Conventional Cardiac Resynchronization Therapy Research Articles

Challenges and pitfalls during CRT implantation in patients with persistent left superior vena cava.

Persistent left superior vena cava (PLSVC) is a rare venous anomaly, affecting 0.3-0.5% of the general population. Cardiac resynchronization therapy (CRT) implantation in patients with PLSVC is challenging due to a complex anatomy. Moreover, data on CRT implantation in this patient population is scarce. Our aim was to report a series of patients with PLSVC and CRT implantation focusing on challenges and pitfalls. Electronic medical databases on patients with CRT implantation at the University Heart Centers in Zurich, Switzerland, and Lübeck, Germany, were screened for individuals with a PLSVC. Clinical and demographic characteristics as well as procedural data were reported in all patients. This study presents six cases with a median age of 66years. CRT implantation was successful in five patients, leading to a reduced QRS duration and improved left ventricular ejection fraction. Atrial fibrillation, ischemic cardiomyopathy, valvular heart disease, and dilated cardiomyopathy were observed in this group as underlying conditions. Specialized tools, such as active fixation left ventricular leads, were utilized. One patient experienced major complications. This case series shows that although challenging, conventional endovascular CRT implantation is feasible in PLSVC patients. Specialized tools for visualization and fixation may help. Our experiences highlight the importance of preprocedural evaluation of the anatomy and precise intervention planning.

Abstract 18159: Cardiac Resynchronization Therapy Response Predicted by Tissue Characterization Using Cardiac Magnetic Resonance Imaging in Non-Ischemic Dilated Cardiomyopathy

Introduction: Tissue characterization using cardiac magnetic resonance (CMR) is helpful for risk stratification in non-ischemic dilated cardiomyopathy (NIDCM). Hypothesis: This study aimed to investigate the predictive role of tissue characterization identified by CMR on cardiac resynchronization therapy (CRT) response. Methods: We retrospectively reviewed the patients who underwent CMR within 1 year before CRT implantation in NIDCM patients at a single tertiary center from January 2018 to September 2022. Late gadolinium enhancement (LGE), native T1, T2 and extracellular volume (ECV) were analyzed. CRT response was defined as a decrease in left ventricular end-systolic volume (LVESV) > 15% or an increase in left ventricular ejection fraction > 5% on TTE after at least 3 months after CRT implantation. Results: Among a total of 101 patients (mean age 66 years, 52.5% of male), 76 (75.2%) patients were defined as CRT responders. CRT responders had more LBBB (96.1% vs. 60.0%, p<0.001) and longer QRS duration (156.0±178.5 vs. 167.0±176.5ms, p=0.005) compared with CRT non-responders. However, LGE burden (34.3 vs. 13.3%, p<0.001), native T1 (1371.6 vs. 1336.8ms, p=0.033), T2 (45.9 vs. 42.1ms, p<0.001), and extracellular volume (ECV, 36.8 vs. 31.0%, p<0.001) were significantly higher in CRT non-responders. The area under the curve (AUC) to predict CRT response is the highest in LGE burden (0.817, 95% confidence interval [CI]: 0.710-0.925), followed by ECV (0.808, 95% CI: 0.711-0.905), T2 (0.779, 95% CI: 0.663-0.895), and native T1 (0.643, 95% CI: 0.520-0.766). After adjustment, LGE burden>20% (odds ratio [OR]: 0.15, 95% CI: 0.02-0.71, p=0.024) and ECV > 34% (OR: 0.13, 95% CI: 0.01-0.78, p=0.037) were independently poor CRT response predictors. Conclusions: The tissue characterization by using CMR is helpful to predict CRT response and clinical outcomes in patients with NIDCM, independently of conventional CRT response predictors.

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<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.

Imaging in patients with cardiovascular implantable electronic devices: part 2-imaging after device implantation. A clinical consensus statement of the European Association of Cardiovascular Imaging (EACVI) and the European Heart Rhythm Association (EHRA) of the ESC.

Cardiac implantable electronic devices (CIEDs) improve quality of life and prolong survival, but there are additional considerations for cardiovascular imaging after implantation-both for standard indications and for diagnosing and guiding management of device-related complications. This clinical consensus statement (part 2) from the European Association of Cardiovascular Imaging, in collaboration with the European Heart Rhythm Association, provides comprehensive, up-to-date, and evidence-based guidance to cardiologists, cardiac imagers, and pacing specialists regarding the use of imaging in patients after implantation of conventional pacemakers, cardioverter defibrillators, and cardiac resynchronization therapy (CRT) devices. The document summarizes the existing evidence regarding the role and optimal use of various cardiac imaging modalities in patients with suspected CIED-related complications and also discusses CRT optimization, the safety of magnetic resonance imaging in CIED carriers, and describes the role of chest radiography in assessing CIED type, position, and complications. The role of imaging before and during CIED implantation is discussed in a companion document (part 1).

Left bundle branch area pacing for heart failure patients requiring cardiac resynchronization therapy: A meta-analysis.

Left bundle branch area pacing (LBBP) is a novel conduction system pacing method to achieve effective physiological pacing and an alternative to cardiac resynchronization therapy (CRT) with biventricular pacing (BVP) for patients with heart failure with reduced ejection fraction (HFrEF). We conduted this meta-analysis and systemic review to review current data comparing BVP and LBBP in patients with HFrEF and indications for CRT. We searched PubMed/Medline, Web of Science, and Cochrane Library from the inception of the database to November 2022. All studies that compared LBBP with BVP in patients with HFrEF and indications for CRT were included. Two reviewers performed study selection, data abstraction, and risk of bias assessment. We calculated risk ratios (RRs) with the Mantel-Haenszel method and mean difference (MD) with inverse variance using random effect models. We assessed heterogeneity using the I2 index, with I2 > 50% indicating significant heterogeneity. Ten studies (9 observational studies and 1 randomized controlled trial; 616 patients; 15 centers) published between 2020 and 2022 were included. We observed a shorter fluoroscopy time (MD: 9.68, 95% confidence interval [CI]: 4.49-14.87, I2 = 95%, p < .01, minutes) as well as a shorter procedural time (MD 33.68, 95% CI: 17.80-49.55, I2 = 73%, p < .01, minutes) during the implantation of LBBP CRT compared to conventional BVP CRT. LBBP was shown to have a greater reduction in QRS duration (MD 25.13, 95% CI: 20.06-30.20, I2 = 51%, p < .01, milliseconds), a greater left ventricular ejection fraction improvement (MD: 5.80, 95% CI: 4.81-6.78, I2 = 0%, p < .01, percentage), and a greater left ventricular end-diastolic diameter reduction (MD: 2.11, 95% CI: 0.12-4.10, I2 = 18%, p = .04, millimeter). There was a greater improvement in New York Heart Association function class with LBBP (MD: 0.37, 95% CI: 0.05-0.68, I2 = 61%, p = .02). LBBP was also associated with a lower risk of a composite of heart failure hospitalizations (HFH) and all-cause mortality (RR: 0.48, 95% CI: 0.25-0.90, I2 = 0%, p = .02) driven by reduced HFH (RR: 0.39, 95% CI: 0.19-0.82, I2 = 0%, p = .01). However, all-cause mortality rates were low in both groups (1.52% vs. 1.13%) and similar (RR: 0.98, 95% CI: 0.21-4.68, I2 = 0%, p = .87). This meta-analysis of primarily nonrandomized studies suggests that LBBP is associated with a greater improvement in left ventricular systolic function and a lower rate of HFH compared to BVP. There was uniformity of these findings in all of the included studies. However, it would be premature to conclude based solely on the current meta-analysis alone, given the limitations stated. Dedicated, well-designed, randomized controlled trials and observational studies are needed to elucidate better the comparative long-term efficacy and safety of LBBP CRT versus BIV CRT.

PO-02-017 CHARACTERIZATION OF PATIENTS WHO STABILIZE AFTER CARDIAC RESYNCHRONIZATION THERAPY

Cardiac resynchronization therapy (CRT) is an effective treatment in appropriately selected patients with heart failure. While a subset responds well, a large proportion either stabilizes or deteriorates. We examined the predictors and outcomes of patients who do not demonstrate a reduction in left ventricular end-systolic volume (LVESV) >15% at 6 months; however, who do stabilize between 6 and 12 months (reduction in LVESV 0-15%). The MORE-CRT MPP study is a prospective, randomized, multicenter study. All patients (n = 5803) initially received conventional biventricular (BiV) CRT for 6 months. At this stage, echocardiographic non-responders (i.e., are reduction in LVESV < 15%) were randomized to either continued conventional BiV pacing, or MultiPoint pacing. This post-hoc analysis evaluated the BiV pacing group only. This group was split into i) the stabilization group (reduction in LVESV between 0-15% at 6- and 12-months follow-ups); ii) deterioration group (increase in LVESV >0% at 6 and 12 months). Of the 464 patients in the analysis, 51.2% (n=238) stabilized, and 48.8% (n=226) deteriorated following CRT implant. On multivariable analysis, increased left ventricular ejection fraction (LVEF) and increased QRS duration/left ventricular end-diastolic volume (LVEDV) ratio at baseline were statistically significant for predicting deterioration (see table). Freedom from heart failure hospitalization was similar in both groups until 6 months, and there was a significant separation of the Kaplan-Meier curves after 6 months (p<0.001) (see figure). Patients with an increased LVEF and higher QRSd/LVEDV ratio (i.e., higher degree of dyssynchrony relative to heart size) were more likely to deteriorate than to stabilize following conventional BiV CRT. The risk of heart failure hospitalization in both groups remained similar at 6 months, however, significantly worsened if there was an echo deterioration following CRT. This suggests the need for longer follow up when evaluating clinical endpoints following CRT.Tabled 1Univariate and multivariate Cox regression model to predict likelihood of deterioration to cardiac resynchronization therapy (CRT).ParametersUnivariable Analysis (n=464)Multivariable Analysis (n=383)OR [95% CI]p-valueOR [95% CI]p-valueAge0.979 [0.961, 0.997]0.01960.98 [0.96, 1.00]0.1296COPD (Yes vs No)0.699 [0.393, 1.244]0.2234Diabetes (Yes vs No)0.750 [0.512, 1.098]0.139Female vs Male1.011 [0.649, 1.577]0.96031.13 [0.67, 1.93]0.644Hypertension (Yes vs No)0.811 [0.556, 1.180]0.2735Ischaemic vs Non-Ischaemic0.732 [0.508, 1.055]0.0939LBBB vs Non-LBBB1.617 [1.077, 2.429]0.02061.52 [0.98, 2.36]0.0626LVEF0.938 [0.913, 0.963]<.00010.95 [0.92, 0.98]0.0007NYHA I/II vs NYHA III/IV1.180 [0.819, 1.699]0.3745QRS duration/LVEDV ratio1.007 [0.999, 1.014]0.08890.43 [0.19, 0.98]0.0439Renal disease (Yes vs No)0.724 [0.451, 1.161]0.1799 Open table in a new tab

PO-02-020 CHARACTERIZING PREDICTORS AND OUTCOMES OF LATE RESPONDERS TO CARDIAC RESYNCHRONIZATION THERAPY

Typically, response to cardiac resynchronization therapy (CRT) is evaluated at 6 months. There is a subset of patients who do not fully respond to CRT at this point, however, do demonstrate improvement at 12 months. Characterizing these patients and their outcomes has not been widely explored. We examined in the MORE-CRT MPP study, the predictors of patients who do not demonstrate a reduction in left ventricular end-systolic volume (LVESV) >15% at 6 months, who however do reach that endpoint at 12 months. The MORE-CRT MPP study is a prospective, randomized, multicenter study. All patients (n = 5803) initially received conventional biventricular (BiV) CRT for 6 months. At this stage, echocardiographic non-responders were randomised to either continued conventional BiV pacing, or MultiPoint pacing. This post-hoc analysis evaluated the BiV pacing group only. This group was split into: i) non-responders (<15% reduction in LVESV at 6 and 12 months), ii) early responders (>15% reduction in LVESV at 6 months), and iii) delayed responders (<15% reduction in LVESV at 6 months, but >15% improvement at 12 months). Logistic regression models were used to assess the baseline characteristics of delayed responders. Heart failure hospitalization was the clinical endpoint. Of the 2,920 patients in the analysis 16.7% (n=486) were non-responders, 78% were early responders (n=2263), and 5.8% (n=171) were delayed responders. On multivariable analysis, only patients with ischaemic aetiology and a reduced QRS duration/left ventricular end-diastolic volume (LVEDV) ratio at baseline were statistically significant for predicting delayed response (see table). Freedom from heart failure hospitalization was similar in the early and late CRT responders, and significantly worse in the non-responder group. Patients with increased scar burden and those with a lower QRS/LVEDV ratio (i.e., reduced relative degree of dyssynchrony) were likely to be delayed responders to conventional BiV CRT. Early and delayed CRT responders have a similar risk of heart failure hospitalization despite the slower echo remodelling.Tabled 1Univariate and multivariate Cox regression model to predict likelihood of delayed response to cardiac resynchronization therapy (CRT).ParameterUnivariate AnalysisMultivariate AnalysisOR [95% CI]p-valueSample SizeOR [95% CI]p-valueAge1.004 [0.990, 1.019]0.5724351.01 [0.99, 1.02]0.46COPD (Yes vs No)0.804 [0.466, 1.388]0.432436Diabetes (Yes vs No)1.106 [0.795, 1.539]0.552436Hypercholesterolaemia (Yes vs No)1.099 [0.800, 1.509]0.562436Hypertension (Yes vs No)0.857 [0.624, 1.176]0.342436Ischaemic vs Non-Ischaemic1.638 [1.198, 2.240]0.00224361.64 [1.13, 2.37]0.009LBBB vs Non-LBBB0.650 [0.448, 0.944]0.02418640.75 [0.51, 1.10]0.14LVEF0.983 [0.961, 1.006]0.152436NYHA I/II vs NYA III/IV1.066 [0.779, 1.459]0.692427QRS duration/LVEDV ratio1.000 [0.993, 1.006]0.9320670.47 [0.22, 0.99]0.047Renal disease (Yes vs No)1.244 [0.799, 1.937]0.332436Female vs Male0.786 [0.555, 1.112]0.1724360.96 [0.63, 1.46]0.84 Open table in a new tab

Conduction System Pacing Versus Conventional Cardiac Resynchronization Therapy in Congenital Heart Disease.

Dyssynchrony-associated left ventricular systolic dysfunction is a major contributor to heart failure in congenital heart disease (CHD). Although conventional cardiac resynchronization therapy (CRT) has shown benefit, the comparative efficacy of cardiac conduction system pacing (CSP) is unknown. To compare the clinical outcomes of CSP vs conventional CRT in CHD with biventricular, systemic left ventricular anatomy. Retrospective CSP data from 7 centers were compared with propensity score-matched conventional CRT control subjects. Outcomes were lead performance, change in left ventricular ejection fraction (LVEF), and QRS duration at 12months. A total of 65 CSP cases were identified (mean age 37 ± 21 years, 46% men). The most common CHDs were tetralogy of Fallot (n=12 [19%]) and ventricular septal defect (n=12 [19%]). CSP was achieved after a mean of 2.5 ± 1.6 attempts per procedure (38 patients with left bundle branch pacing, 17 with HBP, 10 with left ventricular septal myocardial). Left bundle branch area pacing [LBBAP] vs HBP was associated with a smaller increase in pacing threshold (Δpacing threshold 0.2V vs 0.8 V; P=0.05) and similar sensing parameters at follow-up. For 25 CSP cases and control subjects with baseline left ventricular systolic dysfunction, improvement in LVEF was non-inferior (Δ LVEF 9.0% vs 6.0%; P = 0.3; 95% confidence limits: -2.9% to 10.0%) and narrowing of QRS duration was more pronounced for CSP (ΔQRS duration 35ms vs 14ms; P = 0.04). Complications were similar (3 [12%] CSP, 4 [16%] conventional CRT; P = 1.00). CSP can be reliably achieved in biventricular, systemic left ventricular CHD patients with similar improvement in LVEF and greater QRS narrowing for CSP vs conventional CRT at 1 year. Among CSP patients, pacing electrical parameters were superior for LBBAP vs HBP.

Pacing interventions in non-responders to cardiac resynchronization therapy.

Non-responders to Cardiac Resynchronization Therapy (CRT) represent a high-risk, and difficult to treat population of heart failure patients. Studies have shown that these patients have a lower quality of life and reduced life expectancy compared to those who respond to CRT. Whilst the first-line treatment for dyssynchronous heart failure is "conventional" biventricular epicardial CRT, a range of novel pacing interventions have emerged as potential alternatives. This has raised the question whether these new treatments may be useful as a second-line pacing intervention for treating non-responders, or indeed, whether some patients may benefit from these as a first-line option. In this review, we will examine the current evidence for four pacing interventions in the context of treatment of conventional CRT non-responders: CRT optimization; multisite left ventricular pacing; left ventricular endocardial pacing and conduction system pacing.

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Bilateral septal pacing in combination with coronary venous pacing for cardiac resynchronization therapy.

Conventional right ventricular pacing combined with coronary venous pacing (CVP) is a mainstay for cardiac resynchronization therapy (CRT). However, QRS duration of conventional CRT may be frequently more than 130ms. This study aimed to evaluate the effectiveness of QRS narrowing by bilateral septal pacing (BSP) in combination with CVP for CRT (BSP-CRT). Fourteen patients with QRS>130ms of conventional CRT after failure of physiological conduction system pacing were enrolled. Electrophysiologic characteristics were compared among different modes of CRT during procedure. BSP which was defined as capture of both sides of interventricular septum manifested as shortened R wave peak time without a right bundle branch block QRS pattern. BSP-CRT were successfully achieved in 85.7% (12/14) patients. QRS duration at baseline was 185±13ms and significantly narrowed to 156±9ms during conventional CRT (n=14, P<.001), to 143±7ms during left ventricular septal pacing (LVSP) in combination with CVP for CRT (LVSP-CRT) (n=9, P<.001), and further to 122±10ms during BSP-CRT (n=12, P<.001). Notably, among 7 patients in whom both LVSP and BSP were achieved, BSP-CRT outperformed LVSP-CRT at QRS narrowing by 16% (P<.001). At 3-month follow-up, left ventricular ejection fraction improved from 29±6% to 41±8% (P<.001). BSP-CRT resulted in superior acute electrical synchronization to conventional CRT and might be considered as an alternative to conventional CRT with QRS more than 130ms.

Alternative pacing strategies for optimal cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) via biventricular pacing (BVP) improves morbidity, mortality, and quality of life, especially in subsets of patients with impaired cardiac function and wide QRS. However, the rate of unsuccessful or complicated left ventricular (LV) lead placement through coronary sinus is 5–7%, and the rate of “CRT non-response” is approximately 30%. These reasons have pushed physicians and engineers to collaborate to overcome the challenges of LV lead implantation. Thus, various alternatives to BVP have been proposed to improve CRT effectiveness. His bundle pacing (HBP) has been increasingly used by activating the His–Purkinje system but is constrained by challenging implantation, low success rates, high and often unstable thresholds, and low perception. Therefore, the concept of pacing a specialized conduction system distal to the His bundle to bypass the block region was proposed. Multiple clinical studies have demonstrated that left bundle branch area pacing (LBBAP) has comparable electrical resynchronization with HBP but is superior in terms of simpler operation, higher success rates, lower and stable capture thresholds, and higher perception. Despite their well-demonstrated effectiveness, the transvenous lead-related complications remain major limitations. Recently, leadless LV pacing has been developed and demonstrated effective for these challenging patient cohorts. This article focuses on the current state and latest progress in HBP, LBBAP, and leadless LV pacing as alternatives for failed or non-responsive conventional CRT as well as their limits and prospects.

Comparison between conduction system pacing and cardiac resynchronization therapy in right bundle branch block patients.

A significant number of right bundle branch block (RBBB) patients receive cardiac resynchronization therapy (CRT), despite lack of evidence for benefit in this patient group. His bundle (HBP) and left bundle pacing (LBP) are novel CRT delivery methods, but their effect on RBBB remains understudied. We aim to compare pacing-induced electrical synchrony during conventional CRT, HBP, and LBP in RBBB patients with different conduction disturbances, and to investigate whether alternative ways of delivering LBP improve response to pacing. We simulated ventricular activation on twenty-four four-chamber heart geometries each including a His-Purkinje system with proximal right bundle branch block (RBBB). We simulated RBBB combined with left anterior and posterior fascicular blocks (LAFB and LPFB). Additionally, RBBB was simulated in the presence of slow conduction velocity (CV) in the myocardium, left ventricular (LV) or right ventricular (RV) His-Purkinje system, and whole His-Purkinje system. Electrical synchrony was measured by the shortest interval to activate 90% of the ventricles (BIVAT-90). Compared to baseline, HBP significantly improved activation times for RBBB alone (BIVAT-90: 66.9 ± 5.5 ms vs. 42.6 ± 3.8 ms, p < 0.01), with LAFB (69.5 ± 5.0 ms vs. 58.1 ± 6.2 ms, p < 0.01), with LPFB (81.8 ± 6.6 ms vs. 62.9 ± 6.2 ms, p < 0.01), with slow myocardial CV (119.4 ± 11.4 ms vs. 97.2 ± 10.0 ms, p < 0.01) or slow CV in the whole His-Purkinje system (102.3 ± 7.0 ms vs. 75.5 ± 5.2 ms, p < 0.01). LBP was only effective in RBBB cases if combined with anodal capture of the RV septum myocardium (BIVAT-90: 66.9 ± 5.5 ms vs. 48.2 ± 5.2 ms, p < 0.01). CRT significantly reduced activation times in RBBB in the presence of severely slow RV His-Purkinje CV (95.1 ± 7.9 ms vs. 84.3 ± 9.3 ms, p < 0.01) and LPFB (81.8 ± 6.6 ms vs. CRT: 72.9 ± 8.6 ms, p < 0.01). Both CRT and HBP were ineffective with severely slow CV in the LV His-Purkinje system. HBP is effective in RBBB patients with otherwise healthy myocardium and Purkinje system, while CRT and LBP are ineffective. Response to LBP improves when LBP is combined with RV septum anodal capture. CRT is better than HBP only in patients with severely slow CV in the RV His-Purkinje system, while CV slowing of the whole His-Purkinje system and the myocardium favor HBP over CRT.

Rescue left bundle branch area pacing in coronary venous lead failure or nonresponse to biventricular pacing: Results from International LBBAP Collaborative Study Group.

Cardiac resynchronization therapy (CRT) using biventricular pacing (BVP) is effective in patients with heart failure, left bundle branch block (LBBB), and reduced left ventricular function. Left bundle branch area pacing (LBBAP) has been reported as an alternative option for CRT. The purpose of this study was to assess the feasibility and outcomes of LBBAP in patients who failed conventional BVP because of coronary venous (CV) lead complications or who were nonresponders to BVP. At 16 international centers, LBBAP was attempted in patients with conventional CRT indication who failed BVP because of CV lead complications or lack of therapeutic response to BVP. Heart failure hospitalization (HFH) and death, echocardiographic outcomes, procedural data, pacing parameters, and lead complications including CV lead failure are reported. LBBAP was successfully performed in 200 patients (CV lead failures 156; nonresponders 44) (age 68 ± 11 years; female 35%; LBBB 55%; right ventricular pacing 23%; ischemic cardiomyopathy 28%; nonischemic cardiomyopathy 63%; left ventricular ejection fraction [LVEF] ≤35% in 80%). Procedural duration was 119.5 ± 59.6 minutes, and fluoroscopy duration was 25.7 ± 18.5 minutes. LBBAP threshold and R-wave amplitudes were 0.68 ± 0.35 V @ 0.45 ms and 10.4 ± 5 mV at implant, respectively, and remained stable during mean follow-up of 12 ± 10.1 months. LBBAP resulted in significant QRS narrowing from 170 ± 28 ms to 139 ± 25 ms (P <.001) with V6 R-wave peak times of 85 ± 17 ms. LVEF improved from 29% ± 10% at baseline to 40% ± 12% (P <.001) during follow-up. The risk of death or HFH was lower in those with CV lead failure than in nonresponders (hazard ratio 0.357; 95% confidence interval 0.168-0.756; P = .007) CONCLUSION: LBBAP is a viable alternative to CRT in patients who failed conventional BVP due to CV lead failure or who were nonresponders.

Pacing Optimized by Left Ventricular dP/dtmax.

Left ventricular (LV) dP/dtmax provides a sensitive measure of the acute hemodynamic response to cardiac resynchronization therapy (CRT) and can predict reverse remodeling on echocardiography. Its use to guide LV lead placement has been shown to improve outcomes in a multicenter randomized trial. Given the invasive protocol required for measurement, it is unlikely to be universally beneficial for patients undergoing CRT but may be useful for patients who do not respond to conventional CRT, or in those who have borderline indications or risk factors for non-response. In such cases, LV dP/dtmax may help guide LV lead placement, optimize device programming, and select the best alternative method of delivering CRT, such endocardial LV pacing or conduction system pacing.

Design of Mid-Q Response: A prospective, randomized trial of adaptive cardiac resynchronization therapy in Asian patients.

AimsThe aim of the Mid‐Q Response study is to test the hypothesis that adaptive preferential left ventricular‐only pacing with the AdaptivCRT algorithm has superior clinical outcomes compared to conventional cardiac resynchronization therapy (CRT) in heart failure (HF) patients with moderately wide QRS duration (≥120 ms and <150 ms), left bundle branch block (LBBB), and normal atrioventricular (AV) conduction (PR interval ≤200 ms).MethodsThis prospective, multi‐center, randomized, controlled, clinical study is being conducted at approximately 60 centers in Asia. Following enrollment and baseline assessment, eligible patients are implanted with a CRT system equipped with the AdaptivCRT algorithm and are randomly assigned in a 1:1 ratio to have AdaptivCRT ON (Adaptive Bi‐V and LV pacing) or AdaptivCRT OFF (Nonadaptive CRT). A minimum of 220 randomized patients are required for analysis of the primary endpoint, clinical composite score (CCS) at 6 months post‐implant. The secondary and ancillary endpoints are all‐cause and cardiovascular death, hospitalizations for worsening HF, New York Heart Association (NYHA) class, Kansas City Cardiomyopathy Questionnaire (KCCQ), atrial fibrillation (AF), and cardiovascular adverse events at 6 or 12 months.ConclusionThe Mid‐Q Response study is expected to provide additional evidence on the incremental benefit of the AdaptivCRT algorithm among Asian HF patients with normal AV conduction, moderately wide QRS, and LBBB undergoing CRT implant.

Multi-lead pacing for cardiac resynchronization therapy in heart failure: a meta-analysis of randomized controlled trials.

AimsMulti-lead pacing is a potential therapy to improve response to cardiac resynchronization therapy (CRT) by providing rapid activation of the myocardium from multiple sites. Here, we perform a meta-analysis of randomized controlled trials to assess the efficacy of multi-lead pacing.Methods and resultsA literature search was performed which identified 251 unique records. After screening, 6 studies were found to meet inclusion criteria, with 415 patients included in the meta-analysis. Four studies performed multi-lead pacing with two left ventricular (LV) leads and one right ventricular (RV) lead. One study used two RV leads and one LV lead, and one study used both configurations. There was no difference between multi-lead pacing and conventional CRT in LV end-systolic volume [mean difference (MD) −0.54 mL, P = 0.93] or LV ejection fraction (MD 1.42%, P = 0.40). There was a borderline significant improvement in Minnesota Living With Heart Failure Questionnaire score for multi-lead pacing vs. conventional CRT (MD −4.46, P = 0.05), but the difference was not significant when only patients receiving LV-only multi-lead pacing were included (MD −3.59, P = 0.25). There was also no difference between groups for 6-min walk test (MD 15.06 m, P = 0.38) or New York Heart Association class at follow-up [odds ratio (OR) 1.49, P = 0.24]. There was no difference in mortality between groups (OR 1.11, P = 0.77).ConclusionThis meta-analysis does not support the use of multi-lead pacing for CRT delivery. However, significant variation between studies was noted, and therefore a benefit for multi-lead pacing in select patients cannot be excluded, and further investigation may be warranted.

Device treatment of heart failure

Background: The incidence of heart failure (HF) is rapidly increasing, introducing a significant burden and challenges in clinical practice. Non-pharmacological cardiac device therapy has been established as an essential component of optimal HF management, particularly for the prevention of sudden cardiac death and the improvement of HF symptoms, left ventricular (LV) systolic function, quality of life, and eventually survival.Current Concepts: Cardiac resynchronization therapy (CRT) can correct atrioventricular or inter/intraventricular dyssynchrony, thereby improving LV systolic function. Recently, the concept of CRT is being expanded, including His bundle (HB), HB-optimized LV, left bundle branch (LBB), and LBB optimized LV pacing CRTs. Newly introduced CRT approaches by stimulating the cardiac conduction system are expected to correct dyssynchrony better and consequently exhibit better CRT outcomes than the conventional biventricular pacing CRT. The current versions of implantable cardioverter-defibrillators (ICDs) or CRT devices can continuously monitor multiple biosignals. CRT/ICD can calculate a single index by combining these multiple bio-signal data for early detection of HF aggravation. Recently, subcutaneous and transvenous ICDs showed comparable safety and efficacy in HF patients. In drug-refractory HF patients without LV dyssynchrony, cardiac contractility modulation therapy provides some promising results.Discussion and Conclusion: Recent technological advancements have improved the efficacy and safety of cardiac device therapy. Therefore, cardiac device therapy should be used more actively to manage HF patients better.

Impact of adaptive cardiac resynchronization therapy in patients with systolic heart failure: Beyond QRS duration and morphology

BackgroundMechanical and electrical restoration by cardiac resynchronization therapy (CRT) with adaptive pacing algorithm (aCRT) in heart failure patients with a moderately wide (120–149 ms) QRS has not been fully evaluated. The purpose of this study was to investigate the therapeutic effect of aCRT compared with conventional biventricular CRT (BiV-CRT) regardless of QRS morphology. MethodsSeventeen consecutive patients with a QRS ≥120 ms, regardless of morphology, underwent CRT device implantation with an aCRT pacing algorithm. Propensity score matched analysis was performed to evaluate the impact of aCRT on the improvement in mechanical and electrical parameters after CRT device implantation using historical controls (HC) from the clinical registry of BiV-CRT (START trial). ResultsLeft ventricular (LV) volume significantly decreased after CRT in all patients in both the aCRT and HC groups. The difference in relative reduction of LV end-systolic volume (LVESV) was not significantly different between the 2 arms. QRS shortening after CRT was significantly greater in the aCRT group than in the BiV-CRT group, and the difference was prominent in patients with a moderately wide QRS (120–149 ms). In patients with a moderately wide QRS, the relative reduction in LVESV [39 (29–47)% vs. 2 (−6–20)%, p = 0.04] and proportion of LV volume responders (90% vs. 38%, p = 0.04) were significantly greater in the aCRT group than in the HC group. The proportion of volume responders was not significantly different in patients with a wide QRS (≥150 ms). ConclusionsThe aCRT algorithm improved electrical and mechanical parameters in patients with a moderately wide QRS, regardless of QRS morphology.

Strategy for Failed Transvenous Left-Ventricular Lead Placement in Cardiac Resynchronization Therapy: Surrender or Struggle?

Introduction: For those cardiac resynchronization therapy (CRT) candidates who experience left-ventricular (LV) lead placement failure or underwent concomitant cardiac surgeries, surgical placement of epicardial LV lead guided by electroanatomic mapping may be a promising alternative. Methods: Electroanatomic mapping was used to guide positioning of the LV lead through a surgical approach. The LV lead was placed at the region with the latest local LV activation and normal voltage, away from the scar. Results: From April 2010 to September 2018, 10 consecutive patients (3 female) underwent surgical epicardial LV lead implantation. Among them, 3 had other surgical indications simultaneously (including 1 CRT non-responder), and 7 had failed transvenous LV lead placement. After CRT, the QRS duration was shortened from 149.3 ± 20.4 ms to 125.1 ± 15.2 ms (p = 0.01). At 6 months, the LV ejection fraction was significantly improved and remained stable in the follow-up (FU) period thereafter (baseline vs. 6 months, 31.0 ± 8.3% vs. 42.2 ± 13.4%, p = 0.006). Other parameters, including the threshold and impedance of the LV lead, were also stable at a mean FU of 755 ± 406 days, and the NYHA functional classification decreased from 2.9 ± 0.7 to 1.8 ± 0.8 (p = 0.002). Conclusions: Placement of an epicardial LV lead guided by electroanatomic mapping could be used as an adjunctive strategy in patients who were unable or refractory to conventional CRT therapy. This approach could also be applied in patients who had other surgical indications at the same time.