Percentage Of Ventricular Pacing Research Articles

Real-world outcomes in cardiac resynchronization therapy patients: Primary results of the SMART registry.

Cardiac resynchronization therapy (CRT) is guideline recommended for the treatment of symptomatic heart failure (HF) with reduced left ventricular ejection fraction and prolonged QRS. However, patients with common comorbidities, such as persistent/permanent atrial fibrillation (AF), are often under-represented in clinical trials. The Strategic Management to Optimize Response to Cardiac Resynchronization Therapy (SMART) registry (NCT03075215) was a global, multicentre, registry that enrolled de novo CRT implants, or upgrade from pacemaker or implantable cardioverter defibrillator to CRT-defibrillator (CRT-D), using a quadripolar left ventricular lead in real-world clinical practice. The primary endpoint was CRT response between baseline and 12month follow-up defined as a clinical composite score (CCS) consisting of all-cause mortality, HF-associated hospitalization, New York Heart Association (NYHA) class and quality of life global assessment. The registry enrolled 2035 patients, of which 1558 had completed CCS outcomes at 12months. The patient cohort was 33.0% female, mean age at enrolment was 67.5±10.4years and the mean left ventricular ejection fraction was 29.6±7.9%. Notably, there was a high prevalence of mildly symptomatic patients (NYHA class I/II 51.3%), non-left bundle branch block (LBBB) morphology (38.0%), AF (37.2%) and diabetes mellitus (34.7%) at baseline. CCS at 12months improved in 58.9% (n=917) of patients; 20.1% (n=313) of patients stabilized and 21.0% (n=328) worsened. Several patient characteristics were associated with a lower likelihood of response to CRT including older age, ischaemic aetiology, renal dysfunction, AF, non-LBBB morphology and diabetes. Higher HF hospitalization (P<0.001) and all-cause mortality (P<0.001) were observed in patients with AF. These patients also had lower percentages of ventricular pacing than patients in sinus rhythm at baseline and follow-up (P<0.001, both). A further association between AF and non-LBBB was observed with 81.4% of AF non-LBBB patients experiencing an HF hospitalization compared with 92.5% of non-AF LBBB patients (P<0.001). Mortality between subgroups was also statistically significant (P=0.019). This large, global registry enrolled a CRT-D population with higher incidence of comorbidities that have been historically underrepresented in clinical trials and provides new insight into factors influencing response to CRT. As defined by CCS, 58.9% of patients improved and 20.1% stabilized. Patients with AF had particularly worse clinical outcomes, higher HF hospitalization and mortality rates and lower percentages of ventricular pacing. High incidence of HF hospitalization in patients with AF and non-LBBB in this real-world cohort suggests that ablation may play an important role in increasing future CRT response rates.

Is conduction system pacing more effective than right ventricular pacing in reducing atrial high-rate episodes in patients with heart failure and preserved ejection fraction?

The relationship between conduction system pacing (CSP) and the incidence of atrial fibrillation (AF) in patients with heart failure and preserved ejection fraction (HFpEF) remains uncertain. This study aims to investigate the occurrence of atrial high-rate episodes (AHREs) following CSP in patients with HFpEF, in comparison to right ventricular pacing (RVP). Patients with HFpEF who received dual-chamber pacemakers for atrioventricular block were retrospectively enrolled from January 2018 to January 2023. Both new-onset and progressive AHREs were recorded, along with other clinical data, including cardiac performance and lead outcomes. A total of 498 patients were enrolled, comprising 387 patients with RVP and 111 patients with CSP, with a follow-up duration of 44.42 ± 10.41 months. In patients without a prior history of AF, CSP was associated with a significantly lower incidence of new-onset AHREs when the percentage of ventricular pacing was ≥20% (9.52% vs. 29.70%, P = 0.001). After adjusting for confounding factors, CSP exhibited a lower hazard ratio for new-onset AHREs compared to RVP (HR 0.336; [95% CI: 0.142-0.795]; P = 0.013), alongside left atrial diameter (LAD) (HR 1.109; [95% CI: 1.048-1.173]; P < 0.001). In patients with a history of AF, the progression of AHREs in CSP and RVP did not differ significantly (32.35% vs. 34.75%, P = 0.791). Cardiac performance metrics, including left ventricular end-diastolic diameter (LVEDD) (49.09 ± 4.28mm vs. 48.08 ± 4.72mm; P = 0.015), LAD (40.68 ± 5.49mm vs. 39.47 ± 5.24mm; P = 0.001), and NYHA class (2.31 ± 0.46 vs. 1.59 ± 0.73; P < 0.001), improved obviously following CSP, while LVEDD (48.37 ± 4.57mm vs. 49.30 ± 5.32mm; P < 0.001), LAD (39.77 ± 4.58mm vs. 40.83 ± 4.80mm; P < 0.001), NYHA class (2.24 ± 0.43 vs. 2.35 ± 0.83; P = 0.018), and left ventricular ejection fraction (LVEF) (57.41 ± 2.42 vs. 54.24 ± 6.65; P < 0.001) deteriorated after RVP. Our findings suggest that CSP may be associated with improvements in cardiac performance and a reduction in new-onset AHREs compared to RVP in patients with HFpEF. However, prospective randomized trials are anticipated to confirm these potential benefits.

Atrial pacing improves mitochondrial function in peripheral blood mononuclear cells in patients with cardiac implantable electronic devices.

Mitochondrial dysfunction contributes significantly to the development of atrial fibrillation (AF). Conflicting data regarding the atrial pacing and the risk of AF existed, and the impact of atrial pacing on mitochondrial function remains unknown. Therefore, we sought to examine the association between atrial pacing percentage and mitochondrial function in patients with cardiovascular implantable electronic devices (CIEDs) with atrial pacing capability. This is a cross-sectional study involving 183 patients with CIEDs with atrial pacing capability. The oxidative stress and mitochondrial function were determined in peripheral blood mononuclear cells (PBMCs). Among 183 patients, 55.7% had permanent pacemakers, 7.7% had defibrillators, and 36.6% had cardiac resynchronization therapy. Mean age was 67.5 ± 14.7 yr with 51% being male. Mean left ventricular ejection fraction (LVEF) was 53.9 ± 16.8%. We demonstrated that the presence of atrial pacing above 50% correlated with higher levels of mitochondrial spared respiratory capacity (P = 0.043) and coupling efficiency (P = 0.045). After adjusting with multiple linear regression for age, sex, LVEF, history of AF, sick sinus syndrome, comorbidities, estimated glomerular filtration rate (eGFR), cardiac resynchronization therapy (CRT), and percentage of ventricular pacing, our findings revealed a statistically significant association between a higher percentage of atrial pacing and increased spared respiratory capacity (β, 0.217, P = 0.046), lower nonmitochondrial respiration (β, -0.230; P = 0.023), and proton leak (β, -0.247; P = 0.022). We demonstrated that atrial pacing enhances mitochondrial performance in PBMCs and left ventricular contractile performance in patients with CIEDs. This observation may serve as an additional support for the preventive effect of atrial pacing in the prevention of atrial arrhythmia.NEW & NOTEWORTHY Atrial pacing enhances mitochondrial spare respiratory capacity and reduces proton leak. This finding may provide further evidence supporting the preventive role of atrial pacing in reducing the risk of atrial fibrillation in patients with cardiac implantable electronic devices.

Pacing dependency after TAVI, a lasting hazard in every case?

Abstract Introduction Atrioventricular (AV) conductions abnormalities that require permanent pacemaker (PPM) occur in up to 20% of patients after TAVI. The evolution of conduction abnormalities and the long-time pacing burden have not been fully characterized. We aim to characterize ventricular pacing burden after TAVI assessing also the impact of clinical and periprocedural factors. Methods Single centre retrospective registry including all consecutive patients undergoing TAVI between 01/2014 and 08/2021 that had a PPM implanted during index admission. Patients with in-hospital death were excluded. Baseline and pacing follow-up data were collected prospectively and assessed retrospectively using local electronic health records. We examined pacing burden as the percentage of ventricular pacing (VP%) and divided our cohort in 3 groups: i VP% ≤10%, ii 10% &amp;gt; VP% &amp;lt; 90%, iii VP% ≥90%. We assessed the difference between discharge and 1y VP% and the interaction between baseline characteristics. Results 766 patients underwent TAVI and 109 (14.2%) were included. The median age was 84 years (IQR 80 ; 90) and 44% were male (n = 48). 19 patients (17.4%) had previous 1st degree AV block (AVB) and 37 patients (33.9%) had previous right bundle branch block (RBBB). A self-expandable valve was implanted in 78 patients (71.6%). The median time between TAVI and PPM was 2 days (1;5). Sustained complete AVB (cAVB) occurred in 85 patients (78.0%) and was the most common indication for PPM. Data on VP% at discharge was available for 102 patients (93.5%). The median VP% at discharge was 100% (99 ; 100) with 4 patients (3.7%) having ≤10% VP% and 87 patients (79.8%) having ≥90% VP%. 95 patients (87.2%) completed the 1y follow-up. The VP% decreased significantly between discharge and 1y follow-up - 8.0 (IQR -59 ; 0 / p &amp;lt;0.05 Wilcoxon test) (Figure 1), similarly across valve type. At 1y follow-up, 20 patients (18.3%) had ≤10% VP% and 43 patients (39.4%) had ≥90% VP%. In the 18 patients (19.4%) without periprocedural sustained cAVB, 9 patients (50.0%) had ≤10% VP% and 1 patient (5.6%) had ≥90% VP%. In contrast, among patients with sustained cAVB, 11 patients (14.7%) had ≤10% VP% and 40 patients (53.3%) had ≥90% VP% (p &amp;lt;0.05 Chi-squared) (Figure 2). Conclusions In this study cohort the pacing burden significantly decreased in the 1st year after TAVI. It was significantly lower in patients without periprocedural sustained cAVB which suggests that a more conservative management may be considered in a small subgroup of patients.

Study of right atrial and right ventricular function in dual chamber pacemaker patients

Abstract Background Unlike left ventricular function, right ventricular (RV) function in pacemaker patients is less well studied with less studies comparing septal versus apical pacing effects on the RV function and almost none on the right atrial (RA) function. Purpose To assess the effect of RV pacing on the echocardiographic and clinical parameters of the RV and RA function and their correlation with the site of right ventricular lead implantation. Methods The study assessed 59 patients in need of permanent dual chamber pacemaker implantation using clinical and echocardiographic data of the RV and RA size and function using tricuspid annular plane systolic excursion (TAPSE), S wave velocity of the tricuspid annulus and fractional area change (FAC), free wall strain (FWSL), global longitudinal strain (GLS) of the RV, RA strain including reservoir, conduit and contraction phases and 3D ejection fraction of the RV using Epiq 7 Ultrasound machine (Philips Healthcare) by the same echocardiographer before implantation and 6 months after. All programming parameters were recorded postoperative and 6 months later. Results 31 patients had the RV lead in the RV apex whereas 28 had it in the septum and all patients had their RA lead in the right atrial appendage, with no significant difference between both groups regarding baseline demographic, clinical nor echocardiographic data. At 6 months, there was a significant decline of the 3D RVEF from a mean of (58.57% ± 6.35%) to (56.41% ± 6.17%), TAPSE from (2.61 cm ± 0.51) to (2.35 cm ± 0.52) and S wave from (13.73 cm/sec ± 2.84) to (12.64 cm/sec ± 2.61) but none showed a significant difference between septal and apical pacing, on the other hand, the RV strain showed a significant decline 6 months after implantation in both the FWSL from (-31.75% ± 5.39) to (-27.82% ± 5.73) and the GLS from (-25.89% ± 5.17) to (-21.65% ± 4.51) with more decline in the septal group compared to the apical (-20.33% ± 4.70 versus -22.84% ± 4.04 regarding the GLS and -26.11% ± 6.41 versus -29.37% ± 4.62 in the FWSL, respectively). There was no difference in the FAC, tricuspid regurgitation severity, gradient nor the estimated pulmonary artery pressure at 6 months. The RA size showed a significant decline at 6 months but no difference in any of the strain parameters. No clinical RV failure symptoms nor signs were observed. Programming revealed a mean percentage of ventricular pacing of (97.92% ± 2.67%) with a minimum of 91% and atrial pacing of (10.41% ± 12.52%), and the thresholds, impedance and atrial high-rate episodes were comparable postoperatively and 6 months after, with no difference between the septal and apical groups. Conclusion At 6 months follow-up after pacemaker implantation, right ventricular function starts to show decline in both the septal and apical groups with only the right ventricular strain more affected in the septal group compared to the apical.3D right ventricular ejection fraction3D right ventricular strain

Evaluation of ventricular pacing suppression algorithms in dual chamber pacemaker: Results of "LEADER" study.

There is limited research on the intra-individual efficacy of ventricular pacing minimization algorithms developed by Biotronik-the Ventricular Pace Suppression algorithm (VpS) and the Intrinsic Rhythm Support plus algorithm (IRSplus) (BIOTRONIK SE & Co. KG, Berlin, Germany). We performed a randomized pilot trial that evaluated the efficacy of two algorithms in patients with symptomatic sinus node dysfunction (SND) who received a dual-chamber pacemaker. The trial was conducted in 11 tertiary hospitals in South Korea. The patients were randomized to either the VpS or IRSplus algorithm group after a 3-month period of fixed atrioventricular (AV) delay. The primary outcome was the ventricular pacing percentage (Vp%) at each follow-up visit. The secondary outcomes were the occurrence of heart failure (HF) and atrial fibrillation (AF) during the study period. Data from 131 patients were analyzed. Initially, their average Vp% over 3 months with a fixed AV interval was 14.1 ± 19.4%. Patients were randomly assigned to VpS and IRSplus groups, with 66 and 65 in each. Algorithms reduced average Vp% to 4.0 ± 11.3% at 9 months and 6.7 ± 14.9% at 15 months. These algorithms were more effective for patients with paced AV delay (PAVD) ≤300 ms compared to those with PAVD >300 ms. Both algorithms were equally effective in reducing Vp%. Clinical AF or HF hospitalization was not observed during the study period. The VpS and IRSplus algorithms are effective and safe in minimizing unnecessary ventricular pacing in patients with SND.

Atrial standstill in a young patient treated with left bundle branch area pacing

Abstract Atrial standstill is a rare arrhythmogenic condition characterized by the absence of electrical and mechanical activity in the atria. The therapeutic options for these patients described in the current literature, in which no reversible cause is detected, are permanent cardiac pacing, anticoagulant, and heart failure treatment when the latter exists. We present a case of a young male with no personal or family history of cardiovascular disease, diagnosed with atrial standstill after multiple syncopal episodes, in whom, because of the high expected ventricular pacing percentage, we opted for conduction system pacing with left bundle branch area pacing.

Clinical characteristics of patients with better ejection fraction recovery after upgrading to cardiac resynchronization therapy

Abstract Background Chronic right ventricular (RV) pacing can cause cardiac systolic dysfunction and heart failure (HF), increased risk of HF hospitalization and adverse outcomes. In these patients upgrading to cardiac resynchronization therapy (CRT) may improve left ventricular function. Purpose We aimed to identify the profile of patients (their clinical, electrical and echocardiographic characteristics) who are more likely to make a significant change in left ventricular ejection fraction (LVEF) one year after revision of the RV pacing system to CRT. Methods This was a retrospective, observational, single-center study. We included patients with a permanent antibradycardia pacemaker who had no systolic dysfunction and HF symptoms at the time of pacemaker implantation and who experienced a drop in LVEF below 35% during follow-up, with development of HF symptoms and with at least 20% of ventricular pacing. In all patient's revision to CRT was performed at our center between January 2014 and December 2019. We excluded patients who were indicated for a system upgrade regardless of the percentage of ventricular pacing and those in whom the drop in LVEF is due to a new coronary event. We used patients’ medical records to collect data on baseline characteristics. LVEF was measured pre-revision and 12 months after upgrade. To examine the difference in LVEF change between specified subgroups of patients we used a t-test. Results During the defined period, 82 upgrade procedures from conventional pacemaker to CRT were done in our center. We excluded 12 patients with left bundle branch block (LBBB) QRS morphology, 4 with non-LBBB QRS morphology but with QRS duration over 150ms and 4 patients who died within a year after revision to CRT. Therefore, we analyzed 62 patients (20.9% female, mean age 66.9 ± 11.2 years, mean LVEF 25.9 ± 6.8). After 12 months, 58.1% of patients had an increase in EF above 5%, and the mean change in LVEF (ΔLVEF) was 7.8 ± 11.8. Compared to those with non-ischemic cardiomyopathy (NICMP), patients with ischemic etiology had statistically significantly less improvement in LVEF (ΔLVEF 1.8 ± 6.8 vs 13.1 ± 12.7, p &amp;lt; 0.01), as well as patients with an RV apical pacing compared to those with a septal lead position (ΔLVEF 5.1 ± 9.1 vs 14.1 ± 14.7, p = 0.021). Patients with narrower paced QRS complex (&amp;lt;150ms) before upgrade had a significantly greater improvement in LVEF compared to those with a wider paced QRS complex (≥150ms) (ΔLVEF 10.9 ± 12.2 vs 4.8 ± 10.7, p = 0.04), and those with post-revision paced QRS width above 150ms had significantly lower change in LVEF compared to those with a narrower paced QRS (ΔLVEF 4.6 ± 9.8 vs 11.1 ± 12.8, p = 0.028). Conclusion Patients with NICMP and with width of the paced QRS complex before and after revision to CRT below 150ms had significantly greater improvement in LVEF 12 months after the upgrade. The position of RV lead significantly affects the success of the upgrade procedure.

THROW YOUR LEAD OVER THE OBSTACLE: A CHALLENGING CRT UPGRADING

Abstract High percentage of right ventricular pacing could lead to pacing induced cardiomyopathy in a non–negligible proportion of patients. Cardiac resynchronization therapy upgrading could represent an option to improve ventricular function, reducing heart failure hospitalizations. A 82 yo male was admitted to hospital with symptomatic heart failure. He had history of complete AV block treated with dual chamber pacemaker implantation five years earlier following coronary artery bypass graft surgery, bioprosthetic aortic valve replacement and septal myectomy. He had also history of cardiac arrest occurred in the context of acute coronary syndrome treated with PCI so that ICD implant was not considered at that time, and two more HF hospitalizations in previous years. Progressive LVEF decline was documented since PM impantation until last echo showed severe left ventricular dysfunction (EF 20% from baseline EF 60%). The ECG showed sinus rhythm and wide paced QRS (206 ms) with 100% pacing percentage. A CRT device upgrading was planned. Baseline venography initially showed pervious axillary–subclavian left axis, but unfortunately the guidewire encountered a complete occlusion before entering the superior vena cava. Nevertheless, dye contrast injection documented the presence of a proximal collateral branch (fig A) having a vertical course in the thorax and reaching the lateral wall of the left ventricle with an extrapericardic course then entering the right heart through inferior vena cava. Using a IM 5Fr sheath (usually used by interventional cardiologists to cannulate internal mammary artery) we could reach this branch, inserting a guidewire and finally advancing a quadripolar lead (Fig B–C) which reached the lateral left ventricular wall. LV capture was confirmed when pacing from the three proximal poles, while the distal one caused phrenic nerve capture. The quadripolar lead was connected to the LV port of a three chamber PM along with previous implanted leads thus obtaining biventricular pacing. QRS paced was 50 ms shorter than baseline. No peri–procedural complications occurred. Lead–related venous occlusion might represent an obstacle to CRT upgrade requiring high technical expertise. The presence of a complete venous occlusion might cause procedural failure, particularly in hospitals without surgical facility. In this case, the presence of a collateral branch reaching the lateral wall of the left ventricle allowed to successfully complete the CRT upgrade.

Clinical/electrophysiologic characteristics of infranodal Wenckebach in patients with indication for permanent ventricular pacing: A prospective study

BackgroundInfranodal Wenckebach is rare and not well characterized. ObjectiveWe prospectively studied clinical and electrophysiologic characteristics of patients with atrioventricular (AV) Wenckebach with an indication for permanent ventricular pacing. MethodsDuring a 2-year period, all patients with an indication for permanent ventricular pacing underwent targeted preimplantation electrophysiologic study. Clinical and electrophysiologic characteristics at presentation and ventricular pacing percentage at 6-month follow-up were evaluated. ResultsA total of 163 patients (median age, 68 [interquartile range, 60–74] years; male, 59%; median QRS duration, 110 [90–130] ms; complete AV block in 123 [75.5%]) were included. AV Wenckebach was noted in 22 (13.4%) patients (median age, 70 [63–76.5] years; male, 54%; median QRS duration, 120 [110–140] ms) and classified as infranodal (12/163 [7.3%]) vs AV nodal (10/163 [6.1%]). Patients with infranodal Wenckebach (infrahisian in all), compared with AV nodal Wenckebach, demonstrated higher frequency with left ventricular ejection fraction ≤40% (41.7% vs 0%; P = .04), longer median HV interval (90 vs 49 ms; P = .005), lower frequency of isolated first-degree AV block (8.3% vs 60%; P = .02), higher frequency of right bundle branch block with left anterior fascicular block (75% vs 10%; P = .003), lesser PR increment at onset of AV Wenckebach (20.5 vs 80 ms; P = .002), and onset of 2:1 AV block at longer cycle lengths (91.7% vs 20%; P = .002). ConclusionOf patients referred for pacemaker implantation, infranodal Wenckebach was present in 27.5% (11/40) without complete AV block. It was as frequent as AV nodal Wenckebach and associated with characteristic electrophysiologic findings.

Long-term outcome of permanent epicardial pacemaker implantation in neonates: Experience from an Indian center.

Permanent pacemaker implantation (PPI) in neonates is challenging with respect to indications, device selection, implantation technique, and long-term outcomes. Complex anatomy, the need for long-term pacing with high rates, and a problematic postoperative period are the major problems. We prospectively followed up 22 newborns who underwent PPI below 28 days of life at our institute. The median age at implantation was 2 days (interquartile range 1-9 days), and 9% were born preterm. The average heart rate before implantation was 46.4 ± 7.2 bpm. Maternal lupus antibodies were positive in 8 (36.4%) neonates, whereas 11 (50.0%) had associated congenital heart disease. Nineteen neonates underwent single chamber (VVI) and three underwent dual chamber (DDD) pacemaker implantation. Over a median follow-up of 46 months (range 2-123 months), the average ventricular pacing percentage was 87.5 ± 24.9%, with a stable pacing threshold. Seven children underwent pulse generator replacement due to battery depletion at a median age of 47 months. Pacing-induced ventricular dysfunction was seen in five children at a median age of 23.6 months, and two underwent upgradation to cardiac resynchronization therapy. Overall mortality was 13.6%, all due to tissue hypoperfusion and lactic acidosis in the postimplantation period. PPI in neonates has a favorable outcome with excellent lead survival. Overall mortality is 13.6%, which is predominantly in the postimplantation period and related to myocardial dysfunction.

Correlation of ventricular pacing burden and left ventricular function in patients with heart failure with reduced ejection fraction.

Pacemaker-induced cardiomyopathy is a well described phenomenon in patients with preserved ejection fraction at the time of permanent pacemaker implant. One of the identified risk factors for pacemaker-induced cardiomyopathy is the degree of ventricular pacing burden. However, it is unclear how a high right ventricular pacing burden affects patients with depressed left ventricular function at the time of pacemaker implantation. We sought to assess the relationship between right ventricular pacing and change in left ventricular function over time. We conducted an analysis of all patients who had received either a single or dual lead cardiac implantable electronic devices, excluding biventricular devices, and had a prior transthoracic echocardiogram demonstrating an ejection fraction of less than 50%. The primary end-point was the correlation between the percentage of ventricular pacing and the change in LV ejection fraction. Fifty eight patients with preceding heart failure had pacemakers implanted and had follow up echocardiograms. There was no correlation between the degree of ventricular pacing and the absolute change in LV function (r = .04, p = .979). None of the previously identified risk factors for pacemaker induced cardiomyopathy were predictive of a significant fall in ejection fraction. The degree of RV pacing and other established risk factors for pacemaker-induced cardiomyopathy in patients with normal left ventricular function at the time of implantation do not appear to carry the same risk in patients with pre-existing heart failure who receive either single or dual lead pacemakers.

Head-up tilt test induced asystole and recurrent syncope: a follow-up study

Abstract Introduction Head-up tilt test (HUTT) is a valuable diagnostic tool in unexplained and recurrent syncope, especially when reflex etiology is suspected. If asystole is the dominant feature of reflex syncope, permanent pacemaker therapy may be effective for reducing syncope recurrence. Purpose To investigate syncope recurrence, pacemaker implantation and death of patients with syncope and asystole induced by HUTT and carotid sinus message (CSM). Methods Retrospective analysis of consecutive patients referred for HUTT between January 2017 and December 2021 and selection of those with cardioinhibitory response, defined by syncope or pre-syncope and asystolic pause ≥3 seconds. Patients’ follow-up (FUP) was performed via a phone interview and analysis of clinical records, to assess recurrence of syncope, treatments, and death. Results A total of 44 patients were included: 30 (68,2%) were men, with a median age of 69 years (interquartile range (IQR) of 24). Asystole was experienced after CSMin 41 patients and during tilt test alone in 3 patients. Median FUP was 26 months (IQR 23). There were 19 (44,2%) patients who implanted pacemaker (PM), all with cardioinhibitory carotid sinus syndrome ( I-CSS), 57,9% men, with median age of 74 years (IQR 19) and median duration of asystole during CSMof 6,3 seconds (IQR 3,8). Of these, 5 (26,3%) implanted a unicameral PM and the remaininga bicameral PM, with AAI-DDD mode programming. Two patients had PM-related complications: infection and dislodgment of ventricular lead, both in the first 15 days after implantation. Median atrial and ventricular pacing percentage at last PM consultation was 7% (IQR 28) and 1% (IQR 4), respectively. There was a positive strong correlation between the percentage of atrial pacing at first and at last appointment (p&amp;lt;0,001, r=0,867) and a positive moderated correlation between the percentage of ventricular pacingat first and at last appointment (p=0,022, r=0,586), suggesting a similar degree of pacing along FUP-time. Only three patients (6,8%) had syncope recurrence, all men with CI-CSS, median age of 78; one patient had syncope before implantation PM, other relapsed 2-times with a PMimplanted and the third refused PMimplantation despite 5-time recurrence of symptoms. There was no association between the duration of the asystole during HUTT with implantation of PM nor syncope recurrence (p&amp;gt;0.2). Age at HUTT was significantly associated both with CI-CSS and PM implantation (p=0,001 and p=0,045, respectively). Two patients died, both of oncologic causes. Conclusion In agreement with the literature, our cohort of patients with cardioinhibitory response during HUTT and CSM experienced an overall good prognosis, with no cardiac deaths; there was very low syncope recurrence, not allowing a comparison between the groups with and without pacemaker. Age at HUTT was significantly associated both with CI-CSS and PMimplantation.

Conduction system pacing for ventricular pacing requirement is feasible and effective on patients with hypertrophic cardiomyopathy and cardiac dysfunction

ObjectiveWe aimed to evaluate the feasibility and safety of his-bundle pacing (HBP) and left bundle branch pacing (LBBP) in patients with hypertrophic cardiomyopathy (HCM) and heart failure (HF). MethodsPatients with HF and interventricular septal thickness (IVST) ≥ 13 mm resulted from HCM, who accepted conduction system pacing (CSP) with a percentage of ventricular pacing > 40% from May 2018 to April 2022 were consecutively enrolled in our center. LBBP was preferred and HBP was the alternative therapy unless IVST ≥ 16 mm or LBBP failed, whereas LBBP would be the alternative therapy if HBP failed in patients with IVST ≥ 16 mm. All patients were followed up for at least one year. Data including clinical, echocardiographic parameters and electrocardiogram measurements, were collected and evaluated in patients with and without left ventricular ejection fraction (LVEF) < 50%. ResultsA total of 27 patients (65.93 ± 9.09 years old) were enrolled and only 3 patients failed in CSP (11.11%) via LBBP (6/13) and HBP (18/21) procedures. LVEF (P = 0.521), left ventricular end-diastolic diameter (LVEDD) (P = 0.816), and QRS duration (P = 0.928) did not worsen after CSP, and left atrial diameter (LAD) (49.58 ± 8.99 mm vs.47.04 ± 9.82 mm, P = 0.045) tended to improve slightly after 19.19 ± 7.71 months follow-up. Of note, LVEF (39.22%±7.51% vs. 45.22%±9.59%, P = 0.015), LVEDD (52.11 ± 10.10 mm vs. 48.33 ± 9.07 mm, P = 0.037), LAD (50.33 ± 8.93 mm vs. 46.11 ± 5.97 mm, P = 0.013) and New York Heart Association (NYHA) grade (2.67 ± 0.5 vs. 1.38 ± 1.02, P = 0.029) improved in 9 patients with LVEF < 50%, whereas LVEF (P = 0.372), LVEDD (P = 0.665), LAD (P = 0.093) and NYHA grade (P = 0.452) did not deteriorate in patients with preserved ejection fraction. ConclusionCSP was safe and feasible in patients with HCM and cardiac dysfunction, and did not worsen cardiac performance especially in patients with LVEF < 50%. HBP might be an effective alternative to LBBP in patients with significantly thickened interventricular septum.

COMPARATIVE ANALYSIS OF LONG-TERM OUTCOMES FOLLOWING THE STIMULATION OF CARDIAC CONDUCTION SYSTEM AND RIGHT VENTRICULAR PACING IN PATIENTS WITH BRADYARRHYTHMIAS

Introduction. Right ventricular myocardial pacing induces asynchronous ventricular contraction, potentially resulting in pacing-induced cardiomyopathy and adverse long-term clinical outcomes. Conduction system pacing is a physiological alternative to right ventricular myocardial pacing. The objective of this study is to analyze the long-term outcomes of the conduction system pacing in comparison with right ventricular myocardial pacing in patients requiring permanent ventricular pacing and who have preserved initial left ventricular ejection fraction (≥ 50%). Materials and methods. 48 patients with indications for permanent ventricular pacing were selected for comparative analysis. Of these, 18 patients had cardiac conduction system pacing and 30 patients had right ventricular myocardial pacing. Permanent pacemaker implantation in both groups of this study was performed from 2012 to 2022. Patients in both groups had to meet the following selection criteria for this study: 1) preserved systolic function of the left ventricle at the time of pacemaker implantation (≥ 50%); 2) total percentage of ventricular pacing from the time of implantation had to be not less than 90%.&#x0D; Results. The observation period was 35.3 ± 37 months in the conduction system pacing group and 46 ± 28.73 months in the right ventricular pacing group. Since the time of pacemaker implantation, pacing-induced cardiomyopathy occurred in 7 (23%) patients in the right ventricular pacing group and in none in the conduction system pacing group. The mean left ventricular ejection fraction at the control visit was significantly lower in the right ventricular pacing group (51.59 ± 8.55 vs. 58.64 ± 4.58%, p =.004). A significant reduction in global longitudinal strain was observed in the right ventricular pacing group compared to the conduction system pacing group (14.22 ± 3.66 vs. 18.49 ± 2.5%, p = &lt;.001). Paced QRS width was significantly greater in the right ventricular pacing group (152.32 ± 18.13 vs. 119.12 ± 8.8 ms, p &lt;.001). Conclusions. Applying new physiological methods of cardiac pacing enables to avoid the negative consequences of an asynchronous pattern of ventricular activation during conventional right ventricular pacing.

Initial heart rate score predicts new-onset atrial tachyarrhythmias in pacemaker patients.

Heart rate score (HRSc), the per cent of atrial paced and sensed event in the largest 10 b.p.m. rate histogram bin of a pacemaker, predicts survival in patients with cardiac devices. No correlation between HRSc and development of atrial fibrillation (AF) has been reported. In this study, we evaluated the relationship between pacemaker post-implantation HRSc and the incidence of newly developed atrial tachyarrhythmias (ATAs). Patients with dual-chamber pacemakers, implanted 2013-17, with the LATITUDE remote monitoring data with ≥600 000 beats of histogram data collected at baseline were included (N = 34 543). Heart rate score was determined from the initial 3-month post-implantation histogram data. Patients were excluded if they had ATAs, defined as atrial high-rate episodes >5 min or >1% of right atrial beats >170 b.p.m. during the initial 3 months post-implantation. New ATAs, after the baseline period, were defined by each of the following: >1, >10, or >25% of atrial beats >170 b.p.m. or atrial tachycardia response (ATR) events >24 h. Patients were followed a median of 2.8 (1.0-4.0) years. The incidence of ATAs increased in proportion to HRSc (log-rank P-value <0.001), and the initial HRSc ≥70% was associated with increased ATAs by all definitions. Patients with initial HRSc ≥70% were older, had a higher percentage of right atrium pacing (%RA pacing), had a lower percentage of right ventricular pacing (%RV pacing), and were more likely programmed with rate-response vs. subjects with HRSc <70%. Initial HRSc (hazard ratio: 1.07, 95% confidence interval: 1.05-1.09; P < 0.0001) independently predicted ATAs after adjusting for age, gender, %RV pacing, and rate-response programming. The %RA pacing and initial HRSc were correlated. Heart rate score independently predicts any subsequent duration of ATAs in pacemaker patients.

New-onset atrial high-rate episodes between his bundle pacing and conventional right ventricular septum pacing in patients with atrioventricular conduction disturbance.

The effect of His bundle pacing (HBP) on the incidence of new-onset atrial fibrillation (AF) after pacemaker implantation (PMI) for atrioventricular conduction disturbance (AVCD) remains unknown. We compared the incidence of new-onset atrial high-rate episode (AHRE) in conventional right ventricular (RV) septum pacing (RVSP) and His bundle pacing (HBP) after PMI for AVCD. One hundred and four consecutive patients who underwent dual chamber PMI for AVCD in our hospital were screened. Thirty-five patients with mitral or aortic valve disease, history of open-heart surgery, prior AF, subclinical AF, cumulative ventricular pacing percentage < 90%, and RV lead revision were excluded, and 69 patients were effectively enrolled in this study. The primary endpoint was new-onset AHRE within the follow-up period. New-onset AHRE was defined as an atrial high-rate episode that occurred 3months after PMI and lasted for > 6min at an atrial heart rate > 190bpm. RV leads were placed in the His bundle region and RV septum region in 22 and 47 patients, respectively. The mean follow-up period was 539 ± 218days. The follow-up period was 2years after PMI or until the new-onset AHRE occurred. The incidence of new-onset AHRE was lower in the HBP group than in the RVSP group (11% vs. 43%, p = 0.01). Multivariate analysis in the Cox regression hazard model showed that HBP had a significantly lower risk of new-onset AHRE compared with RVSP (HR = 0.21; 95% confidence interval 0.04-0.78, p = 0.02). The incidence of new-onset AHRE was significantly less in HBP compared to RVSP during the 2-year follow-up period after pacemaker implantation in AVCD patients with RV pacing dependence.

Predictors of pacing-induced cardiomyopathy detection and outcomes demonstration after conduction system pacing upgrade on patients with long-term persistent atrial fibrillation.

To identify the predictors of pacing-induced cardiomyopathy (PICM) and illustrate the safety and feasibility of conduction system pacing (CSP) upgrade on patients with long-term persistent atrial fibrillation (AF). All patients with long-term persistent AF and normal left ventricular ejection fraction (LVEF) ≥50% were consecutively enrolled from January 2008 to December 2017, and all the patients with atrioventricular block (AVB) and high right ventricular pacing (RVP) percentage of at least 40%. The predictors of PICM were identified, and patients with PICM were followed up for at least 1 year regardless of CSP upgrade. Cardiac performances and lead outcomes were investigated in all patients before and after CSP upgrade. The present study included 139 patients, out of which 37 (26.62%) developed PICM, resulting in a significant decrease in the left ventricular ejection fraction (LVEF) from 56.11±2.56% to 38.10±5.81% (p<.01). The median duration for the development of PICM was 5.43 years. Lower LVEF (≤52.50%), longer paced QRS duration (≥175ms), and higher RVP percentage (≥96.80%) were identified as independent predictors of PICM. Furthermore, the morbidity of PICM progressively increased with an increased number of predictors. The paced QRS duration (183.90±22.34ms vs. 136.57±20.71ms, p<.01), LVEF (39.35±2.71%vs. 47.50±7.43%, p<.01), and left ventricular end-diastolic diameter (LVEDD) (55.53±5.67mm vs. 53.20±5.78mm, p=.03) improved significantly on patients accepting CSP upgrade. CSP responses and complete reverse remodeling (LVEF ≥50% and LVEDD<50mm) were detected in 80.95% (17/21) and 42.9% (9/21) of patients. The pacing threshold (1.52±0.78V/0.4ms vs. 1.27±0.59V/0.4ms, p=.16) was stable after follow-up. PICM is very common in patients with long-term persistent AF, and CSP upgrade was favorable for better cardiac performance in this patient population.

Significance of effective cardiac resynchronization therapy pacing for clinical responses: An analysis based on the effective cardiac resynchronization therapy algorithm

High percent ventricular pacing maximizes cardiac resynchronization therapy (CRT) response. An effective CRT algorithm classifies each left ventricular (LV) pace as effective or ineffective on the basis of the detection of QS or QS-r morphology on the electrogram; however, the relationship between percent effective CRT pacing (%e-CRT) and responses is unclear. We aimed to clarify the association between %e-CRT and clinical outcomes. Of the 136 consecutive CRT patients, 49 using the adaptive and effective CRT algorithm with percent ventricular pacing > 90% were evaluated. The primary and secondary outcomes were heart failure (HF) hospitalization and prevalence of CRT responders, defined as patients with an improvement in LV ejection fraction of ≥10% or a reduction in LV end-systolic volume of ≥15% after CRT device implantation, respectively. We divided the patients into the effective group (n = 25) and the less effective group (n = 24) by the median value of %e-CRT (97.4%). During the median follow-up period of 507 days (interquartile range 335-730 days), the effective group had a significantly lower risk of HF hospitalization than did the less effective group as revealed by Kaplan-Meier analysis (log-rank, P = .016). Univariate analysis revealed %e-CRT ≥ 97.4% (hazard ratio 0.12; 95% confidence interval 0.01-0.95; P = .045) as a predictor of HF hospitalization. The effective group had a higher prevalence of CRT responders than did the less effective group (23 [92%] vs 9 [38%]; P < .001). Univariate analysis revealed that %e-CRT ≥ 97.4% (odds ratio 19.20; 95% confidence interval 3.63-101.00; P < .001) was a predictor of CRT response. High %e-CRT is associated with high CRT responder prevalence and low HF hospitalization risk.

Variation in optimal hemodynamic atrio-ventricular delay of biventricular pacing with different endocardial left ventricular lead locations using precision hemodynamics.

It is not known whether the optimal atrioventricular (AVopt ) delay varies between left ventricular (LV) pacing site during endocardial biventricular pacing (BiVP) and may therefore needs consideration. We assessed the hemodynamic AVopt in patients with chronic heart failure undergoing endocardial LV lead implantation. AVopt was assessed during atrio-BiVPwith a "roving LV lead."Up to four locations were studied: mid-lateral wall, mid-septum (or a close alternative), site of greatest hemodynamic improvement, and LV lead implant site. The AVopt was compared to a fixed AV delay of 180 ms. Seventeen patients were included (12 male, aged 66.5 ± 12.8 years, ejection fraction 26 ± 7%, 16 left bundle branch block or high percentage of right ventricular pacing [RVP], QRS duration 167 ± 27 ms). In most locations (62/63), AVopt increased systolic blood pressure during BiVP compared with RVP (relative improvement 6 mmHg,interquartile range [IQR] 4-9 mmHg). Compared to a fixed AV delay, the hemodynamic improvement at AVopt was higher (1 mmHg, IQR 0.2-2.6 mmHg, p < .001). Within most patients (16/17), we observed a difference in AVopt between pacing sites (median paced AVopt 209 ms, IQR 117-250). Within this range, the hemodynamic impact of these differences was small (median loss 0.6 mmHg, IQR 0.1-2.6 mmHg). Within a patient, different endocardial LV lead locations have slightly different hemodynamic AVopt which are superior to a fixed AV delay. The hemodynamic consequence of applying an optimum from a different lead location is small.