Changes In QRS Duration Research Articles

Acute Electrical Synchronization Achieved with Dynamic Atrioventricular Delays during Biventricular and Left Ventricular MultiPoint Pacing

BackgroundCardiac resynchronization therapy (CRT) response relies on two factors: when and where to pace. These factors may be enhanced by dynamic atrioventricular delays (AVDs) (e.g., SyncAV CRT, Abbott) and multi-site left ventricular (LV) pacing (e.g., MultiPoint Pacing [MPP], Abbott). Their individual and combined synchronization contributions have not been evaluated across a comprehensive spectrum of pacing configurations. The objective is to distinguish the acute electrical synchrony achieved by (i) static vs. dynamic AVDs, (ii) single- vs. multi-site LV pacing, and (iii) with vs. without RV pacing. MethodsCRT-indicated patients with LBBB and intact AV conduction (PR<250ms) were enrolled and evaluated during implant. Acute changes in 12-lead ECG QRS duration (QRSd) were evaluated during: intrinsic conduction, biventricular pacing (BiV), biventricular MPP, LV-only single-site pacing (LVSS), and LV-only MPP (LVMPP). CRT modes were evaluated with static AVDs and optimized SyncAV AVDs. ResultsCRT implant and QRSd evaluation were completed in 85 patients (71% male, 34% ischemic, 179ms PR). The median intrinsic QRSd of 165ms was reduced by BiV, MPP, LVSS, and LVMPP without SyncAV to 144ms (by 14%), 142ms (16%), 155ms (8%), and 149ms (12%), respectively (P<0.01 vs. intrinsic). BiV+SyncAV, MPP+SyncAV, LVSS+SyncAV, and LVMPP+SyncAV reduced the intrinsic QRSd significantly further to 128ms (by 23%), 124ms (26%), 131ms (21%), and 129ms (24%) (P<0.0001, each corresponding pair). ConclusionsMPP combined with SyncAV achieved the narrowest QRSd, in the overall population and in the most patients, by delivering ventricular pacing from all available sites (RV+LV1+LV2) while timed with dynamic AVDs.

Cardiac resynchronization therapy in adult congenital heart disease: single center cohort study

Abstract Introduction Cardiac resynchronization therapy (CRT) is a recommended therapeutic measure for patients with heart failure. Heart failure is a major morbidity amongst patients with adult congenital heart disease (ACHD). However, the data on the efficacy and safety of CRT amongst ACHD is limited. Methods Data was analyzed from a retrospective cohort of patients with a known diagnosis of ACHD and implantation of CRT between 2015-2022. The primary outcome was echocardiographic response to CRT. This was defined as either:1) an increase in systemic ventricular ejection fraction (EF) of ≥5% in patients with EF &amp;lt;50% (therapeutic) or 2) maintenance of EF in patients with EF≥50% (preventative). Secondary outcomes included change in QRS duration, heart failure admissions, death and CIED (cardiovascular implantable electronic devices) infection during follow up. The outcomes were also assessed by subgroup of systemic left or right ventricle systemic ventricle. Results Our cohort included 46 patients, 96% male and average age was 54±14 years. 26 patients had a systemic left ventricle (56.6%) and 20 patients had a systemic right ventricle (44.4%). The indication for CRT implantation was 1) Reduced EF with wide QRS (n=10, 22%), 2) Reduced EF and RV (right ventricular) pacing (n=22, 49%), and 3) Normal EF with RV pacing (n=14, 33%). 25 patients (55%) had an implanted defibrillator at baseline. Primary outcome amongst patients with preserved EF at baseline was achieved in 22/32 patients (68.7%) and was achieved in 12/14 patients (85.7%) amongst patients with reduced EF at baseline. During follow up, QRS duration was shortened in 68.7%, 13 patients had heart failure admissions (30%), 4 patients underwent heart transplants/mechanical support device implantation (8.6%), death occurred in 11 patients (24%) and 3 had CIED infection (7%). There was no significant difference in complication or efficacy rates between the left systemic and right systemic group. Conclusion CRT is effective in patients with ACHD both as a therapeutic and as a preventative measure for heart failure. There was no difference in clinical response to CRT between patients with SRV compared to SLV. The percentage of patients with a safety outcome was relatively high in this subpopulation due to advanced ACHD.

Relationship of changes in QRS duration with left ventricular ejection fraction in patients with acute ST segment elevation myocardial infarction treated with primary percutaneous coronary intervention

ObjectiveTo assess the changes in QRS duration (△QRSd) before and after primary percutaneous coronary intervention(PPCI) regarding the relation of left ventricular ejection fraction (LVEF) in patients after a first acute ST segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PPCI). MethodsA total of 244 patients with STEMI were enrolled, and clinical, biochemical, and angiographic parameters were compared between two groups based on LVEF at 6 months post-discharge. QRS duration (QRSd) was analyzed in relation to LVEF, and feature selection using least absolute shrinkage and selection operator(LASSO) regression was performed. Logistic regression analysis and receiver operating characteristic (ROC) curve evaluation were conducted to identify predictors and assess model efficacy. ResultsSignificant differences were observed between the two groups in terms of various parameters, including age, time from symptom onset to balloon dilation (STB), N-terminal pro B-type natriuretic peptide (NT-proBNP) levels, Left ventricular end-diastolic volume(LVEDV) at baseline, left ventricular end-systolic volume(LVESV)at baseline, left ventricular end-diastolic diameter (LVDD)at baseline and six months, hospital length of stay(days), ST-segment resolution (STR), the left anterior descending artery as the infarction-related artery (IRA-LAD), frequency of TIMI 3 flow post PPCI, thrombus aspiration and/or intracoronary thrombolysis, the use of tirofiban, and the number of implanted stents(stents).In addition, postoperative QRSd and △QRSd were significantly higher in patients with left ventricular systolic dysfunction(LVSD). LASSO regression selected six variables as predictors of postoperative LVEF. Logistic regression analysis identified age, STB, NT-proBNP, LVESV at baseline,△QRSd, and stents, as independent factors associated with LVSD within six months for patients with a first occurrence of STEMI. The models achieved AUC values of 0.906 (using ΔQRSd),0.922(using 6 variables excluding ΔQRSd) and 0.962 (using 6 variables). ConclusionThis study identified ΔQRSd as a potential predictor of LVSD in patients with STEMI. The developed models showed good efficacy in predicting postoperative LVEF changes. These findings may contribute to risk stratification and individualized management strategies for STEMI patients.

Conduction system pacing upgrade versus biventricular pacing on pacemaker-induced cardiomyopathy: a retrospective observational study.

Objective: The feasibility of the conduction system pacing (CSP) upgrade as an alternative modality to the traditional biventricular pacing (BiVP) upgrade in patients with pacemaker-induced cardiomyopathy (PICM) remains uncertain. This study sought to compare two modalities of CSP (His bundle pacing (HBP) and left bundle branch pacing (LBBP)) with BiVP and no upgrades in patients with pacing-induced cardiomyopathy. Methods: This retrospective analysis comprised consecutive patients who underwent either BiVP or CSP upgrade for PICM at the cardiac department from 2017 to 2021. Patients with a follow-up period exceeding 12months were considered for the final analysis. Results: The final group of patients who underwent upgrades included 48 individuals: 11 with BiVP upgrades, 24 with HBP upgrades, and 13 with LBBP upgrades. Compared to the baseline data, there were significant improvements in cardiac performance at the last follow-up. After the upgrade, the QRS duration (127.81 ± 31.89 vs 177.08 ± 34.35ms, p < 0.001), NYHA class (2.28 ± 0.70 vs 3.04 ± 0.54, p < 0.05), left ventricular end-diastolic diameter (LVEDD) (54.08 ± 4.80 vs 57.50 ± 4.85mm, p < 0.05), and left ventricular ejection fraction (LVEF) (44.46% ± 6.39% vs 33.15% ± 5.25%, p < 0.001) were improved. There was a noticeable improvement in LVEF in the CSP group (32.15% ± 3.22% vs 44.95% ± 3.99% (p < 0.001)) and the BiVP group (33.90% ± 3.09% vs 40.83% ± 2.99% (p < 0.001)). The changes in QRS duration were more evident in CSP than in BiVP (56.65 ± 11.71 vs 34.67 ± 13.32, p < 0.001). Similarly, the changes in LVEF (12.8 ± 3.66 vs 6.93 ± 3.04, p < 0.001) and LVEDD (5.80 ± 1.71 vs 3.16 ± 1.35, p < 0.001) were greater in CSP than in BiVP. The changes in LVEDD (p = 0.549) and LVEF (p = 0.570) were similar in the LBBP and HBP groups. The threshold in LBBP was also lower than that in HBP (1.01 ± 0.43 vs 1.33 ± 0.32V, p = 0.019). Conclusion: The improvement of clinical outcomes in CSP was more significant than in BiVP. CSP may be an alternative therapy to CRT for patients with PICM. LBBP would be a better choice than HBP due to its lower thresholds.

Cardiomyopathy among recipients of immune checkpoint inhibitor therapy: A prospective study.

e24025 Background: Patients treated with immune checkpoint inhibitors (ICI) may develop cardiomyopathy, but data are limited on the rate of cardiomyopathy incidence. The aim of this study was to assess the occurrence of cardiomyopathy among ICI recipients. Methods: In this prospective surveillance study, echocardiograms and EKG were performed at baseline, and quarterly during the first year of ICI therapy. New or worsening cardiomyopathy was defined as left ventricular ejection fraction (EF) decline of &gt; 10% from baseline to &lt; 50%. B-type natriuretic peptide (BNP) and troponin were assessed weekly during the first three weeks of ICI therapy. Subsequent troponin for myocarditis assessment was tested as needed per treating oncology team. Results: A total of 23 patients were enrolled with mean age 73±10 years, 35% female, 74% Caucasian, and body mass index 31±7 kg/m2. Cardiovascular risk factors included hypertension (86%), diabetes mellitus (29%), myocardial infarction (19%) and smoking (10%), and prior radiation treatment (30%). Malignancies included lung cancer (50%), renal cell carcinoma (14%), and Merkel cell carcinoma or urothelial carcinoma (9% each). ICI regimen included pembrolizumab (48%), nivolumab (43%), and ipilimumab or atezolizumab (4% each). There was no change in weekly troponin or BNP, or quarterly QRS duration on EKG, and no myocarditis cases were observed. Between baseline and at 1-year since ICI therapy initiation, there was no change in QRS duration on EKG, as well as no change in median LVEF (59% [IQR 46-67] vs 61% [IQR 58-65], p = 0.48), or global longitudinal strain (18% [IQR 15-20]) vs 19% [IQR 18-21], p = 0.11). New cardiomyopathy occurred in 1 (4%) patient at 3 months following ICI initiation with LVEF drop from 53% to 38% and without troponin elevation to suggest myocarditis, corresponding to an incidence rate of 43.5 cases per 1000 person-years of observation. Conclusions: In this prospective surveillance study, new cardiomyopathy was observed after ICI treatment, although the incidence was low. Larger studies are needed to confirm these findings.

Effectiveness of left bundle branch area pacing to restore narrow QRS in patients with right bundle branch block

Abstract Background/Introduction Left bundle branch area pacing (LBBaP) is an innovative technique used to capture conduction tissue and maintain ventricular synchrony during pacing. There are few data about the efficacy of LBBaP in right bundle branch block (RBBB). Purpose To compare the response to LBBaP, evaluated by the change in QRS duration (QRSd) after pacing, in patients with RBBB, left bundle branch block (LBBB) or without conduction disorder. Methods A total of 162 patients with pacemaker indication underwent LBBaP with stylet driven lead with dedicated sheaths, between November 2020 and April 2023. ECG characteristics were evaluated. Data are presented in mean ± standard deviation (SD) or n (%). Paired sample t-test was used to compare QRSd before and after pacing. Results Indications for pacing were atrioventricular block (AVB) 48,4 %, sinus node dysfunction (SND) 37,7 %, AVB and SND 10,7 % and cardiac resynchronization therapy 3,1 %. LBBaP was successfully performed in 98 % (159/162) of patients (78 ± 10 years, 62 % male). Overall, baseline QRSd was 113,2 ± 26,7 ms and paced QRSd was 112,3 ± 14,8 ms (p = 0,662), with left ventricular activation time (LVAT) of 69 ± 14 ms (table 1). Baseline ECG showed 18 LBBB, 29 RBBB and 11 undetermined conduction disorder. In every kind of conduction disorder, paced QRSd was reduced to &amp;lt; 120 ms (table 2). Notably, paced QRSd was &amp;lt; 120 ms, regardless of baseline QRSd. In patients with most important pre-existing conduction disorder (QRS ≥ 145 ms), an impressive reduction in QRSd was observed (Delta = -40,8 ms , table 1). Conclusion LBBaP with stylet driven lead is an effective approach to obtain short paced QRS regardless of baseline QRSd and of the nature of the initial conduction disorder. This opens new perspectives for cardiac resynchronization in patients with RBBB.

Improved all-cause mortality with left bundle branch area pacing compared to biventricular pacing in cardiac resynchronization therapy: a meta-analysis.

Left bundle branch area pacing (LBBAP) has emerged as a physiological alternative pacing strategy to biventricular pacing (BIVP) in cardiac resynchronization therapy (CRT). We aimed to assess the impact of LBBAP vs. BIVP on all-cause mortality and heart failure (HF)-related hospitalization in patients undergoing CRT. Studies comparing LBBAP and BIVP for CRT in patients with HF with reduced left ventricular ejection fraction (LVEF) were included. The coprimary outcomes were all-cause mortality and HF-related hospitalization. Secondary outcomes included procedural and fluoroscopy time, change in QRS duration, and change in LVEF. Thirteen studies (12 observational and 1 RCT, n = 3239; LBBAP = 1338 and BIVP = 1901) with a mean follow-up duration of 25.8months were included. Compared to BIVP, LBBAP was associated with a significant absolute risk reduction of 3.2% in all-cause mortality (9.3% vs 12.5%, RR 0.7, 95% CI 0.57-0.86, p < 0.001) and an 8.2% reduction in HF-related hospitalization (11.3% vs 19.5%, RR 0.6, 95% CI 0.5-0.71, p < 0.00001). LBBAP also resulted in reductions in procedural time (mean weighted difference- 23.2min, 95% CI - 42.9 to - 3.6, p = 0.02) and fluoroscopy time (- 8.6min, 95% CI - 12.5 to - 4.7, p < 0.001) as well as a significant reduction in QRS duration (mean weighted difference:- 25.3ms, 95% CI - 30.9 to - 19.8, p < 0.00001) and a greater improvement in LVEF of 5.1% (95% CI 4.4-5.8, p < 0.001) compared to BIVP in the studies that reported these outcomes. In this meta-analysis, LBBAP was associated with a significant reduction in all-cause mortality as well as HF-related hospitalization when compared to BIVP. Additional data from large RCTs is warranted to corroborate these promising findings.

The Impact of Intravenous Ferric Carboxymaltose on Reverse Electrical Remodeling Following Cardiac Resynchronization Therapy.

The influence of intravenous ferric carboxymaltose (FCM) on reverse electrical remodeling (RER) in patients with heart failure with reduced ejection fraction (HFrEF) post-cardiac resynchronization therapy (CRT) is unknown. This study examines the effect of iron replacement using intravenous FCM on RER in CRT-implanted HFrEF patients with iron deficiency anemia. We retrospectively analyzed 65 patients with successful CRT-defibrillator between March 2017 and January 2020, all with iron deficiency anemia at implantation. The cohort comprised 35 patients in the FCM group and 30 in the non-FCM group. Follow-up data were obtained from visits 6 months post-CRT implantation including baseline characteristics, echocardiographic left ventricular measurements, and electrocardiograms. Changes in intrinsic QRS duration (iQRS) and left ventricular ejection fraction (LVEF) from baseline to 6 months were assessed. The FCM group showed a greater reduction in iQRS duration compared to the non-FCM group (-10.4 ± 2.2 ms vs. -3 ± 2.9 ms, p < 0.0001). Additionally, at the 6-month follow-up, the increase in LVEF was higher in the FCM group than in the non-FCM group (+3.6 ± 1.6% vs. -0.1 ± 1.7%, p < 0.0001). Correlations were found between changes in ferritin levels and iQRS duration (r = -0.725, p < 0.0001) and LVEF (r = 0.712, p < 0.0001). Multivariate regression analysis revealed that elevated ferritin independently influenced the increase in LVEF (p = 0.006, β = 0.554) and the decrease in iQRS (p < 0.001, β = -0.685). Intravenous iron treatment with FCM may reduce iQRS duration and improve LVEF and functional status in HFrEF patients with iron deficiency anemia following CRT.

Effect of short-term cardiac function changes after cardiac resynchronization therapy on long-term prognosis in heart failure patients with and without diabetes.

The relationship between short-term cardiac function changes and long-term outcomes in heart failure (HF) patients undergoing cardiac resynchronization therapy (CRT) remains uncertain, especially when stratified by diabetes status. This study aims to assess the association between short-term cardiac function changes and outcomes such as all-cause mortality and HF hospitalization in patients undergoing CRT, stratified by diabetes status. This is a cohort longitudinal retrospective study. A total of 666 HF patients, treated with CRT between March 2007 and March 2019, were included in this study. Among them, 166 patients (24.9%) were diagnosed with diabetes. Cardiac function was assessed at baseline and again at 6 months, incorporating evaluations of left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD), left atrial diameter (LAD), N-terminal prohormone of brain natriuretic peptide (NT-proBNP), and QRS duration. The QRS duration represents the time required for a stimulus to spread through the ventricles (ventricular depolarization). The primary endpoints of the study were all-cause mortality and HF-related hospitalization. During a median follow-up of 2.51 years, 172 (25.8%) patients died and 197 (29.6%) were hospitalized for HF. Changes in LVEF, LVEDD, and LAD within 6 months had similar effects on adverse outcomes in both diabetic and nondiabetic patients. However, the presence of diabetes significantly modified the association between changes in NT-proBNP and QRS duration and adverse outcomes. Short-term changes in NT-proBNP and QRS duration were positively associated with all-cause mortality and HF hospitalization in patients without diabetes. However, the relationship between short-term changes in NT-proBNP and QRS duration and adverse outcomes was non-linear in diabetic patients. Improvement of cardiac function after CRT implantation can reduce long-term risk of all-cause mortality and HF hospitalization in HF patients. However, the presence of diabetes may affect the association between short-term changes in NT-proBNP and QRS duration and adverse outcomes.

Long-term QT prolongation in monkeys after doxorubicin administration at doses similar to breast cancer therapy.

Studies in small animals and human patients have suggested that anthracyclines may prolong cardiac repolarization, or at least inhibit repolarization reserve, predisposing to QT prolongation and dangerous arrhythmias such as Torsades de pointes. This association in humans is difficult to confirm due to multiple confounding variables such as the presence of other medications and concurrent illness. Identify a long-term association between anthracycline administration and repolarization prolongation in nonhuman primates, which can be measured as prolonged QT/QTc intervals on surface electrocardiogram. Five female African Green monkeys (AGMs) aged 13 ± 1 years received Doxorubicin (Dox) at doses similar to women treated for breast cancer (30-60 mg/m2/biweekly IV, total cumulative dose: 240 mg/m2) and underwent 12-lead electrocardiogram (ECG) before and 15 weeks after the final dose of Dox treatment. A blinded paired analysis was performed on ECG derived heart rate (HR), QRS, QT and QT corrected for HR (QTc) interval durations. After Dox, all monkeys exhibited increased QT (BL: 323.2 ± 27.4 ms vs. Post-Dox: 366.4 ± 18.7 ms, p = 0.002) and QTc (BL: 440.2 ± 22.8 ms vs. Post-Dox: 500.8 ± 22.0 ms, p = 0.009) intervals, without any significant changes in HR or QRS duration (p = 0.92 and p = 0.47 respectively). AGMs treated with Dox exhibited long-term QT and QTc prolongation, along with the expected cardiotoxicity (LVEF decrease). While similar findings were shown in small animal studies, confounders make human association difficult to prove. Our finding provides a valuable intermediary step, showing direct effect of Dox on repolarization in nonhuman primates.

Outcomes of cardiac resynchronization therapy in congenital heart disease: A meta-analysis and systematic review.

Cardiac resynchronization therapy (CRT) is a standard treatment for patients with heart failure with reduced ejection fraction. However, there is still a gap of evidence in congenital heart disease (CHD) patients regarding resynchronization therapy. We performed a meta-analysis and systematic review of CHD patients who received CRT implantation. We comprehensively searched the databases of MEDLINE, EMBASE, and Cochrane database from inception to June 2023. Studies that reported response rate to CRT, total mortality rate, change in QRS duration, change in left ventricular ejection fraction, and change in New York Heart Association functional class were included. A total of 14 studies were included in the study. There were 10 studies that reported response rates after implantation. The overall response rate to CRT in CHD patients was 68% (95% confidence interval [CI] 61%-75%, I2 32%). The response rates in patients with systemic right ventricle (RV), systemic left ventricle (LV), and single ventricle were 58% (95% CI 46%-70%, I2 0%), 80% (95% CI 74%-86% I2 14%), and 67% (95% CI 49%-80% I2 0%). Response to CRT in systemic RV was inferior to systemic LV with an odds ratio of 0.38 (95% CI 0.15-0.95, I2 38%). The total mortality rate from sevenstudies was 12% (95% CI 8%-18%, I2 55%). The parameters which represented ventricular dyssynchrony improved after CRT implantation. The overall response rate to CRT in CHD was 68%. Patients with systemic RV had a lower response rate to CRT when compared to patients with systemic LV. The total mortality rate after CRT implantation was 12%.

Clinical and echocardiographic impact of physiological estimulation in patients with preserved ejection fraction: a randomized clinical trial

Abstract Introduction Right ventricular stimulation in the apex (RVAS) produce dysynchrony, leading to left ventricle systolic dysfunction (LVSD) in some cases. Circumstances that can worsen the LVSD are a high burden of RVAS, and the presence of previous LVSD and/or intraventricular conduction disease (IVCD). Direct activation of the specialized conduction system with physiological stimulation (PS) can preserve this physiological pattern and shorten de QRS when the impairment is proximal to the pacing site. Most of the studies with PS has been focused on patients with LVSD, with few and scarce evidences regarding pacients without LVSD. Objectives and methods: This is a parallel, single blinded, unicentric, randomized trial of patients with preserved of mild reduced left ventricular ejection fraction (LVEF) submitted to a pacemaker implantation due to atrioventricular block (AVB), with previous IVCD (wide QRS) an anticipated high rate of ventricular pacing. Patients were randomized 1:1 to RVAS vs PS and followed for 6 months. Clinical, ECG, echocardiography and analytic parameters were compared. The primary endpoint was the change in the LVEF at 6 months in each group. The secondary endpoints were the changes in the left ventricular end-diastolic diameter (LVEDD), the QRS duration, the pro–B-type natriuretic peptide (NT-proBNP), the NYHA class, and the Minnesota Living with Heart Failure Questionnaire (MLWHFQ) in each group. Results The study included 57 patients of 77±9,6 years. Of all patients, 53% were treated with RVAS and 47% with PS. There were 2 patients with crossover to RVAS for technical difficulties and 1 patient with crossover to PS due to apical scar. There were no differences in the basal QRS duration (142.08±20,2 ms), LVEF (58.87±7,2%), NT-proBNP (3336,03±7258,68 pg/ml), or MLWHFQ (22,19±14,68), between both groups (Table 1). Acutely significant differences were observed in the change of QRS duration among groups (+16±29 ms in the RVAS group vs -17±25 ms in the PS group, p&amp;lt;0,001). At 6 months follow-up LVEF showed a non-significant reduction of 0.8±1.1% in the PS group compared to a significant reduction of 5.1±1.7% in the RVAS group (difference 4,26% IC 0,1-8,43 p=0,022). No differences were observed regarding the values of the NT-ProBNP and the MLWHFQ between groups at 6 months (Table 2). Conclusions In patients with preserved LVEF requiring pacemaker implantation for AVB, PS shorten the QTS duration and preserves the LVEF compared to RVAS.Basal characteristics of groupsDifferences in outcomes between groups

Abstract 15283: QRS Voltage in Precordial Leads Predicts Survival After Cardiac Resynchronization Therapy in Non-Left Bundle Branch Block Patients

Introduction: The QRS complex reflects the summation of all instantaneous electrical forces during ventricular depolarization. In patients with intraventricular conduction abnormalities, whether left bundle branch block (LBBB) or non-LBBB, the propagation of the electrical wavefront is dyssynchronous and unopposed and is thereby associated with an increase in the QRS voltage in the precordial leads. Hypothesis: The aim of this study was to assess the impact of cardiac resynchronization therapy (CRT) on QRS voltage and its ability to predict survival in non-LBBB patients who are known to have lower response rates to conventional CRT. Methods: Twelve-lead EKGs were analyzed in 101 consecutive non-LBBB patients (age 65±12 years, 79 men, LVEF 22±4%, QRS width 154±21ms) who received CRT for a median duration of 43 months. Results: During the follow-up period 39 patients died. Total QRS amplitude in leads V2-V4 decreased significantly with CRT (values preimplant/immediately postimplant, P&lt;0.001 for all changes): lead V2 2.1±0.9mV/0.9±0.7mV, lead V3 2.3±0.8mV/1.4±0.7mV, and lead V4 1.4±0.7mV/0.8±0.6mV. Patients in whom the total QRS amplitude in lead V4 decreased with CRT had significantly better survival than patients in whom it increased or did not change (Figure). Changes in QRS amplitude in lead V4 correlated with changes in LVEF over a period of 6 months post implant (r=-0.439, p=0.017). Total QRS amplitude in lead V4 and its change with CRT independently predicted event free survival in multivariate Cox models that included age, gender, baseline LVEF and the change in QRS duration. Conclusion: A reduction in the QRS voltage in the precordial lead V4 is predictive of response to CRT in non-LBBB patients.

Safety and efficacy of left bundle branch area pacing compared with right ventricular pacing in patients with bradyarrhythmia and conduction system disorders: Systematic review and meta-analysis

BackgroundRight Ventricular Pacing (RVP) may have detrimental effects in ventricular function. Left Bundle Branch Area Pacing (LBBAP) is a new pacing strategy that appears to have better results. The aim of this systematic review and meta-analysis is to compare the safety and efficacy of LBBAP vs RVP in patients with bradyarrhythmia and conduction system disorders. MethodsMEDLINE, EMBASE and Pubmed databases were searched for studies comparing LBBAP with RVP. Outcomes were all-cause mortality, atrial fibrillation (AF) occurrence, heart failure hospitalizations (HFH) and complications. QRS duration, mechanical synchrony and LVEF changes were also assessed. Pairwise meta-analysis was conducted using random and fixed effects models. ResultsTwenty-five trials with 4250 patients (2127 LBBAP) were included in the analysis. LBBAP was associated with lower risk for HFH (RR:0.33, CI 95%:0.21 to 0.50; p < 0.001), all-cause mortality (RR:0.52 CI 95%:0.34 to 0.80; p = 0.003), and AF occurrence (RR:0.43 CI 95%:0.27 to 0.68; p < 0.001) than RVP. Lead related complications were not different between the two groups (p = 0.780). QRSd was shorter in the LBBAP group at follow-up (WMD: −32.20 msec, CI 95%: −40.70 to −23.71; p < 0.001) and LBBAP achieved better intraventricular mechanical synchrony than RVP (SMD: -1.77, CI 95%: −2.45 to −1.09; p < 0.001). LBBAP had similar pacing thresholds (p = 0.860) and higher R wave amplitudes (p = 0.009) than RVP. ConclusionsLBBAP has better clinical outcomes, preserves ventricular electrical and mechanical synchrony and has excellent pacing parameters, with no difference in complications compared to RVP.

Flecainide for conversion and maintenance of sinus rhythm after mitral valve replacement in rheumatic atrial fibrillation

BackgroundDespite successful mitral valve replacement (MVR), many patients remain in AF. Flecainide can be useful in these patients but has not been used because of underlying structural heart disease. MethodsWe assessed oral flecainide for conversion and maintenance of SR in 25 patients of chronic rheumatic AF following MVR (age 34.4 yrs, mean AF duration: 3.6 yrs). Non-converters underwent DC cardioversion at 24 h and 4 weeks. Patients received flecainide and bb/diltiazem at discharge. ResultsSingle oral dose of Flecainide achieved SR in 6/25 (24%) while 19/25 achieved SR after DCC; at24 h 21/25 (84%) were in SR. With mean flecainide dose (93.10 ± 9.40 mg), successful maintenance of SR at 6 months was seen in 16/23 (69.5%). No significant changes in PR interval, QRS duration or QTc were noted; flecainide was well tolerated. Patients in SR had significantly better functional status, QOL scores and higher LA strain at 6 months (25.25 vs 17.43%, p < .0001). Baseline LA diameter ≤ 61 mm predicted SR at 6 months (sensitivity/specificity 93.7% and 85.71%) while the values for AF duration ≤ 4 years and LA strain > 21% for predicting SR were 87.5/71.43% and 100/85.71% respectively. ConclusionOral flecainide was safe and effective in post MVR rheumatic AF patients; maintenance of SR was achieved in 76% of initial converters and 64% of overall population, with better LA strain values. More studies are needed to validate these results.

Sodium bicarbonate treatment for QRS widening in bupropion overdoses

Introduction Bupropion cardiotoxicity widens QRS complexes by inhibiting cardiac gap junctions. Sodium bicarbonate is the standard treatment for QRS widening from sodium channel blockade, but its effect on QRS widening in bupropion cardiotoxicity is not well-studied. Methods This is a retrospective cohort study of bupropion overdoses from 10 hospitals between January 2010 and June 2022. Patients with documented administration of sodium bicarbonate and QRS duration > 100 milliseconds on pre-bicarbonate electrocardiogram were included. Patients with no electrocardiogram within four hours of treatment or with baseline pre-overdose wide QRS and < 10 milliseconds widening from baseline were excluded. The primary outcome was a change in QRS duration between the pre-bicarbonate electrocardiogram and the first electrocardiogram after initial bicarbonate administration. Secondary outcomes included prevalence of post-bicarbonate QRS < 100 milliseconds, change in electrocardiogram intervals after total bicarbonate administration, and change in metabolic parameters and hemodynamics. Wilcoxon signed-rank testing was performed on the primary outcome. Linear regression modeling was performed to test for an association between change in QRS and bicarbonate dosing. Results Thirteen patients were included for final analysis. The median age was 32 years, and 54% were male. Six patients developed seizures; one developed ventricular tachycardia, and four received vasopressors. The median QRS and QTc pre-bicarbonate were 116 and 495 milliseconds, respectively. The median change in QRS duration was −2.0 milliseconds, which was not statistically significant (P = 0.42). The median bicarbonate dose administered before the first post-bicarbonate electrocardiogram was 100 milliequivalents. We did not identify an association between QRS change and bicarbonate dosing (P = 0.9, R-squared = 0.001). No patient had a QRS duration < 100 milliseconds after the initial bicarbonate dose. There was minimal change in QTc, electrolytes, heart rate, or blood pressure; alkalemia post-bicarbonate was achieved in eight patients. Conclusion Sodium bicarbonate did not significantly decrease QRS duration in this small retrospective cohort of bupropion overdoses.

Cardiac digital twins of the adult population: linking electrophysiological functions to anatomy

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This project is supported by the Wellcome Trust and EPSRC Centre for Medical Engineering. Background QRS duration derived from 12-lead ECGs provides an estimate of the ventricular depolarization time and is an important metric to assess cardiac function. The QRS duration is determined in part by the combination of heart size and conduction velocity (CV). Differences in QRS duration in terms of gender, body mass index (BMI) and age have been well-documented, however, the relative impact of concurrent changes in heart size and CV on QRS duration is poorly understood. Cardiac digital twins, as in-silico replicas, provide a non-invasive physics and physiology-constrained framework to separate the impact of CV and heart anatomy on the QRS duration across populations. Purpose This study aims to identify the impact of CV and heart size on differences in QRS duration and quantify their difference in the general population in different groups of gender, BMI and age. Methods Patient-specific biventricular models (n=400) were constructed using long- and short-axis cardiac magnetic resonance (CMR) images from patients without self-reported cardiovascular diseases in the UK Biobank. Cardiac electrophysiology was simulated using a physiological-detailed model that includes fiber orientation, anisotropic conductivity, the His-Purkinje system activation, and fast endocardial conductivity[1]. 12-lead ECGs were reconstructed from the simulations and the QRS duration was computed based on corresponding vectorcardiogram (VCG) reconstructed from ECG data [2]. We calibrated patient-specific CVs to match the clinically measured QRS duration in ECGs at rest and then compare the heart size, QRS duration and estimated CVs for different patient groups. Results QRS duration was approx. 7% longer in males than females (median: 90ms vs 84ms, P&amp;lt;0.001). Consistent with a longer QRS duration in males had larger hearts (male: 165.5 mL vs 123 mL, P&amp;lt;0.001), while the median CVs were the same between genders (both: 0.594 m/s). QRS duration was longer for obese (BMI≥30) and overweight group compared to healthy (BMI&amp;lt;25) groups (88ms and 86 ms vs 84 ms, P=0.05 and 0.3). Again, the change in QRS duration with BMI was reflected with a corresponding increase in heart size (healthy: 127 mL, overweight: 147.6 mL, obese:160 mL), while CV remained unchanged (healthy: 0.58 m/s vs overweight and obese: 0.594 m/s, P=0.051 and 0.32). There was no significant difference in QRS duration, CV or myocardial volume for different age groups (medians: 86-88 ms and 0.573-0.594 m/s and 138.7-143 mL). Conclusions QRS duration is shorter in females and individuals with healthy weights. Most of the change in QRS duration can be explained by heart size, with the estimated CV remaining consistent across groups.

The impact of intravenous ferric carboxymaltose on reverse electrical remodeling following cardiac resynchronization therapy

Abstract Funding Acknowledgements Type of funding sources: None. Background The effect of intravenous ferric carboxymaltose (FCM) on reverse electrical remodeling (RER) in patients with heart failure with reduced ejection fraction (HFrEF) following cardiac resynchronization therapy (CRT) implantation is unknown. Purpose The current study aims to examine the effect of iron replacement with intravenous FCM on RER in CRT-implanted patients with HFrEF and iron deficiency. Methods The present study retrospectively analyzed 65 patients with successful CRT-D device implantation between March 2017 and January 2020 with iron deficiency (defined as ferritin &amp;lt;100 μg/L) at implantation. Follow-up data were obtained from the 6-month routine follow-up visits of patients following CRT implantation. Demographic characteristics, laboratory results, medical history, medication details, functional status, information on whether intravenous FCM therapy was administered during CRT device implantation, echocardiographic left ventricular (LV) measurements, baseline electrocardiogram (ECG) recorded before CRT device implantation, and follow-up ECG were collected for analysis for each study patient. From baseline to 6-month follow-up, the change in intrinsic QRS duration (without biventricular pacing) was calculated as a primary endpoint, and the change in LV ejection fraction (LVEF) was assessed as a secondary endpoint of the study. Results Thirty-five of 65 patients were in the FCM group, while the remaining 30 study participants were in the non-FCM. The two study groups were similar regarding baseline characteristics, except for ferritin levels, which were minimally significantly lower in the FCM group (10.7±5.0μg/L vs 13.5 ±3.9μg/L, p= 0.012). At the 6-month follow-up, both mean ferritin levels increased significantly in the FCM group compared to baseline (from 10.7±5.0 to 86.5±7.6μg/L, p &amp;lt; 0.0001), while these levels were not significantly increased in the non-FCM group (from 13.5±3.9 to 14.1±4.2μg/L, p = 0.962). There was a significant reduction in intrinsic QRS durations compared to baseline at 6-month follow-up after CRT implantation in both FCM and non-FCM group (from 148.4±5.3 to 138.0±5.1ms, p &amp;lt; 0.0001; from 149.8±5.0 to 146.8±4.6ms, p &amp;lt; 0.0001, respectively). The change in intrinsic QRS duration from baseline to 6-month follow-up was significantly greater in the FCM group than in the non-FCM group (-10.4±2.2ms vs -3±2.9ms, p &amp;lt; 0.0001). At the 6-month follow-up, the change in LVEF from baseline was significantly higher in the FCM group than in the non-FCM group (+3.6±1.6% vs -0.1±1.7%, p &amp;lt; 0.0001). The change in ferritin level was negatively correlated with the change in intrinsic QRS duration (r = -0.725, p &amp;lt; 0.0001), whereas there was a positive correlation between the change in ferritin level and the change in LVEF (r = 0.712, p &amp;lt; 0.0001). Conclusions Treatment with FCM was induced RER and improvement in LVEF in HFrEF patients with iron deficiency following CRT implantation.

Physiological stimulation in preserved ejection fraction: A randomized trial

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Right ventricular stimulation in the apex (RVAS) produce dysynchrony, leading to left ventricle systolic dysfunction (LVSD) in some cases. Circumstances that can worsen the LVSD are a high burden of RVAS, and the presence of previous LVSD and/or intraventricular conduction disease (IVCD). Direct activation of the specialized conduction system with physiological stimulation (PS) can preserve this physiological pattern and shorten de QRS when the impairment is proximal to the pacing site. Most of the studies with PS has been focused on patients with LVSD, with few and scarce evidences regarding pacients without LVSD. Objectives and methods This is a parallel, single blinded, unicentric, randomized trial of patients with preserved of mild reduced left ventricular ejection fraction (LVEF) submitted to a pacemaker implantation due to atrioventricular block (AVB), with previous IVCD (wide QRS) an anticipated high rate of ventricular pacing. Patients were randomized 1:1 to RVAS vs PS and followed for 6 months. Clinical, ECG, echocardiography and analytic parameters were compared. The primary endpoint was the change in the LVEF at 6 months in each group. The secondary endpoints were the changes in the left ventricular end-diastolic diameter (LVEDD), the QRS duration, the pro–B-type natriuretic peptide (NT-proBNP), the NYHA class, and the Minnesota Living with Heart Failure Questionnaire (MLWHFQ) in each group. Results The study included 57 patients of 77±9,6 years. Of all patients, 53% were treated with RVAS and 47% with PS. There were 2 patients with crossover to RVAS for technical difficulties and 1 patient with crossover to PS due to apical scar. There were no differences in the basal QRS duration (142.08±20,2 ms), LVEF (58.87±7,2%), NT-proBNP (3336,03±7258,68 pg/ml), or MLWHFQ (22,19±14,68), between both groups (Table 1). Acutely significant differences were observed in the change of QRS duration among groups (+16±29 ms in the RVAS group vs -17±25 ms in the PS group, p&amp;lt;0,001). At 6 months follow-up LVEF showed a non-significant reduction of 0.8±1.1% in the PS group compared to a significant reduction of 5.1±1.7% in the RVAS group (difference 4,26% IC 0,1-8,43 p=0,022). No differences were observed regarding the values of the NT-ProBNP and the MLWHFQ between groups at 6 months (Table 2). Conclusions In patients with preserved LVEF requiring pacemaker implantation for AVB, PS shorten the QTS duration and preserves the LVEF compared to RVAS.

Electrophysiologic effects of left bundle branch area pacing: comparing left ventricular septal pacing and left bundle branch pacing

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Medtronic Background Left bundle branch area pacing(LBBAP) has been introduced as a more physiological pacing alternative to anti-bradycardia pacing and as an alternative to biventricular pacing in cardiac resynchronization therapy (CRT). LBBAP is the common denominator of left ventricular septal pacing(LVSP) and left bundle branch pacing(LBBP). In LVSP, there is only capture of the myocardium on the left side of the interventricular septum, whereas in LBBP there is additional capture of the left bundle branch(LBB) and subsequent Purkinje fibers. Purpose To investigate the electrophysiological differences between LBBP and LVSP. Methods Patients with a permanent pacemaker indication due to bradycardia or heart failure according to current guidelines were included and underwent LBBAP implantation. At baseline and during implantation, electrical activation parameters were recorded pacing at different sites (Right ventricle, LVSP and LBBP), using the standard 12-lead ECG and the ECG BELT. Electrophysiologic measures included: QRS duration, QRSarea calculated from the vectorcardiogram after conversion from the ECG using the Kors matrix, and standard deviation of activation time(SDAT) measured through the ECG BELT. Both QRS area and SDAT are known markers of ventricular dyssynchrony. Results 28 patients (17 male), with an age of 67±7 yrs underwent LBBAP. 21(75%) had a pacing indication for bradycardia with a baseline narrow QRS and 7(25%) for heart failure with a baseline LBBB. In 17 patients (61%) LBB capture was achieved. The remaining patients were treated with LVSP. In patients with baseline narrow QRS, both LVSP and LBBP showed a significant increase in QRS duration(p&amp;lt;0.001, p&amp;lt;0.001 resp.), without a significant difference in QRS duration between LVSP and LBBP(fig. 1 A). There was no significant difference in SDAT between LVSP and LBBP compared to baseline narrow QRS, and a significant SDAT reduction in patients with underlying LBBB (p=0.005, p&amp;lt;0.001 resp.) Furthermore, there was no significant SDAT difference between LVSP and LBBP(fig. 1 B). LVSP showed a small but significant increase in QRSarea compared to baseline narrow QRS (p=0.011) where LBBP showed no difference compared to baseline narrow QRS. Compared to baseline LBBB both LVSP and LBBP showed a significant QRSarea reduction (p=0.003, p&amp;lt;0.001 resp.). Moreover, there was a small but significant reduction in QRSarea when LBBP was achieved over LVSP(p=0.044) (fig. 1 C). Conclusion LVSP and LBBP showed a similar effect on ventricular synchrony in terms of SDAT, with levels of synchrony comparable to normal physiologic activation. Left bundle branch capture resulted in a small, but significant improvement in QRSarea over LVSP. Fig. 1 Relative changes in QRS duration(A), SDAT (B) and QRS area (C) compared to baseline narrow QRS (bradypacing) and baseline heart failure with LBBB. *p&amp;lt;0.05 compared to baseline, **p&amp;lt;0.05 for bradypacing and heart failure with LBBB combined.