Rationale and design of a randomized clinical trial to assess the safety and efficacy of cardiac resynchronization therapy in patients with advanced heart failure: the Multicenter InSync Randomized Clinical Evaluation (MIRACLE)

Sex differences in CRT device implantation rates, efficacy, and complications following implantation: protocol for a systematic review and meta-analysis of cohort studies

INTRODUCTION

There is abundant evidence for sex differences in the diagnosis, implantation, and outcomes for cardiac resynchronization therapy (CRT) devices. Controversial data suggesting women are less likely to receive the device regardless of the greater benefit. The aim of this review is to assess sex differences in the implantation rate, clinical effectiveness, and safety of patients receiving CRT devices.

METHODS

We will conduct a systematic literature search of MEDLINE, Embase, and Web of Science to identify cohort studies that meet our eligibility criteria. Title and full text screening will be conducted in duplicate independently. Eligible studies report clinical effectiveness or safety of patients receiving CRT device while providing sex-disaggregated data. Implantation rate will be extracted from the baseline characteristics tables of the studies. The effectiveness outcomes include the following: all-cause death, hospitalization, peak oxygen consumption (pVO₂), quality of life (QoL), 6-min walk test, NYHA class reduction, LVEF, and heart failure hospitalization. The complication outcomes include the following: contrast-induced nephropathy, pneumothorax, pocket-related hematoma, pericardial tamponade, phrenic nerve stimulation, device infection, death, pulmonary edema, electrical storm, cardiogenic shock, and hypotension requiring resuscitation. Description of included studies will be reported in detail and outcomes will be meta-analyzed and presented using forest plots when feasible. Risk of bias will be assessed using the Newcastle-Ottawa Scale (NOS) by two review authors independently. GRADE approach will be used to assess the certainty of evidence.

DISCUSSION

The aim of this review is to determine the presence of differences in CRT implantation between women and men as well as differences in clinical effectiveness and safety of CRT after device implantation. Results from this systematic review will provide important insights into sex differences in CRT devices that could contribute to the development of sex-specific recommendations and inform policy.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020204804.

Cardiac resynchronization therapy with a defibrillator (CRTd) in failing heart patients with type 2 diabetes mellitus and treated by glucagon-like peptide 1 receptor agonists (GLP-1 RA) therapy vs. conventional hypoglycemic drugs: arrhythmic burden, hospitalizations for heart failure, and CRTd responders rate

Objectives

To evaluate clinical outcomes in patients with diabetes, treated by cardiac resynchronization therapy with a defibrillator (CRT-d), and glucagon-like peptide 1 receptor agonists (GLP-1 RA) in addition to conventional hypoglycemic therapy vs. CRTd patients under conventional hypoglycemic drugs.

Background

Patients with diabetes treated by CRTd experienced an amelioration of functional New York Association Heart class, reduction of hospital admissions, and mortality, in a percentage about 60%. However, about 40% of CRTd patients with diabetes experience a worse prognosis.

Materials and methods

We investigated the 12-months prognosis of CRTd patients with diabetes, previously treated with hypoglycemic drugs therapy (n 271) vs. a matched cohort of CRTd patients with diabetes treated with GLP-1 RA in addition to conventional hypoglycemic therapy (n 288).

Results

At follow up CRTd patients with diabetes treated by GLP-1 RA therapy vs. CRTd patients with diabetes that did not receive GLP-1 RA therapy, experienced a significant reduction of NYHA class (p value < 0.05), associated to higher values of 6 min walking test (p value < 0.05), and higher rate of CRTd responders (p value < 0.05). GLP-1 RA patients vs. controls at follow up end experienced lower AF events (p value < 0.05), lower VT events (p value < 0.05), lower rate of hospitalization for heart failure worsening (p value < 0.05), and higher rate of CRTd responders (p value < 0.05). To date, GLP-1 RA therapy may predict a reduction of AF events (HR 0.603, CI [0.411–0.884]), VT events (HR 0.964, CI [0.963–0.992]), and hospitalization for heart failure worsening (HR 0.119, CI [0.028–0.508]), and a higher CRT responders rate (HR 3.707, CI [1.226–14.570]).

Conclusions

GLP-1 RA drugs in addition to conventional hypoglycemic therapy may significantly reduce systemic inflammation and circulating BNP levels in CRTd patients with diabetes, leading to a significant improvement of LVEF and of the 6 min walking test, and to a reduction of the arrhythmic burden. Consequently, GLP-1 RA drugs in addition to conventional hypoglycemic therapy may reduce hospital admissions for heart failure worsening, by increasing CRTd responders rate.

Trial registration NCT03282136. Registered 9 December 2017 “retrospectively registered”

Comparison of hemodynamic effects of biventricular versus left ventricular only pacing in patients receiving cardiac resynchronization therapy: A before-after clinical trial

Background

Biventricular (BiV) pacing is the most common mode of delivering cardiac resynchronization therapy (CRT). However, initial clinical studies have indicated that left ventricular (LV) pacing is not inferior to BiV pacing. This study was conducted to address whether LV only pacing can provide the same hemodynamic response as BiV pacing.

Methods

This before–after clinical trial was conducted at Ekbatan Hospital, from July 2012 to November 2014. Patients with a LV ejection fraction ≤35% and a QRS duration ≥0.12 s who had a standard indication for ventricular pacing were enrolled. The CRT devices of all patients had already been set for BiV pacing. Therefore, their CRT devices were set for LV only pacing for 3 months. The hemodynamic status of the patients was assessed by echocardiography before setting the CRT device to LV only pacing (as a control) and 3 months after (as an intervention).

Results

There was no statistically significant difference between the effect of BiV pacing and LV only pacing on the hemodynamic responses including LV ejection fraction, LV end diastolic and systolic volume, and velocity time integral of the aortic valve. Moreover, no significant difference was seen between men and women either.

Conclusions

LV only pacing is not inferior to BiV pacing, and the hemodynamic response was similar in the two groups. However, the LV mode has a number of advantages over the BiV mode. More evidence, based on large clinical trials, is needed to confirm our results.

Association Between a Prolonged PR Interval and Outcomes of Cardiac Resynchronization Therapy: A Report From the National Cardiovascular Data Registry

BACKGROUND

A prolonged PR interval is common among cardiac resynchronization therapy (CRT) candidates; however, the association between PR interval and outcomes is unclear, and the data are conflicting.

METHODS

We conducted inverse probability weighted analyses of 26 451 CRT-eligible (ejection fraction ≤35, QRS ≥120 ms) patients from the National Cardiovascular Data Registry ICD Registry to assess the association between a prolonged PR interval (≥230 ms), receipt of CRT with defibrillator (CRT-D) versus implantable cardioverter defibrillator (ICD), and outcomes. We first tested the association between a prolonged PR interval and outcomes among patients stratified by device type. Next, we performed a comparative effectiveness analysis of CRT-D versus ICD among patients when stratified by PR interval. Using Medicare claims data, we followed up with patients up to 5 years for incident heart failure hospitalization or death.

RESULTS

Patients with a PR≥230 ms (15%; n=4035) were older and had more comorbidities, including coronary artery disease, atrial arrhythmias, diabetes mellitus, and chronic kidney disease. After risk adjustment, a PR≥230 ms (versus PR<230 ms) was associated with increased risk of heart failure hospitalization or death among CRT-D (hazard ratio, 1.23; 95% confidence interval, 1.14-1.31; P<0.001) but not ICD recipients (hazard ratio, 1.08; 95% confidence interval, 0.97-1.20; P=0.17) (P_interaction=0.043). CRT-D (versus ICD) was associated with lower rates of heart failure hospitalization or death among patients with PR<230 ms (hazard ratio, 0.79; 95% confidence interval, 0.73-0.85; P<0.001) but not PR≥230 ms (hazard ratio, 1.01; 95% confidence interval, 0.87-1.17; P=0.90) (P_interaction=0.0025).

CONCLUSIONS

A PR≥230 ms is associated with increased rates of heart failure hospitalization or death among CRT-D patients. The real-world comparative effectiveness of CRT-D (versus ICD) is significantly less among patients with a PR≥230 ms in comparison with patients with a PR<230 ms.

Cardiorespiratory adaptations during the six-minute walk test in chronic heart failure patients

BACKGROUND

The six-minute walk test (6-MWT) is widely used to assess exercise tolerance in chronic heart failure patients (CHF). The aim of this study was to analyse cardiorespiratory parameters kinetics during the 6-MWT in CHF and in healthy subjects.

METHODS

A treadmill, symptom-limited exercise test and a 6-MWT were performed by 14 CHF under optimal drug treatment (CHFD), 17 CHF with cardiac resynchronization (CHFP), and 12 healthy subjects. Cardiorespiratory responses were assessed by a validated portable system.

RESULTS

All subjects exceeded their ventilatory threshold during the 6-MWT. Healthy subjects and CHF performed the 6-MWT around 75 and 90% of peak oxygen uptake (V'O2) respectively (P<0.001). In CHF, a steady state was observed only for walking speed and V'O2, with a slight delay in comparison with healthy subjects, for whom a steady state was also observed for carbon dioxide production and ventilation (V'E). During the 6-MWT, the V'E adaptation was due mainly to an increase in tidal volume (VT) in CHFD, whereas in CHFP, it was due to a similar increase in VT and breathing frequency (f). In these patients, the 6-MWT VT/f slope was lower than in CHFD (P<0.01).

CONCLUSIONS

During the 6-MWT, the V'O2 steady state is slightly delayed in CHF, which could be related partly to their higher exercise intensity. Moreover, each CHF group is characterized by a specific ventilation components response during the 6-MWT.

Prolongation of atrio-ventricular node conduction in a rabbit model of ischaemic cardiomyopathy: Role of fibrosis and connexin remodelling

Conduction abnormalities are frequently associated with cardiac disease, though the mechanisms underlying the commonly associated increases in PQ interval are not known. This study uses a chronic left ventricular (LV) apex myocardial infarction (MI) model in the rabbit to create significant left ventricular dysfunction (LVD) 8 weeks post-MI. In vivo studies established that the PQ interval increases by approximately 7 ms (10%) with no significant change in average heart rate. Optical mapping of isolated Langendorff perfused rabbit hearts recapitulated this result: time to earliest activation of the LV was increased by 14 ms (16%) in the LVD group. Intra-atrial and LV transmural conduction times were not altered in the LVD group. Isolated AVN preparations from the LVD group demonstrated a significantly longer conduction time (by approximately 20 ms) between atrial and His electrograms than sham controls across a range of pacing cycle lengths. This difference was accompanied by increased effective refractory period and Wenckebach cycle length, suggesting significantly altered AVN electrophysiology post-MI. The AVN origin of abnormality was further highlighted by optical mapping of the isolated AVN. Immunohistochemistry of AVN preparations revealed increased fibrosis and gap junction protein (connexin43 and 40) remodelling in the AVN of LVD animals compared to sham. A significant increase in myocyte–non-myocyte connexin co-localization was also observed after LVD. These changes may increase the electrotonic load experienced by AVN muscle cells and contribute to slowed conduction velocity within the AVN.

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Chronic myocardial infarction (MI) causes changes in atrio-ventricular node (AVN) function.

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Isolated hearts post-MI show delays in ventricular activation due to slowed conduction via the AVN.

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Isolated AVN preparations demonstrated AVN electrical remodelling post-MI.

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Electrical remodelling is associated with fibrosis and altered expression of connexins in the AVN.

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AVN dysfunction post-MI is caused by localized functional and structural remodelling.

Implantable cardioverter defibrillators for the treatment of arrhythmias and cardiac resynchronisation therapy for the treatment of heart failure: systematic review and economic evaluation

BACKGROUND

This assessment updates and expands on two previous technology assessments that evaluated implantable cardioverter defibrillators (ICDs) for arrhythmias and cardiac resynchronisation therapy (CRT) for heart failure (HF).

OBJECTIVES

To assess the clinical effectiveness and cost-effectiveness of ICDs in addition to optimal pharmacological therapy (OPT) for people at increased risk of sudden cardiac death (SCD) as a result of ventricular arrhythmias despite receiving OPT; to assess CRT with or without a defibrillator (CRT-D or CRT-P) in addition to OPT for people with HF as a result of left ventricular systolic dysfunction (LVSD) and cardiac dyssynchrony despite receiving OPT; and to assess CRT-D in addition to OPT for people with both conditions.

DATA SOURCES

Electronic resources including MEDLINE, EMBASE and The Cochrane Library were searched from inception to November 2012. Additional studies were sought from reference lists, clinical experts and manufacturers' submissions to the National Institute for Health and Care Excellence.

REVIEW METHODS

Inclusion criteria were applied by two reviewers independently. Data extraction and quality assessment were undertaken by one reviewer and checked by a second. Data were synthesised through narrative review and meta-analyses. For the three populations above, randomised controlled trials (RCTs) comparing (1) ICD with standard therapy, (2) CRT-P or CRT-D with each other or with OPT and (3) CRT-D with OPT, CRT-P or ICD were eligible. Outcomes included mortality, adverse events and quality of life. A previously developed Markov model was adapted to estimate the cost-effectiveness of OPT, ICDs, CRT-P and CRT-D in the three populations by simulating disease progression calculated at 4-weekly cycles over a lifetime horizon.

RESULTS

A total of 4556 references were identified, of which 26 RCTs were included in the review: 13 compared ICD with medical therapy, four compared CRT-P/CRT-D with OPT and nine compared CRT-D with ICD. ICDs reduced all-cause mortality in people at increased risk of SCD, defined in trials as those with previous ventricular arrhythmias/cardiac arrest, myocardial infarction (MI) > 3 weeks previously, non-ischaemic cardiomyopathy (depending on data included) or ischaemic/non-ischaemic HF and left ventricular ejection fraction ≤ 35%. There was no benefit in people scheduled for coronary artery bypass graft. A reduction in SCD but not all-cause mortality was found in people with recent MI. Incremental cost-effectiveness ratios (ICERs) ranged from £14,231 per quality-adjusted life-year (QALY) to £29,756 per QALY for the scenarios modelled. CRT-P and CRT-D reduced mortality and HF hospitalisations, and improved other outcomes, in people with HF as a result of LVSD and cardiac dyssynchrony when compared with OPT. The rate of SCD was lower with CRT-D than with CRT-P but other outcomes were similar. CRT-P and CRT-D compared with OPT produced ICERs of £27,584 per QALY and £27,899 per QALY respectively. The ICER for CRT-D compared with CRT-P was £28,420 per QALY. In people with both conditions, CRT-D reduced the risk of all-cause mortality and HF hospitalisation, and improved other outcomes, compared with ICDs. Complications were more common with CRT-D. Initial management with OPT alone was most cost-effective (ICER £2824 per QALY compared with ICD) when health-related quality of life was kept constant over time. Costs and QALYs for CRT-D and CRT-P were similar. The ICER for CRT-D compared with ICD was £27,195 per QALY and that for CRT-D compared with OPT was £35,193 per QALY.

LIMITATIONS

Limitations of the model include the structural assumptions made about disease progression and treatment provision, the extrapolation of trial survival estimates over time and the assumptions made around parameter values when evidence was not available for specific patient groups.

CONCLUSIONS

In people at risk of SCD as a result of ventricular arrhythmias and in those with HF as a result of LVSD and cardiac dyssynchrony, the interventions modelled produced ICERs of < £30,000 per QALY gained. In people with both conditions, the ICER for CRT-D compared with ICD, but not CRT-D compared with OPT, was < £30,000 per QALY, and the costs and QALYs for CRT-D and CRT-P were similar. A RCT comparing CRT-D and CRT-P in people with HF as a result of LVSD and cardiac dyssynchrony is required, for both those with and those without an ICD indication. A RCT is also needed into the benefits of ICD in non-ischaemic cardiomyopathy in the absence of dyssynchrony.

STUDY REGISTRATION

This study is registered as PROSPERO number CRD42012002062.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Physiology of cardiac resynchronization

Dyssynchronous ventricular contraction, often associated with delayed electrical activation, contributes to worsened clinical status in patients with chronic dilated heart failure. There are three levels of impaired electromechanical synchrony that can be recognized and potentially improved with pacing methods. Prolonged atrioventricular (AV) delay can promote presystolic mitral regurgitation and impaired left ventricular (LV) filling. Interventricular conduction delay with right ventricular (RV) activation preceding LV activation often occurs in the setting of left bundle branch block or RV apical pacing, and can result in impeded LV filling and ejection. Activation delays within the LV itself (intraventricular dyssynchrony) can cause decreased efficiency of contraction, increased mitral regurgitation, and abnormal ventricular remodeling. Cardiac resynchronization therapy (CRT) can improve ventricular performance in two thirds of patients selected based on QRS duration alone. Improved understanding of the pathophysiology of cardiac dyssynchrony will aid in patient selection and in assessment and optimization of response to CRT.

Early procedure-related adverse events by gender in MADIT-CRT

BACKGROUND

Whether gender differences exist in procedure-related adverse events following cardiac resynchronization therapy (CRT-D) implantation is unknown. We investigated the type and frequency of procedure-related adverse events among those enrolled in MADIT-CRT and identified clinical predictors for gender-specific events.

METHODS

We compared differences in the rate of procedure-related adverse events by gender (444 females and 1,346 males) that occurred ≤30 days after the index procedure in the implantable cardioverter defibrillator (ICD) and CRT-D groups. Eight types of major adverse events were identified, defined as procedure-related complications deemed potentially life-threatening. Best subset regression analysis (P < 0.10) was performed to identify baseline clinical factors associated with procedure-related adverse events that differed by gender.

RESULTS

Women randomized to CRT-D received a greater reduction in the risk of heart failure or death versus men (P < 0.001). Women were twice as likely as men to experience a major procedure-related adverse event (6.3% vs. 2.7%; P < 0.001), including pneumothorax/hemothorax (3% vs. 1%; P < 0.001). Women were more likely to experience a major adverse event related to CRT-D than ICD implantation (7.7% vs. 2.9%; P = 0.018). Clinical predictors of major adverse events in females were smaller body mass index (BMI), elevated blood urea nitrogen, and elevated creatinine. The main predictor for pneumothorax/hemothorax was reduced BMI for women and men.

CONCLUSION

Women demonstrate greater clinical benefit from CRT than men but are more likely to experience adverse procedure-related events within the first 30 days after device implantation. A smaller BMI seems to be a major factor associated with pneumothorax/hemothorax in both females and males.

Bifocal right ventricular pacing: an alternative way to achieve resynchronization when left ventricular lead insertion is unsuccessful

PURPOSE

Bifocal pacing in the right ventricle is an option for patients with end-stage heart failure in whom biventricular pacing is not possible, due to failure in left ventricular (LV) lead insertion. The purpose of this prospective study was to document the clinical response of these patients, after bifocal pacing.

METHODS

From the patients referred for cardiac resynchronization therapy (CRT), from 2009 to 2010, 13 cardiac CRT candidates who underwent unsuccessful LV lead implantation were included. The bifocal system's leads were implanted in the right atrium, the right ventricular (RV) apex, and the RV outflow tract. Initial patient assessment and follow-up evaluation after 6 months included clinical criteria, echocardiographic indices, and biochemical parameters.

RESULTS

From 13 patients (age 68 ± 9 years, nine male), 10 improved clinically. New York Heart Association classification was reduced by one grade (from 3.6 ± 0.5 to 2.8 ± 0.8, p < 0.005 and respectively), while hospitalizations in 6-month time were reduced from three to one (p < 0.001). Six-minute walk test (in meters) increased from 176 ± 86 to 297 ± 91 (p < 0.001) and quality of life improved (EQ-VAS scale changed from 42 ± 12.5 % to 70.8 ± 20.3 %, p < 0.001). Mean shortening in QRS duration was 31.3 ms (from 165.1 ± 16.3 to 133.8 ± 12.7, p < 0.001) and B-type natriuretic peptide (in picograms per milliliter) dropped from 834 ± 350 to 621 ± 283 (p < 0.001). Ejection fraction (in percent) increased from 27.5 ± 4.6 to 33.3 ± 4.4 (p < 0.001), and mitral regurgitation severity decreased by one grade (from 2.7 ± 0.9 to 1.8 ± 0.7, p < 0.05).

CONCLUSION

RV bifocal pacing seems to offer a substantial clinical benefit to heart failure patients with traditional CRT indications and could be an alternative option when LV access is unsuccessful.

Robotic-Assisted or Minithoracotomy Incision for Left Ventricular Lead Placement a Single-Surgeon, Single-Center Experience

Objective

Left ventricular (LV) resynchronization with epicardial lead placement after failed coronary sinus cannulation can be achieved with minimally invasive robotic-assisted (RA) or minithoracotomy (MT) incisions. We evaluated early outcomes and costs after RA and MT epicardial LV lead implantation at our academic center.

Methods

From 2005 to 2010, 24 patients underwent minimally invasive RA or MT epicardial LV lead placement for resynchronization. Patient characteristics, electrophysiologic features, outcomes, and costs were analyzed.

Results

Ten patients underwent RA and 14 underwent MT minimally invasive LV lead placement, with no 30-day mortality in either group. Younger patients underwent RA epicardial lead placement (63.8 ± 15.4 vs 75.6 ± 10.0 years; P = 0.03). In addition, although both groups had comparable body surface areas, RA patients had significantly higher body mass index versus MT patients (44.4 ± 17.5 vs 26.9 ± 7.1 kg/m2, respectively; P = 0.003). Premorbid risk and cardiovascular profiles were similar across groups. Importantly, pacing threshold, impedance, and postoperative QRS interval were equivalent between groups. Significantly, both operating room and mechanical ventilation durations were higher with RA epicardial placement (P < 0.001). Despite equivalent outcomes, incision-to-closure interval was 48 minutes shorter with MT (P = 0.002). Absolute differences in direct costs between groups were negligible. Despite these differences, resource utilization and lengths of stay were equivalent.

Conclusions

Epicardial LV lead placement is efficacious with either approach. Early outcomes and mortality are equivalent. Greater tactile feedback during operation and equivalent short-term outcomes suggest that MT minimally invasive LV lead placement is the more favorable approach for epicardial resynchronization.

Association of systolic blood pressure with mortality in patients with heart failure with reduced ejection fraction: a complex relationship

BACKGROUND

In ambulatory patients with heart failure with reduced ejection fraction (HFrEF), high systolic blood pressure (SBP) is associated with better outcomes. However, it is not known whether there is a ceiling beyond which high SBP has a detrimental effect. Thus, our aim was to assess the linearity of association between SBP and mortality.

METHODS

We used the External Peer Review Program (EPRP) and Digitalis Investigation Group (DIG) trial databases of HFrEF patients. Linearity of association of SBP with mortality was assessed by plotting Martingale residuals against SBP. To assess the patterns of relationship of SBP with mortality, we used restricted cubic spline analysis with Cox proportional hazards model.

RESULTS

In patients with mild-to-moderate left ventricular systolic dysfunction (LVSD) (30% ≤ LVEF < 50%), SBP had a nonlinear association with mortality in both EPRP (n = 3,693) and DIG (n = 3,263) databases. In these patients, SBP had a significant U-shaped association with mortality in EPRP and a trend toward U-shaped relationship in DIG database. In patients with severe LVSD (LVEF <30%), SBP had a linear association with mortality in both EPRP (n = 2,906) and DIG (n = 3,537) databases, with lower SBP being associated with increased mortality.

CONCLUSIONS

Systolic blood pressure has a complex nonlinear association with mortality in patients with heart failure. Whereas it has a U-shaped association in patients with mild-to-moderate LVSD, it has a linear association with mortality in patients with severe LVSD. Recognition of this pattern of association of blood pressure profile may help clinicians in providing better care for their patients and help improve existing prediction models.

Effects of the purkinje system and cardiac geometry on biventricular pacing: a model study

Heart failure leads to gross cardiac structural changes. While cardiac resynchronization therapy (CRT) is a recognized treatment for restoring synchronous activation, it is not clear how changes in cardiac shape and size affect the electrical pacing therapy. This study used a human heart computer model which incorporated anatomical structures such as myofiber orientation and a Purkinje system (PS) to study how pacing affected failing hearts. The PS was modeled as a tree structure that reproduced its retrograde activation feature. In addition to a normal geometry, two cardiomyopathies were modeled: dilatation and hypertrophy. A biventricular pacing protocol was tested in the context of atrio-ventricular block. The contribution of the PS was examined by removing it, as well as by increasing endocardial conductivity. Results showed that retrograde conduction into the PS was a determining factor for achieving intraventricular synchrony. Omission of the PS led to an overestimate of the degree of electrical dyssynchrony while assessing CRT. The activation patterns for the three geometries showed local changes in the order of activation of the lateral wall in response to the same pacing strategy. These factors should be carefully considered when determining lead placement and optimizing device parameters in clinical practice.

Design and rationale of the PROTECT study: a placebo-controlled randomized study of the selective A1 adenosine receptor antagonist rolofylline for patients hospitalized with acute decompensated heart failure and volume overload to assess treatment effect on congestion and renal function

BACKGROUND

Current treatment for acute decompensated heart failure (ADHF) is associated with incomplete resolution of symptoms and signs, recurrent symptoms of heart failure in-hospital and after discharge and high mortality. Studies have consistently demonstrated an association between worsening renal function in ADHF and adverse outcomes. Adenosine A(1) receptor antagonists, such as rolofylline, appear in preliminary studies to produce potentially beneficial effects on natriuresis, diuresis, renal blood flow, and glomerular filtration rate. In a previous dose-finding study, rolofylline 30 mg intravenously daily for 3 days was associated with symptom improvement, less worsening of renal function, and trends toward lower 60-day rates of death or readmission for cardiovascular or renal causes.

METHODS AND RESULTS

This manuscript describes the rationale underlying the design of the phase 3 PROTECT (Placebo-controlled Randomized study of the selective A(1) adenosine receptor antagonist rolofylline for patients hospitalized with acute heart failure and volume Overload to assess Treatment Effect on Congestion and renal funcTion) trial.

CONCLUSION

Rolofylline 30 mg or matching placebo was given intravenously as a 4-hour continuous infusion on 3 consecutive days and the hospital course was assessed by measurements dyspnea, clinical status, renal function, and subsequent morbidity and mortality in a large population of patients with ADHF with renal impairment.

Heart failure

Despite advances in management of heart failure, the condition remains a major public-health issue, with high prevalence, poor clinical outcomes, and large health-care costs. Risk factors are well known and, thus, preventive strategies should have a positive effect on disease burden. Treatment of established systolic chronic heart failure includes use of agents that block the renin-angiotensin-aldosterone and sympathetic nervous systems to prevent adverse remodelling, to reduce symptoms and prolong survival. Diuretics are used to achieve and maintain euvolaemia. Devices have a key role in management of advanced heart failure and include cardiac resynchronisation in patients with evidence of cardiac dyssynchrony and implantation of a cardioverter defibrillator in individuals with low ejection fraction. Approaches for treatment of acute heart failure and heart failure with preserved ejection fraction are supported by little clinical evidence. Emerging strategies for heart failure management include individualisation of treatment, novel approaches to diagnosis and tracking of therapeutic response, pharmacological agents aimed at new targets, and cell-based and gene-based methods for cardiac regeneration.

Comparing administration of questionnaires via the internet to pen-and-paper in patients with heart failure: randomized controlled trial

Background

The use of the Internet to administer questionnaires has many potential advantages over the use of pen-and-paper administration. Yet it is important to validate Internet administration, as most questionnaires were initially developed and validated for pen-and-paper delivery. While some have been validated for use over the Internet, these questionnaires have predominately been used amongst the healthy general population. To date, information is lacking on the validity of questionnaires administered over the Internet in patients with chronic diseases such as heart failure.

Objectives

To determine the validity of three heart failure questionnaires administered over the Internet compared to pen-and-paper administration in patients with heart failure.

Methods

We conducted a prospective randomized study using test-retest design comparing administration via the Internet to pen-and-paper administration for three heart failure questionnaires provided to patients recruited from a heart failure clinic in Toronto, Ontario, Canada: the Kansas City Cardiomyopathy Questionnaire (KCCQ), the Minnesota Living with Heart Failure Questionnaire (MLHFQ), and the Self-Care Heart Failure Index (SCHFI).

Results

Of the 58 subjects enrolled, 34 completed all three questionnaires. The mean difference and confidence intervals for the summary scores of the KCCQ, MLHFQ, and SCHFI were 1.2 (CI -1.5 to 4.0, scale from 0 to 100), 4.0 (CI -1.98 to 10.04, scale from 0 to 105), and 10.1 (CI 1.18 to 19.07, scale from 66.7 to 300), respectively.

Conclusions

Internet administration of the KCCQ appears to be equivalent to pen-and-paper administration. For the MLHFQ and SCHFI, we were unable to demonstrate equivalence. Further research is necessary to determine if the administration methods are equivalent for these instruments.

Echo Doppler parameters predict response to cardiac resynchronization therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) has been shown to reduce heart failure related morbidity and mortality. However, approximately 30% of patients do not respond to CRT. We investigated the usefulness of Echo Doppler parameters to predict reverse remodelling, functional improvement and mortality following CRT.

MATERIALS AND METHODS

Our population consists of 200 consecutive heart failure patients evaluated for ventricular dyssynchrony by echocardiography between February 1999 and May 2007 who subsequently received CRT. Patients were reassessed for signs of reverse remodelling after a mean follow-up of 10 months. Information on vital status was obtained from local registration authorities.

RESULTS

Three parameters significantly predicted reverse remodelling in the logistic regression analysis: the Q-to-E-wave-delay (QED) at a cutoff of 550 ms (odds ratio 4.5, P-value 0.001), the interventricular mechanical delay (IVMD) at a cutoff of 60 ms (odds ratio 2.4, P-value 0.02), and the aortic electromechanical delay (A-EMD) at a cutoff of 140 ms (odds ratio 2.9, P-value 0.004). Furthermore, the QED and the IVMD also predicted all-cause mortality (hazard ratio 0.36, P-value 0.02 and 0.21, P-value 0.004, respectively). Adjustment for confounders did not alter the results.

CONCLUSIONS

The QED and IVMD predict reverse remodelling and survival following CRT. These parameters are easy to obtain, provide valuable prognostic information, and should thus be measured in CRT candidates evaluated by echocardiography.

Cardiac resynchronization therapy improves renal function in human heart failure with reduced glomerular filtration rate

BACKGROUND

Renal dysfunction is an important independent prognostic factor in heart failure (HF). Cardiac resynchronization therapy (CRT) improves functional status and left ventricular (LV) function in HF patients with ventricular dyssynchrony, but the impact of CRT on renal function is less defined. We hypothesized that CRT would improve glomerular filtration rate as estimated by the abbreviated Modification of Diet in Renal Disease equation (eGFR).

METHODS AND RESULTS

The Multicenter InSync Randomized Clinical Evaluation (MIRACLE) study evaluated CRT in HF patients with NYHA Class III-IV, ejection fraction <or=35%, and QRS >or=130 ms. Patients were evaluated before and 6 months after randomization to control (n = 225) or CRT (n = 228). Patients were categorized according to their baseline eGFR: >or=90 (category A), 60 <or=eGFR <90 (category B), and 30 <or=eGFR <60 (category C) mL/min per 1.73 m(2). CRT improved LV function in all categories. Compared with control, CRT increased eGFR (-2.4 +/- 1.2 vs. +2.7 +/- 1.2 mL/min per 1.73 m(2); P = .003) and reduced blood urea nitrogen (+6.4 +/- 2.4 vs. -1.1 +/- 1.5 mg/mL; P = .008) in category C, whereas no differences were observed in categories A and B.

CONCLUSIONS

CRT increased eGFR and reduced blood urea nitrogen in HF patients with moderately reduced baseline eGFR. By improving cardiac function, CRT can indirectly improve renal function, underscoring the importance of cardiorenal interaction and providing another mechanism for the beneficial effects of CRT.

Predicting mortality and rehospitalization in heart failure patients with home monitoring--the Home CARE pilot study

The increasing worldwide prevalence of heart failure is associated with numerous and protracted hospital admissions. The multidisciplinary team approach together with telemonitoring aims at reducing the number of rehospitalizations, length of hospital stay, and mortality rates. Novel cardiac resynchronization therapy (CRT) devices have a Home Monitoring capability, offering wireless, everyday transfer of the essential status and therapy data to the attending physician. The transmitted data include potential predictors of death or hospitalization, such as the onset of atrial and ventricular arrhythmias, duration of physical activity, mean heart rates over 24 h and at rest, percentage of CRT delivered, and lead impedances. We present here interim results of the prospective, longitudinal, multicenter Home CARE Phase 0 study, conducted in 123 patients (age: 67+/-9 years, 83% male) with clinical indication for CRT. Twenty-nine patients (24%) received a CRT pacemaker, 52 (42%) a prophylactic implantable cardioverter defibrillator (ICD), and 42 (34%) had other ICD indications. All devices have an integrated Home Monitoring feature. In a mean (interim) follow-up period of 3 months (9194 observational days), 11 unplanned rehospitalizations of cardiovascular etiology and 9 deaths occurred. In 70% of the rehospitalization events, the retrospective analysis of transmitted data via Home Monitoring revealed an increase in mean heart rate at rest and in mean heart rate over 24 h within 7 days preceding hospitalization. A decrease in the percentage of CRT was observed in 43% and a reduction in the patients' daily activity in 30% of rehospitalized patients. These interim findings suggest that Home Monitoring data may predict events leading to hospitalization and encourage further research.

Cardiac resynchronization therapy optimization by ultrasonic cardiac output monitoring (USCOM) device

OBJECTIVES

We investigated the accuracy and feasibility of a 2D echo-independent ultrasonic continuous wave Doppler cardiac output monitoring device (USCOM) operated by trained nurse for the atrio-ventricular interval (AVI) optimization in cardiac resynchronization therapy (CRT).

BACKGROUND

CRT is of proven benefit in patients with advanced chronic heart failure and ventricular conduction delay. Appropriate AVI selection is critical to optimize hemodynamic in CRT. Currently, most non-invasive methods for AVI optimization are often complicated and labor-intensive.

METHODS

USCOM method, Ritter method, and aortic outflow cardiac output method were used to determine the optima AVI in 20 patients with CRT. The accuracy and time for measurement of each method were determined.

RESULTS

The optimal AVI determined by USCOM method had good correlation with Ritter's method and aortic outflow estimated cardiac output method (r2= 0.78, P < 0.01 and r2= 0.73, P < 0.01, respectively). The optimal AVI determined USCOM method showed good agreement (within 10 msec range) with Ritter's method (85% patients) and aortic outflow estimated cardiac output method (80%). The mean time for determining AVI using USCOM method was shorter than that with aortic outflow method (7.1 +/- 0.7 min vs 12.7 +/- 1.1 min, P < 0.01), whereas the mean time was shortest for Ritter method (4.7 +/- 1.6 min vs 7.1 +/- 0.7 min, P < 0.01).

CONCLUSION

USCOM device operated by trained nurse can provide a simple, accurate, and fast non-invasive method for the AVI optimization in CRT population.

Treatment of Ventricular Dysrhythmias and Sudden Cardiac Death: A Guideline-Based Approach for Patients With Chronic Left Ventricular Dysfunction

With the rise in the use of device therapy implants, we are better identifying appropriate chronic heart failure patients for primary implantable defibrillator therapy who are at risk of ventricular arrhythmia. As our knowledge expands, however, controversial issues emerge. Guidelines have been endorsed by the major international societies, such as the American College of Cardiology (ACC), the American Heart Association (AHA), and the European Society of Cardiology. In view of certain variances in recommendations and new data, a recent joint guideline statement has been issued from these 3 societies regarding management of ventricular arrhythmia and preventing sudden cardiac death in patients with left ventricular dysfunction and heart failure. In this review, the recent joint statement is compared with those from the Heart Failure Society of America (Heart Failure Practice Guidelines 2006) and ACC/AHA (Heart Failure Guidelines 2005), with a special emphasis on new expanded criteria for primary prevention in both ischemic and nonischemic heart disease. In addition, the authors review current guidelines for electrophysiology testing in chronic left ventricular dysfunction and the emerging role of microvolt T-wave alternans as a means of risk stratification.

Transvenous Implantation of a Coronary Sinus Lead for Left Ventricular Pacing After Cutting Balloon Angioplasty

We describe a patient in whom a localized proximal vein stenosis at the only possible target vein precluded placement of a coronary sinus lead for left ventricular (LV) pacing. After multiple attempts to perform venoplasty with both compliant and noncompliant balloons, a cutting balloon relieved the obstruction, and an LV pacing lead was successfully placed in the midportion of this lateral vein.

Interatrial Conduction Measured During Biventricular Pacemaker Implantation Accurately Predicts Optimal Paced Atrioventricular Intervals

BACKGROUND

Optimizing atrioventricular (AV) delay during biventricular (BiV) pacemaker implantation can require substantial resources. Hence, a simpler method is desirable. We hypothesized that interatrial conduction time (IACT), measured at the time of BiV device implant, could be a surrogate value for the optimal AV delay.

OBJECTIVE

This study determined the relationship between paced IACT and the optimal paced AV delay (PAV), as determined by echocardiography.

METHODS

Consecutive subjects (N = 25; age = 66 +/- 10 years; M/F: 17/8) undergoing BiV pacemaker implantation and in sinus rhythm were included. Cannulation of the coronary sinus (CS) was at the operator's discretion. A quadripolar electrophysiology catheter was inserted via the guiding sheath into the inferiolateral CS to measure left atrial depolarization. The IACT was calculated as the interval between right atrial stimulation artifact and earliest deflection on the coronary sinus catheter electrogram. Subsequently, during atrial pacing the PAV was determined using transmitral pulsed wave Doppler echocardiography (iterative method). The relationship between paced IACT and PAV was then determined.

RESULTS

The mean +/- SD paced IACT and PAV were 126 +/- 25 msec and 157 +/- 23 msec, respectively. There was a strong positive correlation between the paced IACT and PAV (r = 0.73, P < 0.001). The equation describing the relationship was PAV = 0.68 * (IACT + 104) msec.

CONCLUSIONS

The paced IACT has a strong correlation with the echo derived optimal PAV. This method may be used to program PAV intervals without need for echocardiography in patients undergoing BiV pacemaker implantation.

Cardiac Resynchronization Treatment of Heart Failure

Cardiac resynchronization therapy (CRT) is well established as a treatment for patients with moderate to severe heart failure on optimal medical therapy. Early studies demonstrated improved functional capacity and evidence of reverse remodeling; more recently, CRT has been associated with a survival benefit in advanced heart failure both with and without a defibrillator. We review the eight landmark trials in CRT. To date, criteria have focused on electrical delay, but echocardiographic parameters emphasize the importance of mechanical delay or ventricular dyssynchrony. With the exponential rise in implants, new issues have emerged, such as optimal device programming, identifying appropriate candidates, and accounting for cases without clinical benefit from CRT.

Should UNOS Status 2 Patients Undergo Transplantation?

BACKGROUND

With recent improvements in medical and device therapy, the benefit of cardiac transplantation for UNOS Status 2 patients has been questioned. No randomized trial has been performed to compare transplantation versus contemporary medical therapy.

METHODS

Between January 1996 and December 2003, 203 patients were listed at our institution for heart transplantation as UNOS Status 2. We performed a retrospective review to determine outcomes in these patients.

RESULTS

Demographics of this cohort revealed a mean age of 52 years, female sex in 28%, and ischemic etiology in 47%. Eighty-one patients (40%) had an implantable cardiac defibrillator. A total of 64 patients (32%) had to be upgraded in their UNOS status, with 9 requiring a left ventricular assist device. Of the entire group, 95 (47%) underwent transplantation at a mean time of 303 days, 45 (22%) died while waiting at a mean time of 397 days, and 24 (12%) were removed from the waiting list due to deterioration in medical condition such that transplantation was no longer an option. The remaining patients continue to wait or have been removed from consideration due to improved condition. Survival at 1- and 3-years postlisting was 94% and 87% for patients who received transplants compared to 81% and 57% for patients who did not receive transplants (P < .01).

CONCLUSION

A significant number of patients listed as Status 2 are upgraded in UNOS status or die while on the waiting list. Early and midterm survival is significantly better with transplantation. Identification of variables associated with deterioration may allow for better risk stratification in the future. At this point, transplantation offers the best outcome.

Role of resynchronisation therapy and implantable cardioverter defibrillators in heart failure

The worldwide prevalence of heart failure is increasing in part because of an aging population. In the developed world, heart failure affects 1%-2% of the general population, accounting for 5% of adult hospital admissions. There is now convincing evidence supporting the beneficial effects of cardiac resynchronisation therapy for the treatment of heart failure. Numerous observational studies, as well as a series of randomised controlled trials, have shown the safety, efficacy, and long term benefits for patients with chronic systolic heart failure who have broad QRS complexes and refractory symptoms despite optimal medical therapy. These studies have consistently found statistically significant improvements in quality of life, New York Heart Association functional class, exercise tolerance, and left ventricular reverse remodelling. Recent evidence suggests that the benefit may at least in part be because of a reduction in mechanical dysynchrony.

Load dependence of cardiac output in biventricular pacing: left ventricular volume overload in pigs

OBJECTIVE

Previous work from our laboratory has demonstrated that optimization of biventricular pacing is load dependent. Cardiac output was maximized with a ventricular-ventricular delay of +40 milliseconds (right ventricle-first pacing) during right ventricular pressure overload and with a ventricular-ventricular delay of -40 milliseconds (left ventricle-first pacing) during right ventricular volume overload. We hypothesized that a model of left ventricular volume overload would also have specific timing requirements during biventricular pacing for optimization of cardiac output.

METHODS

After median sternotomy in 6 anesthetized pigs, complete heart block was induced by ethanol ablation. A conduit was grafted from the left ventricle to the left atrium to produce left ventricular volume overload. An ultrasonic flow probe was placed around the conduit to measure retrograde flow that averaged 50% of cardiac output. During epicardial atrial tracking DDD biventricular pacing, atrioventricular delay was varied between 60 and 270 milliseconds in 30-millisescond increments for 20-second intervals. After determination of optimum atrioventricular delay, ventricular-ventricular delay was varied in 20-millisecond increments from +80 to -80 milliseconds for 20-second intervals.

RESULTS

Ventricular-ventricular delays had no significant effect on cardiac output with the graft clamped (control). With the graft unclamped, however, there was a statistically significant (P = .0001 by repeated-measures analysis of variance) trend toward higher cardiac output with right ventricle-first pacing.

CONCLUSIONS

Right ventricle-first pacing in swine significantly increased cardiac output during acute left ventricular volume overload, but not during the control state. Understanding load-specific pacing requirements will facilitate the development of perioperative temporary biventricular pacing for acute heart failure.

The benefit of upgrading chronically right ventricle–paced heart failure patients to resynchronization therapy demonstrated by strain rate imaging

BACKGROUND

RV pacing induces conduction delay (CD), mechanical dyssynchrony, and increased morbidity in patients with HF. CRT improves HF symptoms and survival, but sparse data exist on its direct effect on chronically RV-paced HF patients.

OBJECTIVES

To assess the benefit of cardiac resynchronization therapy (CRT) in chronically right ventricle (RV)-paced heart failure (HF) patients.

METHODS

We studied 12 consecutive patients with class III HF who had a previously implanted pacemaker or implantable cardioverter-defibrillator. These individuals were chronically RV paced and referred for upgrade to a biventricular device by their primary cardiologists. Tissue Doppler and strain rate imaging (TDI and SRI, respectively) were performed immediately before each upgrade and 4-6 weeks afterward to quantify changes in regional wall motion and synchrony with CRT.

RESULTS

CRT significantly reduced the mean QRS duration (205 ms to 156 ms; P<.0001), and it increased the ejection fraction (30.7%+/-5.1% to 35.8%+/-5.1%; P<.01). Left ventricular end-systolic and end-diastolic dimensions were also significantly reduced. Clinically, patients improved by an average of one New York Heart Association (NYHA) functional class after upgrade (P = .006). The parameter exhibiting greatest improvement was the coefficient of variation (CoV: standard deviation/mean) of time to peak systolic strain rate, a marker of ventricular dyssynchrony, which decreased from 34.3%+/-13.0% to 19.0%+/-6.6% (P<.01). Reduction in CoV of time to peak systolic strain rate was maximally seen in the midventricle (38.2%+/-19.6% to 16.5%+/-9.7%; P<.01).

CONCLUSIONS

Upgrading chronically RV-paced HF patients to CRT improves global and regional systolic function. TDI and SRI provide compelling evidence that this benefit parallels that seen in HF patients with CD unrelated to RV pacing, which implies that biventricular pacing synchronizes mechanical activation in different myocardial regions in patients upgraded from RV pacing as well.

Efficacy of the phase images in Fourier analysis using gated cardiac POOL-SPECT for determining the indication for cardiac resynchronization therapy

BACKGROUND

Although cardiac resynchronization therapy (CRT) improves quality of life and survival for patients with heart failure, exact methods to estimate the effect of cardiac asynchrony have not yet been defined.

METHODS AND RESULTS

Initially, to examine whether the phase analysis images in the Fourier analysis using gated cardiac pool single photon emission computed tomography (POOL-SPECT) could be used to evaluate cardiac asynchrony, 19 consecutive patients with dilated cardiomyopathy were studied. Interventricular asynchrony was defined by whether the peak of the picture elements of the right ventricle in the phase histogram fitted that of the left ventricle and intraventricular asynchrony by whether the phase image was described homogenously or not. The patients with both inter- and intraventricular asynchrony had significant deterioration in both left ventricular ejection fraction (p<0.01) and New York Heart Association functional class (p<0.01). To evaluate the efficacy of these phase images for CRT setting, 7 patients were tested before and after CRT. During a 3.9+/-3.6 month follow-up period, all patients had an improvement in their condition, and the inter- and intraventricular asynchrony significantly improved after CRT. The degrees of the inter- and intraventricular asynchrony were related to the degree of cardiac depression pre CRT.

CONCLUSION

These results have shown that the phase images from POOL-SPECT are useful for assessing the effect of CRT in patients with heart failure, which suggests that it may provide information about the indication for CRT.

[Resynchronisation therapy in patients with heart failure: our results]

INTRODUCTION

Resynchronisation therapy with biventricular permanent pacing stimulation is one method of treating patients with systolic heart failure, with echocardiograph signs of ventricular asynchrony and a prolonged QRS of longer than 120 milliseconds. This method has been accepted in most medical centres around the world and was instigated in our Pacemaker Centre in December 2001, 3 months after FDA approval for human use.

OBJECTIVE

The aim of the study was to present this new procedure and the results obtained from our own group of patients.

METHOD

A multi-site, biventricular pacemaker, with a special electrode for left-half heart stimulation was implanted in the coronary sinus of 17 patients who had suffered systolic heart failure (12 male and 5 female, average age 59.9 years). For all of them, the duration of the QRS interval was longer than 120 ms, with left bundle branch morphology, and an ejection fraction below 30%. All the patients were NYHA class II or III. Prior to and after the implantation, a 12-channel ECG and ECHO were carried out, a 6-minute hall walk test was performed, additionally, the total walked distance on a flat surface was measured, the general condition of the patient was evaluated, the number of medications being taken was noted, as was the number of days of hospitalisation.

RESULTS

The average time from diagnosis to implantation was 22 months, and the average post-operative follow-up was 14 months. Two of the patients died 10 and 7 months after the implantation, due to a new myocardial infarction and refractory heart failure. In addition, one patient did not show any improvement after the implantation of the multi-site pacemaker (there were three "non-responder" patients). All the other patients felt much better: decreased NYHA class for I - II class, increased left ventricle ejection fraction, reduced use of diuretics, increased 6-minute hall walk distance and general walk distance on a flat surface, and decreased number of days of hospitalisation.

CONCLUSION

Resynchronisation heart failure therapy in the majority of patients with systolic left ventricular dysfunction and a prolonged QRS interval considerably improves cardiac function, in addition to reducing symptoms and hospital stays.

Cardiac Resynchronization Therapy

Left ventricular (LV) dysynchrony, generally defined as the effect of intraventricular conduction defects or bundle branch block to produce nonsynchronous ventricular activation, places the failing heart at a further mechanical disadvantage. The deleterious effects of ventricular dysynchrony include suboptimal ventricular filling, paradoxical septal wall motion, reduced LV contractility, increased mitral regurgitation, and poor clinical outcomes (eg, increased hospitalization and mortality). The clinical and mechanical manifestations of ventricular dysynchrony can be treated by simultaneously pacing both the right and left ventricles usually in association with right atrial sensing, resulting in atrial-synchronized biventricular pacing or cardiac resynchronization therapy (CRT). The weight of evidence supporting the routine use of CRT in patients with heart failure with ventricular dysynchrony is now quite substantial. More than 4000 patients have been evaluated in randomized controlled trials of CRT, and several thousand additional patients have been assessed in observational studies and in registries. Data from these studies have consistently demonstrated the safety and efficacy of CRT in patients with New York Heart Association class III and IV heart failure. Cardiac resynchronization therapy has been shown to significantly improve LV structure and function, New York Heart Association functional class, exercise tolerance, quality of life, and morbidity and mortality.

Long-Term Effects of Cardiac Resynchronization Therapy on Heart Rate and Heart Rate Variability

Congestive heart failure is characterized by significant autonomic dysfunction. Development of left bundle branch block in congestive heart failure is a predictor of worse outcome. There are several lines of evidence that cardiac resynchronization therapy (CRT), by biventricular stimulation in patients with severe heart failure and left bundle branch block, improves autonomic functions which can be quantified by measuring heart rate variability. The aim of the present study was to assess the effect of CRT on autonomic functions quantified by heart rate variability and mean heart rate (HR) in patients with advanced heart failure and left bundle branch block in short and long-term follow-up. A total of 35 patients with systolic heart failure and left bundle branch block (mean-age 60 +/- 11 years; 24 male and 11 female; mean left ventricular ejection fraction [EF]: 22.3 +/- 3%) were enrolled. Clinical assessment and echocardiographic examination were performed at baseline and every three months. Continuous electrocardiographic monitorization by 24-hour Holter recordings was performed pre-implantation, 3 months and 2 years after implantation. Mean HR and one of the time-domain parameters of heart rate variability, standard deviation of the R-R intervals (SDNN) were measured. CRT was associated with a decrease in the mean duration of QRS, and an increase in diastolic filling time, the rate with which the left ventricular pressure rises (dP/dt), and left ventricular ejection fraction. Decrease in mean heart rate and increase in SDNN were statistically significant in the third month and second year recordings when compared to baseline recording (p values were < 0.001 for both). In conclusion, CRT with biventricular pacing provides sustained improvement in autonomic function in patients with advanced heart failure and left bundle branch block.

Cost effectiveness of biventricular pacemakers in heart failure patients

BACKGROUND

Biventricular pacemakers have been shown to reduce mortality and hospitalizations in heart failure (HF) patients and are indicated for those with a New York Heart Association functional class of III or IV and a QRS interval of >130 ms. However, these devices currently cost in the region of dollar US 33,500 and require replacement upon battery depletion. Therefore, determination of the cost effectiveness of resynchronization therapy is important, although little data have been published to date on this topic.

METHODS AND RESULTS

A cost-utility analysis from the healthcare perspective was performed using HF patients who received a biventricular pacing device in the Cleveland Clinic Foundation. The comparator was a similarly profiled group of patients who did not receive the device but were treated medically. A Markov model was used to investigate the cost effectiveness at 1 and 5 years. Second-order Monte-Carlo simulation was used to determine the variability in results, using probabilistic sensitivity analysis. Medical treatment was dominated by biventricular pacemaker treatment at both 1 and 5 years of follow-up.

CONCLUSION

Biventricular device insertion is an economically attractive treatment option for clinically indicated HF patients.

[Indication for cardiac resynchronization therapy: Consensus 2005]

The indication for cardiac resynchronization therapy (CRT) using biventricular pacing or ICD systems has to be highly differentiated to optimize the proportion of patients who derive significant symptomatic benefit from this therapy, on the one hand, and to avoid this invasive treatment in patients with a low probability of clinical success of CRT, on the other hand. As a consensus in 2005, it can be put forward that there is sufficient evidence for an indication for CRT from clinical studies for the following characteristics: 1) Heart failure in NYHA functional class III or IV (if cardiac recompensation to class III is at least temporarily successful), 2) left ventricular ejection fraction < or =35%, 3) QRS duration >130 ms, particularly if left bundle branch block is present, 4) sinus rhythm. In addition, available data also suggest an indication for CRT in patients with atrial fibrillation if the other criteria listed above are met. The indication for CRT is unclear in patients with other intraventricular conduction delay (particularly right bundle branch block) while patients with left bundle branch block and a QRS duration of 120-130 ms seem to benefit if echocardiographic criteria demonstrate ventricular dyssynchrony. Since a multiplicity of echocardiographic criteria of ventricular dyssynchrony exists which is neither standardized nor evaluated in large-scale randomized trials, ventricular dyssynchrony on echocardiography alone cannot be regarded as an established indication for CRT without a QRS complex > or =120 ms. Similarly, whether heart failure in functional state NYHA II should be regarded as a CRT indication is currently being investigated in the randomized RAFT and MADIT-CRT trials.