How many people with heart failure are appropriate for biventricular resynchronization?

[History of cardiac resynchronization therapy : 30 years of electrotherapeutic management for heart failure]

The first permanent biventricular pacing system was implanted more than 30 years ago. In this article, the historical development of cardiac resynchronization therapy (CRT), starting with the pathophysiological concept, followed by the initial "proof of concept" studies and finally the large prospective-randomized studies that led to the implementation of CRT in heart failure guidelines, is outlined. Since the establishment of CRT, both an expansion of indications, e.g., for patients with mild heart failure and atrial fibrillation, but also the return to patients with broad QRS complex and left bundle branch block who benefit most of CRT has evolved. New techniques such as conduction system pacing will have major influence on pacemaker therapy in heart failure, both as an alternative or adjunct to CRT.

Efficacy of Cardiac Resynchronization Therapy in Patients with a Narrow QRS Complex

Aims. In the guidelines for cardiac resynchronization therapy (CRT), there is a gap between the Japanese Circulation Society (JCS) criteria, which specify a QRS duration of ≥120 ms, and other countries, with a QRS ≥ 130 ms. The efficacy of CRT remains controversial in patients with a narrow QRS <130 ms. The aims of this study are to evaluate the response to CRT in patients with a narrow QRS and to identify predictors of mortality. Methods. We retrospectively studied 212 patients who received CRT. They were divided into narrow QRS (<130 ms) and wide QRS (≥130 ms) groups. We compared CRT response rates and investigated whether age, gender, baseline New York Heart Association (NYHA) class, ischemic etiology, atrial fibrillation, and ventricular arrhythmias are associated with response and also predictive of mortality. Results. The CRT response rate was not significantly different between the wide QRS group and the narrow QRS group (74.6% versus 77.2%, $p$  = 0.6876), and the response rate in the narrow QRS group was as good as that reported worldwide. NYHA class IV was shown to be a predictor of mortality (HR 9.38, 95% CI 5.35–16.3, $p$  < 0.0001). Conclusions. The present study demonstrated that patients with a narrow QRS complex responded well to CRT. Even with QRS <130 ms, CRT should be tried if no other effective treatment is available.

How many patients with heart failure are eligible for cardiac contractility modulation therapy?

BACKGROUND

Increasing evidence exists suggesting that cardiac contractility modulation therapy (CCM) improves symptoms in heart failure patients if various selection criteria are fulfilled. The aim of this study is to analyse an unselected sample of heart failure patients to establish what percentage of patients would meet the current criteria for CCM therapy.

METHODS

All patients admitted to two district general hospitals in the UK in 2018 with a diagnosis of heart failure were audited for eligibility for CCM therapy. The selection criteria were (a) ejection fraction (EF) 25%-45%, (b) QRS duration less than 130 ms, (c) New York Heart Association (NYHA) class 3-4 and (d) treated for heart failure for at least 90 days and on stable medications. Exclusion criteria included: (a) significant valvular disease, (b) permanent or persistent atrial fibrillation, (c) biventricular pacing system implanted or QRS duration more than 130 ms and (4) patients not suitable for device therapy as a result of palliative treatment intent.

RESULTS

A total of 475 patients were admitted with heart failure during the study period. From this group, 24 (5.1%) patients fulfilled the criteria for CCM therapy. The mean age and ejection fraction were 70.8 ± 10.2 and 32.5% ± 7.4%. The majority of patients were men (71%) and had an ischaemic cardiomyopathy (75%). If patients with atrial fibrillation were included, an additional 18 (3.8%) patients potentially may be eligible for CCM.

CONCLUSION

Only 5.1% of all patients presenting with heart failure might benefit from cardiac CCM. This is a small proportion of the overall heart failure population. However, this population has no other current option for device therapy of their condition.

Prognostic value of left-ventricular systolic and diastolic dyssynchrony measured from gated SPECT MPI in patients with dilated cardiomyopathy

BACKGROUND

Left-ventricular systolic dyssynchrony (LVSD) has been an important prognostic factor in the patients with dilated cardiomyopathy (DCM). However, the association between the LV diastolic dyssynchrony (LVDD) and clinical outcome is not well established. This study aims to evaluate the prognostic values of both systolic and diastolic dyssynchrony in patients with DCM.

METHODS

Fifty-two patients with DCM were enrolled and divided into two groups according to cardiac deaths from the follow-up data. The phase-analysis technique was applied on resting gated short-axis SPECT MPI images to measure LV systolic and diastolic dyssynchrony, including phase standard deviation (PSD), phase histogram bandwidth (PBW), and phase entropy (PE). Variables with P < 0.10 in the univariate analysis were included in the multivariate cox analysis.

RESULTS

During the follow-up period (2.9 ± 1.7 years), 18 (34.6%) cardiac deaths were observed. Compared with survivors, patients with cardiac death had lower LVEF (P = 0.011), and more severe LV systolic and diastolic dyssynchrony. The univariate cox regression analysis showed that hypertension, NT-proBNP, LVEF, systolic PSD, systolic PE, and diastolic PBW were statistically significantly associated with cardiac death. The multivariate cox regression analysis showed that systolic PE and diastolic PE were independent predictive factors for cardiac death. Furthermore, the receiver operating characteristic (ROC) analysis, when applied into the combination of systolic PE and diastolic PE for predicting cardiac death, had an area under curve (AUC) of 0.766, a sensitivity of 0.765, and a specificity of 0.722.

CONCLUSIONS

Both the LVSD and LVDD parameters from SPECT MPI have important prognostic values for DCM patients. Both systolic PE and diastolic PE are independent prognostic factors for cardiac death.

Cardiac Contractility Modulation Attenuates Chronic Heart Failure in a Rabbit Model via the PI3K/AKT Pathway

The Akt plays an important role in regulating cardiac growth, myocardial angiogenesis, and cell death in cardiac myocytes. However, there are few studies to focus on the responses of the Akt pathway to cardiac contractility modulation (CCM) in a chronic heart failure (HF) model. In this study, the effects of CCM on the treatment of HF in a rabbit model were investigated. Thirty six-month-old rabbits were randomly separated into control, HF, and CCM groups. The rabbits in HF and CCM groups were pressure uploaded, which can cause an aortic constriction. Then, CCM was gradually injected to the myocardium of rabbits in the CCM group, and this process lasted for four weeks with six hours per day. Rabbit body weight, heart weight, and heart beating rates were recorded during the experiment. To assess the CCM impacts, rabbit myocardial histology was examined as well. Additionally, western blot analysis was employed to measure the protein levels of Akt, FOXO3, Beclin, Pi3k, mTOR, GSK-3β, and TORC2 in the myocardial histology of rabbits. Results showed that the body and heart weight of rabbits decreased significantly after suffering HF when compared with those in the control group. However, they gradually recovered after CCM application. The CCM significantly decreased collagen volume fraction in myocardial histology of HF rabbits, indicating that CCM therapy attenuated myocardial fibrosis and collagen deposition. The levels of Akt, FOXO3, Beclin, mTOR, GSK-3β, and TORC2 were significantly downregulated, but Pi3k concentration was greatly upregulated after CCM utilization. Based on these findings, it was concluded that CCM could elicit positive effects on HF therapy, which was potentially due to the variation in the Pi3k/Akt signaling pathway.

Prognostic Implication of Ventricular Conduction Disturbance Pattern in Hospitalized Patients with Acute Heart Failure Syndrome

Background and Objectives

Conflicting data exist regarding the prognostic implication of ventricular conduction disturbance pattern in patients with heart failure (HF). This study investigated the prognostic impact of ventricular conduction pattern in hospitalized patients with acute HF.

Methods

Data from the Korean Acute Heart Failure registry were used. Patients were categorized into four groups: narrow QRS (<120 ms), right bundle branch block (RBBB), left bundle branch block (LBBB), and nonspecific intraventricular conduction delay (NICD). The NICD was defined as prolonged QRS (≥120 ms) without typical features of LBBB or RBBB. The primary endpoint was the composite of all-cause mortality or rehospitalization for HF aggravation within 1 year after discharge.

Results

This study included 5,157 patients. The primary endpoint occurred in 39.7% of study population. The LBBB group showed the highest incidence of primary endpoint followed by NICD, RBBB, and narrow QRS groups (52.5% vs. 49.7% vs. 44.4% vs. 37.5%, p<0.001). In a multivariable Cox-proportional hazards regression analysis, LBBB and NICD were associated with 39% and 28% increased risk for primary endpoint (LBBB hazard ratio [HR], 1.392; 95% confidence interval [CI], 1.152–1.681; NICD HR, 1.278; 95% CI, 1.074–1.520) compared with narrow QRS group. The HR of RBBB for the primary endpoint was 1.103 (95% CI, 0.915–1.329).

Conclusions

LBBB and NICD were independently associated with an increased risk of 1-year adverse event in hospitalized patients with HF, whereas the prognostic impacts of RBBB were limited.

Trial Registration

ClinicalTrials.gov Identifier: NCT01389843

An early analysis of cost-utility of baroreflex activation therapy in advanced chronic heart failure in Germany

Background

This study aimed to evaluate cost-utility of baroreflex activation therapy (BAT) using the Barostim neo™ device (CVRx Inc., Minneapolis, MN, USA) compared with optimized medical management in patients with advanced chronic heart failure (NYHA class III) who were not eligible for treatment with cardiac resynchronization therapy, from a statutory health insurance perspective in Germany over a lifetime horizon.

Methods

A decision analytic model was developed using the combination of a decision tree and the Markov process. The model included transitions between New York Heart Association (NYHA) health states, each of which is associated with a risk of mortality, hospitalization, cost, and quality of life. The effectiveness of BAT was projected through relative risks for mortality (obtained by application of patient-level data to the Meta-analysis Global Group in Chronic Heart Failure risk prediction model) and hospitalization owing to worsening of heart failure (obtained from BAT Randomized Clinical Trial). All patients were in NYHA class III at baseline.

Results

BAT led to an incremental cost of €33,185 (95% credible interval [CI] €24,561–38,637) and incremental benefits of 1.78 [95% CI 0.45–2.71] life-years and 1.19 [95% CI 0.30–1.81] quality-adjusted life-years (QALYs). This resulted in an incremental cost-effectiveness ratio of €27,951/QALY (95% CI €21,357–82,970). BAT had a 59% probability of being cost-effective at a willingness-to-pay threshold of €35,000/QALY (but 84% at a threshold of €52,000/QALY).

Conclusions

BAT can be cost-effective in European settings in those not eligible for cardiac resynchronization therapy among patients with advanced heart failure.

Eligibility for cardiac resynchronization therapy in patients hospitalized with heart failure

Aims

Recent guidelines recommend cardiac resynchronization therapy (CRT) in mildly symptomatic heart failure (HF) but favour left bundle branch block (LBBB) morphology in patients with moderate QRS prolongation (120–150 ms). We defined how many patients hospitalized with HF fulfil these criteria.

Methods and results

A single‐centre retrospective cohort study of 363 consecutive patients hospitalized with HF (438 admissions) was performed. Electronic imaging, electrocardiograms, and records were reviewed. Overall, 153 patients (42%) had left ventricular ejection fraction (LVEF) ≤ 35%, and 34% of patients had QRS prolongation. Eighty patients (22%) were potentially eligible with LVEF ≤ 35% and QRS ≥ 120 ms or existing CRT. The majority (68 of 80) had a Class I or IIa recommendation according to international guidelines (LBBB or non‐LBBB QRS ≥ 150 ms or right ventricular pacing). Only a minority (12 of 80) had moderate QRS prolongation of non‐LBBB morphology. One‐quarter (n = 22) of patients fulfilling criteria were ineligible for reasons including dementia, co‐morbidities, or palliative care. A further eight patients required optimization of medical therapy. CRT was therefore immediately indicated in 50 patients. Of these, 29 were implanted or had existing CRT systems. Twenty‐one of the 80 patients eligible for CRT were not identified or treated (6% of the total hospitalized cohort).

Conclusions

Twenty‐two per cent of elderly real‐life patients hospitalized with HF fulfil LVEF and QRS criteria for CRT, most having a Class I or IIa indication. However, a large proportion is ineligible owing to co‐morbidities or requires medical optimization. Although uptake of CRT was reasonable, there remain opportunities for improvement.

Clinical and echocardiographic response of apical vs nonapical right ventricular lead position in CRT: A meta-analysis

Background

Traditionally the right ventricular (RV) pacing lead is placed in the RV apex in cardiac resynchronization therapy (CRT). It is not clear whether nonapical placement of the RV lead is associated with a better response to CRT. We aimed to perform a meta‐analysis of all randomized controlled trials (RCTs) that compared apical and nonapical RV lead placement in CRT.

Methods

We searched PubMed, EMBASE, Cochrane, Scopus, and relevant references for studies and performed meta‐analysis using random effects model. Our main outcome measures were all‐cause mortality, composite of death and heart failure hospitalization, improvement in ejection fraction (EF), left ventricle end‐diastolic volume (LVEDV), left ventricle end‐systolic volume (LVESV), and adverse events.

Results

Seven RCTs with a total population of 1641 patients (1199 apical and 492 nonapical) were included in our meta‐analysis. There was no difference in all‐cause mortality (5% vs 4.3%, odds ratio (OR) = 0.86; 95% confidence interval (CI) 0.45‐1.64; P = .65; I² = 11%) and a composite of death and heart failure hospitalization (14.2% vs 12.9%, OR = 0.92; 95% CI: 0.61‐1.38; P = .68; I² = 0) between apical and nonapical groups. No difference in improvement in EF (Weighted mean difference (WMD) = 0.37; 95% CI: −2.75‐3.48; P = .82; I² = 68%), change in LVEDV (WMD = 3.67; 95% CI: −4.86‐12.20; P = .40; I² = 89%) and LVESV (WMD = −1.20; 95% CI: −4.32‐1.91; P = .45; I² = 0) were noted between apical and nonapical groups. Proportion of patients achieving >15% improvement in EF was similar in both groups (OR = 0.85; 95% CI: 0.62‐1.16; P = .31; I² = 0).

Conclusion

In patients with CRT, nonapical RV pacing is not associated with improved clinical and echocardiographic outcomes compared with RV apical pacing.

Effect of expanding evidence and evolving clinical guidelines on the prevalence of indication for cardiac resynchronization therapy in patients with heart failure

AIMS

To assess the prevalence of indication for cardiac resynchronization therapy (CRT) in patients with heart failure (HF) and reduced ejection fraction (EF) when recommendations from evolving European Society of Cardiology (ESC) guidelines are considered.

METHODS AND RESULTS

Unique patients (n=17 193) with EF ≤39% and key data available for evaluation of CRT indication from the Swedish HF Registry were included. Indication for CRT was defined as either CRT implanted or CRT device absent but fulfilling criteria for class I-IIa recommendations in ESC guidelines published between 2005/2007 and 2016. Prevalence was calculated as the ratio of patients with CRT indication to the study population. The prevalence of CRT indication increased from 24.5% when the 2005/2007 ESC guidelines were considered to a peak of 30.0% when the 2013 ESC guidelines were considered (P<0.001, 22.4% relative increase). Compared to the 2013 ESC guidelines, the prevalence declined significantly when the 2016 ESC guidelines were used as determinant for CRT indication (26.8%, 10.7% relative reduction, P<0.001). Actual CRT utilization was 6.8%.

CONCLUSION

Among patients with HF and reduced EF, the prevalence of CRT indication increased significantly comparing recommendations from ESC guidelines published between 2005/2007 and 2013, but then declined when the 2016 ESC guidelines were considered. The 2005-2013 increase may reflect the expansion of documented CRT efficacy to New York Heart Association class II, whereas the subsequent drop likely results from the more stringent criteria for QRS duration in the 2016 ESC guidelines. Actual CRT utilization is lower than indicated, regardless of which guidelines are considered.

Cardiac Resynchronization Therapy in Older Adults with Heart Failure

Heart failure is a disease of poor prognosis marked by frequent hospitalizations, premature death, and impaired quality of life. Despite advances in medical therapy for patients with heart failure and reduced ejection fraction, mortality and hospitalizations with advanced disease are still increased and the quality of life continues to be poor in this population. The advent of cardiac resynchronization therapy has led to a significant improvement in both survival and symptom management in patients with heart failure and reduced ejection fraction. Its beneficial effects in the elderly population, however, are not well-defined.

Clinical Characteristics and Outcome of Acute Heart Failure in Korea: Results from the Korean Acute Heart Failure Registry (KorAHF)

Background and Objectives

The burden of heart failure has increased in Korea. This registry aims to evaluate demographics, clinical characteristics, management, and long-term outcomes in patients hospitalized for acute heart failure (AHF).

Subjects and Methods

We prospectively enrolled a total of 5625 consecutive subjects hospitalized for AHF in one of 10 tertiary university hospitals from March 2011 to February 2014. Descriptive statistics were used to determine the baseline characteristics of the study population and to compare them with those from other registries.

Results

The mean age was 68.5±14.5 years, 53.2% were male, and 52.2% had de novo heart failure. The mean systolic and diastolic blood pressures were 131.2±30.3 mmHg and 78.6±18.8 mmHg at admission, respectively. The left ventricular ejection fraction was ≤40% in 60.5% of patients. Ischemia was the most frequent etiology (37.6%) and aggravating factor (26.3%). Angiotensin converting enzyme inhibitors/angiotensin receptor blockers, beta-blockers, and aldosterone antagonists were prescribed in 68.8%, 52.2%, and 46.6% of the patients at discharge, respectively. Compared with the previous registry performed in Korea a decade ago, extracorporeal membrane oxygenation (ECMO) and heart transplantation have been performed more frequently (ECMO 0.8% vs. 2.8%, heart transplantation 0.3% vs. 1.2%), and in-hospital mortality decreased from 7.6% to 4.8%. However, the total cost of hospital care increased by 40%, and one-year follow-up mortality remained high.

Conclusion

While the quality of acute clinical care and AHF-related outcomes have improved over the last decade, the long-term prognosis of heart failure is still poor in Korea. Therefore, additional research is needed to improve long-term outcomes and implement cost-effective care.

Clinical assessment of intraventricular blood transport in patients undergoing cardiac resynchronization therapy

In the healthy heart, left ventricular (LV) filling generates different flow patterns which have been proposed to optimize blood transport by coupling diastole and systole. This work presents a novel image-based method to assess how different flow patterns influence LV blood transport in patients undergoing cardiac resynchronization therapy (CRT). Our approach is based on solving the advection equation for a passive scalar field from time-resolved blood velocity fields. Imposing time-varying inflow boundary conditions for the scalar field provides a straightforward method to distinctly track the transport of blood entering the LV in the different filling waves of a given cardiac cycle, as well as the transport barriers which couple filling and ejection. We applied this method to analyze flow transport in a group of patients with implanted CRT devices and a group of healthy volunteers. Velocity fields were obtained using echocardiographic color Doppler velocimetry, which provides two-dimensional time-resolved flow maps in the apical long axis three-chamber view of the LV. In the patients under CRT, the device programming was varied to analyze flow transport under different values of the atrioventricular conduction delay, and to model tachycardia (100 bpm). Using this method, we show how CRT influences the transit of blood inside the left ventricle, contributes to conserving kinetic energy, and favors the generation of hemodynamic forces that accelerate blood in the direction of the LV outflow tract. These novel aspects of ventricular function are clinically accessible by quantitative analysis of color-Doppler echocardiograms.

Optimal Cardiac Resynchronization Therapy Pacing Rate in Non-Ischemic Heart Failure Patients: A Randomized Crossover Pilot Trial

Background

The optimal pacing rate during cardiac resynchronization therapy (CRT) is unknown. Therefore, we investigated the impact of changing basal pacing frequencies on autonomic nerve function, cardiopulmonary exercise capacity and self-perceived quality of life (QoL).

Methods

Twelve CRT patients with non-ischemic heart failure (NYHA class II–III) were enrolled in a randomized, double-blind, crossover trial, in which the basal pacing rate was set at DDD-60 and DDD-80 for 3 months (DDD-R for 2 patients). At baseline, 3 months and 6 months, we assessed sympathetic nerve activity by microneurography (MSNA), peak oxygen consumption (pVO₂), N-terminal pro-brain natriuretic peptide (p-NT-proBNP), echocardiography and QoL.

Results

DDD-80 pacing for 3 months increased the mean heart rate from 77.3 to 86.1 (p = 0.001) and reduced sympathetic activity compared to DDD-60 (51±14 bursts/100 cardiac cycles vs. 64±14 bursts/100 cardiac cycles, p<0.05). The mean pVO₂ increased non-significantly from 15.6±6 mL/min/kg during DDD-60 to 16.7±6 mL/min/kg during DDD-80, and p-NT-proBNP remained unchanged. The QoL score indicated that DDD-60 was better tolerated.

Conclusion

In CRT patients with non-ischemic heart failure, 3 months of DDD-80 pacing decreased sympathetic outflow (burst incidence only) compared to DDD-60 pacing. However, Qol scores were better during the lower pacing rate. Further and larger scale investigations are indicated.

Trial Registration

ClinicalTrials.gov NCT02258061

Review of eligibility for cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is underused. Recent guidelines have expanded indications for CRT to include less severe symptoms but now favor left bundle branch block morphology in patients with moderate QRS prolongation. The prevalence of CRT eligibility according to historical and current guidelines is uncertain. The aim of this review was to identify and synthesize all existing published research reporting the prevalence of CRT eligibility. A systematic review of electronic databases including MEDLINE, Embase, and the Cochrane Library was performed. The primary outcome was the proportion of patients eligible for CRT according to historical and current criteria. Secondary outcomes included the individual components of eligibility (the ejection fraction, symptoms, and QRS duration and morphology). Eligibility estimates were pooled using random-effects models because of marked heterogeneity in between-study variance. Thirty studies were identified. No study used current guideline criteria. On the basis of historical criteria, 11 ± 3% of ambulatory and 9 ± 3% of hospitalized patients are eligible for CRT. However, New York Heart Association class II in current guidelines is at least as frequent as New York Heart Association III or IV. Approximately 1/3 of patients have QRS prolongation, 2/3 of whom have left bundle branch block. Only a few patients have non-left bundle branch block with QRS duration <150 ms. Medical contraindication or ineligibility was rarely assessed. In conclusion, current estimates of need are outdated. Inclusion of milder symptoms potentially doubles the eligible population. Studies in unselected cohorts are needed to accurately define the individual components of eligibility, together with the prevalence and reasons for ineligibility.

Optimizing cardiac resynchronization therapy for congestive heart failure

In patients with advanced systolic heart failure and mechanical dyssynchrony, cardiac resynchronization therapy (CRT) is an effective means of improving symptoms and reducing mortality. There are now several recognized approaches to optimize CRT. Imaging modalities can assist with identifying the myocardium with the latest mechanical activation for targeted left ventricular lead implantation. Device programming can be tailored to maximize biventricular pacing, and thereby is its benefit. Cardiac imaging has shown that atrioventricular and interventricular intervals can be adjusted to further reduce dyssynchrony. We review these various approaches that maximize the benefit derived from CRT.

Normality index of ventricular contraction based on a statistical model from FADS

Radionuclide-based imaging is an alternative to evaluate ventricular function and synchrony and may be used as a tool for the identification of patients that could benefit from cardiac resynchronization therapy (CRT). In a previous work, we used Factor Analysis of Dynamic Structures (FADS) to analyze the contribution and spatial distribution of the 3 most significant factors (3-MSF) present in a dynamic series of equilibrium radionuclide angiography images. In this work, a probability density function model of the 3-MSF extracted from FADS for a control group is presented; also an index, based on the likelihood between the control group's contraction model and a sample of normal subjects is proposed. This normality index was compared with those computed for two cardiopathic populations, satisfying the clinical criteria to be considered as candidates for a CRT. The proposed normality index provides a measure, consistent with the phase analysis currently used in clinical environment, sensitive enough to show contraction differences between normal and abnormal groups, which suggests that it can be related to the degree of severity in the ventricular contraction dyssynchrony, and therefore shows promise as a follow-up procedure for patients under CRT.

Video-assisted thoracoscopic left ventricular pacing in patients with and without previous sternotomy

BACKGROUND

Left ventricular epicardial lead placement via video-assisted thoracoscopy (VAT) is a recognized surgical technique to achieve cardiac resynchronization therapy (CRT) when conventional lead placement has failed. Its role in patients with previous sternotomy is uncertain. We describe our experience in a cohort of patients including those with previous sternotomy.

METHODS

This was a retrospective review of consecutive patients undergoing VAT lead implantation for CRT in a single center between 2004 and 2011. All patients fulfilled conventional criteria for CRT and were followed up at 4 to 6 weeks and then at 3-month intervals. Clinical and pacing parameters were compared at baseline and at the latest review.

RESULTS

Thirty-two patients (27 men; mean age, 67 ± 9 years) underwent VAT left ventricular lead implantation. Mean follow-up duration was 704 ± 450 days. Ten patients (31%) had undergone previous sternotomy. Thoracoscopic lead implantation was successful in 31 patients (97%): 1 patient with two previous sternotomies required conversion to open thoracotomy due to bleeding with multiple adhesions. Satisfactory implantation pacing thresholds of 2 volts or less at 0.5 ms were achieved in all patients. Despite a longer operative time in those with previous sternotomy, all clinical and pacing outcomes, including complications, clinical response to CRT, and long-term pacing variables were similar between the groups.

CONCLUSIONS

VAT left ventricular lead placement appears safe and effective in selected patients with previous sternotomy, including coronary artery bypass operations, with postoperative outcomes comparable with those patients without previous sternotomy.

Cardiac resynchronization therapy: a breakthrough in heart failure management

Heart failure is now considered an epidemic. In patients with heart failure, electrical and mechanical dyssynchrony, evident primarily as prolongation of the QRS-complex on the surface electrocardiogram, is associated with detrimental effects on the cardiovascular system at several levels. In the past 10 years, studies have demonstrated that by stimulating both cardiac ventricles simultaneously, or almost simultaneously [cardiac resynchronization therapy (CRT)], the adverse effects of dyssynchrony can be overcome. Here, we provide a comprehensive overview of different aspects of CRT including the rationale behind and evidence for efficacy of the therapy. Issues with regard to gender effects and patient follow-up as well as a number of unresolved concerns will also be discussed.

Indications for cardiac resynchronization therapy: 2011 update from the Heart Failure Society of America Guideline Committee

Cardiac resynchronization therapy (CRT) improves survival, symptoms, quality of life, exercise capacity, and cardiac structure and function in patients with New York Heart Association (NYHA) functional class II or ambulatory class IV heart failure (HF) with wide QRS complex. The totality of evidence supports the use of CRT in patients with less severe HF symptoms. CRT is recommended for patients in sinus rhythm with a widened QRS interval (≥150 ms) not due to right bundle branch block (RBBB) who have severe left ventricular (LV) systolic dysfunction and persistent NYHA functional class II-III symptoms despite optimal medical therapy (strength of evidence A). CRT may be considered for several other patient groups for whom evidence of benefit is clinically significant but less substantial, including patients with a QRS interval of ≥120 to <150 ms and severe LV systolic dysfunction who have persistent mild to severe HF despite optimal medical therapy (strength of evidence B), some patients with atrial fibrillation, and some with ambulatory class IV HF. Several evidence gaps remain that need to be addressed, including the ideal threshold for QRS duration, QRS morphology, lead placement, degree of myocardial scarring, and the modality for evaluating dyssynchrony. Recommendations will evolve over time as additional data emerge from completed and ongoing clinical trials.

Pacing polarity and left ventricular mechanical activation sequence in cardiac resynchronization therapy

OBJECTIVE

The aim of this study is to evaluate the relationship between polarity of left ventricular (LV) pacing and the resultant regional, global, and transmural mechanical sequence of contraction.

BACKGROUND

Cardiac resynchronization therapy (CRT) is widely utilized in patients with drug refractory congestive heart failure with systolic dysfunction (EF <35 %) and intraventricular conduction delay (QRS duration >120 ms). However, little is known about polarity of pacing stimulation and the resultant differences in LV mechanics.

METHODS

The polarity of pacing was altered sequentially in 20 patients (73 ± 13, 16 males) with preexisting biventricular devices with potential choice of multiple vectors for pacing stimulation. Initial unipolar or extended bipolar configurations were switched to bipolar configuration or vice versa, and echocardiographic images were acquired for off-line analysis. Regional and global LV longitudinal and radial mechanics were assessed selectively from the subendocardial and subepicardial regions with 2D speckle-tracking echocardiography. Left ventricular capture by each vector configuration was confirmed by local lead capture and appropriate QRS alteration.

RESULTS

Unipolar pacing resulted in increased dispersion of LV regional endocardial strains with a higher base-to-apex gradients of longitudinal shortening strains (P < 0.05). LV longitudinal shortening strain magnitude was higher at LV base with bipolar stimulation in comparison with unipolar stimulation (-10.5 ± 10.5 vs. -4.2 ± 6.3, P = 0.02).

CONCLUSION

There is a difference in the mechanical activation sequence of the LV between unipolar vs. bipolar pacing stimulation. This may have important implications for CRT.

Contemporary and future trends in cardiac resynchronization therapy to enhance response

The rationale for cardiac resynchronization therapy (CRT), expectations in terms of patient benefit, patient selection for CRT, selection of a CRT pacemaker (CRT-P) vs CRT plus implantable cardioverter-defibrillator (CRT-D) platform, and studies evaluating device programming to enhance benefit from CRT are reviewed. The notion of an "optimal" left ventricular (LV) pacing site, the rationale for identifying and avoiding LV pacing in regions of scar, the use of anatomic, hemodynamic, and electrical parameters to identify an optimal LV pacing site, and the potential utility of multisite LV pacing to enhance benefit from CRT are discussed. Finally, the advantages and disadvantages of the various methods for LV lead delivery are reviewed.

Chronic heart failure: we are fighting the battle, but are we winning the war?

Heart failure represents an end-stage phenotype of a number of cardiovascular diseases and is generally associated with a poor prognosis. A number of organized battles fought over the last two to three decades have resulted in considerable advances in treatment including the use of drugs that interfere with neurohormonal activation and device-based therapies such as implantable cardioverter defibrillators and cardiac resynchronization therapy. Despite this, the prevalence of heart failure continues to rise related to both the aging population and better survival in patients with cardiovascular disease. Registries have identified treatment gaps and variation in the application of evidenced-based practice, including the use of echocardiography and prescribing of disease-modifying drugs. Quality initiatives often coupled with multidisciplinary, heart failure disease management promote self-care and minimize variation in the application of evidenced-based practice leading to better long-term clinical outcomes. However, to address the rising prevalence of heart failure and win the war, we must also turn our attention to disease prevention. A combined approach is required that includes public health measures applied at a population level and screening strategies to identify individuals at high risk of developing heart failure in the future.

Improvement in pump function with endocardial biventricular pacing increases with activation time at the left ventricular pacing site in failing canine hearts

Recently, attention has been focused on comparing left ventricular (LV) endocardial (ENDO) with epicardial (EPI) pacing for cardiac resynchronization therapy. However, the effects of ENDO and EPI lead placement at multiple sites have not been studied in failing hearts. We hypothesized that differences in the improvement of ventricular function due to ENDO vs. EPI pacing in dyssynchronous (DYSS) heart failure may depend on the position of the LV lead in relation to the original activation pattern. In six nonfailing and six failing dogs, electrical DYSS was created by atrioventricular sequential pacing of the right ventricular apex. ENDO was compared with EPI biventricular pacing at five LV sites. In failing hearts, increases in the maximum rate of LV pressure change (dP/dt; r = 0.64), ejection fraction (r = 0.49), and minimum dP/dt (r = 0.51), relative to DYSS, were positively correlated (P < 0.01) with activation time at the LV pacing site during ENDO but not EPI pacing. ENDO pacing at sites with longer activation delays led to greater improvements in hemodynamic parameters and was associated with an overall reduction in electrical DYSS compared with EPI pacing (P < 0.05). These findings were qualitatively similar for nonfailing hearts. Improvement in hemodynamic function increased with activation time at the LV pacing site during ENDO but not EPI pacing. At the anterolateral wall, end-systolic transmural function was greater with local ENDO compared with EPI pacing. ENDO pacing and intrinsic activation delay may have important implications for management of DYSS heart failure.

Left ventricular epicardial lead implantation for resynchronisation therapy using a video-assisted thoracoscopic approach

BACKGROUND

Cardiac resynchronisation therapy using a branch of the coronary sinus is the technique of choice for left ventricular (LV) pacing in patients with poor LV function. An alternative option is the surgical implantation of an epicardial LV lead under direct vision. We describe our initial experience with epicardial LV lead implantation.

METHODS

The records of 10 patients undergoing epicardial LV lead implantation at our institution were retrospectively reviewed. Epicardial leads were implanted on the LV free wall using video-assisted thoracoscopic surgery techniques.

RESULTS

Ten patients (seven men; three women; mean age 66.9 years) underwent surgery. All 10 patients suffered from congestive heart failure (CHF) and had a mean LV ejection fraction of 25%. All patients failed endocardial LV lead implantation via the coronary sinus because of lack of adequate branches or inability to cannulate the coronary sinus. There were no intraoperative complications, intrahospital or late deaths. The mean hospital stay was 5.2 days. Follow-up showed reversal of ventricular asynchrony and improvement in functional class in all patients.

CONCLUSIONS

Thoracoscopic epicardial LV lead implantation is a safe and feasible procedure in a population of high risk patients who need resynchronisation therapy after endocardial LV lead placement has failed.

Minimally invasive video-assisted epicardial lead cardiac resynchronization therapy for the dilated cardiomyopathy heart failure cases

OBJECTIVE

Cardiac resynchronization therapy (CRT) with biventricular pacing has demonstrated cardiac function improvement in treating congestive heart failure. Traditional CRT through coronary sinus lead method is difficult to perform. Minimally invasive video-assisted epicardial lead (Epi-lead) CRT for the dilated cardiomyopathy heart failure cases was explored.

METHODS

From April 2007 to June 2009, a total of 12 patients (age, 63 ± 9 years) with depressed systolic left ventricular (LV) function (ejection fraction, <35%), left bundle branch block (mean QRS [Q wave, R wave, S wave], 158 ± 15 milliseconds), and congestive heart failure of New York Heart Association class III/IV were enrolled. The patients received minimally invasive video-assisted epicardial steroid-eluting LV lead implantation for the CRT. The right atrial and right ventricle leads were implanted, guided by x-ray. The mean follow-up time was 13.7 months (range, 7-27 months).

RESULTS

All patients received LV lead implantation at the most late-activated site. The mean QRS duration decreased significantly from 158 ± 15 to 124 ± 11 milliseconds (P < 0.05). There was no surgical or hospital mortality in the entire series. The mean procedure duration (skin to skin) of the LV lead implantation was 52.4 ± 15.8 minutes. The mean postoperative stay was 7.1 ± 2.7 days. During the follow-up, cardiac function improved significantly in 11 patients. Threshold capture of the Epi-leads remained stable at 1.12 ± 0.3 V/0.5 ms during the follow-up. None died during the follow-up.

CONCLUSIONS

Surgical Epi-lead placement for the resynchronization therapy is a safe and reliable technique and should be considered as an equal alternative.

CRT in Patients with Heart Failure: Time Course of Perfusion and Wall Motion Changes

In patients treated with CRT no data relative to the relationship between regional wall motion and perfusion and reverse remodelling of the left ventricle at short and medium term followup were available. To this aim, 36 heart failure patients were studied by G-SPECT before (T0), within 2 months (T1) and 6 months (T2) after CRT. A clinical followup was completed for 36 months. In 30/36 patients there was an improvement of NYHA Class at T1 that persisted at T2. G-SPECT showed significant improvement of perfusion at T1 in 92% of patients without further changes at T2. A reduction of LV volumes, an increase of EF and an improvement of regional wall motion and thickening were observed at T1 versus baseline, with only minor changes at T2. Moreover, baseline extension of perfusion defects was scarcely correlated with improvement after CRT. Finally, end diastolic volume, perfusion defect and diabetes mellitus were independent predictors of survival. The main effects of CRT on regional myocardial perfusion and wall motion are obtained within 2 months. Volume overload modulates recovery of ventricular function independently of reperfusion and, with extension of perfusion abnormalities and diabetes were independent predictors of survival during followup.

Implication of QRS prolongation and its relation to mechanical dyssynchrony in idiopathic dilated cardiomyopathy in childhood

We explored the role of QRS prolongation (>or=120 ms) and its relation to mechanical dyssynchrony and outcomes in childhood idiopathic dilated cardiomyopathy (IDC). A total of 89 patients <or=18 years old diagnosed as having IDC (21 days to 26 years of follow-up) were investigated. In 20 survivors with residual left ventricular (LV) dysfunction, mechanical (interventricular and intra-LV) dyssynchrony was assessed. The SD of time from the beginning of QRS prolongation to peak systolic contraction was measured in 12 LV segments by tissue Doppler imaging. A cut-off value >32.6 ms was used to define intra-LV dyssynchrony. The 1- and 5-year survivals were 70% and 53%, respectively. Requirement of intravenous inotropes at follow-up (hazard ratio 3.10) and initial LV ejection fraction (hazard ratio 0.95) were major prognostic factors. QRS prolongation, primarily left bundle branch block, was identified in 16 patients (18%) and tended to increase the risk of requiring inotropes. Moreover, none of those with QRS prolongation regained normal cardiac function at follow-up. Two patients with QRS prolongation showed marked improvement in cardiac function after cardiac resynchronization therapy. Mechanical dyssynchrony was noted in all patients with QRS prolongation and in 8% (interventricular) or 38% (intra-LV) of those without. In conclusion, QRS prolongation was common in childhood IDC and was possibly associated with persistent LV dysfunction and worse cardiac outcome. Mechanical (inter- and intraventricular) dyssynchrony was highly prevalent in those with QRS prolongation and was still often observed in those without.

Contemporary pacemakers: what the primary care physician needs to know

Pacemaker therapy is most commonly initiated because of symptomatic bradycardia, usually resulting from sinus node disease. Randomized multicenter trials assessing the relative benefits of different pacing modes have made possible an evidence-based approach to the treatment of bradyarrhythmias. During the past several decades, major advances in technology and in our understanding of cardiac pathophysiology have led to the development of new pacing techniques for the treatment of heart failure in the absence of bradycardia. Left ventricular or biventricular pacing may improve symptoms of heart failure and objective measurements of left ventricular systolic dysfunction by resynchronizing cardiac contraction. However, emerging clinical data suggest that long-term right ventricular apical pacing may have harmful effects. As the complexity of cardiac pacing devices continues to grow, physicians need to have a basic understanding of device indications, device function, and common problems encountered by patients with devices in the medical and home environment.

The cost of medical management in advanced heart failure during the final two years of life

OBJECTIVE

To examine patterns of resource use and the cost of care for patients with advanced heart failure treated with medical management (MM) during the final 2 years of life.

METHODS AND RESULTS

The study population (n=47, mean age 70.4 years+/-7.06) included patients randomized to the MM arm of the Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure trial. Inpatient and outpatient use data were obtained from the clinical dataset and Centers for Medicare and Medicaid Services (beginning January 1, 1998). Cost and resource use were tracked from the date of death (t(d)) backward in 3-month intervals (eg, t(d-1), t(d-2)). In the primary analysis, costs were summed across intervals. The mean cost of MM in the final 2 years of life was $156,169, with 50.5% ($78,880.39) expended in the final 6 months. The mean quarterly cost increased (P < .01) 4.9-fold from t(d-8) ($8,816 +/- $14,270) to t(d-1) ($42,836 +/- $41,407). The number of inpatient days increased (P < .01) 6.6-fold from 3.8+/-4.7 days to 22.2+/-23.5 days during the same time intervals.

CONCLUSION

This current economic analysis extends on previous findings by demonstrating that medical therapy in advanced and end-stage heart failure is associated with significant costs and resource consumption; these costs and resource consumption increase significantly as death approaches.

Assessment of left ventricular dyssynchrony during development of heart failure by a novel program using ECG-gated myocardial perfusion SPECT

BACKGROUND

A novel program, "cardioGRAF", has been developed to analyze regional left ventricular (LV) systolic/diastolic function and dyssynchrony, so the present study aimed to use it confirm the presence of LV dyssynchrony, and to correlate LV function and dyssynchrony with plasma B-type natriuretic peptide (BNP) levels during the early to advanced stages of heart failure (HF).

METHODS AND RESULTS

Fourteen control subjects (G-C) and 50 patients (New York Heart Association functional class I: G-1, 21 patients; class II: G-2, 15 patients; and class III: G-3, 14 patients) were examined by ECG-gated myocardial perfusion single-photon emission computed tomography, using the new index of dyssynchrony, maximal difference (MD), which is the difference between the earliest and latest temporal parameters among 17 segments. First-third filling rate (FR) and the MD of time to peak FR revealing diastolic dyssynchrony were significantly different between G-C subjects and G-1 patients. Ejection fraction, peak ejection rate, peak FR, MD of time to end-systole, and MD of time to peak ejection rate were significantly correlated with plasma BNP levels.

CONCLUSION

Diastolic dyssynchrony was demonstrated even in the early stage of HF, but, although not correlated with the plasma BNP level, systolic dyssynchrony might affect it.

Four-chamber pacing in patients with poor ejection fraction but normal QRS durations undergoing open heart surgery

BACKGROUND

Poor ejection fraction (EF) comprises a critical risk factor in cardiac bypass surgery (CABG). It has been unclear, whether biventricular or four-chamber pacing confers benefit upon patients with intact atrioventricular and interventricular conduction especially following surgery.

METHODS

Twenty-one consecutive patients with an EF <or= 35% underwent hemodynamic evaluation (continuous pressures and thermodilution) 3, 6, and 18 hours post-CABG and biatrial (AA), biatrial-right ventricular (AAV), and biatrial-biventricular (AAVV) pacing were compared.

RESULTS

Patients (65 +/- 9 years) presented with an average EF of 29.5% (15-35%). 514 measurements of cardiac index (CI) were taken. Nineteen patients (91%) showed highly significant increases in CI with AAVV as compared to AA pacing (P < 0,001) at all times post surgery. The increase in CI with pacing mode varied from 6% to 25% and decreased with time following surgery. No consistent difference in CI was seen between four-chamber (AAVV) and biventricular pacing (AVV). The QRS-widths prior to surgery never exceeded 120 ms; postoperatively QRS-complexes widened in all patients on average by 15.9 ms +/-6 and returned to starting values by 48 hours.

CONCLUSIONS

Biventricular pacing improves CI in patients with poor EF following cardiac surgery in the absence of preoperative atrioventricular- or interventricular conduction block. This benefit decreases with time after surgery as the QRS width returns to preoperative values. Four-chamber pacing did not confer additional benefit as compared to biventricular pacing in this series. Biventricular pacing should be considered as an adjunct in patients with critically low EF undergoing cardiac surgery.

Volume overload modulates effects of cardiac resynchronization therapy independently of myocardial reperfusion: results of the RESYNC study

OBJECTIVES

Cardiac resynchronization therapy (CRT) may induce significant changes in regional wall motion and perfusion. However, the link between these variables in patients with heart failure has not been investigated.

METHODS

Thirty-six patients with idiopathic (n = 22) or ischemic (n = 14) cardiomyopathy (mean age 70 +/- 8 years, 24 male) were studied by echocardiography and gated single-photon emission computed tomography (SPECT) before and within 2 months after CRT.

RESULTS

New York Heart Association class improved in all but four patients. The perfusion analysis indicated that, in all but three patients, there was a significant improvement of tracer uptake. Baseline end-diastolic volume index obtained by gated SPECT modulated increase of ejection fraction (P < 0.001), reduction of end-systolic volume index (P < 0.01) and improvement of motion (P < 0.001), as well as of left ventricular wall thickening (P < 0.002). Finally, despite CRT inducing significant reperfusion independently of volume overload (P < 0.05), extension of perfusion defect correlated with global improvement in the follow-up (P < 0.05).

CONCLUSIONS

Volume overload may identify responders to resynchronization therapy. CRT induced a significant 'reperfusion' both in ischemic and idiopathic cardiomyopathies, even if this is not sufficient to improve left ventricular function in patients with more severe volume overload. Finally, simultaneous evaluation of volume overload and perfusion defects may result useful in identifying CRT responders.

What can post market registries tell us about the use of cardiac resynchronization therapy?

Cardiac resynchronization therapy (CRT) has become an established therapeutic option for patients with dilated cardiomyopathies and New York Heart Association class III congestive heart failure symptoms who also have a widened QRS complex on their electrocardiograms (generally > 120 ms). Results from a number of clinical trials have shown that CRT improves patients' exercise tolerance, quality of life, and survival. There is further evidence that CRT has structural effects on the heart with improved cardiac function. Despite these salutary results, clinical trials in CRT study prespecified populations that fit the inclusion criteria for these trials. Many patients have been excluded from these clinical trials and yet may potentially benefit from CRT. Evaluation of the effects of CRT on these populations might reveal the potential to expand the use of this therapy in larger numbers of patients to CRT who may not have been included in the clinical trial. This review article will assess the limitations of some of the clinical trials in CRT and will discuss the potential for CRT registries that are presently underway to extend the patient population that may benefit from this therapeutic option.

Optimizing Therapy for Heart Failure Patients

Heart failure continues to be diagnosed at unprecedented rates. It is essential that the affiliated professional, including the nurse practitioner, clinical nurse specialist, and physician assistant, be aware of the current treatments and technology that improve symptoms and reduce mortality rates in patients with heart failure. Medications remain critical in reducing symptoms. New clinical trial data on cardiac resynchronization therapy and cardiac resynchronization therapy with defibrillation reveal improved mortality and quality of life in patients already on optimal drug therapy. This article addresses current treatment strategies with drugs and devices, summarizes therapy efficacy based on clinical trial data, and provides a case study illustrating a typical patient who could benefit from the addition of device therapy. Through awareness of current guidelines and advocacy for the patient, nurses and affiliated professionals have an essential role in reducing mortality and improving outcomes for heart failure patients.