Cardiac Resynchronization Therapy in Heart Failure in Sub-Saharan Africa Environment: Experience of the Principal Hospital of Dakar (Senegal)

Background: Heart failure is a major public health challenge in sub-Saharan Africa. In patients with chronic Heart Failure and cardiac desynchrony, studies have suggested that cardiac resynchronization, can improve cardiac function and the quality of life of patients. However, in Sub-Saharan Africa, very few studies have been done on cardiac resynchronization which is in its infancy. The aim of this study is to report the local data from our hospital. Method: It was a transversal, descriptive and analytical study conducted from November 2019 to September 2022 at the Cardiology Department of the Principal Hospital of Dakar. Results: Twelve patients were implanted for Cardiac Resynchronization Therapy (CRT). The sex ratio was 8 males/4 females. The average age was 67 ± 11 years. Ten patients had non-ischemic heart disease and the two others had ischemic one. All of them had NYHA III or IV scores before CRT. The Quality of Life (QOL) was judged as poor by all of the patients. The average duration of QRS was 156 ± 9 ms. 27.9% ± 5% was the mean Left Ventricular ejection fraction (LVEF). Complications occur in 3/12 patients (25%). It was one CS vein dissection, one micro LV lead dislodgement and one phrenic nerve stimulation. Nine patients, who were considered as responders, had an improvement of QOL and NYHA, the LVEF increased and the end-diastolic dimension, and the duration of the QRS interval all decreased. Two patients do not respond and one (1) who had permanent atrial fibrillation, was a secondary responder after an atrioventricular junction ablation. Conclusion: Cardiac resynchronization is a therapy that improves the QOL of patients, the LVEF and reduces the duration of the QRS interval. However, this procedure is not without risk of complications. In sub-Saharan Africa, the major challenge is to improve the financial accessibility of this therapy for the population.

Effect of serum γ-glutamyltranferase and albumin levels on the response to cardiac resynchronization therapy in the elderly

Background Several liver function tests have been identified as predictors of hospitalization for heart failure(HF) and death in patients with chronic HF. The relationship between serum γ-glutamyltranferase(GGT) and albumin(SA) levels with the response to cardiac resynchronization therapy(CRT) has not been reliably determined. The aim of the study was to evaluate the impact of liver function tests on the results of CRT in the elderly. Methods Baseline GGT and SA were assessed before CRT device implantation in the elderly(> 70-year-old) patients. The endpoints were:(1) CRT response defined as > 5% left ventricular ejection fraction improvement and no hospitalization for HF or cardiovascular death;(2) hospitalizations;and(3) mortality. Results Eighty of 138(58%) included patients were responders at nine months. Compared to responders, the SA levels were not significantly different(35.1 ± 5.4 vs. 33.6 ± 5.5 g/L, P = 0.103);but the GGT levels, higher(81.6 ± 69.3 vs. 54.7 ± 49.6 U/L, P = 0.013) in non-responders to CRT. GGT level was independently associated with non-response to CRT(P < 0.001, OR = 0.17;95% CI: 0.08–0.38, P < 0.001). GGT cut-off value ≥ 55 U/L was highly predictive of non-response [AUC = 0.65, 64% Sensitivity, 69% Specificity(95% CI: 0.56–0.74)]. GGT ≥ 55 U/L was also associated with higher risk of hospitalization for atrial fibrillation(AF)(95% vs. 83%, P = 0.024). Both SA and GGT had no impact on overall(P = 0.220, P = 0.723) mortality. Conclusions Higher level of GGT is an independent predictor of non-response to CRT in patients over age 70 years and is associated with higher risk of hospitalization for AF. Baseline serum levels of albumin and GGT and have no impact on mortality in elderly patients undergoing CRT.

Predictors of non-response to cardiac resynchronization therapy implantation in patients with class Ⅰ indications: the markedly dilated left ventricular end-diastolic dimension and the presence of fragmented QRS

Background Cardiac resynchronization therapy(CRT)is a highly effective treatment in patients with a class I recommendation.However,a small proportion of the strictly selected patients still fail to respond.This study was designed to identify predictors of non-response in patients with class I indications for CRT and determine the non-response probability of the patients.Methods A total of 296 consecutive patients with a class I recommendation received CRT from January 2009 to January 2017 were retrospectively analyzed.Multivariate logistic regression analysis was performed to identify predictors for non-response(defined as cardiac death,heart transplantation,or HF hospitalization during 1-year follow-up).Results Among 296 patients,30(10.1%)met non-response.Multivariate analysis demonstrated that non-response to CRT was associated with a fragmented QRS(odd ratio(OR)=2.86,95%CI:1.14–7.12;P=0.025)and left ventricular end-diastolic dimension(LVEDD)≥77 mm(OR=3.02,95%CI:1.17–7.82;P=0.022).Patients with both of the predictors had a non-response probability of 46.2%(95%CI:19.1%–73.3%).Conclusion In patients with left bundle branch block and wider QRS duration,the proportion of non-response to CRT is not low in real world.The presence of the dilated LVEDD or fragmented QRS is a strong predictor of non-response to CRT.The probability of non-response in the patients with the two predictors was 46.2%.

Does ‘super-responder’ patients to cardiac resynchronization therapy still have indications for neuro-hormonal antagonists? Evidence from long-term follow-up in a single center

Background Whether cardiac resynchronization therapy super-responders (CRT-SRs) still have indications for neuro-hormonal antagonists or not remains uninvestigated.Methods We reviewed clinical data from 376 patients who underwent CRT implantation in Fuwai Hospital from 2009 to 2015 and followed up to 2017.CRT-SRs were defined by an improvement of the New York Heart Association functional class and left ventricular ejection fraction to ≥ 50% in absolute values at 6-month follow-up.All CRT-SRs were assigned into two groups on the basis of whether persistently receiving neuro-hormonal antagonists (NHA)(defined as angiotensin-converting enzyme inhibitors/ angiotensin receptor blockers and β-blockers) after 6-month follow-up and then we compared long-term outcome.Results A total of 60 patients met criteria for super-response.One of thirteen (7.7%) CRT-SRs without NHA had all-cause death,which also occurred in 2 of 47 (4.3%) in CRT-SRs with NHA (P = 0.526).However,3 of 13 (23.1%) CRT-SRs without NHA had heart failure (HF) hospitalization,1 of 47 (2.1%) CRT-SRs with NHA had this endpoint (P = 0.040).Besides,subgroup analysis indicated that,for ischemic etiology group,CRT-SRs receiving NHA had considerably lower incidence of HF hospitalization than those without NHA (0 vs.75%,P = 0.014),which was not observed in non-ischemic etiology group (2.6% vs.0,P = 1.000) during long-term follow-up.Conclusions Our study found that for ischemic etiology,compared with CRT-SRs with NHA,CRT-SRs without NHA were associated with a higher risk of HF hospitalization.However,for non-ischemic etiology,we found that CRT-SRs with NHA or without NHA at follow-up were associated with similar outcomes,which needed further investigation by prospective trials.

The value of serum metabolomics analysis in predicting the response to cardiac resynchronization therapy

Objective To construct a prediction model based on metabolic profiling for predicting the response to cardiac resynchronization therapy(CRT).Methods Peripheral venous(PV)and coronary sinus(CS)blood samples were collected from 25 patients with heart failure(HF)at the time of CRT implantation,and PV blood samples were obtained from ten healthy controls.The serum samples were analyzed by liquid chromatography-mass spectrometry(LC-MS).As per the clinical and echocardiographic assessment at the 6-month follow-up,the HF patients were categorized as CRT responders and non-responders.Results HF patients had altered serum metabolomic profiles that were significantly different from those of the healthy controls.Differential metabolites were also observed between CRT responders and non-responders.A prediction model for CRT response(CRT-Re)was constructed using the concentration levels of the differential metabolites,L-arginine and taurine.The optimal cutoff value of the CRT-Re model was found to be 0.343 by ROC analysis(sensitivity,88.2%;specificity,87.5%;Area under curve(AUC)=0.897,P=0.002).The concentration levels of the differential metabolites,L-arginine and lysyl-gamma-glutamate,in PV serum were significantly correlated with that in CS serum(r=0.945 and 0.680,respectively,all P<0.001).Conclusions Our results suggest that serum-based metabolic profiling may be a potential complementary screening tool for predicting the outcome of CRT.

The Temporal Relation between Cardiomyopathy and LBBB and Response to Cardiac Resynchronization Therapy:Case Series and Literature Review

Background:Left bundle branch block(LBBB)-induced cardiomyopathy has been proposed,but the association between LBBB and cardiac resynchronization therapy(CRT)response remains unclear and practical criteria for selecting CRT candidates are needed.Methods:One hundred and seventeen consecutive heart failure patients were reviewed,24 of whom received CRT.Only two patients had a clear temporal relation between cardiomyopathy and LBBB.Results:Compared with the patient with“cardiomyopathy-induced LBBB,”the patient with“LBBB-induced cardiomyopathy”had higher left ventricular(LV)wall thickness,higher LV wall thickening rate,higher peak circumferential strain,and longer peak circumferential strain delay.The LV deformation patterns in the two patients were obviously distinct on cardiovascular magnetic resonance tissue tracking.During follow-up,the patient with LBBB-induced cardiomyopathy had a good response to CRT(LV ejection fraction 23 before CRT vs.30%at 6 months vs.29 at 12 months vs.32%at 18 months;LV end-diastolic diameter 77 mm before CRT vs.66 mm at 6 months vs.62 mm at 12 months vs.63 mm at 18 months),and the other patient had no response to CRT(LV ejection fraction 29 before CRT vs.29%at 6 months vs.26 at 12 months vs.22%at 24 months;LV end-diastolic diameter 85 mm before CRT vs.88 mm at 6 months vs.85 mm at 12 months vs.84 mm at 24 months).Conclusion:The temporal relation between cardiomyopathy and LBBB could be a determinant for CRT response.Cardiovascular magnetic resonance tissue tracking may be a useful tool to identify the chronological order and a principal consideration for selecting candidates for CRT.Larger prospective clinical trials are needed to study the prevalence of,time course of,and risk factors for LBBB-induced cardiomyopathy.

Left bundle branch pacing with optimization of cardiac resynchronization treatment:A case report

BACKGROUND Cardiac resynchronization therapy(CRT)is a well-established therapy for patients with cardiomyopathy.CASE SUMMARY The patient underwent left bundle branch area and left ventricular(reaching the left ventricular lateral vein through the coronary sinus)pacing.The optimal CRT was performed under the right bundle branch of the patient by adjusting the optimal a-v and v-v interphases to achieve the maximal benefit of the treatment.CONCLUSION The patient was diagnosed with left bundle branch block and heart failure.A left bundle branch area pacemaker assisted in correcting the complete left bundle branch block.However,the shorter QRS wave shape after pacemaker implantation through the left bundle branch area indicated a complete right bundle branch block pattern.Hence,the left bundle branch area pacemaker is not always considered as the optimal treatment.The left bundle branch pacing with the optimization of cardiac resynchronization treatment may serve as a new CRT strategy.

Determination of the optimal atrioventricular and interventricular delays in cardiac resynchronization therapy

In order to provide the maximum benefit of cardiac resynchronization therapy (CRT), we tried to use an echocardiography method to optimize the atrioventricular and interventricular delay. Methods The study included 6 patients who underwent implantation of biventricular pacemakers for drug-resistant heart failure. Two-dimensional echocardiography and tissue Doppler imaging were carried out before and after the pacemaker implantation. The optimal AV delay was defined as the AV delay resulting in maximum timevelocity integral (TVI) of transmitral filling flow, the longest left ventricular filling time (LVFT) and the minimum mitral regurgitation(MR). The optimal VV delay was defined as the VV delay producing the maximum LV synchrony and the largest aortic TVI. Results CRT was successfully performed in all patients. After pacemaker implantation, an acute improvement in left ventricular ejection fraction (LVEF) was observed from 26.5% to 35%. Meanwhile, the QRS duration decreased from 170ms to 150ms. The optimal AV delay was programmed at 130, 120, 120, 120, 150 and 110ms respectively with heart rate corrected, LVFT significantly lengthened and TVI of MR decreased (non-optimal vs optimal AV delay: LVFT: 469ms vs 523ms; TVI of MR: 16.43cm vs 13.06cm, P＜0.05). The optimal VV delay was programmed at 4, 4, 4, 8, 12 and 8ms with LV preactivation respectively. Programming the optimal VV delay increased the aortic TVI from 17.33cm up to 21.42cm (P＜0.05). In the septal and lateral wall, peak systolic velocities improved from2.70cm/s to 3.02cm/s (P＞0.05) and froml.31cm/s to 2.50cm/s (P＜0.05) respectively. The septal-to-lateral delay in peak velocity improved from 56.4ms to 13.3ms after CRT (P＜0.01). Conclusions Optimization of AV and VV delays may further enhance the efficacy of CRT. However, there was interindividual variability of optimal values, warranting individual patient examination.

Cardiac resynchronization therapy in acute pulmonary edema: A case report

We are reporting a case of 71-year old lady with a dual chamber demand pacemaker,who developed acute pulmonary edema due to an acute left ventricular(LV)dysfunction and worsening in mitral valve regurgitation after atrioventricular nodal ablation for uncontrolled atrial fibrillation.This was attributed to right ventricular apical pacing leading to LV dyssynchronization.Patient dramatically improved within 12-24 h after upgrading her single chamber pacemaker to biventricular pacing.Our case demonstrates that biventricular pacing can be an effective modality of treatment of acute congestive heart failure.In particular,it can be used when it is secondary to LV dysfunction and severe mitral regurgitation attributed to significant dyssynchrony created by right ventricular pacing in patients with atrioventricular nodal ablation for chronic atrial fibrillation.

Cardiac resynchronization therapy in China

Congestive heart failure (HF) is a major and growing public health problem. The therapeutic approach includes non-pharmacological measures, pharmacological therapy,mechanical devices, and surgery. Despite the benefits of optimal pharmacologic therapy, the prognosis is still not ideal. At this time, cardiac resynchronization therapy (CRT)has gained wide acceptance as an alternative treatment for HF patients with conduction delay.1……

Cardiac Resynchronization Therapy in 2015:Lessons Learned

Over 20 years of research has led to the now widely accepted role of cardiac resynchronization therapy(CRT)in medically refractory,mild to severe systolic heart failure(HF)with increased QRS duration.In addition to conferring a mortality benefi t,CRT has been shown to reduce HF hospitalization rates and improve functional status in this population.However,not all patients consistently demonstrate a positive response to CRT.Efforts to improve response to CRT have focused on improving patient selection and optimizing device implantation and follow-up,thereby correcting electrical and mechanical dyssynchrony.In this article we review the pathobiology of cardiac dyssynchrony,the rationale for the use of CRT,the history and the state of the art of CRT,and guidelines and recommendations for CRT,while also focusing on the areas of controversy and potential future applications.

Cardiac resynchronization therapy in the elderly heart failure patient

Ms. BP is an 83 year old white female with a long history of congestive heart failure (HF). She is now symptomatic with minimal exertion, has a left ventricular ejection fraction (LVEF) of 20%. Her CHF is due to hypertension (HTN) plus coronary artery disease (CAD) and she is on angiotensin converting enzyme inhibitor (ACEI), furosemide, digoxin,spironolactone, low dose beta blocker and nitrates. Her beta-natriuretic peptide (BNP) in clinic is 3030 pg/ml, heart rate (HR) 100, blood pressure (BP) 89/43.

Successful upgrade to cardiac resynchronization therapy for cardiac implantation-associated left subclavian vein occlusion:A case report

BACKGROUND Subclavian vein stenosis or occlusion may be caused by a transvenous pacemaker,which makes the reimplantation of a new pacemaker lead difficult.Transvenous pacemaker lead implantation-related subclavian vein occlusion may present difficulty with regard to cardiac resynchronization therapy(CRT)upgrade.CASE SUMMARY We report the case of a 46-year-old man who was admitted with total subclavian vein occlusion caused by a permanent pacemaker that had been implanted 2 years previously.We successfully treated this patient with an upgrade to a CRT pacemaker by utilizing transferable interventional coronary and radiological techniques.The patient recovered uneventfully during the follow-up period.CONCLUSION CRT upgrade is still a viable technique for the treatment of subclavian vein obstruction caused by previous pacemaker implantation.

Predictors of persistence of functional mitral regurgitation after cardiac resynchronization therapy:Review of literature

Functional mitral regurgitation is a common finding among heart failure patients with ischemic and non-ischemic dilated cardiomyopathies.The presence of moderate or severe mitral regurgitation is associated with higher morbidity and mortality.Heart failure patients meeting electrocardiogram and left ventricle function criteria are good candidates for cardiac resynchronization therapy,which may reduce the degree of functional mitral regurgitation in the short and long term,specifically targeting myocardial dyssynchrony and inducing left ventricle reverse remodeling.In this article,we analyze data from the literature about predictors of mitral regurgitation improvement after cardiac resynchronization therapy implantation.

Six-Year Outcome after Valve Replacement and Resynchronization Therapy in TGA Patient

Patients with complete transposition of the great arteries(TGA)treated by the Senning procedure have a higher risk of developing heart failure due to:a)additional work load of the systemic(morphologic right)ventricle(sRV),b)arrhythmias,mainly caused by surgical implications at the atria as well as c)worsening of systemic tricuspid regurgitation.We present a unique case of a female patient who developed all these complications,who was successfully treated and was able to carry out a twin pregnancy.This breakthrough approach was based on:1.detecting reversibility potential of myocardial systolic dysfunction in a severe valvular lesion combined with continuous systemic afterload settings and permanent tachyarrhythmia,and 2.prevention of subsequently iatrogenic worsening of systemic ventricular function due to permanent pacing.Surgical replacement of systemic tricuspid valve(sTV)and cardiac resynchronization device(CRT)implantation after nodal ablation resulted in recovering of the systolic function and a positive remodeling of the sRV.The reversal of a further decline in systolic function was achieved by permanent arrhythmia control,synchronous pacing with epicardial leads of CRT,sTV replacement as well as echocardiographic monitoring during pregnancy to determine the right time for delivery.Two years after delivery,the patient remains in NYHA Class I.

Successful treatment of systemic sclerosis complicated by ventricular tachycardia with a cardiac resynchronization therapydefibrillator:A case report

BACKGROUND Systemic sclerosis is a rare connective tissue disease characterized by localized ordiffuse skin thickening and fibrosis,which usually accumulates in various organsthroughout the body.Tachyarrhythmia is a common clinical manifestation ofcardiovascular damage in systemic sclerosis patients.However,few studies havereported the use of catheter ablation and an implantable cardioverter defibrillatorin patients with systemic sclerosis complicated by ventricular tachycardia.CASE SUMMARY A 39-year woman with an 11-year history of systemic sclerosis was referred toour hospital due to three syncopal episodes in the past 6 mo.The results of anelectrocardiogram and a transthoracic echocardiogram revealed ventriculartachycardia and left ventricular systolic and ventricular septum segmentalmotion abnormalities,respectively.The results of an electrocardiogram showed asinus rhythm with complete blockage of the left bundle branch.In light of theprogressive nature of systemic sclerosis,the presence of a left bundle branchblock,and the decreased ejection fraction,a cardiac resynchronization therapydefibrillatorwas implanted.The patient’s clinical conditions improved,and at the3-mo follow-up,the patient was free of ventricular tachycardia and all cardiacsymptoms.CONCLUSION We report the first case of systemic sclerosis complicated by ventriculartachycardia that was successfully treated with a cardiac resynchronizationtherapy-defibrillator.

Implant Electrical Characteristics Predict Response to Cardiac Resynchronization Therapy

Background: The optimal site for left ventricular (LV) lead placement in cardiac resynchronization therapy (CRT) remains uncertain. Intra-procedural measures for predicting response to CRT have shown mixed results. Hypothesis: This study analyzed intracardiac electrogram (IEGM) characteristics at implant and assessed patients’ response rates (RR) to CRT. Methods: Forty-one consecutive patients undergoing CRT were enrolled. Medically optimized patients in sinus rhythm, with ejection fraction (EF) 34 were included. Right ventricular (RV) leads were positioned mid-septum. LV leads were targeted to the latest mechanical activation on echocardiography. IEGMs were measured, assessing intrinsic RV-to-LV delay (int RV-LV), RV-paced delay (RVp-LV), and LV-paced delay (LVp-RV). The difference between LVp-RV and RVp-LV was recorded as delta-LV. Response was defined as improvement of EF > 10%, reduction in LVEDD > 15% and improvement of ≥1 NYHA class. Results: Overall RR was 79%. LV leads were placed in the target location in 91%. Int RV-LV was 101 ± 14 ms in responders;78 ± 11 ms in non-responders (p 100 had a RR of 87%;int RV-LV 40 ms had a RR of 56%;delta-LV < 40 ms had a RR of 85%. There was no significant correlation between lead position, DI, QRS duration or EF and IEGM measurements. Conclusions: IEGM measures at implant are easily obtained. Significant intrinsic electrical delay and shorter delta-LV both predict response, even when LV leads are implanted in the targeted mechanically-delayed segment. These assessments of electrical dyssynchrony may be used to determine optimal lead positions and response to CRT.

Successful Treatment of Cardiac Failure Due to Cardiomyopathy in Propionic Acidemia by Cardiac Resynchronization Therapy and Hemodialysis in a Young Adult

Propionic acidemia is an autosomal recessive disorder that is due to deficiency in the enzyme propionyl-CoA carboxylase. Cardiomyopathy is a well-known phenomenon in propionic acidemia that it may rapidly progress to death. Here we describe a case of propionic acidemia in a 27-year-old man who developed adult-onset secondary dilated cardiomyopathy. In early infancy he was diagnosed with propionic acidemia and was later noted to have mild mental retardation, mild renal failure, and optic nerve atrophy. Although he was in good energy status with a low-protein diet and carnitine supplementation, he was admitted to our university hospital with decompensate heart failure, which resulted in low-output cardiac syndrome with massive mitral regurgitation and left ventricular dyssynchrony. Cardiac resynchronization therapy (CRT) and continuous hemodiafiltration followed by hemodialysis (HD) dramatically improved his clinical status.

Surgical Results of Left Ventricular Lead Implantation for Cardiac Resynchronization Therapy

Objectives: Cardiac resynchronisation therapy (CRT) has proven its effectiveness in patients with symptomatic heart failure [1,2]. Although rewarding, the procedure of biventricular pacemaker implantation is challenging and subsequently fails in 8%-11% of patients. In patients whose left ventricular (LV) electrode cannot be placed transvenously, surgical implantation of an epicardial electrode can be achieved. Methods: Seventeen patients (14 male, 3 female), among whom LV electrode was failed to be placed transvenously, were included into our study. The epicardial LV electrodes were implanted through anterior mini thoracotomy. The patients were followed up for approximate six months and complications, ejection fraction (EF), New York Heart Association (NYHA) class, QRS durations as well as pacing parameters were recorded. Results: Mean age of the patients was 64.4 ± 7.01 (54-79) years. Preoperative mean EF of the patients was 26.1% ± 3.7%. The LV electrode was placed at the optimal place on the lateral LV wall through left sided mini thoracotomy. The mean duration of the operation was 26.76 ± 8.12 minutes and the mean hospital stay was 2.05 ± 0.42 days. There were no intraoperative or postoperative complications. Only 1 patient had LV electrode displaced on the 3rd postoperative month and the patient was reoperated successfully. The EF on the 6th postoperative month was 29.4% ± 3.81% and NYHA class was 2.58 ± 0.5. The etiology of heart failure had no influence on outcome. Conclusions: Surgical implantation of LV lead is associated with low complication rates and excellent follow-up results without exposure to radiation. Thus epicardial leads can be proposed as equal alternative to transvenous leads.

Exercise Training Post Cardiac Resynchronization Therapy Improves Exercise Tolerance and Quality of Life

Background: Cardiac resynchronization therapy (CRT) results in improved morbidity, mortality, symptoms, quality of life (QOL) and exercise capacity, in appropriate chronic heart failure (CHF) patients. Moreover, combined exercise training (ET) and CRT maximize these improvements in these patients. The study evaluated the effect of ET on these patients in terms of QOL, functional class, exercise capacity and left ventricular ejection fraction (LVEF). Results: There were significant improvements in the QOL, functional class, exercise capacity, and LVEF compared with the Control Group. Comparison of both groups confirmed the cumulative effects of ET with CRT. The QOL improved by the end of training in the exercise group (p = 0.001), compared to the Control Group (p = 0.850). NYHA functional class improved significantly in the Exercise Group (p = 0.013). Percent-predicted peak oxygen consumption (VO2 peak) had significantly improved in the trained (p < 0.001) versus the untrained CRT Group (p= 0.596). There was a mean percent rise of the ejection fraction from 39.2 ± 12.86 to 44.40% ± 14.42% in the Exercise Group compared to a non-significant change in the Control Group. Conclusion: ET in resynchronized CHF patients is feasible and further enhances QOL and exercise tolerance in addition to the improvements seen after CRT. The study therefore recommends for the prescription of ET after implantation in order to maximize the expected benefit.