Tailored electrocardiographic-based criteria for different pacing locations within the left bundle branch.

BACKGROUND: Electrocardiographic (ECG)-based criteria are used to confirm left bundle branch (LBB) pacing (LBBP), but current cutoff values have never been validated for different pacing locations. OBJECTIVE: The purpose of this study was to describe diagnostic performance of V6-R wave peak time (RWPT), V6-V1 interpeak interval, and aVL-RWPT for different pacing sites within the LBB and to determine 100% specific values for each criterion at each pacing location. METHODS: Consecutive patients with confirmed LBBP were selected. Population was divided into subgroups based on the site of pacing: left bundle trunk pacing (LBTP), left septal fascicular pacing (LSFP), left posterior fascicular pacing (LPFP), and left anterior fascicular pacing (LAFP). RESULTS: A total of 147 patients with unequivocal LBB capture were analyzed. Left fascicular pacing was more frequently achieved (82.8%) than LBTP (17.2%). Diagnostic performance of V6-RWPT, V6-V1 interpeak interval, and aVL-RWPT for discrimination of LBBP was good in all subgroups. V6-RWPT cutoff values with 100% specificity (SP) for LBBP discrimination were 75 ms in LBTP, 68 ms in LPFP, 81 ms in LAFP, and 79.5 ms in LSFP. V6-V1 interpeak interval cutoff values with 100% SP for LBBP discrimination were 35.5 ms in LBTP, 53.5 ms in LPFP, 41 ms in LAFP, and 46 ms in LSFP. In LAFP, aVL-RWPT cutoff value with 100% SP for LBBP discrimination was 68 ms, but was 74 ms in LBTP, 74.5 ms in LSFP, and 73.5 ms in LPFP. CONCLUSIONS: Tailored ECG-based criteria might be useful to confirm LBBP at different pacing locations within the LBB.

Atrial mechanical contraction and ambulatory atrioventricular synchrony: Predictors from the OPTIVALL study.

INTRODUCTION: The role that preprocedural factors have on atrioventricular synchrony (AVS) provided by leadless pacemakers requires investigation. METHODS AND RESULTS: We aimed to assess the correlation between mitral inflow echocardiographic parameters and p-wave morphology with the accelerometer A4 signal amplitude. We also sought to identify clinical and echocardiographic predictors of optimal ambulatory AVS (≥85% of cardiac cycles). Forty-three patients undergoing Micra AV implant from June 2020 to March 2023 were prospectively enrolled. Baseline echocardiogram and 12-lead resting ECG were performed. Device follow-up was scheduled at 24 h, 1, 3, and 6 months and yearly after the implant. Ambulatory AVS was studied with a 24 h Holter monitor performed at 3 months follow-up in 35 patients who remained in VDD mode. A4 signal amplitude at 1 month correlated to peak A wave velocity (r = .376; p = .024) at echocardiogram, but no relationship was found with peak A' wave velocity, E/A, or E'/A' ratio. P-wave amplitude in lead I and aVF correlated to A4 signal amplitude at 1- and 3-months follow-up, respectively. Median AVS during 24 h of daily activities was 85.6 ± 7.6% and remained stable up to 100 bpm. Twenty-three out of 35 patients (65.7%) reached optimal ambulatory AVS. There was no association between mitral inflow echocardiographic parameters and optimal AVS. Diabetes (OR: 0.05, 95% CI: 0.01-0.47; p = .009) and chronic obstructive pulmonary disease (COPD) (OR: 0.06, 95% CI: 0.01-0.63; p = .019) strongly predicted ambulatory AVS <85%. CONCLUSIONS: Diabetes and COPD should be considered when selecting candidates for Micra AV. Measurements of pulsed wave Doppler mitral inflow do not systematically reflect the behavior of the A4 signal amplitude.

Redefining QRS transition to confirm left bundle branch capture during left bundle branch area pacing.

Background: QRS transition criteria during dynamic manoeuvers are the gold-standard for non-invasive confirmation of left bundle branch (LBB) capture, but they are seen in <50% of LBB area pacing (LBBAP) procedures. Objective: We hypothesized that transition from left ventricular septal pacing (LVSP) to LBB pacing (LBBP), when observed during lead penetration into the deep interventricular septum (IVS) with interrupted pacemapping, can suggest LBB capture. Methods: QRS transition during lead screwing-in was defined as shortening of paced V6-R wave peak time (RWPT) by ≥10 ms from LVSP to non-selective LBBP (ns-LBBP) obtained during mid to deep septal lead progression at the same target area, between two consecutive pacing manoeuvres. ECG-based criteria were used to compared LVSP and ns-LBBP morphologies obtained by interrupted pacemapping. Results: Sixty patients with demonstrated transition from LVSP to ns-LBBP during dynamic manoeuvers were compared to 44 patients with the same transition during lead screwing-in. Average shortening in paced V6-RWPT was similar among study groups (17.3 ± 6.8 ms vs. 18.8 ± 4.9 ms for transition during dynamic manoeuvres and lead screwing-in, respectively; p = 0.719). Paced V6-RWPT and aVL-RWPT, V6-V1 interpeak interval and the recently described LBBP score, were also similar for ns-LBBP morphologies in both groups. LVSP morphologies showed longer V6-RWPT and aVL-RWPT, shorter V6-V1 interpeak interval and lower LBBP score punctuation, without differences among the two QRS transition groups. V6-RWPT < 75 ms or V6-V1 interpeak interval > 44 ms criterion was more frequently achieved in ns-LBBP morphologies obtained during lead screwing-in compared to those obtained during dynamic manoeuvres (70.5% vs. 50%, respectively p = 0.036). Conclusions: During LBBAP procedure, QRS transition from LVSP to ns-LBBP can be observed as the lead penetrates deep into the IVS with interrupted pacemapping. Shortening of at least 10 ms in paced V6-RWPT may serve as marker of LBB capture.

Combination of current and new electrocardiographic-based criteria: a novel score for the discrimination of left bundle branch capture.

AIMS: Most of the criteria used to diagnose direct capture of the left bundle branch (LBB) have never been validated in an external sample. We hypothesized that lead aVL might add relevant information, and the combination of several electrocardiograph (ECG)-based criteria might discriminate better LBB capture from left ventricular septal (LVS) capture, than each criterion separately. METHODS AND RESULTS: Single-centre study involving all consecutive patients who received LBB area pacing. LBB capture was defined according to QRS morphology transition criteria during decremental pacing. Multivariate logistic regression analysis was performed to develop a predictive score for LBB capture. A total of 71 patients with confirmed LBB capture were analysed. The optimal cut-off values of R wave peak time (RWPT) in lead V6 (V6-RWPT) and V6-V1 interpeak interval for the discrimination of LBB capture were <83 ms and ≥33 ms, respectively. The RWPT in lead aVL (aVL-RWPT) showed a good discrimination power for the differential diagnosis of LBB capture and LVS capture. The optimal value for aVL-RWPT was 79 ms [sensitivity (SN) and specificity (SP) of 71.2% and 88.4%, respectively]. A new score, with a good diagnostic performance (area under the curve of 0.976), was constructed gathering the information from V6-RWPT, aVL-RWPT, and V6-V1 interpeak interval. The optimal score of 3 points showed a SN and SP of 89.2% and 100%, respectively for the differentiation of LBB capture. CONCLUSIONS: ECG-based criteria are useful to confirm the capture of the LBB. The combination of V6-RWPT, aVL-RWPT, and V6-V1 interpeak interval values demonstrated better diagnostic performance than isolated measurements.

Optimizing atrial sensing parameters in leadless pacemakers: Atrioventricular synchrony achievement in the real world.

BACKGROUND: Performance of the leadless pacemaker capable of atrioventricular (AV) synchronous pacing in de novo patients warrants further investigation. OBJECTIVE: The aims of this study were to assess what programming changes are needed to achieve proper atrial tracking and to study the percentage of AV synchrony (AVS) the device can provide under real-world conditions. METHODS: Consecutive patients undergoing Micra AV implantation between June 2020 and November 2021 were studied. Reprogramming of atrial sensing parameters during follow-up was performed by following device counters. AVS was studied with an ambulatory 24-hour Holter monitor and automatically analyzed by an electrocardiogram delineation system. The primary end point was AVS ≥85% of total cardiac cycles during 24-hour Holter electrocardiogram monitoring. RESULTS: Thirty-one patients who remained in VDD mode were studied, and all of them required manual reprogramming. The automatic A3 window end was deactivated, and a fixed and short value was set in all patients throughout follow-up. AVS significantly increased from 68.7% ± 14.7% at 24-hour follow-up to 83.9% ± 7.4% at 1-month visit (P = .001). At 1-month visit, shorter A3 window end time (P = .019), higher A4 threshold (P = .011), and deactivation of the automatic A3 window (P = .054) were independently related to higher AVS. A total of 2,291,953 Holter-recorded cardiac cycles were analyzed. Median AVS during 24-hour daily activities was 87.6% (interquartile range 84.5%-90.6%). Twenty of 26 patients (79.6%) reached AVS ≥85% of cardiac cycles. CONCLUSION: High rates of AVS can be achieved in real-world patients undergoing leadless pacing. Manual reprogramming of the atrial sensing parameters is essential to optimize mechanically sensed atrial tracking.