Reduced Ventricular Volumes and Improved Systolic Function With Cardiac Resynchronization Therapy

Evolution and prognosis of tricuspid and mitral regurgitation following cardiac implantable electronic devices: a systematic review and meta-analysis

AIMS

Significant changes in tricuspid regurgitation (TR) and mitral regurgitation (MR) post-cardiac implantable electronic devices (CIEDs) are increasingly recognized. However, uncertainty remains as to whether the risk of CIED-associated TR and MR differs with right ventricular pacing (RVP) via CIED with trans-tricuspid RV leads, compared with cardiac resynchronization therapy (CRT), conduction system pacing (CSP), and leadless pacing (LP). The study aims to synthesize extant data on risk and prognosis of significant post-CIED TR and MR across pacing strategies.

METHODS AND RESULTS

We searched PubMed, EMBASE, and Cochrane Library databases published until 31 October 2023. Significant post-CIED TR and MR were defined as ≥ moderate. Fifty-seven TR studies (n = 13 723 patients) and 90 MR studies (n = 14 387 patients) were included. For all CIED, the risk of post-CIED TR increased [pooled odds ratio (OR) = 2.46 and 95% CI = 1.88-3.22], while the risk of post-CIED MR reduced (OR = 0.74, 95% CI = 0.58-0.94) after 12 and 6 months of median follow-up, respectively. Right ventricular pacing via CIED with trans-tricuspid RV leads was associated with increased risk of post-CIED TR (OR = 4.54, 95% CI = 3.14-6.57) and post-CIED MR (OR = 2.24, 95% CI = 1.18-4.26). Binarily, CSP did not alter TR risk (OR = 0.37, 95% CI = 0.13-1.02), but significantly reduced MR (OR = 0.15, 95% CI = 0.03-0.62). Cardiac resynchronization therapy did not significantly change TR risk (OR = 1.09, 95% CI = 0.55-2.17), but significantly reduced MR with prevalence pre-CRT of 43%, decreasing post-CRT to 22% (OR = 0.49, 95% CI = 0.40-0.61). There was no significant association of LP with post-CIED TR (OR = 1.15, 95% CI = 0.83-1.59) or MR (OR = 1.31, 95% CI = 0.72-2.39). Cardiac implantable electronic device-associated TR was independently predictive of all-cause mortality [pooled hazard ratio (HR) = 1.64, 95% CI = 1.40-1.90] after median of 53 months. Mitral regurgitation persisting post-CRT independently predicted all-cause mortality (HR = 2.00, 95% CI = 1.57-2.55) after 38 months.

CONCLUSION

Our findings suggest that, when possible, adoption of pacing strategies that avoid isolated trans-tricuspid RV leads may be beneficial in preventing incident or deteriorating atrioventricular valvular regurgitation and might reduce mortality.

Pilot study to evaluate left-to-right ventricular offset in biventricular pacing-comparison of electrocardiographic imaging and ECG

INTRODUCTION

Biventricular pacing (BiVp) improves outcomes in systolic heart failure patients with electrical dyssynchrony. BiVp is delivered from epicardial left ventricular (LV) and endocardial right ventricular (RV) electrodes. Acute electrical activation changes with different LV-RV stimulation offsets can help guide individually optimized BiVp programming. We sought to study the BiVp ventricular activation with different LV-RV offsets and compare with 12-lead ECG.

METHODS

In five patients with BiVp (63 ± 17-year-old, 80% male, LV ejection fraction 27 ± 6%), we evaluated acute ventricular epicardial activation, varying LV-RV offsets in 20 ms increments from -40 to 80 ms, using electrocardiographic imaging (ECGI) to obtain absolute ventricular electrical uncoupling (VEUabs, absolute difference in average LV and average RV activation time) and total activation time (TAT). For each patient, we calculated the correlation between ECGI and corresponding ECG (3D-QRS-area and QRS duration) with different LV-RV offsets.

RESULTS

The LV-RV offset to attain minimum VEUabs in individual patients ranged 20-60 ms. In all patients, a larger LV-RV offset was required to achieve minimum VEUabs (36 ± 17 ms) or 3D-QRS-area (40 ± 14 ms) than that for minimum TAT (-4 ± 9 ms) or QRS duration (-8 ± 11 ms). In individual patients, 3D-QRS-area correlated with VEUabs (r 0.65 ± 0.24) and QRS duration correlated with TAT (r 0.95 ± 0.02). Minimum VEUabs and minimum 3D-QRS-area were obtained by LV-RV offset within 20 ms of each other in all five patients.

CONCLUSIONS

LV-RV electrical uncoupling, as assessed by ECGI, can be minimized by optimizing LV-RV stimulation offset. 3D-QRS-area is a surrogate to identify LV-RV offset that minimizes LV-RV uncoupling.

Progress in Cardiac Resynchronisation Therapy and Optimisation

Cardiac resynchronisation therapy (CRT) has become the cornerstone of heart failure (HF) treatment. Despite the obvious benefit from this therapy, an estimated 30% of CRT patients do not respond ("non-responders"). The cause of "non-response" is multi-factorial and includes suboptimal device settings. To optimise CRT settings, echocardiography has been considered the gold standard but has limitations: it is user dependent and consumes time and resources. CRT proprietary algorithms have been developed to perform device optimisation efficiently and with limited resources. In this review, we discuss CRT optimisation including the various adopted proprietary algorithms and conduction system pacing.

Biventricular versus left ventricular only stimulation: an echocardiographic substudy of the B-LEFT HF trial

BACKGROUND

The noninferiority of left ventricular pacing alone (LVp) compared with biventricular pacing (BIV) has not been yet definitely documented. In this study, we reviewed all the original echocardiographic measures of the Biventricular versus Left Univentricular Pacing with ICD Back-up in Heart Failure Patients (B-LEFT HF) trial in order to investigate mechanisms underlying LV remodelling with both pacing modalities.

METHODS

Patients with New York Heart Association functional class (NYHA) III or IV despite optimal medical therapy, LVEF 35% or less, left ventricular end-diastolic diameter (LVEDD) more than 55 mm, QRS duration at least 130 ms were randomized to BIV or LVp for 6 months. The primary end point was a composite of at least 1 point decrease in NYHA class and at least 5 mm decrease in left ventricular end-systolic diameter (LVESD). An additional end point was a LVp reverse remodelling defined as at least 10% decrease in LVESD. Mitral regurgitation and all echocardiographic measures were reassessed after 6-month follow-up.

RESULTS

One hundred and forty-three patients were enrolled. Seventy-six patients were in the BIV and 67 were in the LVp group. Left ventricular volumes decreased significantly without difference between groups (P = 0.8447). Similarly, left ventricular diameters decreased significantly in both groups with a significant decrease in LVESD with BIV (P < 0.0001), but not with LVp (P = 0.1383). LVEF improved in both groups without difference (P = 0.8072). Mitral regurgitation did not improve either with BIV, or with LVp.

CONCLUSION

The echocardiographic sub-analysis of B-LEFT study showed the substantial equivalence of LVp in favouring left ventricular reverse remodelling as compared with BIV.

Leadless biventricular left bundle and endocardial lateral wall pacing versus left bundle only pacing in left bundle branch block patients

Biventricular endocardial (BIV-endo) pacing and left bundle pacing (LBP) are novel delivery methods for cardiac resynchronization therapy (CRT). Both pacing methods can be delivered through leadless pacing, to avoid risks associated with endocardial or transvenous leads. We used computational modelling to quantify synchrony induced by BIV-endo pacing and LBP through a leadless pacing system, and to investigate how the right-left ventricle (RV-LV) delay, RV lead location and type of left bundle capture affect response. We simulated ventricular activation on twenty-four four-chamber heart meshes inclusive of His-Purkinje networks with left bundle branch block (LBBB). Leadless biventricular (BIV) pacing was simulated by adding an RV apical stimulus and an LV lateral wall stimulus (BIV-endo lateral) or targeting the left bundle (BIV-LBP), with an RV-LV delay set to 5 ms. To test effect of prolonged RV-LV delays and RV pacing location, the RV-LV delay was increased to 35 ms and/or the RV stimulus was moved to the RV septum. BIV-endo lateral pacing was less sensitive to increased RV-LV delays, while RV septal pacing worsened response compared to RV apical pacing, especially for long RV-LV delays. To investigate how left bundle capture affects response, we computed 90% BIV activation times (BIVAT-90) during BIV-LBP with selective and non-selective capture, and left bundle branch area pacing (LBBAP), simulated by pacing 1 cm below the left bundle. Non-selective LBP was comparable to selective LBP. LBBAP was worse than selective LBP (BIVAT-90: 54.2 ± 5.7 ms vs. 62.7 ± 6.5, p < 0.01), but it still significantly reduced activation times from baseline. Finally, we compared leadless LBP with RV pacing against optimal LBP delivery through a standard lead system by simulating BIV-LBP and selective LBP alone with and without optimized atrioventricular delay (AVD). Although LBP alone with optimized AVD was better than BIV-LBP, when AVD optimization was not possible BIV-LBP outperformed LBP alone, because the RV pacing stimulus shortened RV activation (BIVAT-90: 54.2 ± 5.7 ms vs. 66.9 ± 5.1 ms, p < 0.01). BIV-endo lateral pacing or LBP delivered through a leadless system could potentially become an alternative to standard CRT. RV-LV delay, RV lead location and type of left bundle capture affect leadless pacing efficacy and should be considered in future trial designs.

Betablockers and Ivabradine Titration According to Exercise Test in LV Only Fusion CRT Pacing

Background: Betablockers (BB)/ivabradine titration in fusion CRT pacing (CRTP) is understudied. Aim: To assess drug optimization using systematic exercise tests (ET) in fusion CRTP with preserved atrioventricular conduction (AVc). Methods: Changes in drug management were assessed during systematic follow-ups in CRTP patients without right ventricle lead. Shorter AVc (PR interval) allowed BB up-titration, while longer AVc needed BB down-titration, favoring ivabradine. Constant fusion pacing was the goal to improve outcomes. Results: 64 patients, 62.5 ± 9.5 y.o divided into three groups: shorter PR (<160 ms), normal (160−200 ms), longer (200−240 ms); follow-up 59 ± 26 months. Drugs were titrated in case of: capture loss due to AVc shortening (14%), AVc lengthening (5%), chronotropic incompetence (11%), maximum tracking rate issues (9%), brady/tachyarrhythmias (8%). Interventions: BB up-titration (78% shorter PR, 19% normal PR, 5% longer PR), BB down-titration (22% shorter PR, 14% normal PR), BB exclusion (16% longer PR), adding/up-titration ivabradine (22% shorter PR, 19% normal PR, 5% longer PR), ivabradine down-titration (22% shorter PR, 3% normal PR), ivabradine exclusion (11% normal PR, 5% longer PR). Drug strategy was changed in 165 follow-ups from 371 recorded (42% patients). Conclusions: BBs/ivabradine titration and routine ET during follow-ups in patients with fusion CRTP should be a standard approach to maximize resynchronization response. Fusion CRTP showed a positive outcome with important LV reverse remodeling and significant LVEF improvement in carefully selected patients.

Left ventricular-only fusion pacing versus cardiac resynchronization therapy in heart failure patients: A randomized controlled trial

Background

It is unclear whether clinical benefits of cardiac resynchronization can be achieved by pacing only the left ventricle.

Hypothesis

We aimed to compare the effect of a novel adaptive left ventricular‐only fusion pacing (LVP) on ventricular function with conventional biventricular pacing (BVP) in cardiac resynchronization therapy (CRT) indicated patients.

Methods

This prospective, randomized, multicenter study enrolled CRT‐indicated patients with PR interval ≤ 200 ms who were randomized in the adaptive LVP group (using the AdaptivCRT™ algorithm with intentional non‐capture right ventricular pacing) or the echocardiography‐optimized BVP group. Cardiac function and echocardiography were evaluated at baseline and follow‐ups. CRT super response was defined as two‐fold or more increase of left ventricular ejection fraction (LVEF) or final LVEF >45%, and LV end‐systolic volume (LVESV) decrease >15%, and New York Heart Association (NYHA) class improved by at least one level.

Results

Sixty‐three patients were enrolled in the study (LVP = 34 vs. BVP = 29). At 6‐month follow‐up, significant improvements in LVEF, LVESV, and NYHA class were observed in both groups. The CRT super response rate was significantly higher in patients with high‐percentage adaptive LV‐only pacing in LVP group (68.4%) than in BVP group (36.4%, p = .04).

Conclusions

Adaptive LV‐only pacing was comparable to BVP in improving cardiac function and clinical condition in CRT‐indicated patients. This finding raises the possibility that an adaptive LVP algorithm with appropriate right ventricular sensing to fuse with intrinsic right ventricular activation in a two‐lead (right atrium and left ventricle) device may provide clinical benefit in a subset of CRT patients with intact atrioventricular conduction.

Cardiovascular Imaging Applications in Clinical Management of Patients Treated with Cardiac Resynchronization Therapy

Cardiovascular imaging techniques, including echocardiography, nuclear cardiology, multi-slice computed tomography, and cardiac magnetic resonance, have wide applications in cardiac resynchronization therapy (CRT). Our aim was to provide an update of cardiovascular imaging applications before, during, and after implantation of a CRT device. Before CRT implantation, cardiovascular imaging techniques may integrate current clinical and electrocardiographic selection criteria in the identification of patients who may most likely benefit from CRT. Assessment of myocardial viability by ultrasound, nuclear cardiology, or cardiac magnetic resonance may guide optimal left ventricular (LV) lead positioning and help to predict LV function improvement by CRT. During implantation, echocardiographic techniques may guide in the identification of the best site of LV pacing. After CRT implantation, cardiovascular imaging plays an important role in the assessment of CRT response, which can be defined according to LV reverse remodeling, function and dyssynchrony indices. Furthermore, imaging techniques may be used for CRT programming optimization during follow-up, especially in patients who turn out to be non-responders. However, in the clinical settings, the use of proposed functional indices for different imaging techniques is still debated, due to their suboptimal feasibility and reproducibility. Moreover, identifying CRT responders before implantation and turning non-responders into responders at follow-up remain challenging issues.

Cardiac resynchronization therapy in heart failure patients: tough road but clear future

Cardiac resynchronization therapy (CRT) based on biventricular pacing (BVP) is an invaluable intervention currently used in heart failure (HF) patients. The therapy involves electromechanical dyssynchrony, which can not only improve heart function and quality of life but also reduce hospitalization and mortality rates. However, approximately 30% to 40% of patients remain unresponsive to conventional BVP in clinical practice. In the recent years, extensive research has been employed to find a more physiological approach to cardiac resynchronization. The His-Purkinje system pacing (HPSP) including His bundle pacing (HBP) and left bundle branch area pacing (LBBaP) may potentially be the future of CRT. These technologies present various advantages including offering an almost real physiological pacing, less complicated procedures, and economic feasibility. Additionally, other methods, such as isolated left-ventricular pacing and multipoint pacing, may in the future be important but non-mainstream alternatives to CRT because currently, there is no strong evidence to support their effectiveness. This article reviews the current situation and latest progress in CRT, explores the existing technology, and highlights future prospects in the development of CRT.

Effects of coenzyme Q10 on endothelial and cardiac function in patients undergoing haemodialysis: study protocol for a pilot randomised controlled trial

INTRODUCTION

Endothelial and cardiac dysfunction are highly prevalent and are associated with cardiovascular morbidity and mortality among patients undergoing dialysis. For patients undergoing dialysis, no study has explored the effect of supplementation of coenzyme Q10 (CoQ10) on endothelial function. To our best of knowledge, only two small sample studies focused on the efficacy of supplementation of CoQ10 on cardiac function. However, the effect of CoQ10 supplementation on cardiac function remains uncertain in patients who undergo haemodialysis. The aim of this study is to explore whether CoQ10 supplementation can improve endothelial and cardiac function in patients undergoing haemodialysis.

METHODS AND ANALYSIS

This is a pilot randomised controlled study. Eligible patients undergoing haemodialysis in our haemodialysis centre will be randomly allocated to the CoQ10 and control groups. The follow-up time is 12 months. The primary outcome is to assess the change of brachial artery endothelial-dependent flow-mediated dilation, left ventricular systolic function, diastolic function and Myocardial Performance Index at 12 months from baseline. Secondary outcomes are death or hospitalisation due to cardiovascular events, all-cause mortality, change of CoQ10 concentration, the ratio of ubiquinol to ubiquinone, the change of oxidative stress markers (including malondialdehyde and 8-hydroxy-deoxyguanosine) and Left Ventricular Mass Index.

ETHICS AND DISSEMINATION

Risks associated with CoQ10 are minor, even at doses as high as 1800 mg according to previous studies. The trial has received ethics approval from the Medical Ethics Committee for Clinical Trials of Drugs, the 306th Hospital of Chinese PLA. The results of the study are expected to be published in a peer-reviewed journal and presented at academic conferences.

TRIAL REGISTRATION NUMBER

ChiCTR1900022258.

Single- and dual-site ventricular pacing entirely through the coronary sinus for patients with prior tricuspid valve surgery

PURPOSE

Transvenous right ventricular pacing has traditionally been avoided after surgical tricuspid valve repair or replacement because of possible valvular dysfunction. Epicardial pacing has been used but it requires surgical thoracotomy and has higher lead failure rates when compared to transvenous pacing. We evaluated the lead stability and clinical outcomes in patients with isolated coronary sinus (CS) lead due to relative contraindication to transvenous pacing from prior tricuspid valve (TV) surgery.

METHODS

We retrospectively examined a single-center cohort of 34 patients with TV disease and/or surgery who underwent permanent pacemaker implantation with a left ventricular CS lead as the only ventricular pacing lead (to avoid crossing the TV). The clinical outcome, echocardiographic data, and pacing thresholds were evaluated at follow-up.

RESULTS

We implanted 19 patients with a single-CS lead and 15 patients with dual-CS leads. The average left ventricular ejection fraction was 56 ± 13% prior to lead implantation and remained stable at 2-year follow-up. The tricuspid regurgitation remained mild at follow-up. The average lead pacing threshold was 1.2 ± 0.6 V × ms at implant and 1.1 ± 0.4 V × ms at 2-year follow-up (P = 0.39). For patients with dual-CS leads, the pacing threshold was 1.2 ± 0.7 V × ms at implant and 1.1 ± 0.5 V × ms at 2-year follow-up (P = 0.52).

CONCLUSIONS

The use of ventricular pacing entirely through the CS is an effective and minimally invasive method that provides stable pacing for patients with prior TV surgery in whom transvenous lead placement either is not possible or is relatively contraindicated.

2D/3D Echocardiographic features of patients with reverse remodeling after cardiac resynchronization therapy

PURPOSE

To describe clinical and echocardiographic characteristics associated with reverse left ventricular (LV) remodeling after 6 months of cardiac resynchronization therapy (CRT) in patients with nonischemic dilated cardiomyopathy.

METHODS

Twenty-four consecutive patients underwent 2D and 3D echocardiography before and after 6 months of CRT implant. Several echocardiographic parameters including global longitudinal strain (GLS) and 3D mechanical dyssynchrony (MD) index were calculated. CRT response was defined as a decrease in LV end-systolic volume (LVESV) of at least 10% at follow-up. Patients were divided in two groups according to CRT response.

RESULTS

Cardiac resynchronization therapy responder (CRTR+) rate was 50%. Nonresponder (CRTR-) patients showed a less significant improvement in NYHA class at follow-up. At baseline, CRTR- presented with higher LV end-diastolic volume (LVEDV) (P = 0.031), LVESV (P = 0.024), lower left ventricular ejection fraction (LVEF) (P = 0.002) and less negative GLS (P = 0.03), and with higher diastolic dysfunction, more impaired right ventricle (RV), and higher pulmonary artery systolic pressure (PASP) (P = 0.002). No significant differences in echocardiographic parameters of MD were found. Univariate determinants of CRTR+ were LVEF (OR = 1.59, CI 95% = 1.13-2.22, P = 0.007) and TAPSE (OR 1.21, CI 95% = 1.024-1.429, P = 0.025). A ROC curve analysis showed a cutoff value of LVEF of 22.15% significantly related to CRTR+ (SE 80%, SP 50%).

CONCLUSIONS

Our findings suggest that end-stage HF patients, presenting before CRT with LVEF <22.15%, may not benefit from the procedure after 6 months. Mechanical dyssyncronicity did not provide additional information to improve candidate selection.

Cardiac Resynchronization Therapy: the Structural Response Is not Always Necessary

Up to 30-40% of patients undergoing cardiac resynchronization therapy (CRT) are described as nonresponders since the initial studies. This paradigm has inspired several modifications of the devices, electrodes and surgical technique in the implant. The definition of CRT response should be rethought, standardized, and ratings based on structural and/or clinical response should be proposed. The authors discuss a series of cases in which sustained clinical improvement was achieved despite structural worsening. Objective: To assess the profi le of clinical responders to CRT who have worsened structurally. Method: It is a retrospective cohort of patients in outpatient follow-up from January 2012 to March 2017. We included 13 patients (2.7%) out of a total of 476 submitted to CRT. Inclusion criteria were to present an improvement in functional class according to the New York Heart Association criteria (FC-NYHA) ≥ 1 sustained for at least one year and absence of improvement or worsening of the structural parameters evaluated by transthoracic echocardiogram [ejection fraction (EF), diastolic diameter (LVDD) and systolic diameter (LVSD)]. The variables analyzed were age, gender, FC-NYHA, cardiopathy, echocardiographic and electrocardiographic parameters, medications in use, location of implanted electrodes, device programming, cardiary defibrillator therapies, and mortality. Statistical analysis was performed using non-parametric Wilcoxon and McNemar tests. Results: There were 13 patients, 92% male, mean age 60.9 ± 9.2 years and mean follow-up of 3.3 ± 1.1 years, 76% of CRT associated with implantable cardioverter defibrillator (CRT-D). In pre-implantation, 84.6% were in FC-NYHA III and then 61.5% were in FC-NYHA I (p = 0.001). The mean pre-implantation EF was 31.3 ± 7.6% and 26.6 ± 7.3 (p = 0.002) in the last evaluation. The predominant heart disease was non-ischemic in 92.5%, most of which were chagasic cardiomyopathy (CCM) (66%). In the TRC-D group, no shock therapy was recorded in the period; there was one death in a patient with ischemic cardiomyopathy (IC) for the septic shock of pulmonary focus after 2.2 years of follow-up. The mean QRS was 189.9 ± 23.1 ms to 157.9 ± 35.2 after CRT (p = 0.032). There was no signifi cant change in pre-and postimplant medications during follow-up. Conclusion: The absence of structural improvement should not be considered therapeutic failure, since CRT seeks to modify the electrical activation, and may be related to better performance and decrease of symptoms, even in evolutionary heart diseases.

Terapia de Ressincronização Cardíaca: a Resposta Estrutural não se Faz Sempre Necessária

Até 30-40% dos pacientes submetidos à terapia de ressincronização cardíaca (TRC) são descritos como não respondedores desde os trabalhos iniciais. Esse paradigma tem inspirado diversas modificações dos dispositivos, eletrodos e técnica cirúrgica no implante. A definição de resposta à TRC deverá ser repensada, padronizada, e classificações pautadas na resposta estrutural e/ou clínica devem ser propostas. Os autores discutem uma série de casos em que se obteve melhora clínica sustentada a despeito da piora estrutural. Objetivo: Avaliar o perfi l dos pacientes respondedores clínicos à TRC que pioraram estruturalmente. Método: Trata-se de coorte retrospectiva de pacientes em seguimento ambulatorial de janeiro de 2012 a março de 2017. Foram incluídos 13 pacientes (2,7%) de um total de 476 submetidos à TRC. Os critérios de inclusão foram apresentar melhora da classe funcional pelos critérios da New York Heart Association (CF-NYHA) ≥ 1 sustentada por pelo menos um ano e ausência de melhora ou com piora dos parâmetros estruturais avaliados pelo ecocardiograma transtorácico [fração de ejeção (FE), diâmetro diastólico (DDVE) e diâmetro sistólico (DSVE)]. As variáveis analisadas foram idade, gênero, CF-NYHA, cardiopatia, parâmetros ecocardiográficos e eletrocardiográficos, medicações em uso, localização do implante dos eletrodos, programação do dispositivo, terapias do cardiodesfibrilador e mortalidade. A análise estatística foi realizada por meio dos testes não paramétricos de Wilcoxon e McNemar. Resultado: Foram 13 pacientes, sendo 92% do sexo masculino, idade média de 60,9 ± 9,2 anos e seguimento médio de 3,3 ± 1,1 anos, 76% de TRC associada a cardiodesfibrilador implantável (TRC-D). No pré-implante, 84,6% encontravam-se em CF-NYHA III e, em seguida, 61,5% estavam em CF-NYHA I (p = 0,001). A FE média pré-implante foi de 31,3 ± 7,6% e 26,6 ± 7,3 (p = 0,002) na última avaliação. A cardiopatia predominante foi a não isquêmica em 92,5%, sendo a maioria cardiomiopatia chagásica (CMC) (66%). No grupo TRC-D, não foi registrada terapia de choque no período; houve um óbito em um paciente com cardiomiopatia isquêmica (CMI) por choque séptico de foco pulmonar após 2,2 anos de seguimento. O QRS médio foi de 189,9 ± 23,1 ms para 157,9 ± 35,2 após TRC (p = 0,032). Não houve mudança significativa nas medicações administradas pré- e pós-implante durante o seguimento. Conclusão: A ausência de melhora estrutural não deve ser considerada falha terapêutica, pois a TRC procura modificar a ativação elétrica, podendo estar relacionada a melhor desempenho e diminuição dos sintomas, mesmo em cardiopatias evolutivas.

Optimal site selection and image fusion guidance technology to facilitate cardiac resynchronization therapy

INTRODUCTION

Cardiac resynchronization therapy (CRT) has emerged as one of the few effective treatments for heart failure. However, up to 50% of patients derive no benefit. Suboptimal left ventricle (LV) lead position is a potential cause of poor outcomes while targeted lead deployment has been associated with enhanced response rates. Image-fusion guidance systems represent a novel approach to CRT delivery, allowing physicians to both accurately track and target a specific location during LV lead deployment.

AREAS COVERED

This review will provide a comprehensive evaluation of how to define the optimal pacing site. We will evaluate the evidence for delivering targeted LV stimulation at sites displaying favorable viability or advantageous mechanical or electrical properties. Finally, we will evaluate several emerging image-fusion guidance systems which aim to facilitate optimal site selection during CRT.

EXPERT COMMENTARY

Targeted LV lead deployment is associated with reductions in morbidity and mortality. Assessment of tissue characterization and electrical latency are critical and can be achieved in a number of ways. Ultimately, the constraints of coronary sinus anatomy have forced the exploration of novel means of delivering CRT including endocardial pacing which hold promise for the future of CRT delivery.

Potential benefit of optimizing atrioventricular & interventricular delays in patients with cardiac resynchronization therapy

Background & objectives:

The clinical benefit of optimization (OPT) of atrioventricular delay (AVD) and interventricular delay (VVD) in cardiac resynchronization therapy (CRT) remains debatable. This study was aimed to determine the influence of AVD and VVD OPT on selected parameters in patients early after CRT implantation and at mid-term follow up (FU).

Methods:

Fifty two patients (61±10 yr, 23 males) with left bundle branch block, left ventricular ejection fraction (LVEF) ≤35 per cent and heart failure were selected for CRT implantation. Early on the second day (2DFU) after CRT implantation, the patients were assigned to the OPT or the factory setting (FS) group. Haemodynamic and electrical parameters were evaluated at baseline, on 2DFU after CRT and mid-term FU [three-month FU (3MFU)]. Echocardiographic measures were assessed before implantation and at 3MFU. The AVD/VVD was deemed optimal for the highest cardiac output (CO) with impedance cardiography (ICG) monitoring.

Results:

On 2DFU, the AVD was shorter in the OPT group, LV was paced earlier than in FS group and CO was insignificantly higher in OPT group. At 3MFU, improvement of CO was observed only in OPT patients, but the intergroup difference was not significant. At 3MFU in OPT group, reduction of LV in terms of LV end-diastolic diameter (LVeDD), LV end-systolic diameter, LV end-diastolic and systolic volume with the improvement in LVEF was observed. In FS group, only a reduction in LVeDD was present. In OPT group, the paced QRS duration was shorter than in FS group patients.

Interpretation & conclusions:

CRT OPT of AVD and VVD with ICG was associated with a higher CO and better reverse LV remodelling. CO monitoring with ICG is a simple, non-invasive tool to optimize CRT devices.

Advances in atrioventricular and interventricular optimization of cardiac resynchronization therapy - what's the gold standard?

INTRODUCTION

Cardiac resynchronization therapy (CRT) is one of the most important advances in heart failure management in the last twenty years. Approximately one-third of patients appear not to respond to therapy. Although there are a number of possible mechanisms for non-response, an important factor is suboptimal atrioventricular (AV) and interventricular (VV) timing intervals. There remains controversy over whether routinely optimizing intervals is necessary and there is no agreed gold standard methodology. Optimization has classically been performed using echocardiography which has limits related to resource use, time-cost and variable reproducibility. Newer optimization methods using device-based sensors and algorithms show promise in reducing heart-failure hospitalization compared with echocardiography. Areas covered: This review outlines the rationale for optimization, the principles of AV and VV optimization, the standard echocardiographic approach and newer device-based algorithms and the evidence base for their use. Expert commentary: The incremental gains of optimization are likely to be real, but small, compared to the overall improvement gained from cardiac resynchronization itself. At this time routine optimization may not be mandatory but should be performed where there is no response to CRT. Device-based optimization algorithms appear to be practical and in some cases, deliver superior clinical outcomes compared to echocardiography.

Basic Properties And Clinical Applications Of The Intracardiac

The electric signals detected by intracardiac electrodes provide information on the occurrence and timing of myocardial depolarization, but are not generally helpful to characterize the nature and origin of the sensed event. A novel recording technique referred to as intracardiac ECG (iECG) has overcome this limitation. The iECG is a multipolar signal, which combines the input from both atrial and ventricular electrodes of a dual-chamber pacing system in order to assess the global electric activity of the heart. The tracing resembles a surface ECG lead, featuring P, QRS and T waves. The time-course of the waveform representing ventricular depolarization (iQRS) does correspond to the time-course of the surface QRS with any ventricular activation modality. Morphological variants of the iQRS waveform are specifically associated with each activity pattern, which can therefore be diagnosed by evaluation of the iECG tracing. In the event of tachycardia, SVTs with narrow QRS can be distinguished from other arrhythmia forms based upon the preservation of the same iQRS waveform recorded in sinus rhythm. In ventricular capture surveillance, real pacing failure can be reliably discriminated from fusion beats by the analysis of the area delimited by the iQRS signal. Assessing the iQRS waveform correspondence with a reference template could be a way to check the effectiveness of biventricular pacing, and to discriminate myocardial capture alone from additional His bundle recruitment in para-Hisian stimulation. The iECG is not intended as an alternative to conventional intracavitary sensing, which remains the only tool suitable to drive the sensing function of a pacing device. Nevertheless, this new electric signal can add the benefits of morphological data processing, which might have important implications on the quality of the pacing therapy.

Adaptive CRT in patients with normal AV conduction and left bundle branch block: Does QRS duration matter?

BACKGROUND

Adaptive cardiac resynchronization therapy (aCRT) is a dynamic optimization algorithm which paces only the left ventricle (LV) when atrio-ventricular (AV) conduction is normal, thus reducing right ventricular (RV) pacing. However, the impact of QRS duration on aCRT efficacy remains uncertain. We examined whether QRS duration impacts aCRT effectiveness in patients with left bundle branch block (LBBB) and preserved AV conduction.

METHODS

Randomized patients in the Adaptive CRT trial, which enrolled NYHA III/IV patients, were used in this analysis. Patients were randomized to receive aCRT or echo-optimized bi-ventricular CRT (control arm). Endpoints for this analysis were clinical composite score (CCS) at 6months post-implant and time to first heart failure (HF) hospitalization or death.

RESULTS

Among the 199 patients with LBBB and normal AV intervals at baseline, 80 patients (40%) had a baseline moderately wide QRS of 120-150ms. In this subgroup, a greater proportion of aCRT patients had an improved CCS (79% vs. 50%) at 6months compared to the control group (p=0.03). There was also a trend toward a lower risk of death or HF hospitalization (hazard ratio: 0.53; 95% CI: 0.24-1.15; p=0.10) in the moderately wide QRS subgroup with aCRT compared to the control arm. In the wide QRS subgroup, the efficacy was comparable in both treatment arms.

CONCLUSION

Adaptive CRT was associated with improved patient outcomes over echo-optimized bi-ventricular CRT in patients with preserved AV conduction, LBBB, and moderately wide QRS. The adaptive cardiac resynchronization therapy trial (ClinicalTrials.gov Identifier: NCT00980057) was sponsored by Medtronic plc, Mounds View, MN.

Modalities of ventricular pacing for cardiac resynchronization therapy in patients with heart failure: a meta-analysis and systematic review

INTRODUCTION

This meta-analysis evaluated 14 studies which compared clinical and functional outcomes after different cardiac resynchronization therapy (CRT) modalities.

MATERIAL AND METHODS

Relevant studies were selected from the Medline, PubMed, Cochrane, and Google Scholar databases until June 27^th, 2016. We analyzed and compared the clinical outcomes (peak O₂ consumption and LVEF) and functional outcomes (6-min walk distance and quality of life (SF-36)) of HF patients who received different CRT modalities with outcomes in patients who received conventional univentricular therapy.

RESULTS

There was no significant difference in post-treatment 6-min walking distance between the biventricular (BiV) and left/right univentricular (LUV/RUV) groups (standardized difference in means = 0.049, 95% CI: -0.119 to 0.217, p = 0.566), or between the BiV and triventricular (TriV) groups (standardized difference in means = 0.035, 95% CI: -0.270 to 0.340, p = 0.822). Peak O₂ consumption was comparable between BiV and LUV/RUV groups (standardized difference in means = 0.306, 95% CI: -0.002 to 0.614, p = 0.052). Patients in the TriV group had a significant improvement in LVEF compared to the BiV group (standardized difference in means = 0.647, 95% CI: 0.313 to 0.982, p < 0.001).

CONCLUSIONS

TriV CRT is an attractive alternative to univentricular or BiV pacing for heart failure patients. It is necessary to conduct further large randomized trials to validate our present data.

Left univentricular pacing for cardiac resynchronization therapy

This review describes the rationale and published evidence for left univentricular pacing for cardiac resynchronization therapy, gives an overview of the existing optimization algorithms featuring this mode, and discusses future perspectives.

Clinical decision tool for CRT-P vs. CRT-D implantation: Findings from PROSE-ICD

Background

Cardiac resynchronization therapy (CRT) devices reduce mortality through pacing-induced cardiac resynchronization and implantable cardioverter defibrillator (ICD) therapy for ventricular arrhythmias (VAs). Whether certain factors can predict if patients will benefit more from implantation of CRT pacemakers (CRT-P) or CRT defibrillators (CRT-D) remains unclear.

Methods and results

We followed 305 primary prevention CRT-D recipients for the two primary outcomes of HF hospitalization and ICD therapy for VAs. Serum biomarkers, electrocardiographic and clinical variables were collected prior to implant. Multivariable analysis using Cox-proportional hazards model was used to fit the final models. Among 282 patients with follow-up outcome data, 75 (26.6%) were hospitalized for HF and 31 (11%) received appropriate ICD therapy. Independent predictors of HF hospitalization were atrial fibrillation (HR = 1.8 (1.1,2.9)), NYHA class III/IV (HR = 2.2 (1.3,3.6)), ejection fraction <20% (HR = 1.7 (1.1,2.7)), HS-IL6 >4.03pg/ml (HR = 1.7 (1.1,2.9)) and hemoglobin (<12g/dl) (HR = 2.2 (1.3,3.6)). Independent predictors of appropriate therapy included BUN >20mg/dL (HR = 3.0 (1.3,7.1)), HS-CRP >9.42mg/L (HR = 2.3 (1.1,4.7)), no beta blocker therapy (HR = 3.2 (1.4,7.1)) and hematocrit ≥38% (HR = 2.7 (1.03,7.0)). Patients with 0–1 risk factors for appropriate therapy (IR 1 per 100 person-years) and ≥3 risk factors for HF hospitalization (IR 23 per 100-person-years) were more likely to die prior to receiving an appropriate ICD therapy.

Conclusions

Clinical and biomarker data can risk stratify CRT patients for HF progression and VAs. These findings may help characterize subgroups of patients that may benefit more from the use of CRT-P vs. CRT-D systems.

Trial registration

ClinicalTrials.gov NCT00733590

Cardiac resynchronization therapy before and after MitraClip implantation: An advantageous upgrading to reduce mitral regurgitation

MitraClip therapy has been proposed as therapeutic option in selected patients with degenerative or functional mitral regurgitation (FMR), leading to clinical and prognostic benefits. Previous studies demonstrated the safety and the efficacy of MitraClip therapy on symptoms and left ventricular remodeling in cardiac resynchronization therapy (CRT) non-responder patients. We report a case of a CRT non-responder patient treated with MitraClip implantation followed by a new upgrading of the CRT for persistent FMR at the follow-up. The optimization of the interventricular delay, guided by echocardiographic parameters, resulted in a significant clinical and functional benefit. Echo-guided CRT upgrading can provide additive efficacy for patients in whom MitraClip implantation does not significantly improve FMR and symptoms.

The Role of Atrioventricular and Interventricular Optimization for Cardiac Resynchronization Therapy

Many patients with left ventricular systolic dysfunction may benefit from cardiac resynchronization therapy; however, approximately 30% of patients do not experience significant clinical improvement with this treatment. AV and VV delay optimization techniques have included echocardiography, device-based algorithms, and several other novel noninvasive techniques. Using these techniques to optimize device settings has been shown to improve hemodynamic function acutely; however, the long-term clinical benefit is limited. In most cases, an empiric AV delay with simultaneous biventricular or left ventricular pacing is adequate. The value of optimization of these intervals in "nonresponders" still requires further investigation.

Relationship Between Reverse Remodeling and Cardiopulmonary Exercise Capacity in Heart Failure Patients Undergoing Cardiac Resynchronization Therapy

BACKGROUND

Studies on the relationship between left ventricular reverse remodeling and cardiopulmonary exercise capacity in heart failure patients undergoing cardiac resynchronization therapy (CRT) are scarce and inconclusive.

METHODS AND RESULTS

Eighty-four patients with a 1st-time CRT-defibrillator (mean age 65 ± 11; 73% male) underwent echocardiography and cardiopulmonary exercise testing (CPX) before implantation (baseline) and 6 months after implantation. At baseline, patients also completed a set of questionnaires measuring mental and physical health. The association between echocardiographic response (left ventricular end-systolic volume decrease ≥15%) and a comprehensive set of CPX results was examined. Echocardiographic responders (54%) demonstrated higher peak oxygen consumption and better exercise performance than nonresponders at baseline and at 6-month follow-up. Furthermore, only echocardiographic responders showed improvements in ventilatory efficiency during follow-up. Multivariable repeated measures analyses revealed that, besides reverse remodeling, New York Heart Association functional class II and good patient-reported health status before implantation were the most important correlates of higher average oxygen consumption during exercise, and that nonischemic etiology and smaller pre-implantation QRS width were associated with better ventilatory efficiency over time.

CONCLUSIONS

During the first 6 months of CRT there was a significant positive association between reverse remodeling and cardiopulmonary exercise capacity.

Pacing site in pacemaker dependency: is right ventricular septal lead position the answer?

The right ventricular apex has been the traditional site for lead placement in patients with atrioventricular block. Pacing at the right ventricular apex may have long-term deleterious effects on left ventricular (LV) function, promoting heart failure and increasing mortality. Pacing at the right ventricular septum has been proposed to minimize deterioration in LV function. Although experimental data suggest that septal pacing protects LV function, clinical studies have provided conflicting results. A recent large study in patients with heart block did not show a protective effect with septal pacing. Other pacing approaches are becoming increasingly relevant; however, prediction of what method should be employed in which patient is not currently possible. Other factors such as baseline LV function and associated co-morbidities impact LV function, irrespective of pacing site. Continued monitoring of cardiac function post-implant is therefore critical to ongoing care. An algorithm for managing patients with atrioventricular block is proposed.

Cardiac resynchronization therapy update: evolving indications, expanding benefit?

Cardiac resynchronisation therapy (CRT) is an effective intervention for appropriately selected patients with heart failure, but exactly how it works is uncertain. Recent data suggest that much, or perhaps most, of the benefits of CRT are not delivered by re-coordinating left ventricular dyssynchrony. Atrio-ventricular resynchronization, reduction in mitral regurgitation and prevention of bradycardia are other potential mechanisms of benefit that will vary from one patient to the next and over time. Because there is no single therapeutic target, it is unlikely that any single measure will accurately predict benefit. The only clinical characteristic that appears to be a useful predictor of the benefits of CRT is a QRS duration of >140 ms. Many new approaches are being developed to try to improve the effectiveness of and extend the indications for CRT. These include smart pacing algorithms, better pacing-site targeting, new sensors, multipoint pacing, remote device monitoring and leadless endocardial pacing. Whether CRT is effective in patients with atrial fibrillation or whether adding a defibrillator function to CRT improves prognosis awaits further evidence.

Evidence that conflict regarding size of haemodynamic response to interventricular delay optimization of cardiac resynchronization therapy may arise from differences in how atrioventricular delay is kept constant

Aims

Whether adjusting interventricular (VV) delay changes haemodynamic efficacy of cardiac resynchronization therapy (CRT) is controversial, with conflicting results. This study addresses whether the convention for keeping atrioventricular (AV) delay constant during VV optimization might explain these conflicts.

Method and results

Twenty-two patients in sinus rhythm with existing CRT underwent VV optimization using non-invasive systolic blood pressure. Interventricular optimization was performed with four methods for keeping the AV delay constant: (i) atrium and left ventricle delay kept constant, (ii) atrium and right ventricle delay kept constant, (iii) time to the first-activated ventricle kept constant, and (iv) time to the second-activated ventricle kept constant. In 11 patients this was performed with AV delay of 120 ms, and in 11 at AV optimum. At AV 120 ms, time to the first ventricular lead (left or right) was the overwhelming determinant of haemodynamics (13.75 mmHg at ±80 ms, P < 0.001) with no significant effect of time to second lead (0.47 mmHg, P = 0.50), P < 0.001 for difference. At AV optimum, time to first ventricular lead again had a larger effect (5.03 mmHg, P < 0.001) than time to second (2.92 mmHg, P = 0.001), P = 0.02 for difference.

Conclusion

Time to first ventricular activation is the overwhelming determinant of circulatory function, regardless of whether this is the left or right ventricular lead. If this is kept constant, the effect of changing time to the second ventricle is small or nil, and is not beneficial. In practice, it may be advisable to leave VV delay at zero. Specifying how AV delay is kept fixed might make future VV delay research more enlightening.

Vectorcardiography for optimization of stimulation intervals in cardiac resynchronization therapy

Current optimization of atrioventricular (AV) and interventricular (VV) intervals in cardiac resynchronization therapy (CRT) is time consuming and subject to noise. We aimed to prove the principle that the best hemodynamic effect of CRT is achieved by cancelation of opposing electrical forces, detectable from the QRS morphology in the 3D vectorcardiogram (VCG). Different degrees of left (LV) and right ventricular (RV) pre-excitation were induced, using variation in AV intervals during LV pacing in 20 patients with left bundle branch block (LBBB) and variation in VV intervals during biventricular pacing in 18 patients with complete AV block or atrial fibrillation. The smallest QRS vector area identified stimulation intervals with minimal systolic stretch (median difference [IQR] 20 ms [−20, 20 ms] and maximal hemodynamic response (10 ms [−20, 40 ms]). Reliability of VCG measurements was superior to hemodynamic measurements. This study proves the principle that VCG analysis may allow easy and reliable optimization of stimulation intervals in CRT patients.

Device therapies: new indications and future directions

Implantable cardioverter-defibrillator (ICDs), cardiac resynchronization (CRT) and combination (CRT-D) therapy have become an integral part of the management of patients with heart failure with reduced ejection fraction (HFrEF). ICDs treat ventricular arrhythmia and CRTs improve left ventricular systolic function by resynchronizing ventricular contraction. Device therapies (ICD, CRT-D), have been shown to reduce all-cause mortality, including sudden cardiac death. Hospitalizations are reduced with CRT and CRT-D therapy. Major device related complications include device infection, inappropriate shocks, lead malfunction and complications related to extraction of devices. Improvements in device design and implantation have included progressive miniaturization and increasing battery life of the device, optimization of response to CRT, and minimizing inappropriate device therapy. Additionally, better definition of the population with the greatest benefit is an area of active research.

Cardiac Resynchronisation Therapy or MitraClip® Implantation for Patients with Severe Mitral Regurgitation and Left Bundle Branch Block?

Secondary or functional mitral regurgitation (FMR) is a common problem in patients with chronic heart failure (HF). About one-third of patients with chronic HF also have left bundle branch block (LBBB). Approximately one-third of patients with an indication for cardiac resynchronisation therapy (CRT) have moderate-to-severe FMR. This FMR may either be a consequence of systolic dysfunction or it may occur due to dyssynchrony. Both directly reducing FMR and correcting cardiac dyssynchrony are viable therapeutic approaches in selected patients, according to the 2012 European Society of Cardiology (ESC) Guidelines for valvular heart disease. Initial presence of FMR is an independent predictor of lack of clinical response to CRT. Patients undergoing CRT without signs of significant clinical improvement may be considered candidates for the percutaneous MitraClip® procedure. As yet, there are not enough data to select patients that would benefit from being treated primarily with MitraClip. A clinical trial in HF patients to be randomised to either MitraClip procedure or CRT is needed to confirm actual ESC Guideline therapy.

Atrial synchronous left ventricular only pacing with VDD pacemaker system - a cost effective alternative to conventional cardiac resynchronization therapy

INTRODUCTION

Atrial synchronous left ventricular (LV) only pacing using two leads and VDD pacemaker could be a cost effective alternative to conventional cardiac resynchronization therapy (CRT).

METHODS

We implanted right atrial (RA) and LV leads with VDD pulse generator (LV only pacing) in five carefully screened heart failure patients who could not afford conventional CRT. All had NYHA class III/IV symptoms despite maximal guideline directed medical therapy. The sensed atrioventricular delay was programmed to pre-excite the LV and achieve fusion beat. Response to treatment was assessed at 6 months.

RESULTS

Four patients were males. The mean age was 58 ± 12 years. At follow up, there was improvement in electrocardiographic, and echocardiographic parameters: Mean QRS duration decreased from 174 ± 17 msec to 128 ± 10.9 msec (p = 0.009), LV end-diastolic diameter decreased from 73.2 ± 12 mm to 65.8 ± 9.6 mm (p = 0.026), LV end-systolic diameter decreased from 65 ± 12 mm to 54 ± 10 mm (p = 0.020). There was a trend towards reduction of LV end-systolic and end-diastolic volumes. LV ejection fraction improved from 25 ± 6% to 34 ± 6% (p = 0.013) and left atrial dimension reduced from 44 ± 4 mm to 39 ± 5 mm (p = 0.045). All patients improved clinically.

CONCLUSION

RA-LV pacing using VDD pacemaker is a safe and effective technique of CRT. This may be a cost effective alternative to conventional CRT for patients in developing countries.

Efficacy of isolated left ventricular and biventricular pacing is differentially associated with baseline QRS duration in chronic heart failure: a meta-analysis of randomized controlled trials

Cardiac resynchronization therapy can treat chronic heart failure through either biventricular pacing (BVP) or isolated left ventricular pacing (LVP), and the efficacy is depended on QRS duration. However, the optimal therapeutic choice of pacing or how the QRS influences the efficacy remains uncertain. To investigate this uncertainty, we searched available publications in PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials databases regarding differentials in efficacy parameters between BVP and LVP. A meta-analysis of eight randomized controlled trials found that BVP and LVP were comparable with regard to quality-of-life scores, left ventricular ejection fraction, left ventricular end-systolic volume, and mortality or heart transplant rates. However, there was a significant heterogeneity among the trials in 6-min walking distances. Subsequent meta-regression indicated that the baseline QRS duration significantly correlated with the standard mean difference between BVP and LVP. As QRS duration increased, the gain in 6-min walking distance with BVP became significantly greater than that of LVP. This suggests that it is necessary to consider the QRS duration when comparing the clinical effects of BVP and LVP.