His-Optimized Cardiac Resynchronization Therapy to Maximize Electrical Resynchronization: A Feasibility Study

[Management of heart failure with His bundle pacing in right bundle branch block: case report]

La terapia de resincronización cardiaca mediante estimulación hisiana ha demostrado ser efectiva en pacientes con bloqueo de rama izquierda del haz de His e insuficiencia cardiaca. Paciente masculino, con 47 años de edad, con insuficiencia cardiaca, fracción de expulsión del 17% y miocardio dilatada idiopática, electrocardiograma en ritmo sinusal, bloqueo auriculoventricular de 1.er grado, intervalo PR 400 ms, bloqueo completo de rama derecha del haz de His, bloqueo del fascículo anterior de la rama izquierda del haz de His, duración del QRS 200 ms. Se decidió realizar estimulación selectiva del haz de His. La resincronización cardiaca biventricular convencional en pacientes con presencia de bloqueo completo de la rama derecha del haz de His no está indicada debido a la pobre respuesta al tratamiento. La estimulación hisiana permite reclutar la rama bloqueada y reestablecer la conducción a través de ella, de tal forma que, en ausencia de necrosis, se logre sincronía biventricular. En el caso presentado el reclutamiento de la rama derecha mediante estimulación hisiana se reflejó en el restablecimiento de la sincronía biventricular, medida por rastreo de marcas (speckle tracking) e incremento significativo de la fracción de expulsión del ventrículo izquierdo del 17 al 36.6%, con un incremento absoluto del 19.6%.

Cardiac resynchronization therapy has proven to be an effective therapy in patients with left bundle branch block and heart failure. Male, 47 years old, heart failure with a left ventricle ejection fraction of 17%, idiopathic heart failure. ECG with sinus rhythm, 1st degree AV block, PR 400 ms, complete right bundle branch block, anterior hemi-fascicle of the left bundle of His, and QRS duration 200 ms. We decided to perform a selective His bundle pacing. In patients with right bundle branch block the biventricular cardiac resynchronization is not indicated due to low treatment response. His bundle pacing allows recruiting the blocked branch and restoring conduction throughout it, therefore, in the absence of necrosis the biventricular synchrony is achieved. We presented a case of His bundle pacing with recruitment of the right bundle branch, which reestablish biventricular synchrony measured by speckle tracking, and with a significant increase of the left ventricle ejection fraction from 17 to 36.6%, with an absolute increase of 19.6%.

Electrocardiographic characterization of non-selective His-bundle pacing: validation of novel diagnostic criteria

AIMS

Permanent His-bundle (HB) pacing is usually accompanied by simultaneous capture of the adjacent right ventricular (RV) myocardium-this is described as a non-selective (ns)-HB pacing. It is of clinical importance to confirm HB capture using standard electrocardiogram (ECG). Our aim was to identify ECG criteria for loss of HB capture during ns-HB pacing.

METHODS AND RESULTS

Patients with permanent HB pacing were recruited. Electrocardiograms during ns-HB pacing and loss of HB capture (RV-only capture) were obtained. Electrocardiogram criteria for loss/presence of HB capture were identified. In the validation phase, these criteria and the 'HB ECG algorithm' were tested using a separate, sizable set of ECGs. A total of 353 ECG (226 ns-HB and 128 RV-only) were obtained from 226 patients with permanent HB pacing devices. QRS notch/slur in left ventricular leads and R-wave peak time (RWPT) in lead V6 were identified as the best features for differentiation. The 'HB ECG algorithm' based on these features correctly classified 87.1% of cases with sensitivity and specificity of 93.2% and 83.9%, respectively. The criteria for definitive diagnosis of ns-HB capture (no QRS slur/notch in Leads I, V1, V4-V6, and the V6 RWPT ≤ 100 ms) presented 100% specificity.

CONCLUSION

A novel ECG algorithm for the diagnosis of loss of HB capture and criteria for definitive confirmation of HB capture were formulated and validated. The algorithm might be useful during follow-up and the criteria for definitive confirmation of ns-HB capture offer a simple and reliable ancillary procedural endpoint during HB device implantation.

His bundle pacing: Tips and tricks

His bundle (HB) pacing is an established modality for achieving physiological pacing with a low risk of long-term lead-related complications. The development of specially designed lead and delivery tools has improved the feasibility and safety of HB pacing (HBP). Knowledge of the anatomy of HB region and the variations is essential for successful implantation. Newer delivery systems have further improved procedural outcomes. Challenging implant cases can be successfully performed by reshaping the current sheaths, using "sheath in sheath" technique or "two-lead implantation technique." Special attention to the lead parameters at implant, programming, and follow-up is necessary for successful long-term outcomes with HBP. Widespread use of HBP by electrophysiologists and further advances in dedicated delivery systems and leads are essential to further improve the effectiveness of the implantation.

Cardiac resynchronization therapy in heart failure patients: tough road but clear future

Cardiac resynchronization therapy (CRT) based on biventricular pacing (BVP) is an invaluable intervention currently used in heart failure (HF) patients. The therapy involves electromechanical dyssynchrony, which can not only improve heart function and quality of life but also reduce hospitalization and mortality rates. However, approximately 30% to 40% of patients remain unresponsive to conventional BVP in clinical practice. In the recent years, extensive research has been employed to find a more physiological approach to cardiac resynchronization. The His-Purkinje system pacing (HPSP) including His bundle pacing (HBP) and left bundle branch area pacing (LBBaP) may potentially be the future of CRT. These technologies present various advantages including offering an almost real physiological pacing, less complicated procedures, and economic feasibility. Additionally, other methods, such as isolated left-ventricular pacing and multipoint pacing, may in the future be important but non-mainstream alternatives to CRT because currently, there is no strong evidence to support their effectiveness. This article reviews the current situation and latest progress in CRT, explores the existing technology, and highlights future prospects in the development of CRT.

Left bundle branch pacing with optimization of cardiac resynchronization treatment: A case report

BACKGROUND

Cardiac resynchronization therapy (CRT) is a well-established therapy for patients with cardiomyopathy.

CASE SUMMARY

The patient underwent left bundle branch area and left ventricular (reaching the left ventricular lateral vein through the coronary sinus) pacing. The optimal CRT was performed under the right bundle branch of the patient by adjusting the optimal a-v and v-v interphases to achieve the maximal benefit of the treatment.

CONCLUSION

The patient was diagnosed with left bundle branch block and heart failure. A left bundle branch area pacemaker assisted in correcting the complete left bundle branch block. However, the shorter QRS wave shape after pacemaker implantation through the left bundle branch area indicated a complete right bundle branch block pattern. Hence, the left bundle branch area pacemaker is not always considered as the optimal treatment. The left bundle branch pacing with the optimization of cardiac resynchronization treatment may serve as a new CRT strategy.

Clinical outcomes of His-Purkinje conduction system pacing

His-Purkinje conduction system pacing (HPCSP) in the form of His bundle pacing (HBP) and left bundle branch pacing (LBBP) allows normal left ventricular activation, thereby preventing the adverse consequences of right ventricular pacing. HBP has been established for several years with centers from China, Europe, and North America reporting their experience. There is international guidance as to how to implant such systems with the differing patterns of His bundle capture clearly described. LBBP is a more recent innovation with potential advantages including improved pacing parameters. HPCSP has been extensively studied in a variety of indications including cardiac resynchronization therapy, atrioventricular node ablation, and bradycardia pacing. This review will focus on the clinical outcomes of HPCSP including mortality and morbidity of heart failure hospitalization and symptoms.

[Indications for His bundle and left bundle branch pacing]

His bundle pacing (HBP) allows ventricular excitation through the entire cardiac conduction system, resulting in a better synchronicity and efficacy of contraction compared to myocardial pacing. Due to better, dedicated implantation tools and exact practical implantation recommendations, HBP has developed into a form of stimulation that can be successfully applied with reasonable time and effort in >90% of patients. The rate of lead dislodgement and threshold increase is similar to conventional pacemaker systems. Despite a rather weak data base and a paucity of randomized trials, HBS represents an alternative to conventional right or biventricular pacing in the following conditions: (1) high-degree atrioventricular (AV) block with expected ventricular pacing >20% of the time, (2) AV block 1st degree with long PQ (alone or in combination with intermittent 2nd to 3rd degree AV block or sick sinus syndrome), (3) AV node ablation due to refractory atrial fibrillation, and (4) upgrade in pacing-induced cardiomyopathy. Moreover, HBP may be useful in context with cardiac resynchronization therapy (CRT). Left bundle branch block below the level of His represents a limitation of HBP. Therefore, more recently left bundle branch pacing (LBBP) has been introduced to correct left bundle branch block. LBBP seems to be possible in a wider anatomic area and may be easier to implant. However, LBBP requires active screw-in of the lead deep into the ventricular septum. Experience with this new technique is limited, particularly regarding long-term performance.

The efficacy of left bundle branch area pacing compared with biventricular pacing in patients with heart failure: A matched case-control study

BACKGROUND

Left bundle branch area pacing (LBBAP) was reported to improve cardiac function by correcting complete left bundle branch block (CLBBB). Our study aimed to compare the efficacy of LBBAP and biventricular pacing (BIVP) in heart failure patients with CLBBB.

METHODS

Ten patients prospectively underwent LBBAP (LBB-CRT group) and 30 patients received BIVP (BIV-CRT group) were matched using propensity score matching. LBBAP was achieved by the trans-interventricular septum method. Echocardiography, electrocardiogram, NYHA classification, and blood B-type natriuretic peptide concentration were evaluated at preimplantation and at 6-month follow up. CRT response was defined as at least 15% decrease in left ventricular end-systolic volume.

RESULTS

In the LBB-CRT group, CLBBB were successfully corrected by LBBAP with no complications. QRS duration (QRSd) significantly decreased after implantation in both groups, and the decrease of QRSd in the LBB-CRT group was significantly greater than that in the BIV-CRT group (60.80 ± 20.09 vs. 33.00 ± 21.48 ms, p = .0009). The echocardiographic measurements including left ventricular end-diastolic diameter, left ventricular end-systolic diameter, and left ventricular ejection fraction significantly improved after 6 months in both groups. The response rate was significantly higher in LBB-CRT group than BIV-CRT group (100.00% vs. 63.33%, p = .038). The percentage of patients in New York Heart Association classification Grades I and II was significantly higher in the LBB-CRT group compared with that in the BIV-CRT group (median 1.5 vs. 2.0, p = .029) at 6-month follow-up.

CONCLUSIONS

It is effective and safe to correct CLBBB with LBBAP in heart failure patients. Compared with BIVP, LBBAP can better optimize electrical synchrony and improve cardiac function.

Year in Review in Cardiac Electrophysiology

In the past year, there have been numerous advances in our understanding of arrhythmia mechanisms, diagnosis, and new therapies. We have seen advances in basic cardiac electrophysiology with data suggesting that secretoneurin may be a biomarker for patients at risk of ventricular arrhythmias, and we have learned of the potential role of an NPR-C (natriuretic peptide receptor-C) in atrial fibrosis and the role of an atrial specific 2-pore potassium channel TASK-1 as a therapeutic target for atrial fibrillation. We have seen studies demonstrating the role of sensory neurons in sleep apnea-related atrial fibrillation and the association between bariatric surgery and atrial fibrillation ablation outcomes. Artificial intelligence applied to electrocardiography has yielded estimates of age, sex, and overall health. We have seen new tools for collection of patient-centered outcomes following catheter ablation. There have been significant advances in the ability to identify ventricular tachycardia termination sites through high-density mapping of deceleration zones. We have learned that right ventricular dysfunction may be a predictor of survival benefit after implantable cardioverter-defibrillator implantation in patients with nonischemic cardiomyopathy. We have seen further insights into the role of His bundle pacing on improving outcomes. As our understanding of cardiac laminopathies advances, we may have new tools to predict arrhythmic event rates in gene carriers. Finally, we have seen numerous advances in the treatment of arrhythmias in patients with congenital heart disease.

Left bundle branch area pacing delivery of cardiac resynchronization therapy and comparison with biventricular pacing

AIMS

This multicentre observational study aimed to prospectively assess the efficacy of left bundle branch area pacing (LBBAP) in heart failure patients with left bundle branch block (LBBB) and compare the 6-month outcomes between LBBAP and biventricular pacing (BVP).

METHODS AND RESULTS

Consecutive patients with LBBB and left ventricular ejection fraction (LVEF) ≤ 35% were prospectively recruited if they had undergone LBBAP as a primary or rescue strategy from three separate centres from March to December 2018. Patients who received BVP in 2018 were retrospectively selected by using 2 to 1 propensity score matching to minimize bias. Implant characteristics and echocardiographic parameters were assessed during the 6-month follow-up. LBBAP procedure succeeded in 81.1% (30/37) of patients, with selective LBBAP in 10 patients, and 3 of 20 patients combined non-selective LBBAP and LV lead pacing for further QRS narrowing. LBBAP resulted in significant QRS narrowing (from 178.2 ± 18.8 to 121.8 ± 10.8 ms, P < 0.001, paced QRS duration ≤ 130 ms in 27 patients) and improved LVEF (from 28.8 ± 4.5% to 44.3 ± 8.7%, P < 0.001) during the 6-month follow-up. The comparison between 27 patients with LBBAP alone and 54 of 130 matching patients with BVP showed that LBBAP delivered a greater reduction in the QRSd (58.0 vs. 12.5 ms, P < 0.001), a greater increase in LVEF (15.6% vs. 7.0%, P < 0.001), and greater echocardiographic (88.9% vs. 66.7%, P = 0.035) and super response (44.4% vs. 16.7%, P = 0.007) to cardiac resynchronization therapy.

CONCLUSIONS

LBBAP could deliver cardiac resynchronization therapy in most patients with heart failure and LBBB, and might be a promising alternative resynchronization approach to BVP.

Programming and follow-up of patients with His bundle pacing

His bundle pacing (HBP) is being increasingly adopted worldwide, with the aim of providing more physiological stimulation of the heart as opposed to right ventricular pacing or as an alternative to cardiac resynchronization therapy (CRT). Current devices are not specifically designed for HBP, which gives rise to programming challenges. This article aims to provide practical recommendations for HBP programming and follow-up.

PR Prolongation predicts inadequate resynchronization with biventricular pacing in left bundle branch block

BACKGROUND

PR interval prolongation is associated with poor outcome after cardiac resynchronization therapy (CRT) among patients with left bundle branch block (LBBB) but the mechanisms are unknown. We investigated clinical outcomes, electrocardiogram (ECG), and echocardiogram changes after CRT by PR interval.

METHODS

This is a retrospective study of CRT recipients with a baseline ejection fraction ≤35% and ECG showing sinus rhythm and LBBB. Patients were stratified by baseline PR interval quartile and the primary combined endpoint was time to heart transplantation, left ventricular assist device (LVAD) implantation, or death. ECG, echocardiogram, and clinical variables were compared to identify mechanisms for observed differences in outcomes.

RESULTS

Of 291 eligible patients, the mean age was 65 years, 60% were male, and 19% had prior atrial fibrillation. Patients with PR prolongation (quartile 4, PR > 200 ms) more frequently had a history of atrial fibrillation, coronary artery bypass graft surgery, prior implantable cardioverter defibrillator implantation, and use of amiodarone than patients in PR quartiles 1-3. A PR > 200ms was associated with an adjusted hazard ratio of 1.7 (95% CI: 1.1-2.5) for the primary endpoint. Patients with PR > 200 ms had less reduction in QRS duration and QRS area after CRT while having more increase in QT and QTc intervals than patients with PR ≤ 200 ms. No major differences were observed in echocardiography by baseline PR interval quartiles.

CONCLUSIONS

PR prolongation predicts shorter survival free of heart transplantation or LVAD implantation in patients with LBBB. This may be due to inadequate ventricular resynchronization.

His Bundle Pacing – Why Should You be Doing it?

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