Cardiac resynchronization therapy in pacemaker-dependent patients with left ventricular dysfunction

Upgrading right ventricular pacemakers to biventricular pacing or conduction system pacing: a systematic review and meta-analysis

Guidelines recommend patients undergoing a first pacemaker implant who have even mild left ventricular (LV) impairment should receive biventricular or conduction system pacing (CSP). There is no corresponding recommendation for patients who already have a pacemaker. We conducted a meta-analysis of randomized controlled trials (RCTs) and observational studies assessing device upgrades. The primary outcome was the echocardiographic change in LV ejection fraction (LVEF). Six RCTs (randomizing 161 patients) and 47 observational studies (2644 patients) assessing the efficacy of upgrade to biventricular pacing were eligible for analysis. Eight observational studies recruiting 217 patients of CSP upgrade were also eligible. Fourteen additional studies contributed data on complications (25 412 patients). Randomized controlled trials of biventricular pacing upgrade showed LVEF improvement of +8.4% from 35.5% and observational studies: +8.4% from 25.7%. Observational studies of left bundle branch area pacing upgrade showed +11.1% improvement from 39.0% and observational studies of His bundle pacing upgrade showed +12.7% improvement from 36.0%. New York Heart Association class decreased by -0.4, -0.8, -1.0, and -1.2, respectively. Randomized controlled trials of biventricular upgrade found improvement in Minnesota Heart Failure Score (-6.9 points) and peak oxygen uptake (+1.1 mL/kg/min). This was also seen in observational studies of biventricular upgrades (-19.67 points and +2.63 mL/kg/min, respectively). In studies of the biventricular upgrade, complication rates averaged 2% for pneumothorax, 1.4% for tamponade, and 3.7% for infection over 24 months of mean follow-up. Lead-related complications occurred in 3.3% of biventricular upgrades and 1.8% of CSP upgrades. Randomized controlled trials show significant physiological and symptomatic benefits of upgrading pacemakers to biventricular pacing. Observational studies show similar effects between biventricular pacing upgrade and CSP upgrade.

Cardiomyopathy Associated with Right Ventricular Apical Pacing-Systematic Review and Meta-Analysis

AIMS

Bradyarrhythmias are potentially life-threatening medical conditions. The most widespread treatment for slow rhythms is artificial ventricular pacing. From the inception of the idea of artificial pacing, ventricular leads were located in the apex of the right ventricle. Right ventricular apical pacing (RVAP) was thought to have a deteriorating effect on left ventricular systolic function. The aim of this study was to systematically assess results of randomized controlled trials to determine the effects of right ventricular apical pacing on left ventricular ejection fraction (LVEF).

METHODS

we systematically searched the Cochrane Central Register of Controlled Trials, PubMed, and EMBASE databases for studies evaluating the influence of RVAP on LVEF. Pooled mean difference (MD) with a 95% confidence interval (CI) was estimated using a random effect model.

RESULTS

14 randomized controlled trials (RCTs) comprising 885 patients were included. In our meta-analysis, RVAP was associated with statistically significant left ventricular systolic function impairment as measured by LVEF. The mean difference between LVEF at baseline and after intervention amounted to 3.35% (95% CI: 1.80-4.91).

CONCLUSION

our meta-analysis confirms that right ventricular apical pacing is associated with progressive deterioration of left ventricular systolic function.

Detrimental Immediate- and Medium-Term Clinical Effects of Right Ventricular Pacing in Patients With Myocardial Fibrosis

BACKGROUND

Long-term right ventricular (RV) pacing leads to heart failure or a decline in left ventricular (LV) function in up to a fifth of patients. We aimed to establish whether patients with focal fibrosis detected on late gadolinium enhancement cardiovascular magnetic resonance (CMR) have deterioration in LV function after RV pacing.

METHODS

We recruited 84 patients with LV ejection fraction ≥40% into 2 observational CMR studies. Patients (n=34) with a dual-chamber device and preserved atrioventricular conduction underwent CMR in 2 asynchronous pacing modes (atrial asynchronous and dual-chamber asynchronous) to compare intrinsic atrioventricular conduction with forced RV pacing. Patients (n=50) with high-grade atrioventricular block underwent CMR before and 6 months after pacemaker implantation to investigate the medium-term effects of RV pacing.

RESULTS

The key findings were (1) initiation of RV pacing in patients with fibrosis, compared with those without, was associated with greater immediate changes in both LV end-systolic volume index (5.3±3.5 versus 2.1±2.4 mL/m2; P<0.01) and LV ejection fraction (-5.7±3.4% versus -3.2±2.6%; P=0.02); (2) medium-term RV pacing in patients with fibrosis, compared with those without, was associated with greater changes in LV end-systolic volume index (8.0±10.4 versus -0.6±7.3 mL/m2; P=0.008) and LV ejection fraction (-12.3±7.9% versus -6.7±6.2%; P=0.012); (3) patients with fibrosis did not experience an improvement in quality of life, biomarkers, or functional class after pacemaker implantation; (4) after 6 months of RV pacing, 10 of 50 (20%) patients developed LV ejection fraction <35% and were eligible for upgrade to cardiac resynchronization according to current guidelines. All 10 patients had fibrosis on their preimplant baseline scan and were identified by >1.1 g of fibrosis with 90% sensitivity and 70% specificity.

CONCLUSIONS

Fibrosis detected on CMR is associated with immediate- and medium-term deterioration in LV function following RV pacing and could be used to identify those at risk of heart failure before pacemaker implantation.

Long term outcomes in patients with chronic right ventricular pacing upgraded to cardiac resynchronization therapy

INTRODUCTION

In patients with chronic systolic heart failure and frequent right ventricular pacing (RVP), upgrade to cardiac resynchronization therapy (CRT) has become common practice despite a lack of randomized clinical trials. We aimed to evaluate long term outcomes in patients upgraded to CRT from chronic RVP compared with de novo CRT implants.

METHODS AND RESULTS

We reviewed medical charts on consecutive patients with a left ventricular ejection fraction (LVEF) ≤ 35% and a QRSd ≥ 120 ms undergoing CRT. Survival free of left ventricular assist device (LVAD) and a heart transplant was compared amongst patients on the basis of pre-CRT QRS morphology. Improvement in LVEF was also compared across groups. A total of 1260 patients met inclusion criteria of whom 233 were upgraded from chronic RVP. Over a mean follow up 6.5 ± 4.0 years there were 821 endpoints (27 LVAD, 30 heart transplants, and 764 deaths). In a multivariate Cox regression model, upgraded patients had worse outcomes (HR 1.3(1.1-1.7) P = .007) compared with those with native LBBB and similar outcomes to patients with non-LBBB(HR 0.96(0.76-1.21) P = .7). The survival curve for chronic RVP parallels native LBBB for approximately 2.5 years before dropping sharply. Patients with chronic RVP derive similar improvements in LVEF compared with those with LBBB and superior improvements compared with those with non-LBBB.

CONCLUSIONS

Despite achieving similar levels of LVEF improvement, patients with systolic heart failure with chronic RVP undergoing upgrade to CRT have inferior long term outcomes compared with patients with native LBBB. Long term outcomes with CRT in patients with chronic RVP, RBBB, and IVCD are similar.

A cohort study of cardiac resynchronization therapy in patients with chronic Chagas cardiomyopathy

Aims

Cardiac resynchronization therapy (CRT) is an established procedure for patients with heart failure. However, trials evaluating its efficacy did not include patients with chronic Chagas cardiomyopathy (CCC). We aimed to assess the role of CRT in a cohort of patients with CCC.

Methods and results

This retrospective study compared the outcomes of CCC patients who underwent CRT with those of dilated (DCM) and ischaemic cardiomyopathies (ICM). The primary endpoint was all-cause mortality and the secondary endpoints were the rate of non-advanced New York Heart Association (NYHA) class 12 months after CRT and echocardiographic changes evaluated at least 6 months after CRT. There were 115 patients in the CCC group, 177 with DCM, and 134 with ICM. The annual mortality rates were 25.4%, 10.4%, and 11.3%, respectively (P < 0.001). Multivariate analysis adjusted for potential confounders showed that the CCC group had a two-fold [hazard ratio 2.34 (1.47-3.71), P < 0.001] higher risk of death compared to the DCM group. The rate of non-advanced NYHA class 12 months after CRT was significantly higher in non-CCC groups than in the CCC group (DCM 74.0% vs. ICM 73.9% vs. 56.5%, P < 0.001). Chronic Chagas cardiomyopathy and ICM patients had no improvement in the echocardiographic evaluation, but patients in the DCM group had an increase in left ventricular ejection fraction and a decrease in left ventricular end-diastolic diameter.

Conclusion

This study showed that CCC patients submitted to CRT have worse prognosis compared to patients with DCM and ICM who undergo CRT. Studies comparing CCC patients with and without CRT are warranted.

Upgrades from a previous device compared to de novo cardiac resynchronization therapy in the European Society of Cardiology CRT Survey II

BACKGROUND

To date, there are no data from randomized controlled studies on the benefit of cardiac resynchronization therapy (CRT) when implanted as an upgrade in patients with a previous device as compared to de novo CRT. In the CRT Survey II we compared the baseline data of patients upgraded to CRT (CRT-P/CRT-D) from a previous pacemaker (PM) or implantable cardioverter-defibrillator (ICD) to de novo CRT implantation.

METHODS AND RESULTS

In the European CRT Survey II, clinical practice data of patients undergoing CRT and/or ICD implantation across 42 European Society of Cardiology (ESC) countries were collected between October 2015 and December 2016. Out of a total of 11 088 patients, 2396 (23.2%) were upgraded from a previous PM or ICD and 7933 (76.8%) underwent de novo implantation. Compared to de novo implantations, upgraded patients were older, more often male, more frequently had ischaemic heart failure aetiology, atrial fibrillation, reduced renal function, worse heart failure symptoms, and higher N-terminal pro-B-type natriuretic peptide levels. Upgraded patients were more often PM-dependent and less frequently received CRT-D. Total peri-procedural, in-hospital complications and length of hospital stay were similar. Upgraded patients were less frequently treated with heart failure medication at discharge.

CONCLUSION

Despite a lack of evidenced-based data, close to one quarter of all CRT implantations across 42 ESC countries were upgrades from a previous PM or ICD. Despite older age and worse symptoms, the CRT implantation procedures in upgraded patients were equally frequently successful and complications similar to de novo implantations. These results call for more studies.

Devices in heart failure; diagnosis, detection and disease modification

INTRODUCTION/BACKGROUND

Implantable cardiac devices are widely used in chronic heart failure (CHF) therapy. This review covers current CHF treatment with electronic cardiac devices, areas of discussion and emerging technologies.

SOURCES OF DATA

A comprehensive search of available literature resources including Pubmed, MEDLINE and EMBASE was performed. National and international guidelines were accessed.

AREAS OF AGREEMENT

Excessive right ventricular pacing is detrimental to cardiac function. Cardiac resynchronization therapy is beneficial in specific individuals with CHF.

AREAS OF CONTROVERSY

Implantable cardioverter defibrillators might not benefit all. Optimizing CRT delivery. Remote monitoring seems not to be of benefit in CHF.

GROWING POINTS

Device-based optimization.

AREAS TIMELY FOR DEVELOPING RESEARCH

Personalization of device therapy. Focussing implantable cardioverter defibrillator therapy. What to do at implantable cardioverter defibrillator box change?

2017 Comprehensive Update of the Canadian Cardiovascular Society Guidelines for the Management of Heart Failure

Since the inception of the Canadian Cardiovascular Society heart failure (HF) guidelines in 2006, much has changed in the care for patients with HF. Over the past decade, the HF Guidelines Committee has published regular updates. However, because of the major changes that have occurred, the Guidelines Committee believes that a comprehensive reassessment of the HF management recommendations is presently needed, with a view to producing a full and complete set of updated guidelines. The primary and secondary Canadian Cardiovascular Society HF panel members as well as external experts have reviewed clinically relevant literature to provide guidance for the practicing clinician. The 2017 HF guidelines provide updated guidance on the diagnosis and management (self-care, pharmacologic, nonpharmacologic, device, and referral) that should aid in day-to-day decisions for caring for patients with HF. Among specific issues covered are risk scores, the differences in management for HF with preserved vs reduced ejection fraction, exercise and rehabilitation, implantable devices, revascularization, right ventricular dysfunction, anemia, and iron deficiency, cardiorenal syndrome, sleep apnea, cardiomyopathies, HF in pregnancy, cardio-oncology, and myocarditis. We devoted attention to strategies and treatments to prevent HF, to the organization of HF care, comorbidity management, as well as practical issues around the timing of referral and follow-up care. Recognition and treatment of advanced HF is another important aspect of this update, including how to select advanced therapies as well as end of life considerations. Finally, we acknowledge the remaining gaps in evidence that need to be filled by future research.

Cardiac resynchronization therapy in patients with mild heart failure is a reversal therapy

This systematic review with meta-analysis sought to determine the efficacy, safety of implantation of cardiac resynchronization therapy (CRT) in mild heart failure (HF). Medline, Embase, Elsevier, and Sciences online database as well as Google scholar literature were used for selecting appropriate studies with randomized controlled design. The literature search of all major databases retrieved 2035 studies. After screening, a total of 10 trials were identified that reported outcomes of interest. Pooled analysis was performed on left ventricular (LV) ejection fraction (P < 0.001), LV end-diastolic volume (P < 0.001), LV end-systolic volume (P < 0.001), LV end-diastolic diameter (P < 0.001), LV end-systolic diameter (P < 0.001), incidence of progression of heart failure (P < 0.001), mortality (P = 0.06), infection (P = 0.1), and pneumothorax (P = 0.08). Overall, implantation of CRT in patients with asymptomatic and mild HF resulted in improved cardiac function, decreased progression of HF, trend to decrease of mortality in short to long-term follow-up.

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.

The changing landscape of cardiac pacing

A number of trials have shown that irrespective of baseline QRS duration, left ventricular (LV) dysfunction and heart failure are more common in patients with right ventricular (RV) than in those with biventricular (BiV) pacing. By contrast, preliminary results of the BIOPACE trial (follow-up 5.6 years) yielded a disappointing comparison of RV vs. BiV pacing. Pacemaker-induced cardiomyopathy (PIC) may occur in patients with normal and abnormal LV ejection fractions (LVEF) and tends to occur if there is RV pacing more than 40 % of the time. Yet, some pacemaker-dependent patients do not develop LV dysfunction. PIC can be improved in about two thirds of patients by upgrading to a BiV system and the results are comparable to de novo BiV pacing in patients with a wide QRS complex. The findings of the BLOCK HF trial (2013) suggested that patients requiring pacing virtually 100 % of the time might benefit from BiV pacing irrespective of the LVEF (< 50 %), manifestations of heart failure, QRS duration, or functional class. These characteristics would generate many patients for BiV pacing. However, these recommendations should now be weighed against a more conservative approach based on the recently announced results of the BIOPACE trial. Organizational guidelines recommend BiV pacing for bradycardia irrespective of QRS duration for patients with LVEF < 35 %. At this time, BiV pacing for antibradycardia therapy (irrespective of QRS duration) has to be individualized in the setting of a normal or decreased LVEF (> 35 %) and according to the expected percentage of RV pacing. The benefit of BiV pacing should be considered against procedural complications, which are more frequent than with traditional RV pacing.

The role of biventricular pacing in the prevention and therapy of pacemaker-induced cardiomyopathy

Right ventricular (RV) pacing produces well-known long-term deleterious effects not only on already compromised, but also on the normal left ventricle (LV). The activation pattern mimicks that of left bundle branch block, with delayed activation of the LV free wall, and results in electrical and mechanical dyssynchrony. Long-term mandatory (100%) RV pacing, increases LV dimensions and decreases the ejection fraction. Many of these negative effects of pacing can be overcome by biventricular pacing. In this review, we describe the characteristics of pacemaker-induced cardiomyopathy, its incidence, and the use of cardiac resynchronization therapy (CRT) for its therapy and prevention. The gaps in the current organizational guidelines for using CRT in the treatment of bradycardia are identified, and goals for future research are discussed.

Importance of ventricular function in the election of electro heart mode

The integration of the ventricular function is essential when making decisions over a patient subjected to cardiac electrostimulation in order to understand the structure followed in the new cardiac stimulation and resynchronising therapy guides. To support the importance of ventricular function in cardiac electrostimulation it is important to know: (i)the deleterious effect of stimulation on the right ventricle apex; (ii)the effect over the left ventricular function produced by complete blockage of the left branch, and (iii)left ventricular disfunction as arrythmogenic substrate. When it comes to decide what type of cardiac electrostimualtion to apply we will know: the percentage of ventricular stimulation needed and its ventricular function. A normal ventricular function will enable electrostimulation from the right ventricle apex or alternative site. On the contrary, if this value is lower than 50% the most recommended electrostimulation is cardiac resynchronisation (CRT-P), which will be accompanied by defibrillation (CRT-D) if FEVI is lower than 35%.

Cardiomyopathy induced by artificial cardiac pacing: myth or reality sustained by evidence?

Implantable cardiac pacing systems are a safe and effective treatment for symptomatic irreversible bradycardia. Under the proper indications, cardiac pacing might bring significant clinical benefit. Evidences from literature state that the action of the artificial pacing system, mainly when the ventricular lead is located at the apex of the right ventricle, produces negative effects to cardiac structure (remodeling, dilatation) and function (dissinchrony). Patients with previously compromised left ventricular function would benefit the least with conventional right ventricle apical pacing, and are exposed to the risk of developing higher incidence of morbidity and mortality for heart failure. However, after almost 6 decades of cardiac pacing, just a reduced portion of patients in general would develop these alterations. In this context, there are not completely clear some issues related to cardiac pacing and the development of this cardiomyopathy. Causality relationships among QRS widening with a left bundle branch block morphology, contractility alterations within the left ventricle, and certain substrates or clinical (previous systolic dysfunction, structural heart disease, time from implant) or electrical conditions (QRS duration, percentage of ventricular stimulation) are still subjecte of debate. This review analyses contemporary data regarding this new entity, and discusses alternatives of how to use cardiac pacing in this context, emphasizing cardiac resynchronization therapy.

Chronic right ventricular apical pacing: adverse effects and current therapeutic strategies to minimize them

The permanent cardiac pacemaker is the only effective therapy for patients with symptomatic bradycardia and hundreds of millions are implanted worldwide every year. Despite its undisputed clinical benefits, the last two decades have drawn much attention to the negative effects associated with long-term pacing of the right ventricle (RV). Experimental and clinical studies have shown that RV pacing produces ventricular dyssynchrony, similar to that of left bundle branch block, with consequent detrimental effects on cardiac structure and function, with adverse clinical outcomes such as atrial fibrillation, heart failure and death. Although clinical evidence largely comes from subanalyses of pacemaker and implantable cardiac defibrillator studies, there is strong evidence that patients with reduced left ventricular function are at high risk of suffering from the detrimental effects of long-term RV pacing. Biventricular pacing in cardiac resynchronization therapy devices can prevent ventricular dyssynchrony and has emerged as an attractive option in this patient group with promising results and more clinical studies underway. Moreover, there is evidence that specific pacemaker algorithms that minimize RV pacing can reduce the negative effects of RV stimulation on cardiac function and may also prevent clinical deterioration. The extent of the long-term clinical effects of RV pacing in patients with normal ventricular function and how to prevent this are less clear and subject to future investigation.

The importance of avoiding unnecessary right ventricular pacing in clinical practice

Symptomatic bradycardia is effectively treated with the implantation of a cardiac pacemaker. Although a highly successful therapy, during recent years there has been a focus on the negative effects associated with long-term pacing of the apex of the right ventricle (RV). It has been shown in both experimental and clinical studies that RV pacing leads to ventricular dyssynchrony, similar to that of left bundle branch block, with subsequent detrimental effects on cardiac structure and function, and in some cases adverse clinical outcomes such as atrial fibrillation, heart failure and death. There is substantial evidence that patients with reduced left ventricular function (LVEF) are at particular high risk of suffering the detrimental clinical effects of long-term RV pacing. The evidence is, however, incomplete, coming largely from subanalyses of pacemaker and implantable cardiac defibrillator studies. In this group of patients with reduced LVEF and an expected high amount of RV pacing, biventricular pacing (cardiac resynchronization therapy) devices can prevent the negative effects of RV pacing and reduce ventricular dyssynchrony. Therefore, cardiac resynchronization therapy has emerged as an attractive option with promising results and more clinical studies are underway. Furthermore, specific pacemaker algorithms, which minimize RV pacing, can also reduce the negative effects of RV stimulation on cardiac function and may prevent clinical deterioration.