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.

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.

Ablación de fibrilación auricular, ictus y hemorragia digestiva: desenlace fatal / Atrial fibrillation ablation, stroke, and hematemesis: fatal outcome

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