Background: Left bundle branch pacing (LBBP) has emerged as an alternative to biventricular pacing (BVP) for delivering cardiac resynchronization therapy. We sought to compare the acute improvement of electrical and mechanical synchrony, and hemodynamics between LBBP and BVP in patients with heart failure and left bundle branch block. Methods: LBBP and BVP were performed and compared in a crossover fashion in patients with heart failure and left bundle branch block undergoing cardiac resynchronization therapy implantation. Electrical synchrony was assessed by QRS duration and area, mechanical synchrony by the SD of time to peak velocity of 12 left ventricular segments (Ts-SD) and interventricular mechanical delay, and hemodynamics by the maximum rate of left ventricular pressure rise (dP/dt _max ). Results: Twenty-one patient with heart failure and left bundle branch block (mean age 67±10 years, 48% male, and 90% nonischemic cause) were included. Both LBBP and BVP provided significant improvements in electrical and mechanical synchrony, and hemodynamics compared to the baseline. Compared with BVP, LBBP achieved a larger reduction in QRS duration (−11 ms [95% CI, −17 to −4 ms]; P =0.003) and QRS area (−85 µVs [95% CI, −113 to −56 µVs]; P <0.001); LBBP achieved a greater decrease in Ts-SD (−14 ms [95% CI, −21 to −7 ms]; P =0.001), with no significant difference in interventricular mechanical delay (−2 ms [95% CI, −13 to 8 ms]; P =0.63). The increase in dP/dt _max from LBBP was significantly higher than that from BVP (6% [95% CI, 2%–9%]; P =0.002). Conclusions: LBBP delivers greater acute electrical and mechanical resynchronization and hemodynamic improvement than BVP in predominantly nonischemic heart failure patients with left bundle branch block. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04505384.

BACKGROUND: Left bundle branch-optimized cardiac resynchronization therapy (LOT-CRT) has shown encouraging results for QRS duration reduction and heart function improvement. However, the feasibility and efficacy of LOT-CRT have not been well established in intraventricular conduction delay patients. This study aims to assess and compare the efficacy and clinical outcome of CRT based on left bundle branch pacing, combined with coronary sinus left ventricular pacing (LOT-CRT) with CRT via biventricular pacing (BiV-CRT) in intraventricular conduction delay patients indicated for CRT. METHODS: Consecutive patients with intraventricular conduction delay and CRT indications were assigned nonrandomized to LOT-CRT (n=30) or BiV-CRT (n=55). Addition of the left bundle branch pacing (or coronary venous) lead was at the discretion of the implanting physician guided by suboptimal paced QRS complex and on clinical grounds. Echocardiographic parameters and clinical characteristics were accessed at baseline and during 2-years’ follow-up. RESULTS: Success rate for LOT-CRT and BiV-CRT was 96.8% and 96.4%. LOT-CRT had greater reduction of QRS duration compared with BiV-CRT (42.7±17.4 ms versus 21.9±21.5 ms; P <0.001). Higher left ventricular ejection fraction was also achieved in LOT-CRT than BiV-CRT at 6-month (36.7±9.8% versus 30.5±6.4%; P <0.05), 12-month (34.8±7.6% versus 30.3±6.2%; P <0.05), 18-month (36.3±7.9% versus 28.1±6.6%; P <0.005), and 24-month follow-up (37±9.5% versus 30.5±7%; P <0.05). Adverse clinical outcomes including heart failure rehospitalization and mortality were lower in LOT-CRT group for 24 months follow-up (hazard ratio, 0.33; P =0.035). CONCLUSIONS: LOT-CRT improves ventricular electrical synchrony and may provide greater clinical outcomes as compared with BiV-CRT in intraventricular conduction delay patients. These findings need further evaluation in future randomized controlled trials.

Cardiac resynchronization therapy (CRT) nonresponders account for nearly 30% of CRT candidates. Left-bundle branch pacing (LBBP) is an alternative to CRT. This study aimed to evaluate the feasibility, clinical efficacy, and outcomes of upgrading to LBBP in CRT nonresponders, using propensity-score matching (PSM) analysis. CRT nonresponders were defined as those with an implantable CRT-pacemaker or CRT-defibrillator for more than 12 months who remained nonresponsive (a decrease in left ventricular end-systolic volume of <15% or a left ventricular ejection fraction [LVEF] absolute increase of <5%) after optimal medical therapy and device optimization compared with baseline. In total, 145 CRT nonresponders were prospectively enrolled and randomly divided into 2 groups: upgraded to LBBP (n = 48), and continuing biventricular pacing (BVP) (control; n = 97). PSM was performed at a 1:1 ratio, and clinical evaluation and echocardiographic assessments were compared at baseline and follow-up in paired cohorts. The primary composite endpoint for clinical outcomes (heart failure-related rehospitalization events, all-cause death, or heart transplantation) was analyzed. Successful upgrading to LBBP was achieved in 48/49 patients (97.96%), with a significant decrease in QRS duration (P < 0.001). In the paired LBBP group, LVEF significantly increased (baseline: 29.75% ± 7.79%; 6 months: 37.78% ± 9.25% [P < 0.001]; 12 months: 38.84% ± 12.13% [P < 0.001]) with 21/44 patients (47.73%) classified as echocardiographically responsive, whereas in the BVP control group, no significant improvement was observed (29.55% ± 6.74% vs 29.22% ± 8.10%; P = 0.840). In a multivariate logistic regression model, LV end-diastolic volume and baseline LBBB QRS morphology were independent predictors of echocardiographic response after upgrading to LBBP. At a median 24 months, the primary composite endpoint was significantly lower in the LBBP group (HR: 0.31; 95% CI: 0.14-0.72; log-rank P = 0.007). Upgrading to LBBP is feasible and effective in achieving significant heart function improvement and better clinical outcomes in CRT nonresponders, making it a reasonable and promising pacing strategy. (LBBP in CRT Non-Response patients; ChiCTR1900028131).

Background and Aims: Valvular heart disease (VHD) is a significant source of morbidity and mortality, though early intervention can improve outcomes. This study aims to develop artificial intelligence-enhanced electrocardiography (AI-ECG) models to diagnose and predict future moderate or severe regurgitant VHDs (rVHDs), including mitral regurgitation (MR), tricuspid regurgitation (TR), and aortic regurgitation (AR). Methods: The AI-ECG models were developed in a data set of 988 618 ECG and transthoracic echocardiogram pairs from 400 882 patients from Zhongshan Hospital, Shanghai, China. The AI-ECG models used a residual convolutional neural network with a discrete-time survival loss function. External evaluation was performed in outpatients from a secondary care data set from Beth Israel Deaconess Medical Center, Boston, USA, consisting of 34 214 patients with linked echocardiography. Results: In the internal test set, the AI-ECG models accurately predicted future significant MR [C-index 0.774, 95% confidence interval (CI) 0.753–0.792], AR (0.691, 95% CI 0.657–0.720), and TR (0.793, 95% CI 0.777–0.808). In age- and sex-adjusted Cox models, the highest risk quartile had a hazard ratio (HR) of 7.6 (95% CI 5.8–9.9, P < .0001) for risk of future significant MR, compared with the lowest risk quartile. For future AR and TR, the equivalent HRs were 3.8 (95% CI 2.7–5.5) and 9.9 (95% CI 7.5–13.0), respectively. These findings were confirmed in the transnational external test set. Imaging association analyses demonstrated AI-ECG predictions were associated with subclinical chamber remodelling. Conclusions: This study developed AI-ECG models to diagnose and predict rVHDs and validated the models in a transnational and ethnically distinct cohort. The AI-ECG models could be utilized to guide surveillance echocardiography in patients at risk of future rVHDs, to facilitate early detection and intervention.