mechanisms of action.

INTRODUCTION: Cardiac resynchronization therapy (CRT) has been developed as a treatment for patients with conduction system dysfunction and impairment of ventricular performance. The aim is to restore more physiological cardiac activation and thereby improve cardiac function, symptoms, and outcomes. AREAS COVERED: In this review, we discuss potential electrical treatment targets for patients with heart failure and how these electrical treatment targets may determine the optimal pacing approach for delivering CRT. EXPERT OPINION: The most well-established method for delivering CRT is biventricular pacing (BVP). BVP improves symptoms and reduces mortality in patients with left bundle branch block (LBBB). However, patients continue to suffer from heart failure symptoms and decompensations despite receiving BVP. There may be scope to deliver more effective CRT since BVP does not restore physiological ventricular activation. Furthermore, the results with BVP in patients with non-LBBB conduction system disease have been generally disappointing. Alternative pacing approaches to BVP are now available, including conduction system pacing and left ventricular endocardial pacing. These newer pacing approaches offer exciting potential to not only offer an alternative to coronary sinus lead implantation in the case of implant failure but to potentially deliver more effective treatment in LBBB and maybe even extend the indications for CRT beyond LBBB.

Computational Modelling Enabling In Silico Trials for Cardiac Physiologic Pacing.

Conduction system pacing (CSP) has the potential to achieve physiological-paced activation by pacing the ventricular conduction system. Before CSP is adopted in standard clinical practice, large, randomised, and multi-centre trials are required to investigate CSP safety and efficacy compared to standard biventricular pacing (BVP). Furthermore, there are unanswered questions about pacing thresholds required to achieve optimal pacing delivery while preventing device battery draining, and about which patient groups are more likely to benefit from CSP rather than BVP. In silico studies have been increasingly used to investigate mechanisms underlying changes in cardiac function in response to pathologies and treatment. In the context of CSP, they have been used to improve our understanding of conduction system capture to optimise CSP delivery and battery life, and noninvasively compare different pacing methods on different patient groups. In this review, we discuss the in silico studies published to date investigating different aspects of CSP delivery.

High predictive value of paced QRS frequency in verification of left bundle branch pacing.

BACKGROUND: Left bundle branch area pacing (LBBAP) is a newer technique to deliver more synchronous left ventricular activation. Several criteria have been proposed, but not fully validated, to confirm LBBAP during implantation of the pacing lead. Spectral analysis has been used to characterize the frequency components of the clinical QRS utilizing the Fourier transform algorithm. We hypothesized that higher frequency content of the paced QRS complex may show predictive value of successful LBBAP. METHODS: We evaluated 84 patients with ejection fraction > 50%, who underwent LBB lead placement (n = 42) using ≥ 1 current criteria and right ventricular midseptal (RVsp) lead placement (n = 42) from 2000 to 2022. Time frequency analysis (Matlab) was used to determine the frequency content of the paced QRS complex. The centroid frequency (CF), which is the weighted average QRS frequency, was calculated. RESULTS: Patients in RVsp group had a longer paced QRS duration (155.6 ± 28.0 vs 127.1 ± 17.2, p < 0.002) compared to the LBBAP group. Of all standard ECG leads, the paced QRS in V2 gave the greatest difference of the CF of the LBBAP group at 8.8 ± 1.6 Hz versus 5.7 ± 0.7 Hz of the RVsp group. This difference was significant by both univariate (p < 0.003) and multivariate (p < 0.010) analysis. Predictive value of the CF for successful LBB pacing in lead V2 was highest with an AUC of 0.98. The sensitivity and specificity were 88.1% and 97.6%, respectively. CONCLUSION: Spectral analysis predicts successful LBBAP with higher frequency content when compared to RVsp pacing. Given the limitations to the current criteria to confirm LBBAP, intraprocedural use of frequency content analysis of the paced QRS complex in patients may prove useful at verifying LBB capture if verified by prospective clinical trials.

Comparison between conduction system pacing and cardiac resynchronization therapy in right bundle branch block patients.

A significant number of right bundle branch block (RBBB) patients receive cardiac resynchronization therapy (CRT), despite lack of evidence for benefit in this patient group. His bundle (HBP) and left bundle pacing (LBP) are novel CRT delivery methods, but their effect on RBBB remains understudied. We aim to compare pacing-induced electrical synchrony during conventional CRT, HBP, and LBP in RBBB patients with different conduction disturbances, and to investigate whether alternative ways of delivering LBP improve response to pacing. We simulated ventricular activation on twenty-four four-chamber heart geometries each including a His-Purkinje system with proximal right bundle branch block (RBBB). We simulated RBBB combined with left anterior and posterior fascicular blocks (LAFB and LPFB). Additionally, RBBB was simulated in the presence of slow conduction velocity (CV) in the myocardium, left ventricular (LV) or right ventricular (RV) His-Purkinje system, and whole His-Purkinje system. Electrical synchrony was measured by the shortest interval to activate 90% of the ventricles (BIVAT-90). Compared to baseline, HBP significantly improved activation times for RBBB alone (BIVAT-90: 66.9 ± 5.5 ms vs. 42.6 ± 3.8 ms, p < 0.01), with LAFB (69.5 ± 5.0 ms vs. 58.1 ± 6.2 ms, p < 0.01), with LPFB (81.8 ± 6.6 ms vs. 62.9 ± 6.2 ms, p < 0.01), with slow myocardial CV (119.4 ± 11.4 ms vs. 97.2 ± 10.0 ms, p < 0.01) or slow CV in the whole His-Purkinje system (102.3 ± 7.0 ms vs. 75.5 ± 5.2 ms, p < 0.01). LBP was only effective in RBBB cases if combined with anodal capture of the RV septum myocardium (BIVAT-90: 66.9 ± 5.5 ms vs. 48.2 ± 5.2 ms, p < 0.01). CRT significantly reduced activation times in RBBB in the presence of severely slow RV His-Purkinje CV (95.1 ± 7.9 ms vs. 84.3 ± 9.3 ms, p < 0.01) and LPFB (81.8 ± 6.6 ms vs. CRT: 72.9 ± 8.6 ms, p < 0.01). Both CRT and HBP were ineffective with severely slow CV in the LV His-Purkinje system. HBP is effective in RBBB patients with otherwise healthy myocardium and Purkinje system, while CRT and LBP are ineffective. Response to LBP improves when LBP is combined with RV septum anodal capture. CRT is better than HBP only in patients with severely slow CV in the RV His-Purkinje system, while CV slowing of the whole His-Purkinje system and the myocardium favor HBP over CRT.

Leadless biventricular left bundle and endocardial lateral wall pacing versus left bundle only pacing in left bundle branch block patients.

Biventricular endocardial (BIV-endo) pacing and left bundle pacing (LBP) are novel delivery methods for cardiac resynchronization therapy (CRT). Both pacing methods can be delivered through leadless pacing, to avoid risks associated with endocardial or transvenous leads. We used computational modelling to quantify synchrony induced by BIV-endo pacing and LBP through a leadless pacing system, and to investigate how the right-left ventricle (RV-LV) delay, RV lead location and type of left bundle capture affect response. We simulated ventricular activation on twenty-four four-chamber heart meshes inclusive of His-Purkinje networks with left bundle branch block (LBBB). Leadless biventricular (BIV) pacing was simulated by adding an RV apical stimulus and an LV lateral wall stimulus (BIV-endo lateral) or targeting the left bundle (BIV-LBP), with an RV-LV delay set to 5 ms. To test effect of prolonged RV-LV delays and RV pacing location, the RV-LV delay was increased to 35 ms and/or the RV stimulus was moved to the RV septum. BIV-endo lateral pacing was less sensitive to increased RV-LV delays, while RV septal pacing worsened response compared to RV apical pacing, especially for long RV-LV delays. To investigate how left bundle capture affects response, we computed 90% BIV activation times (BIVAT-90) during BIV-LBP with selective and non-selective capture, and left bundle branch area pacing (LBBAP), simulated by pacing 1 cm below the left bundle. Non-selective LBP was comparable to selective LBP. LBBAP was worse than selective LBP (BIVAT-90: 54.2 ± 5.7 ms vs. 62.7 ± 6.5, p < 0.01), but it still significantly reduced activation times from baseline. Finally, we compared leadless LBP with RV pacing against optimal LBP delivery through a standard lead system by simulating BIV-LBP and selective LBP alone with and without optimized atrioventricular delay (AVD). Although LBP alone with optimized AVD was better than BIV-LBP, when AVD optimization was not possible BIV-LBP outperformed LBP alone, because the RV pacing stimulus shortened RV activation (BIVAT-90: 54.2 ± 5.7 ms vs. 66.9 ± 5.1 ms, p < 0.01). BIV-endo lateral pacing or LBP delivered through a leadless system could potentially become an alternative to standard CRT. RV-LV delay, RV lead location and type of left bundle capture affect leadless pacing efficacy and should be considered in future trial designs.

Left bundle branch pacing in hypertrophic cardiomyopathy-a novel approach.

Symptomatic bradycardia attributed by sick sinus syndrome in hypertrophic cardiomyopathy (HCM) is not commonly seen. Dual chamber pacing with right ventricular apical lead placement is conventional strategy in such scenario. Now physiological pacing which includes left bundle branch (LBB) pacing emerging as new technology for pacemaker implantation. Use of this technique is difficult in HCM due to septal hypertrophy. There is no such case reported so far in the literature where LBB pacing was performed in adult HCM for sick sinus syndrome. Here we present a novel approach of treating irreversible, symptomatic sinus node dysfunction in non-obstructive HCM with implementation of left bundle pacing strategy. Pacing parameters remain stable after 3 months of follow-up.

Left Posterior Fascicular Pacing.

Left bundle branch pacing (LBBP) is emerging as an alternative to His bundle pacing that overcomes the latter's limitations. Several studies have reported on the safety, efficacy, and electrophysiological properties of LBBP, while postoperative success rates range from 80.5% to 94%. The left posterior fascicle is composed of broad bands of fibers coursing inferiorly and posteriorly toward the papillary muscle, while the anterior fascicle is a thin, tendon-like structure. We report a case of a 70-year-old man in whom left posterior fascicular pacing was done after LBBP failed. We were able to demonstrate all the features of left posterior fascicular capture, including fascicular potential and a left anterior hemiblock pattern, using surface 12-lead electrocardiography. Left posterior fascicular pacing could be an alternative technique when attempts to deploy LBBP fail.

Mid-term feasibility, safety and outcomes of left bundle branch pacing-single center experience.

BACKGROUND: His bundle pacing (HBP) has evolved as the most physiological form of pacing but associated with limitations. Recently, left bundle branch pacing (LBBP) is emerging as an effective alternative strategy for HBP. OBJECTIVES: Our study was designed to assess the feasibility, efficacy, electrophysiological parameters, and mid-term outcomes of LBBP in Indian population. METHODS: All patients requiring permanent pacemaker implantation for symptomatic bradycardia and heart failure were prospectively enrolled. Echocardiography, QRS duration, pacing parameters, left bundle (LB) potentials, paced QRS duration, and peak left ventricular activation time (pLVAT) were recorded. RESULTS: LBBP was successful in 93 out of 99 patients (94% acute success). Mean age was 62.6 ± 13 years, male 59%, diabetes 69%, and coronary artery disease 65%. Follow-up duration was 4.8 months (range1-12 months). Indication for pacing included atrioventricular (AV) block 43%, cardiac resynchronization therapy 44%, and AV node ablation 4%. LB potential was noted in 37 patients (40%). QRS duration reduced from 144.38 ± 34.6 at baseline to 110.8 ± 12.4 ms after LBBP (p < 0.0001). Pacing threshold was 0.59 ± 0.22 V and sensed R wave 14.14 ± 7.19 mV, and it remained stable during follow-up. Lead depth in the septum was 9.62 mm. LV ejection fraction increased from 44.96 to 53.3% after LBBP (p < 0.0001). One died due to respiratory tract infection on follow up. CONCLUSION: LBBP is a safe and effective strategy (94% acute success) of physiological pacing. The pacing parameters remained stable over a period of 12 months follow-up. LBBP can effectively overcome the limitations of HBP.

Left Bundle Pacing for Left Bundle Branch Block and Intermittent Third-Degree Atrioventricular Block in a MYH7 Mutation-Related Hypertrophic Cardiomyopathy With Restrictive Phenotype in a Child.

Hypertrophic cardiomyopathy (HCM) is a group of myocardial diseases defined by cardiac hypertrophy which cannot be explained by secondary causes with a non-dilated left ventricle and preserved or increased ejection fraction. Sometimes it can be combined with restrictive cardiomyopathy. Here we describe a very rare case of a 12-year-old girl with non-obstructive hypertrophic cardiomyopathy accompanied by restrictive phenotype, complete left bundle branch block and intermittent third-degree atrioventricular block, who presented with recurrent syncope. Her father was also found to have hypertrophic cardiomyopathy and treated with implantable cardioverter defibrillator for ventricular tachycardia. Her younger brother is currently asymptomatic but echocardiogram showed hypertrophic cardiomyopathy. Genetic analysis identified a heterozygous missense mutation (c.2155C>T, p.R719W) of MYH7 in the proband girl, her father and her brother. The girl was treated with left bundle pacing and recovered well. The case we present further demonstrates the feasibility of left bundle pacing in children.