Implantable Defibrillators Improve Survival in Patients With Mildly Symptomatic Heart Failure Receiving Cardiac Resynchronization Therapy

Sex-Specific Differences in Ventricular Remodeling and Response After Cardiac Resynchronization Therapy

In this study, we investigated the baseline characteristics and "trajectories" of clinical response in men and women after cardiac resynchronization therapy (CRT) implantation. Although women enjoy improved echocardiographic response after CRT compared with men, the kinetics of this response and its relation to functional performance and outcomes are less clear. We identified 592 patients who underwent CRT implantation at our center between 2004 and 2017 and were serially followed in a multidisciplinary clinic. Longitudinal linear mixed effects regression for cardiac response was specified, including interaction terms between time after CRT and sex , and Cox regression models were used to assess differences in all-cause mortality by gender after CRT. Women in our cohort were younger than men, had less frequent ischemic etiology of heart failure (24% vs 60% in men), a shorter QRS (151 vs 161 ms) and more frequent left bundle branch block (77% vs 52%) at baseline. Women had a greater improvement in left ventricular ejection fraction that was evident starting at approximately 1-month after CRT. We did not observe effect modification by gender in New York Heart Association class or 6-minute walk distance after CRT. Although women had improved mortality after CRT, after adjustment for potential confounders, gender was not associated with mortality after CRT. In conclusion, women were more likely to have CRT implantation for left bundle branch block and exhibited improved echocardiographic but not functional response within the first year after CRT. Clinical outcomes after CRT were not associated with gender in adjusted analysis.

Association Between Changes in Physical Activity and New-Onset Atrial Fibrillation After ICD/CRT-D Implantation

Background: Changes in physical activity (PA) after implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy defibrillators (CRT-D) implantation were unknown. The association of PA changes with new-onset atrial fibrillation (AF), cardiac death and all-cause mortality was unclear in patients at high risk of sudden cardiac death.

Methods: Patients receiving ICD/CRT-D implantation from SUMMIT registry were retrospectively analyzed. Changes in PA were considered from baseline status to 1 year after implantation. New-onset AF was defined as the first atrial high-rate episode ≥1% of the daily AF burden detected after implantation.

Results: Over a mean follow-up of 50.3 months, 124 new-onset AF events (36.2%), 61 cardiac deaths (17.8%), and 87 all-cause deaths (25.4%) were observed in 343 patients with ICD/CRT-D implantation. PA at 1 year after implantation was increased compared with PA at baseline (11.97 ± 5.83% vs. 10.82 ± 5.43%, P = 0.008), and PA at 1 year was improved in 210 patients (61.2%). Per 1% decrease in PA was associated with 12.4, 18.3, and 14.3% higher risks of new-onset AF, cardiac death and all-cause mortality, regardless of different baseline characteristics. Patients with decreased PA had 2-fold risks of new-onset AF (hazard ratio [HR] = 1.972, 95% confidence interval [CI]: 1.352–2.877, P < 0.001) as high as those with unchanged/increased PA. Decreased PA was an independent risk factor for cardiac death (HR = 3.358, 95% CI: 1.880–5.996, P < 0.001) and all-cause mortality (HR = 2.803, 95% CI:1.732–4.535, P < 0.001).

Conclusion: PA decrease after ICD/CRT-D implantation is associated with a higher incidence of new-onset AF, resulting in worsened outcomes in cardiac death and all-cause mortality.

Cardiac resynchronization therapy with or without defibrillator in patients with heart failure

Aims

Randomized data on the efficacy/safety of cardiac resynchronization therapy with vs. without defibrillator (CRT-D,-P) in heart failure with reduced ejection fraction (HFrEF) are scarce. We aimed to evaluate survival associated with use of CRT-D vs. CRT-P in a contemporary cohort with HFrEF.

Methods and results

Patients from Swedish HF Registry treated with CRT-D/CRT-P and fulfilling criteria for primary prevention defibrillator use were included. Logistic regression was used to evaluate predictors of CRT-D non-use. All-cause mortality was compared in CRT-D vs. CRT-P by Cox regression in a 1 : 1 propensity-score-matched cohort. Of 1988 patients with CRT, 1108 (56%) had CRT-D and 880 (44%) CRT-P. Older age, higher ejection fraction (EF), female sex, and the lack of referral to HF nurse-led outpatient clinic were major determinants of CRT-D non-use. After matching, 645 CRT-D patients were compared with 645 with CRT-P. The CRT-D use was associated with lower 1- and 3-year all-cause mortality [hazard ratio (HR):0.76, 95% confidence interval (CI):0.58–0.98; HR: 0.82, 95% CI: 0.68–0.99, respectively]. Results were consistent in all pre-specified subgroups except for CRT-D use being associated with lower 3-year mortality in patients with an EF < 30% but not in those with an EF ≥ 30% (HR: 0.73, 95% CI: 0.59–0.89 and HR: 1.24, 95% CI: 0.83–1.85, respectively; P-interaction = 0.02).

Conclusion

In a contemporary HFrEF cohort, CRT-D was associated with lower mortality compared with CRT-P. The CRT-D use was less likely in older patients, females, and in patients not referred to HF nurse-led outpatient clinic. Our findings support the use of CRT-D vs. CRT-P in HFrEF, in particular with severely reduced EF.

Sex-Specific Ventricular Arrhythmias and Mortality in Cardiac Resynchronization Therapy Recipients

OBJECTIVES

The study goal was to examine whether there are sex-related differences in the incidence of ventricular arrhythmias and mortality in CRT-defibrillator (CRT-D) recipients.

BACKGROUND

Few studies have evaluated sex-related benefits of cardiac resynchronization therapy (CRT). Moreover, data on sex-related differences in the occurrence of ventricular tachyarrhythmias in this population are limited.

METHODS

A multicenter retrospective study was conducted in 460 patients (355 male subjects and 105 female subjects) from the UMBRELLA (Incidence of Arrhythmia in Spanish Population With a Medtronic Implantable Cardiac Defibrillator Implant) national registry. Patients were followed up through remote monitoring after the first implantation of a CRT-D during a median follow-up of 2.2 ± 1.0 years. Sex differences were analyzed in terms of ventricular arrhythmia-treated incidence and death during the follow-up period, with a particular focus on primary prevention patients.

RESULTS

Baseline New York Heart Association functional class was worse in women compared with that in men (67.0% of women in New York Heart Association functional class III vs. 49.7% of men; p = 0.003), whereas women had less ischemic cardiac disease (20.8% vs. 41.7%; p < 0.001). Female sex was an independent predictor of ventricular arrhythmias (hazard ratio: 0.40; 95% confidence interval: 0.19 to 0.86; p = 0.020), as well as left ventricular ejection fraction and nonischemic cardiomyopathy. Mortality in women was one-half that of men, although events were scarce and without significant differences (2.9% vs. 5.6%; p = 0.25).

CONCLUSIONS

Women with left bundle branch block and implanted CRT have a lower rate of ventricular tachyarrhythmias than men. All-cause mortality in patients is, at least, similar between female and male subjects.

Cardiac resynchronization therapy with or without defibrillation: a long-standing debate

Cardiac resynchronization therapy (CRT) was shown to improve cardiac function, reduce heart failure hospitalizations, improve quality of life and prolong survival in patients with severe left ventricular dysfunction and intraventricular conduction disturbances, mainly left bundle branch block, on optimal medical therapy with ACE-inhibitors, β-blockers and mineralocorticoid receptor antagonists up-titrated to maximum tolerated evidence-based doses. CRT can be achieved by means of pacemaker systems (CRT-P) or devices with defibrillation capabilities (CRT-D). CRT-Ds offer an undoubted advantage in the prevention of arrhythmic death, but such an advantage may be of lesser degree in non-ischemic heart failure aetiologies. Moreover, the higher CRT-D hardware complexity compared to CRT-P may predispose to device/lead malfunctions and the higher current drainage may cause a shorter battery duration with consequent premature replacements and the well-known incremental complications. In a period of financial constraints, also device costs should be carefully evaluated, with recent reports suggesting that CRT-Ps may be favoured over CRT-Ds in patients with non-ischemic cardiomyopathy and no prior history of cardiac arrhythmias from a cost-effectiveness point of view. The choice between a CRT-P or a CRT-D device should be patient-tailored whenever straightforward defibrillator indications are not present. The Goldenberg score may facilitate this decision-making process in ambiguous settings. Age, comorbidities, kidney disease, atrial fibrillation, advanced functional class, inappropriate therapy risk, implantable device infections and malfunctions are factors potentially reducing the expected benefit from defibrillating capabilities. Future prospective, randomized controlled trials are warranted to directly compare the efficacy and safety of CRT-Ps and CRT-Ds.

The benefits of defibrillator in heart failure patients with cardiac resynchronization therapy: A meta-analysis

BACKGROUND

Current guidelines did not provide recommendations on indications of an additional implantable cardioverter-defibrillator (ICD) to patients receiving cardiac resynchronization therapy (CRT), and it still remains controversial due to lack of evidence from randomized controlled trials.

METHOD

PubMed, Embase, and Cochrane CENTRAL from the inception to May 2020 were systematically screened for studies reporting on the comparison of cardiac resynchronization therapy with defibrillator (CRT-D) and cardiac resynchronization therapy with pacemaker (CRT-P), focusing on the adjusted hazard ratio (aHR) of all-cause mortality. We pooled the effects using a random-effect model.

RESULTS

Twenty-one studies encompassing 69,919 patients were included in this meta-analysis. With no restriction to characteristics of including population, CRT-D was associated with a lower all-cause mortality compared with CRT-P significantly (aHR: 0.80, 95% confidence interval [CI]: 0.74-0.87, I²  = 36.8%, p < .001). This mortality benefit was also observed in patients with ischemic cardiomyopathy (aHR: 0.74, 95% CI: 0.64-0.86, I²  = 0%, p < .001). However, there is no significant difference in patients with nonischemic cardiomyopathy (NICM) (aHR: 0.91, 95% CI: 0.82-1.01, I²  = 0%, p = .087), older age (age ≥75 years, aHR: 0.96, 95% CI: 0.83-1.12, I²  = 0%, p = .610). Subgroup analysis was performed and indicated the survival benefit of CRT-D for primary prevention compared with CRT-P (aHR: 0.87, 95% CI: 0.79-0.95, I²  = 0%, p = .003).

CONCLUSION

After adjusted the differences in clinical characteristics, additional ICD therapy was associated with a reduced all-cause mortality in patients receiving CRT. However, our work suggested that additional ICD may not be applied to elderly (≥75 years) or patients with NICM.

Trends in the use of implantable cardioverter-defibrillator and cardiac resynchronization therapy device in advancing age: Analysis of the Japan cardiac device treatment registry database

BACKGROUND

Trends of de novo implantation of cardiac implantable electronic devices (CIEDs) including implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy with a defibrillator (CRT-D) or pacemaker (CRT-P) in advancing age are unknown.

METHODS

Analysis of data from the Japan cardiac device treatment registry (JCDTR) with an implantation date between January 2006 and December 2016 was performed focusing on advancing age of ≧75 years.

RESULTS

The cohort included 17 564 ICD, 9470 CRT-D and 1087 CRT-P recipients for de novo implantation. The rate of patients ≧75 years of age increased from 17.1% to 20.5% in ICD implantation (P = .052), from 19.7% to 30.0% in CRT-D implantation (P < .0001), and from 40.0% to 64.0% in CRT-P implantation (P = .17). There was an apparent increase in the percentage of nonischemic patients aged ≧75 years receiving ICD (10.9% in 2006 to 16.4% in 2016, P = .0008) and CRT-D (17.1% in 2006 to 27.8% in 2016, P = .0001). The implantation for primary prevention ICD (P = .059) and CRT-D (P = .012) was also associated with a temporal increase in the percentage of patients aged ≧75 years.

CONCLUSIONS

Proportion of patients ≧75 years of age for de novo CIED implantation gradually increased from 2006 to 2016, presumably because of the growing number of nonischemic cardiomyopathy and heart failure patients requiring primary prevention of sudden cardiac death.

Sex-Specific Outcomes in Cardiovascular Device Evaluations

Background: Females have historically been underrepresented in cardiovascular device trials. As a result, differences in outcomes for males and females are not possible to be determined in subanalyses. Materials and Methods: Against a backdrop of troubling trends in cardiovascular outcomes for females, we provide a narrative review on the differences in outcomes observed in females undergoing device evaluations in multiple fields of cardiovascular medicine, including coronary revascularization, structural heart disease, and heart failure. We also review predictors of cardiovascular trial nonparticipation as it may provide avenues by which female enrollment in cardiovascular device trials can be improved. Results: Advances have been made in structural heart therapy, where female representation in transcatheter aortic valve replacement studies was nearly 50%. For other indications, coronary revascularization and heart failure, there was clearly a disparity in female recruitment. On average, female representation was 25% in major clinical trials evaluating drug eluting stents, implantable cardioverter defibrillators, cardiac resynchronization defibrillators, and ventricular assist devices. As a result, the best treatment recommendations for females in these fields are currently guided by outcomes evaluated primarily in males. Conclusions: Female enrollment in device clinical trials for coronary revascularization and heart failure has lagged, leaving uncertainty in making benefit/risk assessments of device therapy. The predictors of female nonparticipation in clinical trials can inform a comprehensive strategy to facilitate and enrich the enrollment of females in cardiovascular device trials. This is critical to ensure that sex differences can be considered in treatment selection, so that patients can receive the best available care.

Time trends in sudden cardiac death risk in heart failure patients with cardiac resynchronization therapy: a systematic review

Aims

While data from randomized trials suggest a declining incidence of sudden cardiac death (SCD) among heart failure patients, the extent to which such a trend is present among patients with cardiac resynchronization therapy (CRT) has not been evaluated. We therefore assessed changes in SCD incidence, and associated factors, in CRT recipients over the last 20 years.

Methods and results

Literature search from inception to 30 April 2018 for observational and randomized studies involving CRT patients, with or without defibrillator, providing specific cause-of-death data. Sudden cardiac death was the primary endpoint. For each study, rate of SCD per 1000 patient-years of follow-up was calculated. Trend line graphs were subsequently constructed to assess change in SCD rates over time, which were further analysed by device type, patient characteristics, and medical therapy. Fifty-three studies, comprising 22 351 patients with 60 879 patient-years of follow-up and a total of 585 SCD, were included. There was a gradual decrease in SCD rates since the early 2000s in both randomized and observational studies, with rates falling more than four-fold. The rate of decline in SCD was steeper than that of all-cause mortality, and accordingly, the proportion of deaths which were due to SCD declined over the years. The magnitude of absolute decline in SCD was more prominent among CRT-pacemaker (CRT-P) patients compared to those receiving CRT-defibrillator (CRT-D), with the difference in SCD rates between CRT-P and CRT-D decreasing considerably over time. There was a progressive increase in age, use of beta-blockers, and left ventricular ejection fraction, and conversely, a decrease in QRS duration and antiarrhythmic drug use.

Conclusion

Sudden cardiac death rates have progressively declined in the CRT heart failure population over time, with the difference between CRT-D vs. CRT-P recipients narrowing considerably.

Association Between Use of Primary-Prevention Implantable Cardioverter-Defibrillators and Mortality in Patients With Heart Failure

Background:

Most randomized trials on implantable cardioverter-defibrillator (ICD) use for primary prevention of sudden cardiac death in heart failure with reduced ejection fraction enrolled patients >20 years ago. We investigated the association between ICD use and all-cause mortality in a contemporary heart failure with reduced ejection fraction cohort and examined relevant subgroups.

Methods:

Patients from the Swedish Heart Failure Registry fulfilling the European Society of Cardiology criteria for primary-prevention ICD were included. The association between ICD use and 1-year and 5-year all-cause and cardiovascular (CV) mortality was assessed by Cox regression models in a 1:1 propensity score–matched cohort and in prespecified subgroups.

Results:

Of 16 702 eligible patients, only 1599 (10%) had an ICD. After matching, 1305 ICD recipients were compared with 1305 nonrecipients. ICD use was associated with a reduction in all-cause mortality risk within 1 year (hazard ratio, 0.73 [95% CI, 0.60–0.90]) and 5 years (hazard ratio, 0.88 [95% CI, 0.78–0.99]). Results were consistent in all subgroups including patients with versus without ischemic heart disease, men versus women, those aged <75 versus ≥75 years, those with earlier versus later enrollment in the Swedish heart failure registry, and patients with versus without cardiac resynchronization therapy.

Conclusions:

In a contemporary heart failure with reduced ejection fraction population, ICD for primary prevention was underused, although it was associated with reduced short- and long-term all-cause mortality. This association was consistent across all the investigated subgroups. These results call for better implementation of ICD therapy.

Long-term clinical outcomes of cardiac resynchronization therapy with or without defibrillation: impact of the aetiology of cardiomyopathy

Aims

There is a continuing debate as to whether cardiac resynchronization therapy-defibrillation (CRT-D) is superior to CRT-pacing (CRT-P), particularly in patients with non-ischaemic cardiomyopathy (NICM). We sought to quantify the clinical outcomes after primary prevention of CRT-D and CRT-P and identify whether these differed according to the aetiology of cardiomyopathy.

Methods and results

Analyses were undertaken in the total study population of patients treated with CRT-D (n = 551) or CRT-P (n = 999) and in propensity-matched samples. Device choice was governed by the clinical guidelines in the United Kingdom. In univariable analyses of the total study population, for a maximum follow-up of 16 years (median 4.7 years, interquartile range 2.4–7.1), CRT-D was associated with a lower total mortality [hazard ratio (HR) 0.72] and the composite endpoints of total mortality or heart failure (HF) hospitalization (HR 0.72) and total mortality or hospitalization for major adverse cardiac events (MACE; HR 0.71) (all P < 0.001). After propensity matching (n = 796), CRT-D was associated with a lower total mortality (HR 0.72) and the composite endpoints (all P < 0.01). When further stratified according to aetiology, CRT-D was associated with a lower total mortality (HR 0.62), total mortality or HF hospitalization (HR 0.63), and total mortality or hospitalization for MACE (HR 0.59) (all P < 0.001) in patients with ischaemic cardiomyopathy (ICM). There were no differences in outcomes between CRT-D and CRT-P in patients with NICM.

Conclusion

In this study of real-world clinical practice, CRT-D was superior to CRT-P with respect to total mortality and composite endpoints, independent of known confounders. The benefit of CRT-D was evident in ICM but not in NICM.

Mid-term feasibility and safety of downgrade procedure from defibrillator to pacemaker with cardiac resynchronization therapy

Backgrounds

Some patients who undergo implantation of cardiac resynchronization therapy with defibrillator (CRT-D) survive long enough, thus requiring CRT-D battery replacement. Defibrillator therapy might become unnecessary in patients who have had significant clinical improvement and recovery of left ventricular ejection fraction (LVEF) after CRT-D implantation.

Methods

Forty-nine patients who needed replacement of a CRT-D battery were considered for exchange of CRT-D for cardiac resynchronization therapy with pacemaker (CRT-P) if they met the following criteria: LVEF >45%; the indication for an implantable cardioverter defibrillator was primary prevention at initial implantation and no appropriate implantable cardioverter defibrillator therapy was documented after initial implantation of the CRT-D.

Results

Seven patients (14.2%) were undergone a downgrade from CRT-D to CRT-P without any complications. No ventricular tachyarrhythmic events were observed during a mean follow-up of 39.7 ± 21.1 months and there was no significant change in LVEF between before and 1 year after device replacement (53.5% ± 6.2% vs. 56.4% ± 7.3%, P = 0.197).

Conclusions

This study confirmed mid-term feasibility and safety of downgrade from CRT-D to CRT-P alternative to conventional replacement with CRT-D.

•

Downgrade from CRT-D to CRT-P is feasible for patients with improved LVEF of >45%.

•

Patients without VT/VF after initial CRT-D implantation are suitable for downgrade.

•

Patients had no ventricular arrhythmias or HF hospitalization after the downgrade.

Cardiac resynchronization therapy: a comprehensive review

Despite improved understanding of heart failure (HF) and advances in medical treatments, its prevalence continues to rise, and the role of implantable devices continues to evolve. While cardiac resynchronization therapy (CRT) is an accepted form of treatment for many suffering from HF, there is an ever-evolving body of evidence examining novel indications, optimization of lead placement and device programming, with several competing technologies now also on the horizon. This review aims to take a clinical perspective on the major trials, current indications, controversies and emerging aspects of CRT in the treatment of HF.

Implantable cardioverter defibrillators for primary prevention in patients with nonischemic cardiomyopathy: A systematic review and meta-analysis

BACKGROUND

Implantable cardioverter defibrillators (ICDs) have proved their favorable outcomes on survival in selected patients with cardiomyopathy. Although previous meta-analyses have shown benefit for their use in primary prevention, the evidence remains less robust for patients with nonischemic cardiomyopathy (NICM) in comparison to patients with coronary artery disease (CAD).

OBJECTIVES

To evaluate the effect of ICD therapy on reducing all-cause mortality and sudden cardiac death (SCD) in patients with NICM.

DATA SOURCES

PubMed (1993-2016), the Cochrane Central Register of Controlled Trials (2000-2016), reference lists of relevant articles, and previous meta-analyses. Search terms included defibrillator, heart failure, cardiomyopathy, randomized controlled trials, and clinical trials.

STUDY SELECTION

Eligible trials were randomized controlled trials with at least an arm of ICD, an arm of medical therapy and enrolled some patients with NICM. The primary endpoint in the trials should include all-cause mortality or mortality from SCD.

DATA EXTRACTION

Hazard ratios (HRs) for all-cause mortality and mortality from SCD were either extracted or calculated along with their standard errors.

DATA SYNTHESIS

Of the 1047 abstracts retained by the initial screen, eight randomized controlled trials were identified. Five of these trials reported relevant data regarding patients with NICM and were subsequently included in this meta-analysis. Pooled analysis of HRs suggested a statistically significant reduction in all-cause mortality among a total of 2573 patients randomized to ICD vs medical therapy (HR 0.80; 95% CI, 0.67-0.96; P=.02). Pooled analysis of HRs for mortality from SCD was also statistically significant (n=1677) (HR 0.51; 95% CI, 0.34-0.76; P=.001).

CONCLUSION

ICD implantation is beneficial in terms of all-cause mortality and mortality from SCD in certain subgroups of patients with NICM.

Prognostic significance of nonsustained ventricular tachycardia in patients receiving cardiac resynchronization therapy for primary prevention: Analysis of the Japan cardiac device treatment registry database

Background

Whether nonsustained ventricular tachycardia (NSVT) is a marker of increased risk of sustained ventricular tachyarrhythmias (VTAs) remains to be established in patients receiving cardiac resynchronization therapy with a defibrillator (CRT‐D) for primary prevention.

Methods

Among the follow‐up data of the Japan cardiac device treatment registry (JCDTR) with an implantation date between January 2011 and August 2015, information regarding a history of NSVT before the CRT‐D implantation for primary prevention had been registered in 269 patients. Outcomes were compared between two groups with and without NSVT: NSVT group (n = 179) and No NSVT group (n = 90).

Results

There was no significant difference with regard to age, gender, and NYHA class between the two groups. Left ventricular ejection fraction (LVEF) was 25.6% in the NSVT group and 28.0% in the No NSVT group (P = .046). The rate of appropriate therapy at 24 months was 26.0% and 18.4% in the NSVT and No NSVT groups (P = .22), respectively. Survival free from heart failure death was reduced in the NSVT group, as compared with the No NSVT group, with the rate of 90.2% vs 97.2% at 24 months (P = .030). A multivariate analysis identified a history of NSVT, anemia, and no use of angiotensin‐converting enzyme inhibitor (ACEI) or angiotensin‐receptor blocker (ARB) as predictors of heart failure death.

Conclusions

NSVT appears to be a surrogate marker of severe heart failure rather than a substrate for subsequent sustained VTAs in patients with CRT‐D for primary prevention.

Implantable cardioverter-defibrillator use in elderly patients receiving cardiac resynchronization: A meta-analysis

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy (CRT) reduce sudden cardiac death and all-cause mortality in patients with heart failure with reduced ejection fraction (HFrEF). Current guidelines do not suggest any upper age limit for ICD and CRT but recommend avoidance of ICD and CRT in frail patients with a life expectancy of less than 1 year. It remains unclear whether elderly patients undergoing CRT derive the same additional benefit from ICDs as younger patients. We aimed to assess the use of ICDs in elderly compared to younger patients receiving CRT.

METHODS

We searched electronic databases, up to April 11, 2016, for all studies reporting on ICD use stratified by age in patients who received CRT. We used random-effects meta-analysis models to calculate the summarized baseline characteristics and rates of implantation of ICD among patients enrolled in the studies.

RESULTS

We retained six observational studies enrolling 613 patients ≥75 years old and 2810 patients <75 years old. The aggregate mean age was 82.7 years for the elderly patients compared to 66.3 years in the younger patients. There was a significantly lower use of ICDs in elderly patients compared to that in younger patients (37.9% versus 64.3%) (odds ratio: 0.26; 95% confidence intervals: 0.14-0.46; p < 0.0001).

CONCLUSIONS

In conclusion, ICD was less frequently used in patients ≥75 years old receiving CRT compared to younger patients receiving CRT. Future studies that evaluate the efficacy and effectiveness of ICDs in elderly patients with indications for CRT are needed to guide management of this increasing population.

Survival and Heart Failure Hospitalization in Patients With Cardiac Resynchronization Therapy With or Without a Defibrillator for Primary Prevention in Japan - Analysis of the Japan Cardiac Device Treatment Registry Database

BACKGROUND

Randomized control trials comparing the effectiveness of cardiac resynchronization therapy devices, with (CRT-D) or without (CRT-P) a defibrillator, are scarce in heart failure patients with no prior sustained ventricular tachyarrhythmias.

METHODS AND RESULTS

The Japan Cardiac Device Treatment Registry (JCDTR) has data for 2714 CRT-D and 555 CRT-P recipients for primary prevention with an implantation date between January 2011 and August 2015. Of these patients, follow-up data were available for 717. Over the mean follow-up period of 21 months, Kaplan-Meier curves of survival free of combined events for all-cause death or heart failure hospitalization (whichever came first) diverged between the CRT-D (n=620) and CRT-P (n=97) groups with a rate of 22% vs. 42%, respectively, at 24 months (P=0.0011). However, this apparent benefit of CRT-D over CRT-P was no longer significant after adjustment for covariates. With regard to mortality, including heart failure death or sudden cardiac death, there was no significant difference between the 2 groups.

CONCLUSIONS

In patients without sustained ventricular tachyarrhythmias enrolled in the JCDTR, there was no significant difference in mortality between the CRT-D and CRT-P groups, despite a lower trend in CRT-D recipients. This study was limited by large clinical and demographic differences between the 2 groups.

Cardiac resynchronization therapy in ischemic and non-ischemic cardiomyopathy

Cardiac resynchronization therapy (CRT) using a biventricular pacing system has been an effective therapeutic strategy in patients with symptomatic heart failure with a reduced left ventricular ejection fraction (LVEF) of 35% or less and a QRS duration of 130 ms or more. The etiology of heart failure can be classified as either ischemic or non-ischemic cardiomyopathy. Ischemic etiology of patients receiving CRT is prevalent predominantly in North America, moderately in Europe, and less so in Japan. CRT reduces mortality similarly in both ischemic and non-ischemic cardiomyopathy, whereas reverse structural left ventricular remodeling occurs more favorably in non-ischemic cardiomyopathy. Because the substrate for ventricular arrhythmias appears to be more severe in cases of ischemic as compared with non-ischemic cardiomyopathy, the use of an implantable cardioverter-defibrillator (ICD) backup method could prolong the long-term survival, especially of patients with ischemic cardiomyopathy, even in the presence of CRT. The aim of this review article is to summarize the effects of CRT on outcomes and the role of ICD backup in ischemic and non-ischemic cardiomyopathy.

Economic Value and Cost-Effectiveness of Cardiac Resynchronization Therapy Among Patients With Mild Heart Failure: Projections From the REVERSE Long-Term Follow-Up

OBJECTIVES

This study investigated the cost effectiveness of early cardiac resynchronization therapy (CRT) implantation among patients with mild heart failure (HF). The differential cost effectiveness between CRT using a defibrillator (CRT-Ds) and CRT using a pacemaker (CRT-P) was also assessed.

BACKGROUND

Cardiac resynchronization has been shown to be cost effective in New York Heart Association (NYHA) functional classes III/IV but is less studied in class II HF. The incremental costs of early CRT implementation in mild HF compared with the costs potentially avoided because of delaying disease progression to advanced HF are also unknown. Finally, combined biventricular pacing and defibrillator (CRT-D) devices are more expensive than biventricular pacemakers (CRT-P), but the relative cost effectiveness is controversial.

METHODS

Data from the 5-year follow-up phase of REVERSE (REsynchronization reVErses Remodeling in Systolic Left vEntricular Dysfunction) were used. The economics were evaluated from the U.S. Medicare perspective based on published clinical projections.

RESULTS

Probabilistic estimates yielded $8,840/quality-adjusted life year (QALY) gained (95% confidence interval [CI]: $6,705 to $10,804/QALY gained) for CRT-ON versus CRT-OFF (i.e., programmed "ON" or "OFF" at pre-specified post-implantation timings) and $43,678/QALY gained for CRT-D versus CRT-P (95% CI: $35,164 to $53,589/QALY gained) over the patient's lifetime. Results were robust to choice of patient subgroup and alterations of ±10% to key model parameters. An "early" CRT-D class II strategy totaled $95,292 compared with $91,511 for a "late" implantation. An "early" implant offered on average 1.00 year of additional survival for $3,781, resulting in an ICER of $3,795/LY gained.

CONCLUSIONS

This study demonstrates CRT cost effectiveness in mild HF. The incremental CRT-D costs are justified by the anticipated benefits, despite increased procurement costs and shorter generator longevities. "Early" CRT-D implants have essential cost parity with "late" implants while increasing the patient's survival. (REsynchronization reVErses Remodeling in Systolic Left vEntricular Dysfunction [REVERSE]; NCT00271154).

Why We Have to Use Cardiac Resynchronization Therapy-Pacemaker More

Both cardiac resynchronization therapy with a pacemaker (CRT-P) and with a biventricular implantable cardioverter-defibrillator (CRT-D) are electrical treatment modalities validated for the management of chronic heart failure. There is no strong scientific evidence that a CRT-D must be offered to all candidates. Common sense should limit the prescription of these costly and complicated devices. The choice of CRT-P is currently acceptable. A direction to explore could be to downgrade from CRT-D to CRT-P at the time of battery depletion in patients with large reverse remodeling and no ventricular tachycardia and ventricular fibrillation detected.

Effect of Continued Cardiac Resynchronization Therapy on Ventricular Arrhythmias After Left Ventricular Assist Device Implantation

Cardiac resynchronization therapy (CRT) reduces ventricular arrhythmia (VA) burden in some patients with heart failure, but its effect after left ventricular assist device (LVAD) implantation is unknown. We compared VA burden in patients with CRT devices in situ who underwent LVAD implantation and continued CRT (n = 39) to those who had CRT turned off before discharge (n = 26). Implantable cardioverter-defibrillator (ICD) shocks were significantly reduced in patients with continued CRT (1.5 ± 2.7 shocks per patient vs 5.5 ± 9.3 with CRT off, p = 0.014). There was a nonsignificant reduction in cumulative VA episodes per patient with CRT continued at discharge (42 ± 105 VA per patient vs 82 ± 198 with CRT off, p = 0.29). On-treatment analysis by whether CRT was on or off identified a significantly lower burden of VA (17 ± 1 per patient-year CRT on vs 37 ± 1 per patient-year CRT off, p <0.0001) and ICD shocks (1.2 ± 0.3 per patient-year CRT on vs 1.7 ± 0.3 per patient-year CRT off, p = 0.018). In conclusion, continued CRT is associated with significantly reduced ICD shocks and VA burden after LVAD implantation.

Geographic and Temporal Variation in Cardiac Implanted Electric Devices to Treat Heart Failure

BACKGROUND

Cardiac implantable electric devices are commonly used to treat heart failure. Little is known about temporal and geographic variation in use of cardiac resynchronization therapy (CRT) devices in usual care settings.

METHODS AND RESULTS

We identified new CRT with pacemaker (CRT-P) or defibrillator generators (CRT-D) implanted between 2008 and 2013 in the United States from a commercial claims database. For each implant, we characterized prior medication use, comorbidities, and geography. Among 17 780 patients with CRT devices (median age 69, 31% women), CRT-Ps were a small and increasing share of CRT devices, growing from 12% to 20% in this study period. Compared to CRT-D recipients, CRT-P recipients were older (median age 76 versus 67), and more likely to be female (40% versus 30%). Pre-implant use of β-blockers and angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers was low in both CRT-D (46%) and CRT-P (31%) patients. The fraction of CRT-P devices among all new implants varied widely across states. Compared to the increasing national trend, the share of CRT-P implants was relatively increasing in Kansas and relatively decreasing in Minnesota and Oregon.

CONCLUSIONS

In this large, contemporary heart failure population, CRT-D use dwarfed CRT-P, though the latter nearly doubled over 6 years. Practice patterns vary substantially across states and over time. Medical therapy appears suboptimal in real-world practice.

Trends and determinant factors in the use of cardiac resynchronization therapy devices in Japan: Analysis of the Japan cardiac device treatment registry database

Background

The choice of cardiac resynchronization therapy device, with (CRT-D) or without (CRT-P) a defibrillator, in patients with heart failure largely depends on the physician׳s discretion, because it has not been established which subjects benefit most from a defibrillator.

Methods

We examined the annual trend of CRT device implantations between 2006 and 2014, and evaluated the factors related to the device selection (CRT-D or CRT-P) for primary prevention of sudden cardiac death in patients with heart failure by analyzing the Japan Cardiac Device Treatment Registry (JCDTR) database from January 2011 and August 2015 (CRT-D, n=2714; CRT-P, n=555).

Results

The proportion of CRT-D implantations for primary prevention among all the CRT-D recipients was more than 70% during the study period. The number of CRT-D implantations for primary prevention reached a maximum in 2011 and decreased gradually between 2011 and 2014, whereas CRT-P implantations increased year by year until 2011 and remained unchanged in recent years. Multivariate analysis identified age (odds ratio [OR] 0.92, 95% confidence interval [CI] 0.90–0.95, P<0.0001), male sex (OR 1.99, 95% CI 1.28–3.11, P<0.005), reduced left ventricular ejection fraction (LVEF) (OR 0.96, 95% CI 0.94–0.98, P<0.0001), and non-sustained ventricular tachycardia (NSVT) (OR 2.85, 95% CI 1.87–4.35, P<0.0001) as independent factors favoring the choice of CRT-D.

Conclusions

Younger age, male sex, reduced LVEF, and a history of NSVT were independently associated with the choice of CRT-D for primary prevention of sudden cardiac death in patients with heart failure in Japan.

Developments in Cardiac Resynchronisation Therapy

Cardiac resynchronisation therapy (CRT) is an important therapy for patients with heart failure with a reduced ejection fraction and interventricular conduction delay. Large trials have established the role of CRT in reducing heart failure hospitalisations and improving symptoms, left ventricular (LV) function and mortality. Guidelines from major medical societies are consistent in support of CRT for patients with New York Health Association (NYHA) class II, III and ambulatory class IV heart failure, reduced LV ejection fraction and QRS prolongation, particularly left bundle branch block. The current challenge facing practitioners is to maximise the rate of patients who respond to CRT and the magnitude of that response. Current areas of interest for achieving these goals include tailoring patient selection, individualising LV lead placement and application of new technologies and techniques for CRT delivery.

Why We Have to Use Cardiac Resynchronization Therapy-Pacemaker More

Both cardiac resynchronization therapy with a pacemaker (CRT-P) and with a biventricular implantable cardioverter-defibrillator (CRT-D) are electrical treatment modalities validated for the management of chronic heart failure. There is no strong scientific evidence that a CRT-D must be offered to all candidates. Common sense should limit the prescription of these costly and complicated devices. The choice of CRT-P is currently acceptable. A direction to explore could be to downgrade from CRT-D to CRT-P at the time of battery depletion in patients with large reverse remodeling and no ventricular tachycardia and ventricular fibrillation detected.

Importance of Implantable Cardioverter-Defibrillator Back-Up in Cardiac Resynchronization Therapy Recipients: A Systematic Review and Meta-Analysis

BACKGROUND

It remains to be determined whether patients receiving cardiac resynchronization therapy (CRT) benefit from the addition of an implantable cardioverter-defibrillator (ICD).

METHODS AND RESULTS

We performed a literature search looking for studies of patients implanted with CRTs. Comparisons were performed between patients receiving CRT-defibrillator (CRT-D) versus CRT-pacemaker (CRT-P). The primary outcome was all-cause mortality. Data were pooled using a random-effects model. The relative risk (RR) and hazard ratio (HR, when available) were used as measurements of treatment effect. Nineteen entries were entitled for inclusion, comprising 12 378 patients (7030 receiving CRT-D and 5348 receiving CRT-P) and 29 799 patient-years of follow-up. Those receiving CRT-D were younger, were more often males, had lower NYHA class, lower prevalence of atrial fibrillation, higher prevalence of ischemic heart disease, and were more often on beta-blockers. Ten studies showed significantly lower mortality rates with the CRT-D device, while the remaining 9 were neutral. The pooled data of studies revealed that CRT-D patients had significantly lower mortality rates compared with CRT-P patients (mortality rates: CRT-D 16.6% versus CRT-P 27.1%; RR=0.69, 95% CI 0.62-0.76; P<0.00001). The number needed to treat to prevent one death was 10. The observed I(2) values showed moderate heterogeneity among studies (I(2)=48%). The benefit of CRT-D was more pronounced in ischemic cardiomyopathy (HR=0.70, 95% CI 0.59-0.83, P<0.001, I(2)=0%), but a trend for benefit, albeit of lower magnitude, could also be seen in non-ischemic dilated cardiomyopathy (HR=0.79, 95% CI 0.61-1.02, P=0.07, I(2)=36%).

CONCLUSIONS

The addition of the ICD associates with a reduction in the risk of all-cause mortality in CRT patients. This seems to be more pronounced in patients with ischemic cardiomyopathy.

Biventricular pacemaker/defibrillators versus biventricular pacemakers in patients with non-ischemic cardiomyopathy

The decision to employ defibrillator therapy in patients with non-ischemic cardiomyopathy is driven by reduction in mortality. The strength of data supporting this therapy has led to its incorporation in medical guidelines and general practice across the world. Cardiac resynchronization therapy has also been proven to reduce heart failure hospitalization and improve quality of life. Although trends toward reduction in arrhythmic events have been observed, results in multicenter, randomized controlled trials have not been compelling for stand-alone use in most patients who currently meet criteria for defibrillator therapy.

Long-Term Extrapolation of Clinical Benefits Among Patients With Mild Heart Failure Receiving Cardiac Resynchronization Therapy: Analysis of the 5-Year Follow-Up From the REVERSE Study

OBJECTIVES

This study sought to assess the lifelong extrapolated patient outcomes with cardiac resynchronization therapy (CRT) in mild heart failure (HF), beyond the follow-up of randomized clinical trials (RCTs).

BACKGROUND

RCTs have demonstrated short-term survival and HF hospitalization benefits of CRT in mild HF. We used data from the 5-year follow-up of the REVERSE (REsynchronization reVErses Remodeling in Systolic left vEntricular dysfunction) study to extrapolate survival and HF hospitalizations. We compared CRT-ON versus CRT-OFF and CRT defibrillators (CRT-D) versus CRT pacemakers (CRT-P).

METHODS

Multivariate regression models were used to estimate treatment-specific all-cause mortality, disease progression, and HF-related hospitalization rates. Rank-preserving structural failure time (RPSFT) models were used to adjust for protocol-mandated crossover in the survival analysis.

RESULTS

CRT-ON was predicted to increase survival by 22.8% (CRT-ON 52.5% vs. CRT-OFF 29.7%; hazard ratio [HR]: 0.45; p = 0.21), leading to an expected survival of 9.76 years (CRT-ON) versus 7.5 years (CRT-OFF). CRT-D showed a significant improvement in survival compared with CRT-P (HR: 0.47; 95% confidence interval [CI]: 0.25 to 0.88; p = 0.02) and were predicted to offer 2.77 additional life-years. New York Heart Association (NYHA) functional class II patients had a 30.6% higher HF hospitalization risk than class I (I vs. II incident rate ratio [IRR]: 0.69; 95% CI: 0.57 to 0.85; p < 0.001) and 3 times lower rate compared with class III (III vs.

II IRR

2.98; 95% CI: 2.29 to 3.87; p < 0.001).

CONCLUSIONS

RPSFT estimates yielded results demonstrating clinically important long-term benefit of CRT in mild HF. CRT was predicted to reduce mortality, with CRT-D prolonging life more than CRT-P. NYHA functional class I/II patients were shown to have a significantly reduced risk of HF hospitalization compared with class III, leading to CRT reducing HF hospitalization rates.

Reduced appropriate implantable cardioverter-defibrillator therapy after cardiac resynchronization therapy-induced left ventricular function recovery: a meta-analysis and systematic review

AIMS

For patients undergoing cardiac resynchronization therapy (CRT) with implantable cardioverter-defibrillator (ICD; CRT-D), the effect of an improvement in left ventricular ejection fraction (LVEF) on appropriate ICD therapy may have significant implications regarding management at the time of ICD generator replacement.

METHODS AND RESULTS

We conducted a meta-analysis to determine the effect of LVEF recovery following CRT on the incidence of appropriate ICD therapy. A search of multiple electronic databases identified 709 reports, of which 6 retrospective cohort studies were included (n = 1740). In patients with post-CRT LVEF ≥35% (study n = 4), the pooled estimated rate of ICD therapy (5.5/100 person-years) was significantly lower than patients with post-CRT LVEF <35% [incidence rate difference (IRD): -6.5/100 person-years, 95% confidence interval (95% CI): -8.8 to -4.2, P < 0.001]. Similarly, patients with post-CRT LVEF ≥45% (study n = 4) demonstrated lower estimated rates of ICD therapy (2.3/100 person-years) compared with patients without such recovery (IRD: -5.8/100 person-years, 95% CI: -7.6 to -4.0, P < 0.001). Restricting analysis to studies discounting ICD therapies during LVEF recovery (study n = 3), patients with LVEF recovery (≥35 or ≥45%) had significantly lower rates of ICD therapy compared with patients without such recovery (P for both <0.001). Patients with primary prevention indication for ICD, regardless of LVEF recovery definition, had very low rates of ICD therapy (0.4 to 0.8/100-person years).

CONCLUSION

Recovery of LVEF post-CRT is associated with significantly reduced appropriate ICD therapy. Patients with improvement of LVEF ≥45% and those with primary prevention indication for ICD appear to be at lowest risk.

Sex Differences in Utilisation and Response to Implantable Device Therapy

Multiple studies have demonstrated that implantable cardioverter-defibrillators (ICDs) and cardiac resynchronisation therapy (CRT) provide significant mortality and morbidity benefits to eligible patients irrespective of gender. However, female patients are less likely to receive this life-saving therapy and are significantly under-represented in cardiac device trials. Various performance improvement programmes have proved that this gender disparity can be reduced and these therapies should be offered to all eligible patients regardless of sex. Efforts should be made to enrol more women in clinical trials and sex-specific analysis in medical device clinical studies should be encouraged. In this article we review the data on sex differences in clinical outcomes with ICDs and CRT and explore the reasons for this sex-based disparity.

Sex differences in device therapy for heart failure: utilization, outcomes, and adverse events

BACKGROUND

Multiple studies of heart failure patients demonstrated significant improvement in exercise capacity, quality of life, cardiac left ventricular function, and survival from cardiac resynchronization therapy (CRT), but the underenrollment of women in these studies is notable. Etiological and pathophysiological differences may result in different outcomes in response to this treatment by sex. The observed disproportionate representation of women suggests that many women with heart failure either do not meet current clinical criteria to receive CRT in trials or are not properly recruited and maintained in these studies.

METHODS

We performed a systematic literature review through May 2014 of clinical trials and registries of CRT use that stratified outcomes by sex or reported percent women included. One-hundred eighty-three studies contained sex-specific information.

RESULTS

Ninety percent of the studies evaluated included ≤ 35% women. Fifty-six articles included effectiveness data that reported response with regard to specific outcome parameters. When compared with men, women exhibited more dramatic improvement in specific parameters. In the studies reporting hazard ratios for hospitalization or death, women generally had greater benefit from CRT.

CONCLUSIONS

Our review confirms women are markedly underrepresented in CRT trials, and when a CRT device is implanted, women have a therapeutic response that is equivalent to or better than in men, while there is no difference in adverse events reported by sex.

The clinical course of patients with implantable cardioverter-defibrillators: Extended experience on clinical outcome, device replacements, and device-related complications

BACKGROUND

Large randomized trials demonstrated the beneficial effect of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy-defibrillator (CRT-D) treatments in selected patients. Data on long-term follow-up of patients outside the setting of clinical trials are scarce.

OBJECTIVE

The aim of this study was to evaluate the long-term outcome of ICD and CRT-D recipients.

METHODS

All patients who underwent ICD (n = 1729 [57%]) or CRT-D (n = 1326 [43%]) implantation at the Leiden University Medical Center since 1996 were evaluated. Follow-up visits were performed every 3-6 months, and events were registered. Cumulative incidence curves of device therapy and device-related complications were adjusted for the competing risk of all-cause mortality.

RESULTS

After a median follow-up of 5.1 years (25th-75th percentile 3.1-7.8 years), 842 patients (28%) died. The cumulative incidence of all-cause mortality was 49% (95% confidence interval [CI] 45%-54%) in ICD recipients after 12 years of follow-up and 55% (95% CI 52%-58%) in CRT-D recipients after 8 years of follow-up. A total of 1081 patients (35%) received appropriate defibrillator therapy. The cumulative incidence of appropriate therapy in ICD patients was 58% (95% CI 54%-62%) after 12 years of follow-up and 39% (95% CI 35%-43%) in CRT-D patients after 8 years of follow-up. Twelve-year cumulative incidences of adverse events were 20% (95% CI 18%-22%) for inappropriate shock, 6% (95% CI 5%-8%) for device-related infection, and 17% (95% CI 14%-21%) for lead failure.

CONCLUSION

After long-term follow-up of ICD (12 years) and CRT-D (8 years) recipients, 49% of ICD recipients and 55% of CRT-D recipients had died. Appropriate ICD therapy was received by the majority (58%) of ICD recipients and by almost 40% of CRT-D recipients.

Outcome of prolonged QRS interval in dilated cardiomyopathy: role of implantable cardioverter-defibrillators on mortality

AIM

The main objectives of this study were to investigate the relationship between prolonged QRS interval and its prognosis in patients with dilated cardiomyopathy (DCM), and to determine the effects of cardiac pacing with an implantable cardioverter-defibrillator (ICD) on mortality in patients with a QRS width > 150 ms.

METHODS

We retrospectively queried the healthcare enterprise data warehouse and the patient medical records from January 2007 to December 2012 for 1453 cases of DCM at a university- affiliated hospital. Of the 1453 cases, 989 patients were included in the final analyses. Primary outcome variable was all-cause mortality.

RESULTS

Of the 989 patients, 20% (n = 198) of the patients had a QRS width > 150 ms. Compared with patients who had a QRS < 120 ms, patients with a QRS > 150 ms had significantly higher rates of death (p < 0.001). Among the subgroup of 198 patients who had a QRS width > 150 ms, survival (84.3%, n = 75) was significantly higher (p < 0.001) in patients with a pacemaker inserted compared with those (45.0%, n = 49) who had not been paced.

CONCLUSIONS

Prolonged QRS interval is significantly associated with a higher rate of mortality. However, we believe that cardiac pacing with an ICD in such patients can significantly improve outcomes.

The effect of reverse remodeling on long-term survival in mildly symptomatic patients with heart failure receiving cardiac resynchronization therapy: results of the REVERSE study

BACKGROUND

Cardiac resynchronization therapy (CRT) reduces mortality, improves functional status, and induces reverse left ventricular remodeling in selected populations with heart failure (HF). The magnitude of reverse remodeling predicts survival with many HF medical therapies. However, there are few studies assessing the effect of remodeling on long-term survival with CRT.

OBJECTIVE

The purpose of this study was to assess the effect of CRT-induced reverse remodeling on long-term survival in patients with mildly symptomatic heart failure.

METHODS

The REsynchronization reVErses Remodeling in Systolic Left vEntricular Dysfunction trial was a multicenter, double-blind, randomized trial of CRT in patients with mild HF. Long-term follow-up of 5 years was preplanned. The present analysis was restricted to the 353 patients who were randomized to the CRT ON group with paired echocardiographic studies at baseline and 6 months postimplantation. The left ventricular end-systolic volume index (LVESVi) was measured in the core laboratory and was an independently powered end point of the REsynchronization reVErses Remodeling in Systolic Left vEntricular Dysfunction trial.

RESULTS

A 68% reduction in mortality was observed in patients with ≥15% decrease in LVESVi compared to the rest of the patients (P = .0004). Multivariable analysis showed that the change in LVESVi was a strong independent predictor (P = .0002), with a 14% reduction in mortality for every 10% decrease in LVESVi. Other remodeling parameters such as left ventricular end-diastolic volume index and ejection fraction had a similar association with mortality.

CONCLUSION

The change in left ventricular end-systolic volume after 6 months of CRT is a strong independent predictor of long-term survival in mild HF.

The characteristics and outcome of infective endocarditis involving implantable cardiac devices

Infection of implantable cardiac electronic devices in particular lead endocarditis (cardiac device infective endocarditis (CDIE)) is an emerging problem with significant morbidity, mortality and health care costs. The epidemiology is characterised with advanced age and health care association in cases presenting within 6 months of implantation. Risk factors include those of the patient, the procedure and the device. Staphylococcal species predominate as the causative organisms. Diagnosis is reliably made by blood cultures and transesophageal echocardiography. Complications include pulmonary and systemic emboli, persistent bacteremia and concomitant valvular involvement. Management includes complete device removal and prolonged antimicrobial therapy. With long-term follow-up to 1 year, the mortality of CDIE is as high as 23 %. It is associated with patient co-morbidities and concomitant valvular involvement and may be prevented by device removal during index admission.

Left ventricular ejection fraction normalization in cardiac resynchronization therapy and risk of ventricular arrhythmias and clinical outcomes: results from the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy (MADIT-CRT) trial

BACKGROUND

Appropriate guideline criteria for use of implantable cardioverter-defibrillators (ICDs) do not take into account potential recovery of left ventricular ejection fraction (LVEF) in patients treated with CRT-defibrillator.

METHODS AND RESULTS

Patients randomized to CRT-defibrillator from the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy (MADIT-CRT) trial who survived and had paired echocardiograms at enrollment and at 12 months (n=752) were included. Patients were evaluated by LVEF recovery in 3 groups (LVEF ≤35% [reference], 36%-50%, and >50%) on outcomes of ventricular tachyarrhythmias (VTAs), VTA ≥200 bpm, ICD shock, heart failure or death, and inappropriate ICD therapy by multivariable Cox models. A total of 7.3% achieved LVEF normalization (>50%). The average follow-up was 2.2±0.8 years. The risk of VTA was reduced in patients with LVEF >50% (hazard ratio [HR], 0.24; 95% confidence interval [CI], 0.07-0.82; P=0.023) and LVEF of 36% to 50% (HR, 0.44; 95% CI, 0.28-0.68; P<0.001). Among patients with LVEF >50%, only 1 patient had VTA ≥200 bpm (HR, 0.16; 95% CI, 0.02-1.51), none were shocked by the ICD, and 2 died of nonarrhythmic causes. The risk of HF or death was reduced with improvements in LVEF (LVEF >50%: HR, 0.29; 95% CI, 0.09-0.97; P=0.045; and LVEF of 36%-50%: HR, 0.44; 95% CI, 0.28-0.69; P<0.001). For inappropriate ICD therapy, no additional risk reduction for LVEF>50% was seen compared with an LVEF of 36% to 50%. A total of 6 factors were associated with LVEF normalization, and patients with all factors present (n=42) did not experience VTAs (positive predictive value, 100%).

CONCLUSIONS

Patients who achieve LVEF normalization (>50%) have very low absolute and relative risk of VTAs and a favorable clinical course within 2.2 years of follow-up. Risk of inappropriate ICD therapy is still present, and these patients could be considered for downgrade from CRT-defibrillator to CRT-pacemaker at the time of battery depletion if no VTAs have occurred.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT00180271.