Improvement in electrocardiographic parameters of repolarization related to sudden death in patients with ventricular dysfunction and left bundle branch block after cardiac resynchronization through His bundle pacing.

BACKGROUND: Cardiac resynchronization therapy (CRT) through permanent His bundle pacing (p-HBP) normalizes interventricular conduction disorders and QRS. Similarly, there are immediate and long-term changes in repolarization, which could be prognostic of a lower risk of sudden death (SD) at follow-up. We aimed to compare the changes in different electrocardiographic (ECG) repolarization parameters related to the risk of SD before and after CRT through p-HBP. METHODS: In this prospective, descriptive single-center study (May 2019 to December 2021), we compared the ECG parameters of repolarization related to SD in patients with non-ischemic dilated cardiomyopathy, left bundle branch block (LBBB), and CRT indications, at baseline and after CRT through p-HBP. RESULTS: Forty-three patients were included. Compared to baseline, after CRT through p-HBP, there were immediate significant changes in the QT interval (ms): 445 [407.5-480] vs 410 [385-440] (p = 0.006), QT dispersion (ms): 80 [60-100] vs 40 [40-65] (p < 0.001), Tp-Te (ms): 90 [80-110] vs 80 [60-95] (p < 0.001), Tp-Te/QT ratio: 0.22 [0.19-0.23] vs 0.19 [0.16-0.21] (p < 0.001), T wave amplitude (mm): 6.25 [4.88-10] vs - 2.5 [- 7-2.25] (p < 0.001), and T wave duration (ms): 190 [157.5-200] vs 140 [120-160] (p = 0.001). In the cases of the corrected QT (Bazzett and Friederichia) and the Tp-Te dispersion, changes only became significant at 1 month post-implant (468.5 [428.8-501.5] vs 440 [410-475.25] (p = 0.015); 462.5 [420.8-488.8] vs 440 [400-452.5] (p = 0.004), and 40 [30-52.5] vs 30 [20-40] (p < 0.001), respectively) (Table 1). Finally, two parameters did not improve until 6 months post-implant: the rdT/JT index, 0.25 [0.21-0.28] baseline vs 0.20 [0.19-0.23] 6 months post-implant (p = 0.011), and the JT interval, 300 [240-340] baseline vs 280 [257-302] 6 months post-implant (p = 0.027). Additionally, most of the parameters continued improving as compared with immediate post-implantation. CONCLUSIONS: After CRT through His bundle pacing and LBBB correction, there was an improvement in all parameters of repolarization related to increased SD reported in the literature.

His bundle pacing success and electrical parameter stability regardless of three-dimensional transthoracic echocardiography lead localization.

BACKGROUND OR PURPOSE: His bundle pacing (HBP) is the most physiological form of ventricular pacing. Few prospective studies have analyzed lead localization using imaging techniques and its relationship with electrical parameters and capture patterns. The objective of this study is to examine the correlation between electrical parameters and lead localization using three-dimensional transthoracic echocardiography (3D TTE). METHODS: This single-center, prospective, nonrandomized clinical research study (January 2018 to June 2020) included patients with an indication of permanent pacing, in whom 3D TTE was performed to define lead localization as supravalvular or subvalvular. RESULTS: A total of 92 patients were included: 56.5% of leads were supravalvular, and 43.5% were subvalvular, which resembles previous anatomic descriptions of autopsied hearts of His bundle localization within the triangle of Koch (ToK). R-wave sensing was higher when the His lead was localized subvalvular instead of supravalvular. His lead localization was not associated with HBP threshold or impedance differences, nor with the two different HBP patterns of capture, or with the ability of HBP to correct baseline BBB. The thresholds remained stable during follow-up visits, regardless of His lead localization. Higher R-wave sensing was observed during follow-up than at baseline, mainly in the subvalvular His leads. However, lead impedances in both positions decreased during follow-up. CONCLUSIONS: Lead localization in relation to the tricuspid valve did not influence the electrical performance of HBPs. Wide anatomical variations of the His bundle within the ToK explain our findings, reinforcing the idea that the technique for HBP should be fundamentally guided by electrophysiological and not anatomical parameters.

Cardiac resynchronization therapy in non-ischemic cardiomyopathy: a comparative non-randomized study of His Bundle pacing versus biventricular pacing.

BACKGROUND: Cardiac resynchronization therapy (CRT) via permanent His bundle pacing (pHBP) has gained acceptance globally, but robust studies comparing pHBP-CRT with classic CRT are lacking. In this study, we aimed to compare the improvement in left ventricular ejection fraction (LVEF) after pHBP-CRT versus classic CRT. METHODS: This was a single-center study comparing a prospective series of pHBP-CRT with a historical series of CRT via classic biventricular pacing (BVP). Patients with non-ischemic cardiomyopathy, baseline LVEF < 35%, left bundle branch block (LBBB), and CRT indications were selected. RESULTS: Fifty-one patients underwent classic CRT and 52 patients underwent pHBP-CRT. In the classic CRT group, the median (interquartile range) basal LVEF was 30% (IQR, 29-35%) before implantation and 40% (35-48%) at follow-up. In the pHBP-CRT group, the median basal LVEF was 30% (28-34%) before implantation and 55% (45-60%) at follow-up, with significant differences between both modalities at follow-up (p = 0.001). The median long term His recruitment threshold with LBBB correction was 1.25 (1-2.5) V at 0.4 ms in cases of pHBP-CRT, compared to a left ventricular coronary sinus threshold of 1.25 (1-1.75) V in cases of classic CRT (p = 0.48). After CRT, the median paced QRS was 135 (120-145) ms for pHBP-CRT versus 140 (130-150) ms for BVP-CRT (p = 0.586). CONCLUSIONS: The improvement in LVEF was superior with pHBP-CRT than with classic CRT. The thresholds at follow-up were similar in both groups.

Time to -30°C as a predictor of acute success during cryoablation in patients with atrial fibrillation.

BACKGROUND: Freezing rate of second-generation cryoballoon (CB) is a biophysical parameter that could assist pulmonary vein isolation. The aim of this study is to assess freezing rate (time to reach -30°C ([TT-30C]) as an early predictor of acute pulmonary vein isolation using the CB. METHODS: Biophysical data from CB freeze applications within a multicenter, nation-wide CB ablation registry were gathered. Successful application (SA), was defined as achieving durable intraprocedural vein isolation. And SA with time to isolation under 60 s (SA-TTI<60) as achieving durable vein isolation in under 60 s. Logistic regressions were performed and predictive models were built for the data set. RESULTS: 12,488 CB applications from 1,733 atrial fibrillation (AF) ablation procedures were included within 27 centers from a Spanish CB AF ablation registry. SA was achieved in 6,349 of 9,178 (69.2%) total freeze applications, and SA-TTI<60 was obtained in 2,673 of 4,784 (55.9%) freezes where electrogram monitoring was present. TT-30C was shorter in the SA group (33.4 ± 9.2 vs 39.3 ± 12.1 s; p < 0.001) and SA-TTI<60 group (31.8 ± 7.6 vs. 38.5 ± 11.5 s; p < 0.001). Also, a 10 s increase in TT-30C was associated with a 41% reduction in the odds for an SA (odds ratio [OR] 0.59; 95% confidence interval [CI] 0.56-0.63) and a 57% reduction in the odds for achieving SA-TTI<60 (OR 0.43; 95% CI 0.39-0.49), when corrected for electrogram visualization, vein position, and application order. CONCLUSIONS: Time to reach -30°C is an early predictor of the quality of a CB application and can be used to guide the ablation procedure even in the absence of electrogram monitoring.

Effectiveness and safety of AV node ablation after His bundle pacing in patients with uncontrolled atrial arrhythmias.

INTRODUCTION: In patients with uncontrolled atrial fibrillation, atrioventricular (AV) node ablation after permanent His bundle pacing (p-HBP) could be a therapeutic option for heart rate (HR) control. We aimed to demonstrate the advantages of AV node ablation with p-HBP, and to describe its effectiveness and safety. METHODS: This descriptive observational study included patients with uncontrolled permanent atrial arrhythmias who were candidates for HR control (January 2019 to July 2020) and underwent p-HBP and AV node ablation. RESULTS: A total of 39 patients were included. The median left ventricular ejection fraction (LVEF) was 55% (45-60); 46.1% in NYHA class II and 43.6% in NYHA class III. p-HBP was achieved in 92.3% (n = 36), and AV node ablation was successfully performed in all patients. The LVEF improved in patients with reduced LVEF (baseline, 35% [23.8-45.3%]; follow-up, 40% [35-56.5%], p < 0.05); the NYHA class also showed improvement (baseline, 71.4% patients in class III and 7.1% in class II, and at follow-up, 78.6% patients in class II and 14.3% in class I). In patients with previously normal LVEF, LVEF remained stable; nevertheless, a significant NYHA class improvement was observed (baseline, 63.6% class II and 31.8% class III patients; follow-up, 54.5% class I and 45.5% class II patients). The His thresholds and lead parameter values did not significantly change during the follow-up and remained stable. CONCLUSIONS: In patients with uncontrolled atrial arrhythmias who underwent AV node ablation after p-HBP, the NYHA class improved and the LVEF increased in those with reduced baseline LVEF. The values of pacing parameters were acceptable and remained stable during the follow-up.

Electrocardiographic patterns predictive of left bundle branch block correction with His bundle pacing.

INTRODUCTION: Permanent His bundle pacing (p-HBP) could be an alternative for traditional cardiac resynchronization therapy (CRT), but an important limitation is that p-HBP cannot always correct the left bundle branch block (LBBB). The purpose of this article is to assess electrocardiographic patterns of LBBB that can predict electrocardiographic response (QRS narrowing) to His bundle pacing. METHODS: We designed a prospective descriptive study of patients with LBBB and CRT indication proposed for CRT by p-HBP. We analyzed the correlation between the different electrocardiographic patterns and the correction of conduction disturbance (LBBB). RESULTS: We included 70 patients. Pacing at the location where His bundle electrogram was recorded narrowed the QRS in 81.4% (n = 57). Basically, we identified two electrocardiographic patterns in lead V1: QS or rS. The QS pattern was a sensitivity of 56%, a specificity of 84.6%, and a positive predictive value (PPV) of 94.1% to predict the correction of the LBBB (area under the curve [AUC] = .70). In patients with rS pattern, a ratio between the descending and the ascending S wave component duration ≥0.64 was a very good predictor of the correction of the LBBB (AUC = .968); with a value ≥0.64, the sensitivity, specificity, and PPV was 92%, 100%, and 100%, respectively. CONCLUSIONS: In patients with LBBB and CRT indication, the QS pattern in lead V1 predicts the correction of the QRS with HBP. In the case of rS pattern in lead V1, the ratio descending/ascending S wave component duration has a strong correlation with the LBBB correction.

Early improvement of left ventricular ejection fraction by cardiac resynchronization through His bundle pacing in patients with heart failure.

AIMS: Permanent His bundle pacing (p-HBP) can correct intraventricular conduction disorders and could be an alternative to traditional cardiac resynchronization therapy (CRT) via the coronary sinus. We describe the short-term impact of HBP on left ventricular ejection fraction (LVEF) and improvement of left intraventricular synchrony. METHODS AND RESULTS: This prospective descriptive study, performed from January 2018 to February 2019, included patients with left bundle branch block (LBBB) and an CRT indication who were resynchronized by p-HBP. We used the Medtronic C315 His catheter or a combination of the CPS-Direct-Universal introducer, CPS-AIM™-Universal subselector (Abbot), and SelectSecure™ MRI-SureScan™ 3830 lead. Correction of the LBBB by HBP had been previously checked. At 1 month of follow-up, we analysed the quantification of LVEF and measurement of the delay of the septal wall with the posterior wall as a parameter of intraventricular synchrony. We included 48 patients with LBBB and an indication for CRT. With HBP, we corrected the LBBB in 81% of patients (n = 39), and we achieved cardiac resynchronization through permanent HBP in 92% of these patients (n = 36). Left ventricular ejection fraction and intraventricular mechanical resynchronization improved in all patients, which was demonstrated by echocardiography through the improvement of the delay of the septal wall with the posterior wall from 138 ms (range 131-151) to 41 ms (19-63). CONCLUSION: There is early improvement after p-HBP in LVEF and left ventricular electromechanical synchronization in patients with LBBB, heart failure, and an indication for CRT.

Exclusion of fluoroscopy use in catheter ablation procedures: six years of experience at a single center.

BACKGROUND: Nonfluoroscopic mapping systems have demonstrated significant reduction of radiation exposure in radiofrequency (RF) catheter ablation procedures. However, their use as only imaging guide is still limited. OBJECTIVE: To evaluate the usefulness of a completely nonfluoroscopic approach to catheter ablation of supraventricular arrhythmias using the Ensite-NavX™ electroanatomical navigation system. METHODS: During 6 years, all consecutive patients referred for RF catheter ablation of regular supraventricular tachycardia (SVT) were admitted for a "zero-fluoroscopy" approach and studied prospectively. The only exclusion criterion was the need to perform a transseptal puncture. RESULTS: A total of 340 procedures were performed on 328 patients (179 men, age 55.7 ± 18.6 years). One hundred fifty-three patients had typical atrial flutter (AFL), 146 had AV nodal reentrant tachycardia (AVNRT), 35 had AV reciprocating tachycardia (AVRT), 4 patients had incisional atrial flutter (IAF), and 2 had focal atrial tachycardia (AT). Procedural success was achieved in 337 of the cases (99.1%). In 322 (94.7%), the procedure was completed without any fluoroscopy use. Mean procedure time was 110.5 ± 51.8 minutes. Mean RF application time was 9.8 ± 12.8 minutes and the number of RF lesions was 16.43 ± 15.8. Only 1 major complication related to vascular access was recorded. During follow-up, there were 12 recurrences (3.5%) (8 patients from the AVNRT group, 4 patients from the AP group). CONCLUSION: RF catheter ablation of SVT with an approach completely guided by the NavX system and without use of fluoroscopy is feasible, safe, and effective.

Direct left ventricular endocardial pacing: an alternative when traditional resynchronization via coronary sinus is not feasible or effective.

BACKGROUND: Biventricular pacing through the coronary sinus (CS) is effective for the treatment of patients with heart failure and left bundle-branch block. However, this approach is not always feasible. Although surgical epicardial lead implantation is an alternative, the technique may be deleterious in some patients. Thus, direct left ventricular (LV) endocardial pacing under local anesthesia may be an option. OBJECTIVE: We describe our technique and analyze the results of direct LV endocardial pacing. METHOD: Fourteen patients with failed resynchronization via CS (April 2006-September 2011) were selected. Using a femoral approach, we performed transseptal puncture and LV mapping, then fixed the active lead where the longest electrical delay was observed; the generator was placed in the anterior thigh. For resynchronization, eight patients with a device previously implanted through the upper veins received a single-chamber generator that was set to the VVT mode to sense the subclavian pacing spike. Six patients received a complete femoral resynchronization system with either a defibrillator or pacemaker. Patients were followed for 6-54 months. RESULTS: The LV lead was successfully implanted in all cases. Two patients experienced excessive bleeding and two died during follow-up. All except one improved at least one New York Heart Association class and experienced improved left ventricle ejection fraction. One patient with recurrent episodes of ventricular fibrillation was asymptomatic. CONCLUSION: Direct LV endocardial pacing is safe and may be a less risky, more efficient alternative than surgical epicardial lead implantation for resynchronization via CS.

Ventricular resynchronization therapy by direct His-bundle pacing using an internal cardioverter defibrillator.

AIMS: Cardiac resynchronization therapy (CRT) has been demonstrated to improve the functional class of patients with refractory heart failure if QRS width is >120 ms. Addition of an internal cardioverter defibrillator diminishes the prevalence of mortality of such patients. The technique for CRT requires selective stimulation of the left ventricle (LV), commonly undertaken through the coronary sinus. This procedure is not always feasible. Direct His-bundle pacing (DHBP) might be an alternative for CRT. METHODS AND RESULTS: Patients were selected from a population with refractory heart failure derived for CRT and internal cardioverter defibrillator insertion. Of those, patients in whom LV stimulation via the coronary sinus was not achievable and DHBP obtained left bundle branch block disappearance were included. Direct His-bundle pacing corrected basal conduction disturbances in 13 of the 16 patients (81%) selected. In four patients in whom DHBP was attempted, the electrode was not successfully fixed. In the nine remaining patients, a definitive resynchronization by DHBP was achieved, with consequent improvement in functional class and parameters of LV function as assessed by echocardiography. CONCLUSION: Direct His-bundle pacing might be an alternative treatment for CRT in selected cases.

Permanent His-bundle pacing: seeking physiological ventricular pacing.

AIMS: Right ventricular apical pacing can have deleterious effects and the His bundle has been widely reported to be an alternative site. This paper presents our experience with permanent His-bundle pacing (HBP). METHODS AND RESULTS: Patients referred for pacemaker implants (regardless of block type) were screened to determine if temporary HBP corrected conduction dysfunctions (threshold < or =2.5 V for 1 ms) and provided infra-Hisian 1:1 conduction of at least 120 s/m. Of the 182 patients selected, HBP corrected conduction dysfunctions in 133 (73%) patients, 42 (32%) of whom were rejected for the permanent procedure due to high thresholds. His-bundle lead implantation was attempted in the remaining 91 patients and was successful in 59 (65% of all attempts, 44% of all possible cases). CONCLUSION: In some patients, permanent HBP may be an alternative to right ventricular apical pacing.

Implante de un desfibrilador biventricular con estimulación endocárdica transeptal de ventrículo izquierdo vía venosa femoral / Implantation via the femoral vein of a biventricular defibrillator with transseptal endocardial left ventricular pacing

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Posibilidades y realidades de la estimulación permanente del haz de His / The potential and reality of permanent his bundle pacing

La estimulación apexiana puede ser perjudicial. Intentamos averiguar cuántos pacientes propuestos para estimulación cardiaca definitiva podrían ser estimulados permanentemente en el haz de His y en cuántos se consigue. La totalidad de los bloqueos suprahisianos y la mayoría de los considerados «infrahisianos» (71,4%) se corrigen con la estimulación del His, pero sólo se consigue permanentemente en el 55% de los intentos y en el 35,4% de todos los casos posibles (AU)

Right ventricular apex pacing can have deleterious effects. Our aims were to investigate how many patients referred for permanent pacing were suitable candidates for permanent His bundle pacing, and to determine the proportion in whom such pacing was successful. All cases of suprahisian block and most cases of infrahisian block (71.4%) were corrected by temporary His bundle pacing. However, permanent His bundle pacing was achieved in only 55% of cases in which it was attempted, and in only 35.4% of all possible cases (AU)

The potential and reality of permanent his bundle pacing.

Right ventricular apex pacing can have deleterious effects. Our aims were to investigate how many patients referred for permanent pacing were suitable candidates for permanent His bundle pacing, and to determine the proportion in whom such pacing was successful. All cases of suprahisian block and most cases of infrahisian block (71.4%) were corrected by temporary His bundle pacing. However, permanent His bundle pacing was achieved in only 55% of cases in which it was attempted, and in only 35.4% of all possible cases.

[Permanent His-bundle pacing in patients with infra-Hisian atrioventricular block]. / Estimulación hisiana definitiva en pacientes con bloqueos infrahisianos.

INTRODUCTION AND OBJECTIVES: Permanent His-bundle pacing is effective in patients with supra-Hisian atrioventricular block. We report our experience in patients with infra-Hisian atrioventricular block. METHODS: The study involved selected patients referred for syncope and intraventricular conduction disturbance, infra-Hisian atrioventricular block, with left ventricular dyssynchrony and no coronary sinus access. All patients underwent electrophysiological study to evaluate infra-Hisian atrioventricular conduction, both at baseline and after flecainide administration. We selected patients with an indication for permanent pacing in whom His-bundle pacing produced a narrow QRS complex. Leads were implanted in the right atrium, in the bundle of His, and at the apex of the right ventricle, and connected to the atrial, left ventricular, and right ventricular terminals, respectively, of a biventricular pacemaker generator. All pacemakers were programmed in DDD mode with a left ventricle-right ventricle interval of 80 ms. RESULTS: Between February and December 2004, seven patients met the study's inclusion criteria. The His-bundle lead was implanted successfully in five. The His-bundle pacing threshold remained stable in two patients, whereas it increased in three. During follow-up, at between 2 and 12 months, no lead dislodgement or failure to capture was observed. Echocardiography did not disclose any deterioration in ventricular function, or any worsening of or new valvular incompetence, but showed that ventricular dyssynchrony had disappeared in previously affected patients. CONCLUSIONS: His-bundle pacing is the only pacing mode capable of inducing a physiologically normal ventricular contraction. It can be used in some patients with infra-Hisian atrioventricular block.

Estimulación hisiana definitiva en pacientes con bloqueos infrahisianos / Permanent his-bundle pacing in patients with infra-hisian atrioventricular block

Introducción y objetivos. La estimulación permanente del haz de His es eficaz en los bloqueos auriculoventriculares suprahisianos. Mostramos nuestra experiencia en bloqueos infrahisianos. Métodos. Seleccionamos a pacientes derivados por síncopes y trastornos de la conducción intraventricular, bloqueo auriculoventricular completo y con asincronía intraventricular izquierda con seno coronario no accesible. En todos se practicó un estudio electrofisiológico en el que se evaluó la conducción infrahisiana basal y tras la administración de flecainida. Entre los pacientes con indicación de marcapasos permanente se seleccionó a aquellos en los que la estimulación del haz de His provocaba un complejo QRS estrecho. Implantamos electrodos en la aurícula derecha, el haz de His y el ápex de ventrículo derecho, conectándolos a las salidas auricular, ventricular izquierda y ventricular derecha de un marcapasos biventricular. Se programaron en modo DDD con un intervalo ventrículo izquierdo-ventrículo derecho de 80 ms. Resultados. Desde febrero hasta diciembre de 2004 se estudió a 10 pacientes, de los que 7 cumplieron criterios de inclusión; en 5 pudo implantarse un electrodo hisiano. El umbral de estimulación hisiana permaneció estable en 2 y mostró incrementos en 3. Durante el seguimiento de 2 a 12 meses no se han observado dislocamientos o pérdidas de captura. Ecocardiográficamente no ha habido deterioro de la función ventricular ni incompetencias valvulares, y la asincronía intraventricular mejoró en el caso de que estuviera presente. Conclusiones. La estimulación hisiana constituye el único modo de provocar una contracción ventricular más fisiológica y su utilización es posible en algunos casos de bloqueo infrahisiano

Introduction and objectives. Permanent His-bundle pacing is effective in patients with supra-Hisian atrioventricular block. We report our experience in patients with infra-Hisian atrioventricular block. Methods. The study involved selected patients referred for syncope and intraventricular conduction disturbance, infra-Hisian atrioventricular block, with left ventricular dyssynchrony and no coronary sinus access. All patients underwent electrophysiological study to evaluate infra-Hisian atrioventricular conduction, both at baseline and after flecainide administration. We selected patients with an indication for permanent pacing in whom His-bundle pacing produced a narrow QRS complex. Leads were implanted in the right atrium, in the bundle of His, and at the apex of the right ventricle, and connected to the atrial, left ventricular, and right ventricular terminals, respectively, of a biventricular pacemaker generator. All pacemakers were programmed in DDD mode with a left ventricle-right ventricle interval of 80 ms. Results. Between February and December 2004, seven patients met the study's inclusion criteria. The His-bundle lead was implanted successfully in five. The His-bundle pacing threshold remained stable in two patients, whereas it increased in three. During follow-up, at between 2 and 12 months, no lead dislodgement or failure to capture was observed. Echocardiography did not disclose any deterioration in ventricular function, or any worsening of or new valvular incompetence, but showed that ventricular dyssynchrony had disappeared in previously affected patients. Conclusions. His-bundle pacing is the only pacing mode capable of inducing a physiologically normal ventricular contraction. It can be used in some patients with infra-Hisian atrioventricular block

Cardiac resynchronization through selective His bundle pacing in a patient with the so-called InfraHis atrioventricular block.

We present a case of infraHis AV block in which selective His bundle pacing with His-ventricular conduction through the conduction system was accomplished. While further investigations are developed, this approach may be an alternative for cardiac resynchronization in cases of difficult coronary sinus access.