Paced QRS Morphology Research Articles

Electrocardiographic predictors of clinical outcomes in nonischemic cardiomyopathy patients with left bundle branch area pacing cardiac resynchronization therapy

BackgroundPaced QRS morphology may vary during left bundle branch area pacing (LBBAP) per the pacing location. It remains unclear whether electrocardiographic changes observed during LBBAP can predict clinical outcomes. ObjectiveWe aimed to assess correlation between characteristics of paced QRS on the electrocardiogram and clinical outcomes in heart failure patients with nonischemic cardiomyopathy. MethodsOf 79 consecutive heart failure patients receiving LBBAP, 59 patients were included in this prospective study after exclusions. LBBAP was performed using Medtronic 3830 lead. Patients were assigned to various groups on the basis of paced QRS morphology in lead V1 (qR and Qr), QRS axis (normal, left, or right), and V6 R-wave peak time (RWPT, ≤80 ms or >80 ms) to compare echocardiographic outcomes. ResultsRWPT was significantly shorter (75.7 ± 17.5 ms vs 85.3 ± 11.3 ms; P = .014), transition during threshold testing was more commonly observed (81.5% vs 53%; P = .02), and improvement in left ventricular ejection fraction (LVEF) was significantly greater in the qR group (21.4% ± 6.4% vs 16.4% ± 8.3%; P = .013) compared with the Qr group. RWPT or LVEF did not differ in patients with different paced QRS axis (P > .05). Whereas qR morphology and presence of transition during threshold testing independently predicted LVEF improvement, RWPT lacked predictive value. Nonresponders had greater incidence of loss of R′ (P = .009) and prolonged RWPT (P = .003) on follow-up compared with average responders and superresponders. ConclusionPaced qR morphology and transition during threshold testing predicted greater improvement in LVEF, whereas RWPT lacked predictive value. Loss of terminal R in lead V1 and prolongation of RWPT on follow-up prognosticated nonresponse to LBBAP.

Comparison of electrocardiogram parameters and echocardiographic response between distinct left bundle branch area pacing modes in heart failure patients.

Left bundle branch area pacing (LBBAP) has become an alternative method for cardiac resynchronization therapy. Various modes of LBBAP have been determined, including left bundle trunk pacing (LBTP), left anterior branch pacing (LAFP) and left posterior branch pacing (LPFP). However, whether the outcomes of various pacing modes differ in heart failure (HF) patients is still unclear. This study aimed to compare the electrophysiological characteristics and echocardiographic response rate among those distinct modes of LBBAP. HF patients undergoing successful LBBAP were retrospectively included. Distinct modes of pacing were determined based on paced QRS morphology. The fluoroscopic images were collected to compare the lead tip position between the groups. The electrocardiograms (ECG) before and after LBBAP were used to measure the depolarization (QRS duration [QRSd] and the interventricular delay [IVD]), and the repolarization parameters [QTc, TpeakTend(TpTe), and TpTe/QTc]. The left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDD) of patients were also recorded. In addition, the lead parameters and certain complications were compared. A total of 64 HF patients were finally included, consisting of 16 (25.0%) patients in the LBTP group, 22 (34.4%) patients in the LAFP group, and 26 (40.6%) patients in the LPFP group. The distribution features of LBBAP lead tips were significantly related to pacing modes: LBTP was more likely to be in zone 4 while LAFP or LPFP was prone to locate in zone 5. After LBBAP, the ventricular ECG parameters were significantly improved, regardless of pacing modes. Besides, the LVEF of the patients was significantly increased (P < 0.001), and LVEDD was significantly decreased (P < 0.001). There was no difference in the response rate and super-response rate among groups (P > 0.05). In addition, the lead parameters remained stable and no significant difference was observed among groups. LPFP was the main pacing mode among HF patients after LBBAP. The paced QRS morphology was significantly related to the position of lead tips. After LBBAP, the ventricular depolarization synchronization and repolarization stability were both significantly improved, regardless of pacing modes. There was no significant difference in the echocardiographic response rate among distinct LBBAP modes.

Outcomes with physiologic His bundle pacing in patients with narrow QRS complex

BackgroundIn patients with narrow QRS complex, both ventricular and biventricular pacing is associated with increased cardiac morbidity and mortality. This risk is not decreased by ventricular pacing avoidance algorithms, which cause nonphysiologic atrioventricular (AV) delays. ObjectiveThis study aimed to report outcomes in patients with narrow QRS complex when the paced complex is in normal range and physiologic AV delays are programmed. MethodsIn 196 patients with QRS duration of 92 ± 10 ms, permanent pacing was done at the site of the His bundle electrogram. The pacemakers were then programmed to maintain physiologic AV delays and to increase heart rates in response to exercise. Patients received usual care and were observed for 3 years. ResultsThe paced complex exhibited a delta wave, and the ventricular activation time, QRS axis, and lead I voltage remained in normal range. Physiologic programming resulted in His bundle pacing burden of 92%. In patients with decreased ejection fraction, there was significant improvement in left ventricular function, left ventricular dilation, and mitral regurgitation (P < .003). In patients with normal ejection fraction, left ventricular function remained normal without new valvular abnormalities. The 3-year all-cause mortality was 10%, and there was no increase in heart failure admissions. ConclusionIn patients with narrow QRS complex, when paced QRS morphology is maintained in normal range and AV dyssynchrony is avoided, His bundle pacing is associated with low all-cause mortality and improvement in abnormal echocardiographic parameters. The paced QRS morphology and physiologic AV delays may be important factors to evaluate in future trials of conduction system pacing.

Paced QRS morphology mimicking complete left bundle branch block induced by right ventricular pacing is associated with pacing-induced cardiomyopathy.

Right ventricular (RV) pacing sometimes causes left ventricular (LV) systolic dysfunction, also known as pacing-induced cardiomyopathy (PICM). However, the association between specifically paced QRS morphology and PICM development has not been elucidated. This study aimed to investigate the association between paced QRS mimicking a complete left bundle branch block (CLBBB) and PICM development. We retrospectively screened 2009 patients who underwent pacemaker implantation from 2010 to 2020 in seven institutions. Patients who received pacemakers for an advanced atrioventricular block or bradycardia with atrial fibrillation, baseline LV ejection fraction (LVEF) ≥ 50%, and echocardiogram recorded at least 6 months postimplantation were included. The paced QRS recorded immediately after implantation was analyzed. A CLBBB-like paced QRS was defined as meeting the CLBBB criteria of the American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society in 2009. PICM was defined as a ≥10% LVEF decrease, resulting in an LVEF of <50%. Among the 270 patients analyzed, PICM was observed in 38. Baseline LVEF was lower in patients with PICM, and CLBBB-like paced QRS was frequently observed in PICM. Multivariate analysis revealed that low baseline LVEF (odds ratio [OR]: 0.93 per 1% increase, 95% confidence interval [CI]: 0.89-0.98, p = 0.006) and CLBBB-like paced QRS (OR: 2.69, 95% CI: 1.25-5.76, p = 0.011) were significantly associated with PICM development. CLBBB-like paced QRS may be a novel risk factor for PICM. RV pacing, which causes CLBBB-like QRS morphology, may need to be avoided, and patients with CLBBB-like paced QRS should be followed-up carefully.

QRS axis and polarity in the inferior leads during left bundle branch pacing: Novel criteria in the search for better results.

Left bundle branch pacing (LBBP) may be achieved in various anatomical sites within the interventricular septum (IVS), thus influencing paced QRS duration (QRSd).The purpose of this study was to determine whether paced QRS axis (QRSâ) and predominant polarity in inferior leads could be associated with a shorter paced QRSd. We analyzed paced QRSd, QRSâ, polarity in inferior leads, and IVS thickness in patients referred for LBBP. Three paced morphology patterns in the inferior leads were considered: All positive (P), all negative (N) and intermediate (combination of isoelectric, positive, and negative complexes, (I). Patients were divided into two groups according to a paced QRSd<120 or ≥ 120ms. A total of 125 patients were included (age 76±10 years, 46% female). Mean baseline QRSâ was 8±37°. Paced QRSd was significantly shorter as compared to baseline (120±10vs. 127±33ms; p=.017) and significantly different according to paced QRS morphology pattern in the inferior leads (P 49%, 119±9; N 30%, 126±12; I 21%; 113±10ms; p<.001) or paced QRSâ (Normal 59%, 116±1; Right 6%, 129±1; Left 35%, 124±11ms; p<.001). On multivariate analysis, a QRSâ>-30°(OR 5.79 [2.40-13.93; 95% CI] p=.001), an Intermediate pattern in inferior leads (OR 3.00 [1.67-8.43; 95% CI] p=.037), and an IVS thickness ≤ 10mm (OR 2.59 [1.10-6.10; 95% CI]; p=.029) were significantly associated with a paced QRSd<120ms. During LBBP, a QRSâ>-30° and intermediate final polarity in inferior leads are associated with a shorter paced QRSd.

PO-05-065 HIGH DENSITY PACE-MAPPING TO IDENTIFY FUNCTIONAL ARRHYTHMOGENIC SUBSTRATE IN SCAR-MEDIATED VENTRICULAR TACHYCARDIA

The location of conduction abnormality including activation slowing and wavefront discontinuity, which often corresponds to the critical zones of reentrant circuit in scar-mediated ventricular tachycardia (VT), is affected by the wavefront direction during substrate mapping. We hypothesized that an abrupt change in paced-QRS morphologies may occur at the region with conduction abnormality. This study assessed the conduction velocity in substrate mapping during at least two rhythms at the region where an abrupt change in paced-QRS morphologies was obtained. In a retrospective review of 57 patients who underwent functional substrate mapping for scar-mediated VT, 21 patients underwent it during multiple rhythms, that is intrinsic rhythm and paced rhythm with high-density pace-mapping in the area of interest. In 10 of these patients, those critical sites, as determined by direct termination during ablation (4 VTs, 33%) or pace-mapping findings (8 VTs, 67%) were identified in a total of 12 VTs. Conduction velocities during an intrinsic rhythm or paced rhythm at the isthmus area were assessed based on the difference of local activation time between two sites along the site where pace-mapping scores changed abruptly. Pace-mapping scores, which were obtained at two adjacent sites along the presumed isthmus, showed 92% [interquartile range [IQR] 89-96%] at the exit side and 48% [IQR 41-56%] at the adjacent entrance side. Ten patients (71±9 years, 9 (90%) male, 6 (60%) nonischemic) underwent high-density substrate mapping during multiple rhythms, that is intrinsic rhythm including sinus rhythm (n=7) or right ventricular pacing (n=5) and paced rhythm including right (n=5) or left ventricular pacing (n=7). Conduction velocity during intrinsic rhythm at the location of abrupt pacemap change was 0.37m/sec [IQR 0.19-0.43 m/sec], which was no slower than 0.25 m/sec, defined as activation slowing in previous studies. However, conduction velocity at abrupt pacemap change site that was faster in one of the multiple rhythms, was significantly slowed down when changing to the other rhythm (0.41 m/sec [IQR 0.25-1.05 m/sec] vs. 0.09 m/sec [IQR0.07-0.22 m/sec], P<0.01) (Fig.1). The abrupt change in paced-QRS morphology in a novel high-density pace-mapping strategy, which is shown independent of wavefront direction during substrate mapping, can identify the high-yield regions with conduction abnormality being critical for reentry.

PO-02-109 FACILITATING LEFT BUNDLE BRANCH PACING BY IDENTIFYING THE TIP OF THE TRIANGLE OF KOCH WITH RIGHT ATRIAL SEPTOGRAM

Left bundle branch (LBB) pacing has emerged as an alternative to His bundle (HB) pacing for physiological stimulation of the ventricles. Current techniques to achieve LBB pacing can be challenging and time consuming, as they require the placement of a catheter/lead to reference the HB We sought to develop a method to facilitate the achievement of LBB pacing. Permanent LBB pacing was performed in 104 consecutive patients with symptomatic bradycardia. A right atrial septogram (RAS) was performed in all the patients to locate the His bundle region (HBR). Briefly, 8-10 cc of contrast were injected trough the Medtronic C315 His delivery sheath while fluoroscopy and cine runs were obtained in the RAO 20-degree projection. These images provided the visualization of an approximately 90-degree angle composed by the medial aspect of the tricuspid valve annulus (TV) anteriorly and the superior aspect of the interatrial septum (IAS) superiorly. The apex of this angle coincides with the tip of the triangle of Koch, where the HBR resides (Figure 1A). This area was referenced by placing a sticky paper arrow on the monitor screen (green arrow). The C315 sheath was then advanced approximately 2 cm anteriorly and 1 cm inferiorly from the level of the HBR to the right ventricular septum (RVS) in the location of the LBB area (LBBA) (Figure 1B). Subsequently, a 3830 Medtronic SelectSecure bipolar lead was advanced through the C315 sheath into the interventricular septum by turning the lead clockwise multiple times in the selected LBBA. The advancement of the lead was monitored by fluoroscopy visualization of the interventricular septum plane with intermittent injections of small amounts of contrast media in the LAO 30-degree projection (Figure 1C), by tracking the impedance measurements and analyzing morphology changes of the unipolar paced QRS morphology. LBB capture was confirmed by current ECG criteria. LBB pacing was successfully achieved in 96 % of the patients (100 out of 104 patients). Twenty nine female. Mean age 75 +/10 years. The mean procedure time for LBB lead insertion was 17.5 +/- 15 minutes. For LBB lead performance see table within figure 1. No acute complications were observed. This study demonstrates that the RAS guided technique provides a highly successful and safe approach to achieve LBB pacing by readily identifying the HBR.

Approach to Left Bundle Branch Pacing.

Cardiac pacing refers to the implantation tool serving as a treatment modality for various indications, the most common of which is symptomatic bradyarrhythmia. Left bundle branch pacing has been noted in the literature to be safer than biventricular pacing or His-bundle pacing in patients with left bundle branch block (LBBB) and heart failure, thereby becoming the focus of further research on cardiac pacing. A review of the literature was conducted using a combination of keywords, including "Left Bundle Branch Block," "Procedural techniques," "Left Bundle Capture," and "Complications." The following factors have been investigated as key criteria for direct capture: paced QRS morphology, peak left ventricular activation time, left bundle potential, nonselective and selective left bundle capture, and programmed deep septal stimulation protocol. In addition, complications of LBBP, inclusive of septal perforation, thromboembolism, right bundle branch injury, septal artery injury, lead dislodgement, lead fracture, and lead extraction, have also been elaborated on. Despite clinical implications based on clinical research comparing the use of LBBP with other forms such as right ventricular apex pacing, His-bundle pacing, biventricular pacing, and left ventricular septal pacing, a paucity in the literature on long-term effects and efficacy has been noted. LBBP can thus be considered to have a promising future in patients requiring cardiac pacing, assuming that additional research on clinical outcomes and the limitation of significant complications such as thromboembolism can be established.

A Continuous Pacing and Recording Technique for Differentiating Left Bundle Branch Pacing From Left Ventricular Septal Pacing: Electrophysiologic Evidence From an Intrapatient-Controlled Study.

Left bundle branch pacing (LBBP) is a promising approach for achieving near-physiologic pacing. However, differentiating LBBP from left ventricular septal endocardial pacing (LVS(e)P) remains a challenge. This study aimed to establish a simple and effective method for differentiating LBBP from LVS(e)P and to evaluate their electrophysiologic characteristics. LBBP, using continuous uninterrupted pacing and real-time monitoring of electrocardiograms along with intracardiac electrograms, was performed in 97 consecutive patients. We evaluated the electrophysiologic characteristics observed during LBBP using 6 modalities: right ventricular septal pacing (RVSP), intraventricular septal pacing (IVSP 1 and 2), LVS(e)P, nonselective LBBP (NSLBBP), and selective LBBP (SLBBP). Of the 97 patients, 87 (89.7%) met the criteria (abrupt change in paced QRS morphology with a transition from Qr to QR/qR in lead V1 and shortening of stimulus to V6 R-wave peak time [Stim-V6RWPT] of ≥ 10 ms with constant output while rather than after lead screwing) for nonselective left bundle branch (LBB) capture. Selective LBB capture was observed in 82 patients (84.5%). The Stim-V6RWPT of NSLBBP and SLBBP were significantly shorter than LVS(e)P (respectively, 67.1 ± 8.7 ms, 67.0 ± 9.3 ms, and 82.1 ± 10.9 ms). Stim-QRSend was the narrowest in IVSP2 (136.6 ± 15.2 ms) instead of NSLBBP (140.0 ± 17.1 ms). The uninterrupted pacing technique for differentiating LBBP from LVS(e)P in the same group of patients is feasible. Electrophysiologic evidence from our intrapatient-controlled study shows that LBBP and LVS(e)P differ in ventricular electrical synchronization.

Global left ventricular myocardial work efficiency in left bundle branch pacing versus right ventricular septal pacing: preliminary results of a randomized trial

Abstract Background Recently, the concept of left bundle branch pacing (LBBP) has emerged in clinical practice, in an attempt to prevent the deteriorating effects of right ventricular pacing (Vp). Purpose The aim of this study is to compare the effect of Vp on left ventricular (LV) dyssynchrony in patients with atrioventricular block (AVB) and preserved ejection fraction (EF), subjected to either LBBP or right ventricular septal pacing (RVSP). Methods Patients with AVB are randomized 1:1 to LBBP or RVSP. The effect of Vp is evaluated by echocardiographic indices of dyssynchrony, such as global myocardial work efficiency (GWE) and peak systolic dispersion (PSD). GWE represents the ratio of constructive work divided by the sum of constructive and wasted work [1]. Successful LBBP is defined by the presence of right bundle branch block paced QRS morphology in lead V1 and stim to LV activation time &amp;lt;75 msec [2]. No back-up right Vp lead was used in LBBP group. Results We conducted a preliminary analysis of the first 20 patients. Enrollment is still ongoing and total follow-up period is one year. We sought to investigate the acute effect of Vp on LV dyssynchrony 24 hours post procedure. Patients' baseline characteristics were similar in both groups and are presented in Table 1. One crossover was noted from LBBP to RVSP group, due to high ventricular capture threshold during implant. Implantation time was increased in LBBP arm (130±17.4 min in LBBP versus 47.7±4.5 min in RVSP group, p=0.004). Left bundle branch potential was recorded in 3 out of 10 LBBP patients. No statistically significant difference was demonstrated in GWE between the two groups (91.3% in LBBP versus 87.4% in RVSP group, p=0.052). PSD was numerically shorter in LBBP (53.3 msec) versus in RVSP (63.6 msec), p=0.114. There were no complications during both the acute perioperative phase and the running period of the follow-up. Moreover, no acute ventricular threshold capture rise, or lead dislodgement has been observed in neither group. The increased implantation time may be attributed to the more demanding technique, or the learning curve period required in the arm of LBBP. In the present analysis, a remarkable difference regarding GWE in favor of the LBBP group was demonstrated, although statistically not significant. However, even in this initial phase of the study, there is a trend of better LV synchrony and less wasted myocardial work in the LBBP group. The final difference of these indices will be assessed at the end of the one-year follow-up, when comparative results will be available. Conclusion LBBP is a novel, safe pacing method. Despite the longer procedural time and the risk of crossover, LBBP seems to offer better – without however statistical significance – LV synchrony even in the acute postoperative phase compared to RVSP. Longer follow-up studies are required to test whether LBBP compared to RVSP confers substantial clinical benefit. Funding Acknowledgement Type of funding sources: None.

Left ventricular septal pacing: how deep is enough?

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Charles University Research Program Background When pacing in the left septal area, it is not clear where the pacing lead needs to be implanted to obtain the most physiological ventricular activation during pure myocardial pacing. Objective To use UHF-ECG to compare ventricular activation between myocardial pacing of the left septum with and without the possibility to capture the left bundle branch by high output pacing. Methods This was a retrospective study of patients with bradycardia and deep septal myocardial pacing close to LBB (paraLBBP) or deep septal pacing more distant from LBB (DSTP), which both produced a pseudo-right bundle branch morphology in V1. During paraLBBP, left bundle branch capture was feasible during increasing pacing output up to 5V at 0.5 ms, but during DSTP, LBB capture was not possible during high output pacing. Only patients with both paraLBBP and DSTP were analyzed. Paced QRS morphology, presence of LBBpotential, QRSduration, R wave peak time (RWPT) in V5, lead depth in the septum and UHF-ECG parameters of dyssynchrony, i.e., e-DYS as the difference between the first and last ventricular activation and local depolarization durations in precordial leads (V1-V8d) were compared between them. Results From 119 consecutive bradycardia patients enrolled, we identified 23 with both paraLBBP and DSTP during an implant procedure. On X-ray, a lead tip was placed shallower during DSTP than paraLBBP (12 ± 3 vs. 15 ± 3 mm, p &amp;lt; 0.001). A pseudo right bundle branch block morphology was present in all cases, but LBB potential was more frequently present in paraLBBP (17 of 23) than in DSTP (4 of 36; p &amp;lt; 0.0001). QRSd was not significantly different (146 ± 14 vs. 142 ± 14 ms, p = 0.08), but DSTP had longer V5RWPT (86 ± 11 vs. 83 ± 9 ms; p = 0.03). paraLBBP resulted in larger interventricular dyssynchrony, e-DYS (-20 ± 15 vs. -12 ± 18 ms; p = 0.046), the same V1-6d, but its local depolarization durations in V7 and V8 (V7 and V8d) were shorter compared to DSTP (-5 and -7 ms; p &amp;lt; 0.05). Conclusion Interventricular dyssynchrony and LV lateral wall depolarization during myocardial pacing of the left septum are dependent on the relation of the leads´ tip to the LBB. Pacing positions closer to the LBB are responsible for bigger interventricular dyssynchrony and more physiological LV lateral wall depolarization.

Left bundle branch area pacing guided by continuous uninterrupted monitoring of unipolar pacing characteristics.

During left bundle branch area pacing (LBBAP) lead implantation, intermittent monitoring of unipolar pacing characteristics confirms LBB capture and can detect septal perforation. We aimed to demonstrate that continuous uninterrupted unipolar pacing from an inserted lead stylet (LS) is feasible and facilitates LBBAP implantation. Thirty patients (mean age 76 ± 14 years) were implanted with a stylet-driven pacing lead (Biotronik Solia S60). In 10 patients (comparison-group) conventional implantation with interrupted unipolar pacing was performed, with comparison of unipolar pacing characteristics between LS and connector-pin (CP)-pacing after each rotation step. In 20 patients (uninterrupted-group) performance and safety of uninterrupted implantation during continuous pacing from the LS were evaluated. In the comparison group, LS and CP-pacing impedances were highly correlated (R2 = 0.95, p < .0001, bias 12 ± 37 Ω) with comparable sensed electrograms and paced QRS morphologies. In the uninterrupted group, continuous LS-pacing allowed beat-to-beat monitoring of impedance and QRS morphology to guide implantation. This resulted in successful LBBAP in all patients, after a mean of 1 ± 0 attempts, with mean threshold 0.81 ± 0.4 V, median sensing 6.5 mV [IQR 4.4-9.5], and mean impedance 624 ± 101 Ω. Positive LBBAP-criteria were seen in all patients with median paced QRS duration of 120 ms [IQR 112-152 ms] and median pLVAT 73 ms [IQR 68-80.5 ms]. No septal perforation occurred. Unipolar pacing from the LS allows accurate determination of pacing impedance and generates similar paced QRS morphologies and sensed electrograms to CP pacing. Continuous LS pacing allows real-time monitoring of impedance and paced QRS morphology, which facilitates safe and successful LBBAP lead implantation.

Rate-related QRS morphological changes in left bundle branch pacing: A case report

Studies have shown that a permanent left bundle branch pacing (LBBP) is feasible and may be clinically beneficial. The paced QRS morphology in a permanent LBBP typically manifests as a right bundle branch block pattern (RBBB) because the left ventricle is activated earlier than the right ventricle. We present one such case in which a small change in the pacing rate strongly influenced the LBBP QRS morphology. A 71-year-old man diagnosed with sick sinus syndrome had a dual-chamber pacemaker (LBBP) implanted. During the transition from non-selective LBBP to selective LBBP, a shrinking R' wave of the rsR' in V1 was observed. We also observed that the amplitude of the R' wave in lead V1 increased as the pacing rate increased and finally manifested as a complete RBBB. Thus, we demonstrated the impact of retrograde impulse conduction from this pacing site on the QRS complex.

3D electro-anatomical mapping to guide conduction system pacing in complex cardiac anatomies

Abstract Background Conduction System Pacing (CSP) includes both His Bundle Pacing (HBP) and Left Bundle Branch Pacing (LBBP). It guarantees physiological cardiac activation and it is essential to avoid pacing-induced dyssynchrony. Markedly dilated atria, up-grading to CRT, and congenital cardiopathies still represent complex anatomical scenarios in which the available tools could often result inadequate and graved by suboptimal results. Objective To evaluate the feasibility and effectiveness of 3D electro-anatomical mapping (EAM) to guide CSP (both HBP and LBBP) in patients with characteristics that allows “a priori” classification as complex anatomical scenario with low probability of success using only fluoroscopic guidance and available tools. Left atrium area &amp;gt;40 cm2; post-PICM up-grading and congenital heart disease were considered signs of anatomical complexity. Methods and results The study includes 25 patients (19 males, mean age 76–11 years; mean baseline EF 34.2–12.6%; 17 BBB; 5 post-PICM up-grading), candidates for CSP. 16 and 9 were respectively implanted with PM and ICD (13/12 dual/three-chamber devices). CARTO system was used in 6 ptss and EnsiteTM Precision in 19. EAM involved reconstruction of the right atrium and sub-tricuspid septum with the use of a decapolar catheter. Several “tags” have been placed on the His signals, in order to reconstruct the “His Cloud” and distinguish within it the proximal, medium, and distal area (Fig. 1). The sub-tricuspid septum was always reconstructed so that intra-procedurally operator could easily move from HBP to LBBP based on electrical parameters or paced QRS morphology. The mapping catheter was removed after the mapping phase and replaced with the pacing lead. Both exposed fixed screw 3830 leads and standard stylet-driven leads were used. HBP was achieved in 10 pts and LBBP in 13 pts. Three failures were resolved by CS lead implant. The time spend for His cloud mapping was 18±7 min. The mean threshold was 1.1±0.5 V; sensing 11.6±9.3 mV and impedance 786±339 ohm. Baseline QRS 155±19 ms and paced QRS 119±7 ms. In cases of LBBP we were also able to measure on the EAM map the depth of the catheter within the septum, resulting in 11.5±3.1 mm and the distance of the initial screw site from the His of 26.5±10.3 mm. Conclusions The electro-anatomical mapping allows the accurate reconstruction of “His cloud” by properly distinguishing proximal, middle, distal His. The sub-tricuspid zone of the interventricular septum is also reconstructed in high definition, so that intra-procedurally it is possible to easily move from HBP to LBBP and vice-versa based on the electrical parameters and paced QRS morphology. This method appears safe and effective even in complex cardiac anatomies possibly saving time and fluoroscopy use. The tags on the His cloud and sub-tricuspid septum can satisfactorily guide lead placement with high reproducibly. Funding Acknowledgement Type of funding sources: None. Figure 1. 3D-EAM used to guide HBP implant

ELECTROCARDIOGRAPHIC CHARACTERISTICS WITH LEFT BUNDLE BRANCH AREA PACING: A SINGLE CENTER PROSPECTIVE STUDY

<h3>BACKGROUND</h3> Pure left bundle branch (LBB) capture should result in typical RBBB (rsR') morphology. However, numerous paced QRS morphologies are observed during LBB area pacing (LBBAP). There are limited papers describing the various electrocardiographic (ECG) morphologies seen with LBBAP. Objective: To evaluate the various ECG characteristics encountered in LBBAP. <h3>METHODS AND RESULTS</h3> Patients referred for pacemaker implantation between 08/2019-01/2021 were considered for LBBAP. LBBAP was performed by implantation of a Medtronic 3830 lead 2 cms distal to His and confirmed by previously published criteria. Paced QRS morphology and QRS axis was analyzed. Baseline, ECG, and implantation characteristics are summarized in table 1. Of 264 LBBAP ECGs, the most common morphology seen during unipolar tip pacing was an incomplete RBBB pattern (qR) in V1 in 165 (69.9%) patients. rSR' pattern was seen in 9 (3.2%) and a narrow QS pattern in 60 (21.5%) patients. <h3>CONCLUSION</h3> Various ECG morphologies may be encountered during successful LBB area capture and are associated with similar QRSd, pacing characteristics and short-term lead performance. These morphologies are due to capture of various structures (RV or LV septum, capture of LBB, LPF +/- RBB) and are likely due to virtual-electrode effect.

Combined endo- and epicardial pace-mapping to localize ventricular tachycardia isthmus in ischaemic and non-ischaemic cardiomyopathy.

A high-density pace-mapping can depict an abrupt transition in paced QRS morphology from a poor to excellent match, unmasking the critical component of ventricular tachycardia (VT) isthmus from the entrance to exit. We sought to assess pace-mapping at multiple sites within the endo- and epicardial scars to identify the VT isthmus in patients with ischaemic (ICM) and non-ischaemic cardiomyopathy (NICM). Colour-coded maps correlating to the percentage matches between 12-lead electrocardiograms during VT and pace-mapping [referred to as correlation score maps (CSMs)] were analysed. We studied 115 CSMs (80 endo- and 35 epicardial CSMs) in 37 patients (17 ICM, 20 NICM). The CSM with an abrupt change (AC) in pacemap score (AC-type) on the endocardium was more frequently observed in ICM than in NICM [11/39 (28%) vs. 1/41 (2%); P = 0.001]. Among 35 CSMs that were analysed by the combined endo- and epicardial mapping, 10 (29%) CSMs exhibited non-AC-type on the endocardium; however, AC-type was present on the opposite epicardium. Although 24 (69%) CSMs did not show AC-type on both the endocardium and epicardium, 16 of them had either an excellent (>90%) or poor (<0%) correlation score on either side, associated with isthmus exit or entrance, respectively. However, the remaining eight CSMs had neither excellent nor poor scores. The CSM may provide electrophysiological information to localize the endo- and epicardial VT isthmus. The absence of AC-type CSM on the endocardium, which is frequently observed in NICM, appears to indicate the sub-epicardial or intramural course of the critical isthmus.

Left bundle branch area pacing: Electrocardiographic features.

BackgroundLeft bundle branch (LBB) area pacing emerged as a promising alternative to His bundle (HB) pacing in difficult cases of physiological pacing and failed cases of cardiac resynchronization. So, it is important to understand ECG features of LBB area pacing in various subsets of patients.ObjectiveWe wanted to find out different morphological patterns and characteristic ECG features of LBB area pacing.MethodMedtronic 3830 pacing lead was used to pierce the interventricular septum 1‐2 cm distal towards the RV cavity to a previously placed electrophysiology catheter at distal HB region to reach the LBB area in the right anterior oblique (RAO) 30 degree projection. We observed paced QRS morphology in lead V1 and paced QRS duration.ResultsWe have analyzed ECG features of 60 patients who had undergone LBB area pacing and 60 patients with RV apical pacing. LBB area pacing resulted in narrower‐paced QRS complex than conventional RV apical pacing. In patients with baseline LBBB QRS shortening from LBB area pacing was more in comparison to patients with RBBB (34.45 ± 8.07 ms vs 19.78 ± 10.24 ms, P value .004). Paced QRS morphological pattern in lead V1 was most commonly qR pattern followed by Qr pattern.ConclusionsLBB area pacing results in narrower‐paced QRS duration than RV apical pacing. The morphological pattern is most commonly a qR or Qr pattern in lead V1. Patients with baseline RBBB showed lesser paced QRS shortening in comparison to patients with baseline LBBB.

B-PO05-037 ELECTROCARDIOGRAPHIC CHARACTERISTICS WITH LEFT BUNDLE BRANCH AREA PACING: A SINGLE CENTER PROSPECTIVE STUDY

Pure left bundle branch (LBB) capture should result in typical RBBB (rsR’) morphology. However, numerous paced QRS morphologies are observed during LBB area pacing (LBBAP). There are limited papers describing the various electrocardiographic (ECG) morphologies seen with LBBAP. To evaluate the various ECG characteristics encountered in LBBAP. Patients referred for pacemaker implantation between 02/2019-02/2021 were considered for LBBAP. LBBAP was performed by implantation of a Medtronic 3830 lead 2 cms distal to His and confirmed by previously published criteria. If unsuccessful, lead was repositioned distally and inferiorly on the septum to capture the left posterior fascicle (LPF). Paced QRS morphology and QRS axis was analyzed. Baseline, ECG, and implantation characteristics are summarized in table 1. Of 274 LBBAP ECGs, the most common morphology seen during unipolar tip pacing was an incomplete RBBB pattern (qR) in V1 in 131 (48%) patients. rSR’ pattern was seen in 38 (14%) and a narrow QS pattern in 34 (12.5%) patients. qR or rsR’ with left axis deviation, i.e., LPF capture was noted in 69 (25%) patients. One patient exhibited monophasic R in lead V1. Unipolar ring pacing resulted in wide QS in all patients due to RV septal capture only. Various ECG morphologies may be encountered during successful LBB area capture and are associated with similar QRSd, pacing characteristics and short-term lead performance. These morphologies are due to capture of various structures (RV or LV septum, capture of LBB, LPF +/- RBB) and are likely due to virtual-electrode effect.

Evaluation of the Criteria to Distinguish Left Bundle Branch Pacing From LeftVentricular Septal Pacing.

This study sought to assess the predictive value of the proposed electrocardiogram and intracardiac electrogram characteristics for confirmation of left bundle branch (LBB) capture. Previously proposed criteria to distinguish left bundle branch pacing (LBBP) and left ventricular septum (LVS) pacing (LVSP) have not been fully validated. A His bundle pacing lead, an LBBP lead, and a multielectrode catheter at the LVS were placed. Direct LBB capture was defined as demonstration of retrograde His potential on the His bundle pacing lead and/or anterograde left conduction system potentials on the multielectrode catheter during LBBP. The routinely used parameters-His, LBB potential, time from stimulus to peak ventricular activation (Stim-LVAT), and paced QRS morphology during LVSP and LBBP at various depths and outputs were analyzed. Thirty patients (21 non-left bundle branch block [LBBB], 9 LBBB) who demonstrated direct LBB capture using the defined criteria were included. The proportion of paced right bundle branch block was 100% during LBB capture in all patients compared to 23.4% in non-LBBB and 44.4% in LBBB during LVSP. LBB potential was recorded in all patients during intrinsic rhythm (non-LBBB group) or His corrective pacing in LBBB. Paced QRS duration was longer during selective LBBP compared to nonselective LBBP or LVSP only. All patients with characteristics of selective LBBP or abrupt decrease in Stim-LVAT of≥10ms demonstrated LBB capture. Direct LBB capture can be confirmed by recording retrograde His potential and anterograde left conduction system potentials. Abrupt decrease in Stim-LVAT of≥10ms and demonstration of selective LBBP could be used as simple criteria to confirm LBB capture.

Relationship of paced left bundle branch pacing morphology with anatomic location and physiological outcomes

Left bundle branch pacing (LBBP) is an emerging physiological pacing modality. However, little is known about pacing at different locations on the left bundle branch (LBB). The purpose of this study was to explore pacing and physiological characteristics associated with different LBBP locations. The study included 68 consecutive patients with normal unpaced QRS duration and successful LBBP implantation. Patients were divided into 3 groups according to the paced QRS complex as left bundle branch trunk pacing (LBTP), left posterior fascicular pacing (LPFP), or left anterior fascicular pacing (LAFP). Electrocardiographic (ECG) characteristics, pacing parameters, and fluoroscopic localization were collected and analyzed. There were 17 (25.0%), 35 (51.5%), and 16 (23.5%) patients in the LBTP, LPFP, and LAFP groups, respectively. All subgroups had relatively narrow paced QRS complex (128.6 ± 9.1 ms vs 133.7 ± 11.2 ms vs 134.8 ± 9.6 ms; P = .170), fast left ventricular activation (70.4 ± 9.0 ms vs 70.6 ± 10.2 ms vs 71.0 ± 9.0 ms; P = .986), as well as low and stable pacing thresholds. Delayed right ventricular activation and interventricular dyssynchrony were similar between groups. Fluoroscopic imaging indicated that the lead tip was located most commonly in the basal-middle region of the septum (67.7%), and this was independent of paced QRS morphology group (88.2% vs 57.1% vs 68.8%; P = .106). Pacing at different sites of the LBB resulted in similar intraventricular and interventricular electrical synchrony in patients with an intact conduction system. Fluoroscopic imaging alone could not predict specific LBBP paced ECG morphology.