Paced QRS Research Articles

Micra Leadless and Transvenous Pacemaker: A Single-Center Comparative Study of QRS Wave Duration Resulting From Different Pacing Sites.

To compare the paced QRS duration on different sites in age-, gender-, and indication-matched patients implanted with Micra leadless pacemakers and conventional transvenous pacemakers (TV-PM). A total of 82 patients from Xinhua Hospital, Shanghai Jiaotong University, were enrolled, including two groups of 41 patients matched according to gender, age, and pacemaker indications, who underwent Micra and TV-PM implantations, respectively. The baseline data of the patients, the pacing site described using three- and nine-partition methods, and the paced QRS duration on 12-lead electrocardiogram were then analyzed. Overall, patients in our population were on average 79.2 years of age and mostly male (75.6%). Atrioventricular node dysfunction was the most common indication (56.1%) for pacemaker therapy. Mid-septum, especially Site 5, is the implantation site for most patients in both groups. Micra (145 ms) and TV-PM (133 ms) both had the narrowest-paced QRS at high septum, but Micra may exhibit significantly more reduced QRS duration than TV-PM at low septum (Micra vs. TV-PM: 143.0 [142.8-156.5] ms vs. 163.5 ± 17.5 ms, p = 0.044). The narrowest-paced QRS complex for Micra leadless pacemakers is achieved at high septum, and pacing at low septum by Micra may acquire shorter QRS duration than conventional TV-PM.

Deep Septal Pacing for Pacemaker-Induced Cardiomyopathy.

Right ventricular (RV) pacing can impair left ventricular function and cause heart failure, known as pacing-induced cardiomyopathy (PICM). Upgrade to cardiac resynchronization (CRT) is its usual treatment; recently left bundle branch area pacing (LBBAP) has emerged as a potential alternative. Deep septal pacing (DSP), a simplified alternative to LBBAP, is still able to achieve narrower paced QRS than during conventional RV pacing. The aim of this study was to assess the effect of DSP in a cohort of patients with PICM. Consecutive patients diagnosed with PICM were included. The aim was to upgrade patients to DSP. The procedure was considered successful if a paced QRS duration ≤140ms was obtained, in the absence of a terminal R wave in V1. Twelve patients were included. The mean baseline LVEF was 33% (SD 4%), and the mean percentage of RV pacing was 99% (SD 1%). All patients had symptomatic heart failure. The mean paced QRS duration was 172ms (SD 14ms) with RV pacing, and 130ms (SD 7ms) with DSP (mean difference 42ms, p<0.001). At 6 months, the mean LVEF after the upgrade was 46% (SD 9%), significantly superior to LVEF with RV pacing (p = 0.001), a mean improvement of 13% (SD 10%). All patients except one experienced an improvement in LVEF of at least 5%. Our data suggest that DSP may be an effective and simpler alternative to biventricular or LBBAP in patients with PICM. Narrower paced QRS complexes can be achieved, which may lead to an improvement in left ventricular function.

Left Bundle Branch Area Pacing Compared to Right Ventricular Outflow Tract Septal Pacing: Mid-term Results and Learning Curve.

Our study evaluated the efficacy and feasibility of left bundle branch area pacing (LBBAP) compared to right ventricular outflow tract septal pacing (RVOSP). We conducted a prospective, single-center, observational study involving 200 consecutive patients who required pacemaker implantation. The patients were divided into two groups (LBBAP and RVOSP), with 100 patients in each group. We aimed to compare the safety and efficacy, as well as the procedure and fluoroscopy times, between the two groups. Additionally, we aimed to describe the learning curve for the LBBAP group. The success and acute complication rates were similar (P = .56 vs. P = .65). The procedure time was longer in the LBBAP group compared to the RVOSP group (18 [13-28] vs. 11 [7-17] min; P < .001), while the fluoroscopy time was shorter in the LBBAP group compared to the RVOSP group (2.8 [1.3-3.7] vs. 3.1 [2-5.9] min; P = .02). The paced QRS interval was narrower in the LBBAP group (123.77 ± 10.25 vs. 159.79 ± 17.0 ms; P = .001). There were no significant differences in pacing parameters like R-wave sensing (9.6 ± 5.2 vs. 9.1 ± 4.7 mV; P = .91), bipolar impedance (685.9 ± 151.8 vs. 686.5 ± 158.6 Ω; P = .98), or pacing threshold (0.70 ± 0.29 vs. 0.64 ± 0.26 V @ 0.4 ms; P = .63). In the LBBAP group, both the procedure time (12 [10.5-15] vs. 32 [28.5-38.5] min; P < .001) and the fluoroscopy time (2 [1-4.6] vs. 5.1 [3.4-12] min; P < .01) were shorter in the last quartile (Q4) compared to the first quartile (Q1). The procedure time was similar between LBBAP Q4 and RVOSP (12 [10.5-15] vs. 11 [7-17] min; P = .33). LBBAP is as safe as RVOSP and achieves a narrower paced QRS compared to RVOSP. After a rapid learning curve, a shorter fluoroscopy time and a similar procedure time can be achieved.

Transesophageal 3-dimensional echocardiographic guidance for pacemaker lead placement improves lead position accuracy and reduces fluoroscopy.

Pacemaker and implantable cardioverter-defibrillator (ICD) lead placement traditionally uses fluoroscopy, often with inaccurate lead placement on the free wall rather than on the ventricular septum, with associated longer QRS duration and pacemaker-induced cardiomyopathy while exposing staff and patients to radiation. We sought to determine whether transesophageal 3-dimensional echocardiography (3DE) guidance improves lead placement accuracy in the ventricular septum, results in shorter paced QRS durations, and reduces fluoroscopy exposure. In a single-center case-control study, 3DE guided right ventricular or atrial pacemaker and ICD leads to the desired location, with fluoroscopy used per operator preference. Ventricular lead location, paced QRS duration, and fluoroscopy times were recorded and compared with historical controls that used only fluoroscopy during procedures. In 59 patients, 3DE guidance substantially improved ventricular lead placement in the septum (78.4% vs 29.8%; P < .001) rather than in the free wall (3.9% vs 57.4%; P < .001) compared with 72 historical controls; this difference was more pronounced when only pacemaker leads were considered (90.2% vs 39.4% [P < .001] for septal and 2.4% vs 45.5% [P < .001] for free wall locations). Compared with controls, 3DE guidance reduced fluoroscopy times (6.6 vs 11.2 minutes for all leads [P = .005] and 4.7 vs 9.5 minutes for right ventricular leads [P = .014]) and trended toward shorter paced QRS durations (133 ms vs 141.5 ms; P = .084). For pacemaker and ICD lead placement, 3DE guidance substantially improves the accuracy of lead placement in the septum, with a shorter QRS duration, while reducing fluoroscopy exposure.

Abstract 4138640: Learning Curve for Left Bundle Branch Area Pacing Lead Implantation

Background: Left bundle branch area pacing (LBBAP) has shown promising outcomes at experienced centers, but less is known about the learning curve with new adoption of LBBAP. We conducted a retrospective analysis (2020-2023) of the learning curve for LBBAP at our center. Methods: Procedural success and complications in adult patients undergoing LBBAP by operators with &gt;5-years’ experience in device implantation were compared between operators’ experience ≤10th (LBBAP inexp ) vs. &gt;10th (LBBAP exp ) LBBAP implant. Successful LBBAP was defined as left ventricular activation time (LVAT) ≤80 ms. Results: Seven operators implanted LBBAP in 288 patients (age 73±11 years, 38% women): 68 (24%) in LBBAP inexp vs. 220 (76%) patients in LBBAP exp groups with similar baseline characteristics (all p &gt;0.05). The median number of implants per operator was 22 (range 8-83). Table 1 shows the procedural characteristics and ECG results. Post-implant LVAT ≤80 ms was less frequent in LBBAP inexp compared to LBBAP exp (56.9% vs 72.4%, p=0.04, Figure 1 ). There were no differences in paced QRS duration ≤130 ms (75.9% vs. 76.1 %, p=1.0) or operator self-identified success (85% vs. 91%, p=0.2). With new single-/dual-chamber device implants, there was no difference in implant duration (103.4±31.8 vs. 101.6±38.5 minutes, p=0.3) but there was longer fluoroscopy in LBBAP inexp (12.6±10.1 vs. 8.2±8.0 minutes, p&lt;0.0001, Figure 1 ). The average number of attempts at LBBAP was lower in LBBAP inexp vs. LBBAP exp (2.0 ± 1.5 vs. 2.9 ± 2.9, p=0.03). There was no difference in complications between the 2 groups ( Table 2 ). Conclusion: Operators use less fluoroscopy, make more attempts at LBBAP and more frequently achieve LVAT ≤80 ms after their first 10 implants.

Mitigation of pacing-induced cardiomyopathy with superficial right ventricular mid-septal pacing: A long-term retrospective comparison with apical pacing.

It remains unclear if pacing induced cardiomyopathy (PICM) may be minimized by standard pacing of the right ventricle (RV) at sites other than the RV apex. The purpose of this study is to compare the relative frequency of PICM in a population of patients paced at either the superficial RV mid septum (RVMS) or RV apex (RVA), and other outcomes that may differ between these sites. A retrospective evaluation was performed on all patients undergoing pacemaker implantation between 2011 and 2022. Potential study patients were those with Medtronic 3830 superficial RVMS leads placed with septal specific guidance catheters, and any with RVA leads. Patients were included if they had ≥20% RV pacing, available baseline and follow-up measurements of left ventricular ejection fraction (LVEF) at least 6 months postimplantation, and a baseline LVEF ≥50%. PICM was defined as a decline in the LVEF of at least 10%, resulting in LVEF <50%. Patients were excluded for Biventricular devices, and for alternative causes of cardiomyopathy. The study criteria were met in 324 patients, with 220 RVMS and 104 RVA paced patients. PICM occurred in 4.5% of RVMS patients, and 22.1% of RVA patients (p < .001). Additional differences were demonstrated in paced QRS duration (144 ± 15.5 ms in RVMS, 166 ± 19.4 ms in RVA; p < .001); QRS axis (2.3 ± 64.9 in RVMS, -65.2 ± 49.5 in RVA; p < .001), and various qualitative QRS morphologic characteristics. Patients with normal LVEF experienced significantly less PICM with superficial RVMS pacing performed via septal specific guidance catheters than similar counterparts with RVA pacing. Narrower paced QRS duration and less left axis deviation was also demonstrated.

Comparative study of the surface and endocavitary signals of cardiac pacing system analyzers with respect to the conventional polygraphy systems signals during implantation of conduction system pacing

Abstract Introduction and objectives Left bundle branch area pacing (LBBAP), is a novel modality of physiologic pacing that requires an adequate assessment of the endocardium as well as the body-surface electrocardiographic signals for a successful pacing-lead implantation. We aimed to assess if LBBAP criteria(1), specifically left ventricular septal pacing (LVSP) and left bundle branch pacing (LBBP) criteria, can be satisfactory measured using the signals resulting from different cardiac pacing analyzers (PSAs) by comparing them to the ‘conventional’ signals obtained from multichannel polygraph systems (MPSs) during the implantation procedure. Methods Comparative observational, prospective, multicenter study of consecutive patients who underwent a LBBAP strategy as first intention. LBBP was defined in the presence of a paced QRS with right bundle branch morphology in V1 (initial r wave in lead V1) and at least one of the following criteria: 1. V6-R-Wave Peak Time (RWPT) &amp;lt; 80 ms. 2. V1–V6 interpeak interval &amp;gt; 33 ms. 3. QRS transition from non-selective left bundle branch pacing to selective left bundle branch pacing or NS-LBBP to left ventricular septal pacing during pacing threshold. 4. Sudden increase of V6-RWPT &amp;gt; 15 ms because of reducing pacing output. 5. Left bundle potential-V6RWPT = stim-V6RWPT (±10 ms). For patients without initial r wave in V1, LBBP was considered in the presence of QRS transition during pacing. LVSP was defined by a paced QRS showing a typical terminal R-wave in V1, anatomical position of the lead in the left ventricular septum documented by fluoroscopy and not fulfilling the additional criteria previously described for LBBP. Results 63 patients were included. The basal characteristics of the patients are shown in Figure I. No significant differences (p&amp;lt;0.96) were observed in the basal QRS between the MPSs (129±29ms) and the PSAs (129±28ms). Initial "W" morphology in V1 during initial pacing was obtained in 90% of patients, without differences between both measurement systems. There were no significant differences between the MPSs and the PSAs in the paced QRS in V1 (140±10ms vs 141±12ms, p&amp;lt;0.746) nor in V6 (127.4±13ms vs 128.2±14.6ms, p&amp;lt;0.96). The measurement of the R wave peak time (RWPT) in V6 was 78.3±15ms vs 77±14 ms (p&amp;lt;0.72), and the V1-V6 inter-peak was 41.1±16ms in the MPSs vs 39±16 ms the PSAs (p&amp;lt;0.6), respectively, the Pearson correlation coefficients for these last two measurements being 0.91 (p &amp;lt;0.0001) and 0.91 (p &amp;lt;0.0001) (Figure II). Finally, according to electrocardiographic criteria measured by the MPSs, LBBP was achieved in 69% of patients, accomplishing 31% of the patients LVSP criteria, being the same proportions observed when PSAs measures where applied. Conclusions The signals resulting from the different PSAs can be useful to assess septal as well as LBBP criteria as an alternative to the ‘conventional’ signals obtained from MPSs.

Dual-chamber CRT-D using ICD lead implantation in the LBBAP position

Abstract Background Interest in conduction system pacing (CSP) has increased in recent years. For left bundle branch area pacing (LBBAP), 4F and 6F pacing leads have been shown to be effective and safe. No information is available on the potential use of ICD leads for LBBAP. Aim The objective of the study was to demonstrate the feasibility of implanting an ICD lead in the LBBAP position to reduce the number of leads for CRT-D therapy. Patients and Methods We implanted the 7F ICD lead in the LBBAP position through a new 10F CSP delivery sheath in ten consecutive patients. Periprocedural data, QRS morphology and degree of QRS reduction were analyzed. Results Ten consecutive patients (one female) aged 69.5±9.2 years were treated with the above-mentioned method. Eight patients had ischemic cardiomyopathy and two patients had nonischemic cardiomyopathy. All patients had a CRT-D indication. Eight patients had a wide QRS complex with complete LBB and a QRS complex of 184.8±25.8 ms. Two patients had a narrow QRS complex but first-degree AV block with a PR interval greater than 240 ms. Left ventricular ejection fraction was 31.8±8.6%. Operative and fluoroscopy times were 103.6±30.3 minutes and 10.5±6.1 minutes, respectively. On average, 1.7 ± 0.6 screwing attempts were required per patient. The intraprocedural LBBAP threshold was 0.78±0.6V/1.0ms, the impedance was 530.8±86.5 ohm, and the R-wave amplitude was 9±3.3mV. The unipolar paced QRS complex was 123.6±15.9ms, the bipolar paced QRS complex was 129.5±12.8ms, and the bipolar paced QRS complex on the next day was 133.3±11.7. The mean duration from stimulus to R-wave peak in lead V6 was 82.9 ± 19.7 ms. The R-wave interpeak interval between leads V6 and V1 was 43.4 ± 9.7 ms. All but one patient received an effective defibrillation threshold test at 30J (n=8) and 36J (n=1). One patient was not tested during the procedure due to high risk. Conclusion This first-in-human study of ICD lead implantation in the LBBAP position demonstrated its feasibility and efficacy in achieving conduction system stimulation. This approach may lead to a reduction in the number of leads implanted for cardiac resynchronization therapy. Figure 1. A- RAO view, angiography of the RV for verification of the TVA-summit. B- LAO view, angiography from the CSP- sheath after reaching final position of the LBBAP lead (right sided interventricular septum - yellow dotted line). C – 12 lead ECG (speed 50mm/sec) demonstrating paced and native QRS complexes. D – Fluoroscopy in RAO view, final result. E – Fluoroscopy in LAO view, final result. F – Transthoracic echocardiography the next day (4Ch view) demonstrates optimal LBBAP lead position.. RAO – right anterior oblique; LAO – left anterior oblique; TVA – tricuspid valve anulus; CSP – conduction system pacing; LBBAP – left bundle branch area pacing.Figure 1.

Impact of QRS complex fragmentation on all-cause mortality before and after cardiac resynchronization therapy

Abstract Introduction Cardiac resynchronization therapy (CRT) have demonstrated to reduce all-cause mortality in selected patients with HFrEF. However, there is still a high rate of non-responders, so risk stratification is crucial. Fragmentation of the QRS complex (QRSf) has been suggested as a valuable prognostic factor in different cardiac diseases, but the evidence in patients undergoing CRT is controversial and limited. Purpose To evaluate if changes in QRSf status before and after CRT implantation has a prognostic role in patients undergoing CRT in terms all-cause mortality. Methods Consecutive patients undergoing CRT were prospectively included from October 2009 to December 2022. Demographic clinical, electrocardiographic and echocardiographic variables were recorded. Prospective follow-up variables were collected from electronic clinical records and telephone interview. QRSf complex was defined by the presence of different RSR′ patterns including additional R-waves (R′) and notches of the R-wave and S-wave in two contiguous leads corresponding to a main coronary artery territory in a 12-lead electrocardiogram performed before and after CRT. Results A total of 244 patients (mean age 71.8 ± 9.8 years, 79.5% male) were included. The etiology of LV systolic disfunction was ischemic in 50.0%. Mean LVEF before implantation was 25 ± 9%. A CRT-D was implanted in 176 patients (72.2%). The mean width of the paced QRS was 141 ± 23 ms. At baseline, 150 patients had a QRSf. After CRT implantation, 69 (28.4%) patients experimented a change in QRSf status: 29 patients (11.9%) without prior QRSf developed QRSf, whereas 40 patients (16.5%) resolved QRSf after CRT. Median follow-up time was 36.0 months (interquartile range 18.2-75.7). During the follow-up period, 90 patients died. In the multivariate Cox regression survival analysis, the presence of QRSf before the implantation with or without paced QRSf after CRT were independently associated with all-cause mortality (HR 4.43; 95% CI 1.53-12.80 and HR 3.69; 95% CI 1.16-11.80 respectively). Those without QRSf prior implantation who developed QRSf after CRT did not present significantly higher risk of all-cause mortality. Univariate and multivariate Cox regression analyses for all-cause mortality are presented in Table 1. Figure 1 presents Kaplan-Meier curves for all-cause mortality according to QRSf status before and after CRT implantation. Conclusions According to our results, preimplantation QRSf is an independent predictor of all-cause mortality regardless the resolution or maintenance of QRSf after CRT in patients with HFrEF undergoing CRT. Therefore, patients with QRSf before CRT implantation regardless the paced QRSf status, should be followed more strictly because they are at higher mortality risk.Table 1.Cox Regression Analyses

A novel formula to assess the QT interval in ventricular paced rhythm

Abstract Background QT interval measurement in the presence of right ventricular pacing (RVP) represents a clinical challenge due to altered ventricular activation resulting in a prolonged QT-interval. The aim of this study is to compare the QT interval in patients before and after ventricular pacing to develop a new formula for QT interval assessment in patients with RVP. Methods and results All patients presenting to our pacemaker clinic with single- or dual chamber device were included in this prospective observational study. Inclusion criteria were no permanent right ventricular stimulation, an intrinsic QRS interval of &amp;lt;120 ms, and ventricular rate &amp;gt;35 bpm and &amp;lt;150 bpm. Three 12-lead electrocardiograms were recorded for each patient: during intrinsic rhythm and 2 following an atrial paced and a ventricular paced QRS at the same rate. The intrinsic QRS and QT time/JT time (QTi/JTi) were measured during intrinsic and subsequent RVP. To obtain the formula, all measurements were performed on 100 patients (mean age 74 ± 11.3, male 33%) (RV apical lead 30% and non-apical lead 70%). Based on our measurements, a new formula QT (non-paced) = 139.23 + 0.55 xQT (paced) was derived. A population of 482 individuals (mean age 75.5±13.2 years (SD), 64% male) with permanent RV pacing were used as a validation group. The intrinsic QRS and QT time were measured during SR and subsequent RVP. To assess the relationship between the predicted QT with RVP and the measured QT without RVP, linear correlations analyses were performed. Our formula had a strong correlation with the irrespective QT without RVP (r=0.50) Conclusion We proposed a new simple formula to accurately estimate QT during RVP. This formula can be easily utilized in clinical practice. Figure 1: MAD characteristic value via plots stands for Median Absolute Difference (i.e. by how many ms the prediction is estimated on average). Figure 2: "Forest Plot" illustrates the correlation coefficients in the form of a forest plot. The dot r represents r and the bars the 95% confidence intervalsMAD characteristic value via plots standForest Plot" illustrates the correlation

LBBAP versus conventional CRT reimplantation after transvenous lead extraction: report from a monocentric experience

Abstract Background Cardiac resynchronization therapy – defibrillator (CRT-D) reimplantation after transvenous lead extraction (TLE) can be challenging due to fibrotic remnants and absence of target veins. Left bundle branch area pacing (LBBAP) is emerging as an alternative to conventional CRT, but data is lacking about its feasibility after TLE. Purpose To explore the feasibility and safety of LBBAP as alternative to conventional CRT though epicardial pacing (EP) in patients undergoing CRT-D TLE. Methods We prospectively enrolled all patients admitted for complete CRT-D extraction and replacement from July 2022 to September 2023. At the moment of reimplantation, the choice between EP and LBBAP was made on the basis of posterolateral CS branches viability at post-extraction CS venography. Procedural success was defined as effective stimulation and absence of major complications while the primary endpoints were procedural time, QRS complex duration and electrical lead parameters. Patients undergoing LBBAP and EP reimplantation were compared. Results Twenty-six patients were enrolled (mean age 68.3 ± 7.2 years, p = 0.538; 12% females, p = 0.859). The most frequent cause of device extraction was pocket infection (58%, p = 0.773). Seventeen (65%, p = 0.783) patients had estimated high risk of procedural severe complications measured by EROS score. Overall, 80 leads were extracted. Mechanical extractors and snares were deemed necessary in 35 cases (43%, p = 0.917) and in 2 cases, respectively. Almost all patients (n=25, 96%) underwent right-sided reimplantation. Procedural success was achieved in 24 cases (92%). Compared to standard CRT through EP, LBBAP reimplantation accounted for a faster procedure (109.5 ± 34.2 vs. 126.5 ± 46.8 min; p = &amp;lt;0.001), less radiologic exposure (877.0 ± 234.6 vs. 1332.0 ± 515.1 sec, p &amp;lt;0.001) and better ventricular pacing thresholds (0.7± 0.1 vs. 1.8± 0.6 V, p &amp;lt;0.001). Despite a similar pre-extraction paced QRS duration (127.4 ± 13.8 vs. 133.0 ± 14.4 msec; p = 0.610), LBBAP reported significant improvement in final QRS duration (105.0 ± 13.1 vs. 127.1 ± 10.4 msec, p &amp;lt; 0.001) with major reduction in QRS duration (- 10.9 ± 7.5 vs - 6.8 ± 10.1, p &amp;lt; 0.001). Conclusion After a CRT TLE procedure, LBBAP reimplantation accounted for lower procedure duration, lower radiologic exposure, narrower QRS and lower ventricular pacing thresholds, demonstrating to be a valuable alternative to EP.

Relationship Between Electrical Parameters and Cardiac Synchrony in Patients Underwent Left Bundle Branch Area Pacing.

The study aims to assess cardiac synchrony under different left bundle branch area pacing (LBBAP) and evaluate the relationship between different surface or intracardiac electrical parameters and mechanical synchrony. Eighty-two patients with successful LBBAP were recruited. The electrical synchrony, evaluated by paced QRS duration (pQRSD) and Stim-LVAT (stimulus to left ventricular activation time), and mechanical synchrony, evaluated by thestandard deviation of the time-to-peak contraction velocity in 12 left ventricular segments (Tsd-12-LV), were compared between groups in patients underwent LBBAP. To investigate the relationship between different electrical parameters with mechanical synchrony under LBBAP, patients were divided into subgroups according to left ventricular activation time (LVAT, < 60, 60-70, and > 70ms), presence of left bundle branch (LBB) potential (positive, negative), QRS axis (normal, left axis deviation [LAD]), and potential to ventricular interval (PVI, < 20 and > 20ms). Mechanical synchrony was compared among the subgroups respectively 3 days post LBBAP procedure. No statistically significant differences were documented in electrical synchrony, evaluated by pQRSD, and mechanical synchrony, evaluated by Tsd-12-LV among the subgroups divided by the stim-LVAT, LBB potential, PVI duration, or paced QRS axis in the LBBAP group. LBB potential, PVI, or normal paced QRS axis is not the prerequisite for successful LBBAP and optimal cardiac synchrony. Adopting a Stim-LVAT value of less than 75ms to attain ideal electrical and mechanical synchrony during theLBBAP procedure may be applicable. http://www.chictr.org.cn/index.aspx. gov identifier: ChiCTR1800021104.

Cardiac Resynchronization Therapy with Defibrillator in Ischemic Versus Nonischemic Cardiomyopathy.

Cardiac resynchronization therapy with implantable cardioverter defibrillators (CRT-Ds) are established therapy options for patients suffering from heart failure (HF). Several aspects of HF modification have yet to be described regarding etiology-dependent outcome differences in the long-term.The Mannheim CArdiac Resynchronization TherApy RetrospeCtive ObservAtioNAl (MARACANA) Registry retrospectively included all patients provided with CRTs in our center from 2013 to 2021. CRT-D recipients (n = 380) were grouped to either ischemic cardiomyopathy (ICM, n = 206) or nonischemic cardiomyopathy (NICM, n = 174). Both groups were compared regarding survival, left ventricular ejection fraction (LVEF), hospitalizations due to HF, intrinsic and paced QRS width, NYHA classification, and several further aspects of HF modification in the long-term (59.1 ± 4.81 months).Patients with ICM were older (73.3 ± 8.4 versus 67.7 ± 10.8 years) and predominantly male (86.4 versus 74.7%) and presented with higher creatinine values (1.57 ± 0.92 versus 1.31 ± 0.66 mg/dL, each P < 0.05) at baseline. The mean survival for patients with NICM was better (51.9 ± 1.2 versus 54.4 ± 1.1 months, P = 0.03). Improvements in NYHA (2.93 ± 0.4 versus 2.79 ± 0.5-2.19 ± 0.7 versus 1.79 ± 0.7) and LVEF (26.4 ± 6.8 versus 27% ± 6.9% to 35.7 ± 9.6 versus 44 ± 11%, each P < 0.05) were similar for both groups after 5 years. Patients with ICM experienced more hospitalizations due to HF within the first year (odds ratio 1.9, P < 0.05), whereas electrical remodeling was more impressive for NICM (QRS width 157.1 ± 19.4 milliseconds versus intrinsic 116.6 ± 12.7 milliseconds and paced 131.9 ± 21 milliseconds after 5 years, both P < 0.05).Patients with HF might experience long-term improvements in functional status and left ventricular reverse remodeling following CRT-D, regardless of underlying etiology. Alterations in some aspects of HF modification could be influenced by time- and etiology-associated comorbidities.

Paced QRS Duration as the Major Determinant of Pacing Induced Cardiomyopathy in Complete AV Block

Patients with complete heart block often develop pacing-induced cardiomyopathy (PICM) after placement of a permanent pacemaker. Objective: To establish paced QRS duration as determinant of pacing induced cardiomyopathy in complete Atrioventricular (AV) block. Methods: This descriptive study included 115 male and female patients that had a permanent pacemaker implanted for complete AV block, at the department of Cardiology, Hayatabad Medical Complex, Peshawar, during the period 1st November 2023 till 30th June 2024. Patients were evaluated for the presence of PICM and subsequently grouped as PICM and non-PICM. Paced QRS duration in both groups was compared. Results: PICM was confirmed in 63 patients (54.8%) and 52 (45.2%) were non-PICM. Mean age in PICM group was 71.2 ± 8.7 years and 66.8 ± 9.5 years in non-PICM group. The mean paced QRS duration in PICM group was 200.5 ± 22.3 milliseconds and 168.3 ± 15.7milliseconds in non-PICM group (p value &lt;0.001). Conclusion: Prolonged paced QRS duration was found as key indicator for predicting pacing induced cardiomyopathy in patients with permanent pacing for complete AV block.

Rate-Dependent Pacemap Matching in Scar-Related Ventricular Tachycardia: Impact of “TR Fusion” Phenomenon

BackgroundThe impact of varying rates of pacemapping (PM) rates on QRS morphology and PM score matching in patients with scar-related ventricular tachycardia (VT) has not been systematically assessed. ObjectivesIn this study, the authors sought to assess the variability in PM score matching at different pacing rates. MethodsDuring substrate mapping for VT ablation, PM was performed at cycle lengths (CLs) of 600 ms, 500 ms, 400 ms, 300 ms, and VT CL. PM scores were compared for the entire QRS, the first half (H1) of QRS, and the second half (H2) of QRS to examine the influence of the preceding T-wave superimposed into the onset of paced QRS complex (TR fusion). ResultsA total of 269 PMs in 40 patients undergoing scar-related VT ablation were systematically analyzed. The PM score improved at rates closer to VT with a median difference of 6% (Q1-Q3: 4%-10%; range: 0%-33%) between the lowest and the highest PM scores at a given site. Greater slurring of the QRS onset was observed at faster-paced CL, corresponding to a superimposition of the preceding T-wave into QRS onset, with significant differences in H1 but not H2 of the QRS complex. At faster PM rates, 32% of overall sites developed pseudo delta wave and 69% of endocardial pacing sites fulfilled epicardial criteria. ConclusionsThe rate of pacemapping can significantly alter morphologic score matching, with the most optimal match observed closest to VT CL. The onset of QRS complex morphology is influenced by superimposition of the preceding T-wave at faster rates, resulting in an underrecognized TR fusion phenomenon that may confound epicardial electrocardiographic criteria predicated upon the initial QRS slope and vector.

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.

Relationship of different left bundle branch pacing sites and clinical outcomes in patients with heart failure

BackgroundLeft bundle branch pacing (LBBP) is a novel physiological pacing modality. However, whether it delivers comparable efficacy with different capture sites in patients with heart failure remains unclear. ObjectiveThis study aimed to assess the association between different pacing sites and the response of LBBP. MethodsForty-three consecutive patients with heart failure, referred for successful LBBP implantation, were prospectively recruited in this study. Patients were assigned to 3 subgroups according to the paced QRS complex morphology (left bundle branch trunk pacing [LBTP], left posterior fascicular pacing, or left anterior fascicular pacing groups). Echocardiograms and electrocardiograms were recorded and analyzed at baseline and 6-month follow-up. ResultsThe response rate was 95.0%, 88.2%, and 83.3% in LBTP, left posterior fascicular pacing, and left anterior fascicular pacing groups, respectively. All subgroups were efficient in narrowing the QRS complex (QRS complex narrowing: 38.1 ± 10.8 ms, 36.4 ± 12.6 ms, and 40.8 ± 10.8 ms) and improving cardiac function (LVEF improvement： 25.7% ± 8.1%, 15.3% ± 8.1%, and 18.8% ± 4.4%). Compared with left fascicular pacing, LBTP resulted in longer peak left ventricular activation time (76.5 ± 10.2 ms vs 82.3 ± 6.5 ms; P = .037) and shorter duration from intrinsicoid deflection in V1 or V2 to QRS end (128.0 ± 6.0 ms vs 113.3 ± 5.2 ms; P＜.0001), along with better improvement in septal systolic longitudinal strain (P = .007) and lateral-septal myocardial loading inhomogeneity (P = .036). Linear regression analysis further revealed that left bundle branch capture sites were strongly associated with the improvement in peak strain dispersion (model R2 = 0.586; P = .042) and LVEF (model R2 = 0.425; P < .0001). ConclusionDifferent left bundle branch capture sites led to a subtle difference in mechanical synchrony, which may, in turn, affect LVEF improvement in patients with heart failure.

Long-term outcomes of left bundle branch area pacing compared with right ventricular pacing in TAVI patients

BackgroundNew-onset permanent pacemaker implantation (PPMI) is still a common complication after transcatheter aortic valve implantation (TAVI) with adverse clinical outcomes. ObjectiveThe purpose of this study was to investigate whether left bundle branch area pacing (LBBAP) improves long-term clinical results compared with traditional right ventricular pacing (RVP) in patients requiring PPMI after TAVI. MethodsA total of 237 consecutive patients undergoing RVP (N = 117) or LBBAP (N = 120) after TAVI were retrospectively included. Long-term outcomes, including all-cause death, heart failure rehospitalization (HFH), and left ventricular ejection fraction (LVEF) change compared to baseline, were obtained until 5 years post-TAVI. ResultsThe mean age of the overall population was 74 years, with a mean surgical risk score of 4.4%. The paced QRS duration was significantly longer in the RVP group compared with the LBBAP group (151 ± 18 vs 122 ± 12 ms; P < .001). No difference was found between the 2 groups in all-cause death (13.7% vs 13.3%; adjusted hazard ratio [HR], 0.76; 95% confidence interval [CI], 0.37–1.58; P = .466) or the composite endpoint of death and HFH (29.9% vs 19.2%; adjusted HR, 1.22; 95% CI, 0.70–2.13; P = .476); however, the risk of HFH was significantly higher in the RVP group at 5 years after TAVI (21.4% vs 7.5%; adjusted HR, 2.26; 95% CI, 1.01–5.08; P = .048). There was greater improvement of LVEF over time in the LBBAP group (P = .046 for LVEF changes over time between groups). ConclusionsLBBAP improved long-term clinical outcomes compared with RVP in patients undergoing PPMI after TAVI in terms of less HFH and better LVEF improvement.

Comparison of clinical and echocardiographic outcomes between left bundle branch area pacing and right ventricular pacing in older patients.

Left bundle branch area pacing (LBBAP) is safe and effective, but studies in older patients are lacking. This study compared the clinical and echocardiographic outcomes of LBBAP and right ventricular pacing (RVP) in patients aged ≥75 years. This prospective observational study included older patients with symptomatic bradycardia who underwent LBBAP or RVP between 2019 and 2022. Clinical data, including pacing and electrophysiological characteristics, echocardiographic measurements, and device-related complications were collected. The primary endpoint was a composite of all-cause mortality, heart failure hospitalization, and upgrade to biventricular pacing. Secondary outcomes included changes in left ventricular ejection fraction (LVEF). Of 267 included patients, 110 underwent LBBAP and 157 underwent RVP. LBBAP was successful in 109 patients (success rate: 99.1%), with one patient eventually undergoing RVP. The pacing parameters of LBBAP were similar to those of RVP, except for a significantly narrower paced QRS duration (112.8±11.6vs. 138.3±23.9ms, p<.001). Ventricular lead implanting procedural duration was longer for LBBAP than RVP (14.0vs. 6.0min, p<.001), as was the fluoroscopy time (4.0vs. 2.0min, p<.001). During a mean follow-up period of 31.0±16.8 months, the primary outcome incidence was significantly lower following LBBAP than RVP (15.1%vs. 21.1%; hazard ratio, 0.471; 95% confidence interval, 0.215-1.032; p=.036) in 149 patients (55.8%) with ventricular pacing burden>20%. RVP reduced LVEF from 62.7±4.1% at baseline to 59.8±7.8% at the final follow-up (p=.001), whereas LBBAP preserved LVEF (61.4±6.3%vs. 60.1±7.4%, p=.429). LBBAP demonstrated improved clinical outcomes compared with RVP and maintained LVEF in older patients with high ventricular pacing burdens.

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.