Long-Term Outcomes of CRT-PM Versus CRT-D Recipients

Time-trend treatment effect of cardiac resynchronization therapy with or without defibrillator on mortality: a systematic review and meta-analysis

AIMS

This study aimed to investigate the impact of cardiac resynchronization therapy with a defibrillator (CRT-D) on mortality, comparing it with CRT with a pacemaker (CRT-P). Additionally, the study sought to identify subgroups, evaluate the time trend in treatment effects, and analyze patient characteristics, considering the changing indications over the past decades.

METHODS AND RESULTS

PubMed, CENTRAL, and Embase up to October 2021 were screened for studies comparing CRT-P and CRT-D, focusing on mortality. Altogether 26 observational studies were selected comprising 128 030 CRT patients, including 55 469 with CRT-P and 72 561 with CRT-D device. Cardiac resynchronization therapy with defibrillator was able to reduce all-cause mortality by almost 20% over CRT-P [adjusted hazard ratio (HR): 0.85; 95% confidence interval (CI): 0.76-0.94; P < 0.01] even in propensity-matched studies (HR: 0.83; 95% CI: 0.80-0.87; P < 0.001) but not in those with non-ischaemic aetiology (HR: 0.95; 95% CI: 0.79-1.15; P = 0.19) or over 75 years (HR: 1.08; 95% CI 0.96-1.21; P = 0.17). When treatment effect on mortality was investigated by the median year of inclusion, there was a difference between studies released before 2015 and those thereafter. Time-trend effects could be also observed in patients' characteristics: CRT-P candidates were getting older and the prevalence of ischaemic aetiology was increasing over time.

CONCLUSION

The results of this systematic review of observational studies, mostly retrospective with meta-analysis, suggest that patients with CRT-D had a lower risk of mortality compared with CRT-P. However, subgroups could be identified, where CRT-D was not superior such as non-ischaemic and older patients. An improved treatment effect of CRT-D on mortality could be observed between the early and late studies partly related to the changed characteristics of CRT candidates.

Sex-specific mortality differences in heart failure patients with ischemia receiving cardiac resynchronization therapy

Background

Recent studies have reported prognosis differences between male and female heart failure patients following cardiac resynchronization therapy (CRT). However, the potential clinical factors that underpin these differences remain to be elucidated.

Methods

A meta-analysis was performed to investigate the factors that characterize sex-specific differences following CRT. This analysis involved searching the Medline (Pubmed source) and Embase databases in the period from January 1980 to September 2016.

Results

Fifty-eight studies involving 33445 patients (23.08% of whom were women) were analyzed as part of this study. Only patients receiving CRT with follow-up greater than six months were included in our analysis. Compared with males, females exhibited a reduction of 33% (hazard ratio, 0.67; 95% confidence interval, 0.62–0.73; P < 0.0001) and 42% (hazard ratio, 0.58; 95% confidence interval, 0.46–0.74; P = 0.003) in all-cause mortality and heart failure hospitalization or heart failure, respectively. Following a stratified analysis of all-cause mortality, we observed that ischemic causes (p = 0.03) were likely to account for most of the sex-specific differences in relation to CRT.

Conclusion

These data suggest that women have a reduced risk of all-cause mortality and heart failure hospitalization or heart failure following CRT. Based on the results from the stratified analysis, we observed more optimal outcomes for females with ischemic heart disease. Thus, ischemia are likely to play a role in sex-related differences associated with CRT in heart failure patients. Further studies are required to determine other indications and the potential mechanisms that might be associated with sex-specific CRT outcomes.

Meta-analysis of rate ratios with differential follow-up by treatment arm: inferring comparative effectiveness of medical devices

Modeling events requires accounting for differential follow-up duration, especially when combining randomized and observational studies. Although events occur at any point over a follow-up period and censoring occurs throughout, most applied researchers use odds ratios as association measures, assuming follow-up duration is similar across treatment groups. We derive the bias of the rate ratio when incorrectly assuming equal follow-up duration in the single study binary treatment setting. Simulations illustrate bias, efficiency, and coverage and demonstrate that bias and coverage worsen rapidly as the ratio of follow-up duration between arms moves away from one. Combining study rate ratios with hierarchical Poisson regression models, we examine bias and coverage for the overall rate ratio via simulation in three cases: when average arm-specific follow-up duration is available for all studies, some studies, and no study. In the null case, bias and coverage are poor when the study average follow-up is used and improve even if some arm-specific follow-up information is available. As the rate ratio gets further from the null, bias and coverage remain poor. We investigate the effectiveness of cardiac resynchronization therapy devices compared with those with cardioverter-defibrillator capacity where three of eight studies report arm-specific follow-up duration.

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.

More Favorable Response to Cardiac Resynchronization Therapy in Women Than in Men

Background—

Data on sex difference in response to cardiac resynchronization therapy (CRT) remain controversial. We conducted a meta-analysis to summarize all published studies to determine whether sex-based differences in response to CRT exist.

Methods and Results—

We performed a literature search using MEDLINE (source PubMed; January 1966 to March 2014) and EMBASE (January 1980 to March 2014) with no restrictions. Pooled effect estimates were obtained by using random-effects meta-analysis. Seventy-two studies involving 33 434 patients were identified. Overall, female patients had better outcomes from CRT compared with male patients, with a significant 33% reduction in the risk of death from any cause (hazard ratio, 0.67; 95% confidence interval, 0.61–0.74; P <0.001), 20% reduction in death or hospitalization for heart failure (hazard ratio, 0.80; 95% confidence interval, 0.71–0.90; P <0.001), 41% reduction in cardiac death (hazard ratio, 0.59; 95% confidence interval, 0.42–0.84; P <0.001), and 41% reduction in ventricular arrhythmias or sudden cardiac death (hazard ratio, 0.59; 95% confidence interval, 0.49–0.70; P <0.001). These more favorable responses to CRT in women were consistently associated with greater echocardiographic evidence of reverse cardiac remodeling in women than in men.

Conclusions—

Women obtained greater reductions in the risk of death from any cause, cardiac cause, death or hospitalization for heart failure, and ventricular arrhythmias or sudden cardiac death with CRT therapy compared with men, with consistently greater echocardiographic evidence of reverse cardiac remodeling in women than in men. Further studies are needed to investigate the exact reasons for these results and determine whether indications for CRT in women should be different from men.

Sex and gender differences in myocarditis and dilated cardiomyopathy

Heart failure due to nonischemic dilated cardiomyopathy (DCM) contributes significantly to the global burden of cardiovascular disease. Myocarditis is, in turn, a major cause of acute DCM in both men and women. However, recent clinical and experimental evidence suggests that the pathogenesis and prognosis of DCM differ between the sexes. This seminar provides a contemporary perspective on the immune mediators of myocarditis, including interdependent elements of the innate and adaptive immune response. The heart's acute response to injury is influenced by sex hormones that appear to determine the subsequent risk of chronic DCM. Preliminary data suggest additional genetic variations may account for some of the differences in epidemiology, left ventricular recovery, and survival between men and women. We highlight the gaps in our knowledge regarding the management of women with acute DCM and discuss emerging therapies, including bromocriptine for the treatment of peripartum cardiomyopathy.

Cardiac resynchronization therapy-defibrillator improves long-term survival compared with cardiac resynchronization therapy-pacemaker in patients with a class IA indication for cardiac resynchronization therapy: data from the Contak Italian Registry

AIMS

In candidates for cardiac resynchronization therapy (CRT), the choice between pacemaker (CRT-P) and defibrillator (CRT-D) implantation is still debated. We compared the long-term prognosis of patients who received CRT-D or CRT-P according to class IA recommendations of the European Society of Cardiology (ESC) and who were enrolled in a multicentre prospective registry.

METHODS AND RESULTS

A total of 620 heart failure patients underwent successful implantation of a CRT device and were enrolled in the Contak Italian Registry. This analysis included 266 patients who received a CRT-D and 108 who received a CRT-P according to class IA ESC indications. Their survival status was verified after a median follow-up of 55 months. During follow-up, 73 CRT-D and 44 CRT-P patients died (rate 6.6 vs. 10.4%/year; log-rank test, P = 0.020). Patients receiving CRT-P were predominantly older, female, had no history of life-threatening ventricular arrhythmias, and more frequently presented non-ischaemic aetiology of heart failure, longer QRS durations, and worse renal function. However, the only independent predictor of death from any cause was the use of CRT-P (hazard ratio, 1.97; 95% confidence interval, 1.21-3.16; P = 0.007).

CONCLUSION

The implantation of CRT-D, rather than CRT-P, may be preferable in patients presenting with current class IA ESC indications for CRT. Indeed, CRT-D resulted in greater long-term survival and was independently associated with a better prognosis.

Lead complications, device infections, and clinical outcomes in the first year after implantation of cardiac resynchronization therapy-defibrillator and cardiac resynchronization therapy-pacemaker

AIMS

The decision to implant a cardiac resynchronization therapy (CRT) system with (defibrillator, CRT-D) or without (pacemaker, CRT-P) cardioverter defibrillator should weigh its benefits and risks. This study examined the (i) incidence of loss of capture and infectious complications and (ii) 1-year clinical outcomes of 402 CRT-D and CRT-P recipients enrolled in the MASCOT study.

METHODS AND RESULTS

The indications for CRT-D or CRT-P were posed by the implanting physicians. All (i) losses of atrial and right and left ventricular capture, (ii) system-related infections, and (iii) clinical outcomes, including hospitalizations for worsening heart failure (HF) and deaths from all causes, were recorded up to 1 year of follow-up. Cardiac resynchronization therapy-defibrillator was implanted in 228 (57%) and CRT-P in 174 (43%) patients. The incidence of loss of capture was greater in CRT-D with 21 patients (9.2%) than in CRT-P with 6 patient (3.5%) recipients (P = 0.01), while the infection rates were 1.3% (3 patients) and 1.2% (2 patients), respectively (ns). In the CRT-D group, 42 of 228 patients (18.4%) died or were hospitalized for HF, compared with 38 of 174 patients (21.8%) in the CRT-P group (ns). In the CRT-D group, 23 patients (10.1%) were hospitalized for worsening HF and 20 (8.8%) patients died, vs. 22 (12.6%) and 19 (10.9%) patients, respectively, in the CRT-P group (ns for both comparisons).

CONCLUSIONS

Cardiac resynchronization therapy-defibrillator was implanted in 57% of candidates for CRT. Within 1 year after device implant, the incidence of loss of capture at any lead was nearly three-fold greater among CRT-D than among CRT-P recipients. System-related infections were infrequent and clinical outcomes were similar in both groups.

Outcomes of cardiac resynchronization therapy in patients with versus those without atrial fibrillation: a systematic review and meta-analysis

BACKGROUND

Whether the benefits observed with cardiac resynchronization therapy (CRT) are similar in patients with versus those without atrial fibrillation (AF) is unclear. Furthermore, whether patients with AF receiving CRT should undergo atrioventricular nodal (AVN) ablation remains uncertain.

OBJECTIVE

The purpose of this study was to compare outcomes in patients with and those without AF receiving CRT and to evaluate the influence of AVN ablation on outcomes in patients with AF.

METHODS

A systematic review and meta-analysis was performed. Outcomes included death, CRT nonresponse, and changes in left ventricular (LV) remodeling, quality of life (QoL), and 6-minute hall walk distance (6MWD).

RESULTS

Twenty-three observational studies were included and followed a total of 7,495 CRT recipients, 25.5% with AF, for a mean of 33 months. AF was associated with an increased risk of nonresponse to CRT (34.5% vs 26.7%; pooled relative risk [RR] 1.32; 95% confidence interval [CI] 1.12, 1.55; P = .001)) and all-cause mortality (10.8% vs 7.1% per year, pooled RR 1.50, 95% CI 1.08, 2.09; P = .015). The presence of AF was also associated with less improvement in QoL, 6-minute hall walk distance, and LV end-systolic volume but not LV ejection fraction. Among patients with AF, AVN ablation appeared favorable with a lower risk of clinical nonresponse (RR 0.40; 95% CI 0.28, 0.58; P <.001) and a reduced risk of death.

CONCLUSION

The benefits of CRT appear to be attenuated in patients with AF. The presence of AF is associated with an increased risk of clinical nonresponse and death than in patients without AF. AVN ablation may improve CRT outcomes in patients with AF.

Cardiac resynchronization therapy: a review of CRT-D versus CRT-P

Current evidence-based guidelines recommend an implantable cardioverter-defibrillator for the primary prevention of sudden cardiac death in selected patients with impaired left ventricular function, and cardiac resynchronization therapy for improvement of symptoms and survival in selected patients with impaired left ventricular function and abnormal ventricular conduction. Many patients may be eligible for both treatments, but it does not necessarily follow that such patients would obtain additional benefit from the combined treatment over one treatment alone. A simple pragmatic approach would be to use resynchronisation therapy, in order to reduce symptoms and extend life in patients with New York Heart Association class III or IV heart failure, with the addition of an implantable cardioverter-defibrillator left to clinical judgment on an individual basis when additional indications exist. When such an addition is contemplated the hypothesized incremental benefits in survival would need to be balanced by the possible increase in morbidity owing to, for example, inappropriate shocks.

Implementation of device therapy (cardiac resynchronization therapy and implantable cardioverter defibrillator) for patients with heart failure in Europe: changes from 2004 to 2008

AIMS

Heart failure (HF) patients increasingly receive device therapy, either an implantable cardioverter defibrillator (ICD) or a biventricular pacemaker, also called cardiac resynchronization therapy (CRT), or a CRT device with an ICD (CRT-D). However, epidemiological data on the use of device therapy in Europe are limited.

METHODS AND RESULTS

Data on implantation rates for conventional pacemakers, ICD, CRT, and CRT-D in 15 Western European countries were obtained from the Eucomed Registry for the 5-year period 2004-2008. Implantation of conventional pacemakers increased by 9% in Europe over the 5 years (reaching 907/million in 2008) and there were significant differences between countries. Implantable cardioverter defibrillator implantations increased by 75% from 80/million in 2004 to 140/million in 2008, and differences between countries were larger than those for conventional pacemakers. Implantation rates for CRT-P alone increased slightly from 2004 to 2006, but remained at 25/million thereafter in Europe overall. The total number of CRT implants (CRT-P and -D) markedly increased from 46/million in 2004 to 99/million in 2008 (115%), but this was mainly due to more CRT-D implants, i.e. an increase in the proportion of CRT-D (from 55% in 2004 to 75% in 2008). Implantation rates for ICD, CRT, and CRT-D remained markedly different throughout the study period between countries.

CONCLUSION

Implantation rates of devices for HF, in particular ICD and CRT-D, have increased significantly between 2004 and 2008 in Europe, but there remain major differences between countries.