Sex differences in outcome after implantable cardioverter defibrillator implantation in nonischemic cardiomyopathy

Differences in presentation, diagnosis and management of heart failure in women. A scientific statement of the Heart Failure Association of the ESC

Despite the progress in the care of individuals with heart failure (HF), important sex disparities in knowledge and management remain, covering all the aspects of the syndrome, from aetiology and pathophysiology to treatment. Important distinctions in phenotypic presentation are widely known, but the mechanisms behind these differences are only partially defined. The impact of sex-specific conditions in the predisposition to HF has gained progressive interest in the HF community. Under-recruitment of women in large randomized clinical trials has continued in the more recent studies despite epidemiological data no longer reporting any substantial difference in the lifetime risk and prognosis between sexes. Target dose of medications and criteria for device eligibility are derived from studies with a large predominance of men, whereas specific information in women is lacking. The present scientific statement encompasses the whole scenario of available evidence on sex-disparities in HF and aims to define the most challenging and urgent residual gaps in the evidence for the scientific and clinical HF communities.

Sex-related similarities and differences in responses to heart failure therapies

Although sex-related differences in the epidemiology, risk factors, clinical characteristics and outcomes of heart failure are well known, investigations in the past decade have shed light on an often overlooked aspect of heart failure: the influence of sex on treatment response. Sex-related differences in anatomy, physiology, pharmacokinetics, pharmacodynamics and psychosocial factors might influence the response to pharmacological agents, device therapy and cardiac rehabilitation in patients with heart failure. In this Review, we discuss the similarities between men and women in their response to heart failure therapies, as well as the sex-related differences in treatment benefits, dose-response relationships, and tolerability and safety of guideline-directed medical therapy, device therapy and cardiac rehabilitation. We provide insights into the unique challenges faced by men and women with heart failure, highlight potential avenues for tailored therapeutic approaches and call for sex-specific evaluation of treatment efficacy and safety in future research.

Disparities in Referral and Utilization of Implantable Cardioverter-Defibrillators for Primary Prevention of Sudden Cardiac Death

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) reduce mortality in patients with reduced left ventricular ejection fraction (LVEF). We investigated sex disparities in a contemporary Canadian population for utilization of primary prevention ICDs.

METHODS

This was a retrospective cohort study on patients with reduced LVEF admitted to hospitals from 2010 to 2020 in Nova Scotia (population = 971,935).

RESULTS

There were 4406 patients eligible for ICDs: 3108 (71%) men and 1298 (29%) women. The mean follow-up time was 3.9 ± 3.0 years. Rates of coronary disease were similar between men and women (45.8% vs 44.0%; P = 0.28), but men had lower LVEF (26.6 ± 5.9% vs 27.2 ± 5.8%; P = 0.0017). The referral rate for ICD was 11% (n = 487), with 13% of men (n = 403) and 6.5% of women (n = 84) referred (P < 0.001). The ICD implantation rate in the population was 8% (n = 358), with 9.5% of men (n = 296) and 4.8% of women (n = 62) (P < 0.001) receiving the device. Men were more likely than women to receive an ICD (odds ratio 2.08, 95% confidence interval 1.61-2.70; P < 0.0001)). There was no significant difference in mortality between men and women (P = 0.2764). There was no significant difference in device therapies between men and women (43.8% vs 31.1%; P = 0.0685).

CONCLUSIONS

A significant disparity exists in the utilization of primary prevention ICDs between men and women in a contemporary Canadian population.

Sex differences in ventricular arrhythmias epidemiology, risk factors, and mortality in congestive heart failure

BACKGROUND

Female patients are underrepresented in randomized controlled clinical trials and registries of ventricular arrhythmia (VA). Personalized prevention and therapies require an understanding of sex differences in risk factors and prognosis of VA.

OBJECTIVE

We aimed to assess sex differences in the incidence, risk factors, and mortality of VA in congestive heart failure (HF) patients.

METHODS

This study included 10,889 patients (mean [SD] age, 73.8 [13.4] years; 5917 [53.8%] male) with congestive HF, of which 1555 (14.3%) patients developed VA during hospitalization. VA incidence, potential risk factors, and in-hospital mortality were evaluated in both sexes.

RESULTS

Men were more strongly associated with incident VA compared with women (odds ratio [OR]: 2.006, 95% CI: 1.790-2.248, p < 0.001). Thirteen potential predictors, which accounted for 91.0% of the risk of VA in men and 88.2% in women, were included in this study. There were significant interactions by sex in the association between incident VA, atrial fibrillation (AF) (relative risk ratio = 0.730, 95% CI: 0.571-0.933, interaction p = 0.012), and non-ischemic cardiomyopathy (NICM) (relative risk ratio = 1.391, 95% CI: 1.029-1.872, interaction p = 0.030). Congestive HF patients developed with VA had an approximately 1.5-fold risk of in-hospital mortality, which was not affected by sex.

CONCLUSIONS

In congestive HF patients, incident VA was an independent risk factor of in-hospital mortality, and male sex was strongly associated with an increased risk of VA. Awareness of sex differences in the association of AF and NICM with VA may enhance therapeutic decisions, thus improving their clinical outcomes.

Differences in mode of death between men and women receiving implantable cardioverter-defibrillators or cardiac resynchronization therapy in the MADIT trials

BACKGROUND

Studies have reported sex differences in outcomes following implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy-defibrillator (CRT-D) implantation. However, little is known about sex differences with regard to mode of death or device efficacy following ICD or CRT-D implantation.

OBJECTIVES

The purpose of this study was to investigate whether sex influenced mode of death or device efficacy in ICD and CRT-D subjects enrolled in the MADIT (Multicenter Automatic Defibrillator Implantation Trial) studies (MADIT-II, MADIT-CRT, and MADIT-RIT).

METHODS

The combined MADIT cohort consisted of 3038 men and 1000 women with ischemic cardiomyopathy (ICM) or nonischemic cardiomyopathy (NICM), left ventricular ejection fraction ≤30%; New York Heart Association functional class I-III heart failure who received ICD or CRT-D. Mode of death was divided into cardiac and noncardiac causes, reviewed by independent adjudication committees.

RESULTS

A total of 295 men and 66 women died (9.7% vs 6.6%; P =.003) during 26 months. The most common cause of death was nonarrhythmic cardiac death in men (n = 121 [41%]) and noncardiac death in women (n = 22 [33%]). All-cause mortality and cardiac deaths were 1.5- to 2.0-fold higher in men vs women with ICM but similar for those with NICM after adjustment for covariates. ICD efficacy was similar in men and women, resulting in a 50% reduction in all-cause mortality. CRT-D was more effective at reducing all-cause and cardiac death in women than men.

CONCLUSION

Mode of death differs between sex and is dependent on the underlying cardiac substrate. Compared to women, cardiac death is higher in men with ICM but similar in those with NICM. ICDs are equally effective at reducing mortality in both men and women. However, CRT-D may be more effective at reducing mortality in women.

Ventricular Arrhythmias and Implantable Cardioverter-Defibrillator Therapy in Women: A Propensity Score-Matched Analysis

BACKGROUND

Causes of sex differences in incidence of sustained ventricular arrhythmias (SVAs) are poorly understood.

OBJECTIVES

This study aims to investigate sex-specific risk of SVAs and device therapies by balancing sex groups in relation to several baseline characteristics with the propensity score (PS).

METHODS

We used a large remote monitoring dataset from implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-Ds). Study endpoints were time to the first appropriate SVA, time to the first device therapy for SVA, and time to the first ICD shock. Results were compared between females and a PS-matched male subgroup.

RESULTS

In a cohort of 2,532 patients with an ICD or CRT-D (median age, 70 years), 488 patients (19.3%) were women. After selecting 488 men PS-matched for 19 variables relative to baseline demographics, implant indications, principal comorbidities, and concomitant therapy, yet the SVA rate at the 2.1-year median follow-up was significantly lower in women than in man (adjusted HR: 0.65; 95% CI: 0.51-0.81; P < 0.001). Women also showed a reduced risk of any device therapy (HR: 0.59; 95% CI: 0.45-0.76; P < 0.001) and shocks (HR: 0.66; 95% CI: 0.47-0.94; P = 0.021). Differences in sex-specific SVA risk profile were not confirmed in CRT-D patients (HR: 0.78; 95% CI: 0.55-1.09; P = 0.14) nor in those with an ejection fraction <30% (HR: 0.80; 95% CI: 0.52-1.23; P = 0.31).

CONCLUSIONS

After matching demographics, indications, principal comorbidities, and concomitant therapy, women still exhibited a lower SVA risk profile than men, except in the subgroups of CRT-D or/and ejection fraction <30%.

Comparison of Frequency of Ventricular Tachyarrhythmia in Men-Versus-Women in Patients with Implantable Cardioverter-Defibrillator for Primary Prevention

Current guidelines do not account for possible sex differences in the risk of ventricular tachyarrhythmia (VTA). We sought to identify specific factors associated with increased risk for VTA in women implanted with a primary prevention implantable cardioverter-defibrillator (ICD). Our study cohort consisted of 4,506 patients with an ICD or cardiac resynchronization therapy-defibrillator who were enrolled in the 4 landmark MADIT studies - MADIT-II, MADIT-RISK, MADIT-CRT and MADIT-RIT (1,075 women [24%]). Fine and Gray regression models were used to identify female-specific risk factors for the primary end point of VTA, defined as ICD-recorded, treated, or monitored, sustained ventricular tachycardia ≥170 beats per minute or ventricular fibrillation. At 3.5 years of follow-up, the cumulative incidence of VTA was significantly lower in women than men (17% vs 26%, respectively; p <0.001 for the entire follow-up). Use of amiodarone at enrollment, Black race, and history of previous myocardial infarction without previous revascularization was found to be independent risk factors of VTA in women. Of these factors, only Black race was associated with a statistically significant risk increase in men. At 3.5 years, the cumulative incidence of VTA in women with one or more of these risk factors was 27% compared with 14% in women with none of the risk factors (hazard ratio [confidence interval] = 2.08 [1.49 to 2.91]). In conclusion, our study, comprising 4 landmark ICD clinical trials, shows that sex and race have the potential to be used for improved risk stratification of patients who are candidates for primary prevention ICD.

Inequality between women and men in ICD implantation

Background

The impact of sex on ICD implantation practice and survival remain a topic of controversy. To assess sex-specific differences in ICD implantation practice we compared clinical characteristics and survival in women and men.

Methods

From a nationwide registry, all new ICD implantations performed between 01/02/2010 and 31/01/2019 in Belgian patients were analyzed retrospectively. Baseline characteristics and survival rates were compared between sexes. To identify predictors of mortality, multivariable Cox regression was performed.

Results

Only 3096 (20.9%) of 14,787 ICD implantations were performed in women. Within each type of underlying cardiomyopathy, the proportion women were lower than men. The main indication in men was ischemic vs dilated cardiomyopathy in women. Women were overall younger (59.1 ± 15.1 vs 62.6 ± 13.1 years; p < 0.001) and had less comorbidities except for oncological disease. More women functioned in NYHA-class III (33.6% vs 27.9%; p < 0.001) and had a QRS > 150 ms (29.4% vs 24.3%; p < 0.001), consistent with a higher use of CRT-D devices (31.7% vs 25.1%; p < 0.001). Women had more complications, reflected by the need to more re-interventions within 1 year (4.3% vs 2.7%, p < 0.001). After correction for covariates, sex-category was not a significant predictor of mortality (p = 0.055).

Conclusion

There is a significant sex-disparity in ICD implantation rates, not fully explained by epidemiological differences in the prevalence of cardiomyopathies, which could imply an undertreatment of women. Women differ from men in baseline characteristics at implantation suggesting a selection bias. Further research is necessary to evaluate if women receive equal sudden cardiac death prevention.

Sex Differences in the Risk of First and Recurrent Ventricular Tachyarrhythmias Among Patients Receiving an Implantable Cardioverter-Defibrillator for Primary Prevention

Importance

Current guidelines for primary implantable cardioverter-defibrillator (ICD) therapy do not account for sex differences in arrhythmic risk in ICD candidates.

Objective

To evaluate the association between sex and risk of ventricular tachyarrhythmia (VTA) and mortality.

Design, Setting, and Participants

This cohort study compared differences in the risk of VTA and mortality between 4506 men and women enrolled in the 4 Multicenter Automatic Defibrillator Implantation Trials (MADIT) between July 1, 1997, and December 31, 2011. Data from prospective randomized controlled multicenter studies were analyzed retrospectively. Men and women with an ICD or cardiac resynchronization therapy defibrillator who were enrolled in all MADIT studies were included. Data were analyzed between January 10 and June 10, 2021.

Exposures

ICD implant.

Main Outcomes and Measures

The primary end point was sustained VTA, defined as ICD-recorded, treated or monitored VTA at least 170/min or ventricular fibrillation. Secondary VTA end points included VTA at least 200/min, appropriate ICD shocks, and appropriate antitachycardia pacing. All end points were included in a first and recurrent event analysis.

Results

Of the 4506 study participants, 3431 were men (76%). Mean (SD) age of the cohort was 64 (12) years. For women vs men, the mean (SD) age (64 [12] years vs 64 [11] years) and left ventricular ejection fraction (24% vs 25%) were similar, but women exhibited a higher frequency of nonischemic cardiomyopathy (454 of 1075 women [42%] vs 2535 of 3431 men [74%]). Women had significantly lower 3-year cumulative probability of sustained VTA (16% vs 26%), fast VTA (9% vs 17%), and appropriate ICD shocks (7% vs 15%) compared with men (P < .001 for all). Multivariable analysis showed that female sex was independently associated with at least 40% lower risk of all first and recurrent VTA end points (P < .001 for all), including the primary end point (first event, HR = 60 [95% CI, 50-73], P < .001; recurrent event, HR = 49 [95% CI, 43-55], P < .001), after accounting for the competing risk of all-cause mortality and nonarrhythmic mortality. The lower VTA risk associated with female sex was consistent in risk subsets but was significantly more pronounced in patients with nonischemic cardiomyopathy (female vs male in the ischemic group: hazard ratio, 0.73 [95% CI, 0.56-0.95], P = .02; nonischemic group: hazard ratio, 0.50 [95% CI, 0.38-0.66], P < .001; P = .03 for interaction between female sex and cardiomyopathy).

Conclusions and Relevance

Findings suggest that women display a significantly lower risk of first and recurrent life-threatening VTA events than men, and that it is more pronounced in patients with nonischemic cardiomyopathy, suggesting a need for sex-specific risk assessment for primary prevention ICD therapy.

Underrepresentation of women in implantable cardioverter defibrillator trials

There are sex differences in the epidemiology and presentation of ventricular arrhythmias. Sudden cardiac death (SCD) is less common in women than in men. Women have been under-represented in implantable cardioverter defibrillator (ICD) trials evaluating the benefit of ICD therapy for primary and secondary prevention of SCD. Following ICD implantation, women are less likely to experience appropriate ICD therapy for ventricular arrhythmias, consistent with epidemiological findings of a lower rate of SCD in women. Sex differences in ICD implantation rates have also been noted for primary and secondary prevention of SCD in registries and large observational cohort studies. Reasons for these differences are unclear. Age and comorbidities at the time of presentation may be partially responsible, although sex bias, patient preference, or contribution of social determinants of health cannot be excluded. There are many unanswered questions regarding reasons for sex differences in ICD usage and under-representation of women in clinical device trials. Additional investigation is needed to better understand these differences to improve outcome of all patients who are at risk for sudden cardiac arrest.

Representation of women in heart failure clinical trials: Barriers to enrollment and strategies to close the gap

Heart failure is a significant public health burden that differentially impacts women. Important sex- and gender-based differences in HF risk factors, presentation, and treatment exist, and the generation of high-quality evidence is critical to elucidate these differences. Despite the remarkable growth of the heart failure clinical research enterprise over the last four decades, women remain underrepresented in heart failure clinical trials relative to the population prevalence of heart failure in women. This disparity has resulted in significant knowledge gaps regarding the optimal care of women with heart failure. In this review, we summarize the existing literature regarding the participation of women in heart failure clinical trials. Additionally, we explain the evidence surrounding sex- and gender-specific barriers to enrollment in heart failure clinical trials and describe interventions that should be implemented throughout the clinical trial lifespan to achieve sex and gender parity.

Arrhythmia in Cardiomyopathy: Sex and Gender Differences

PURPOSE OF REVIEW

There is emerging evidence for important sex differences in cardiac arrhythmias. In this up-to-date review, we summarise the differences in incidence, aetiology, treatment and prevention of ventricular arrhythmias (VAs) and sudden cardiac death (SCD) in women versus men, in the context of ischaemic and nonischaemic cardiomyopathies.

RECENT FINDINGS

The incidence of ventricular tachyarrhythmia and SCD is significantly lower in women than in men with ischaemic cardiomyopathy, whereas sex differences in nonischaemic cardiomyopathy are less clear. Women who receive a primary prevention implantable cardioverter-defibrillator (ICD) are less likely to receive appropriate activations, compared to men; however, such findings are limited by under-representation of women. Women with ischaemic cardiomyopathy have significantly lower incidence of VA and SCD compared to men and may not derive the same benefit from a primary prevention ICD. However, further clinical ICD studies are needed that ensure adequate female participation, in order to examine sex differences in outcomes in both ischaemic and nonischaemic cardiomyopathies.

Sex differences in implantable cardiac defibrillator therapy according to arrhythmia detection times

OBJECTIVE

In implantable cardiac defibrillators (ICDs), long-detection times safely reduce unnecessary and inappropriate therapies. We aimed to evaluate ICD treatment of ventricular arrhythmias in women, compared with men, also taking into account ICD detection.

METHODS

The Advance III trial randomised patients implanted with an ICD for primary or secondary prevention in two arms-long and nominal ventricular arrhythmias detection times before therapy delivering (number of intervals needed to detect (NID) 30/40 and 18/24, respectively). The main endpoint of this post hoc analysis was the incidence of ICD therapies evaluated through Kaplan-Meier method and univariate Cox regression models.

RESULTS

Overall, 1902 patients (304 women, 65±11 years) were randomised. Women showed a lower risk of ICD therapy (HR 0.63, 95% CI 0.43 to 0.93, p=0.022); this difference was observed only in the long-detection arm (HR 0.37, p=0.013) and not in the short detection arm (HR 0.82, p=0.414). No significant sex differences were observed concerning inappropriate therapies and mortality rate. Long-detection settings significantly reduced overall ICD therapies and appropriate ICD therapies, both in women (overall HR 0.31, p=0.007; appropriate HR 0.33, p=0.033) and in men (overall HR 0.69, p=0.006; appropriate HR 0.73, p=0.048).

CONCLUSIONS

In patients with ICDs, the strategy of setting a long-detection time to treat ventricular arrhythmias (NID 30/40) reduces overall delivered therapies, both in women and men, when compared with nominal setting (NID 18/24). The reduction was significantly higher in women. Overall, women were less likely to experience ICD therapies than men; this result was only observed in the long-detection arm.

CLINICAL TRIAL REGISTRATION

NCT00617175.

Implantable Cardioverter-Defibrillators and Cardiac Resynchronization Therapy in Women

Implantable cardioverter-defibrillator and cardiac resynchronization therapy devices have been prescribed for patients with heart failure for several decades. Factors leading to increased usage include significant enhancements in technology and availability of multiple randomized clinical trials demonstrating their benefit with improved implementation of evidence-based guidelines. Despite these advances, gaps still exist in the utilization and referral of these devices, particularly among women. This article reviews the literature on these devices with a focus on gender differences and proposes reasons for why they exist.

Implantable cardiac defibrillators for people with non-ischaemic cardiomyopathy

BACKGROUND

There is evidence that implantable cardioverter-defibrillator (ICD) for primary prevention in people with an ischaemic cardiomyopathy improves survival rate. The evidence supporting this intervention in people with non-ischaemic cardiomyopathy is not as definitive, with the recently published DANISH trial finding no improvement in survival rate. A systematic review of all eligible studies was needed to evaluate the benefits and harms of using ICDs for primary prevention in people with non-ischaemic cardiomyopathy.

OBJECTIVES

To evaluate the benefits and harms of using compared to not using ICD for primary prevention in people with non-ischaemic cardiomyopathy receiving optimal medical therapy.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and the Web of Science Core Collection on 10 October 2018. For ongoing or unpublished clinical trials, we searched the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov, the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP), and the ISRCTN registry. To identify economic evaluation studies, we conducted a separate search to 31 March 2015 of the NHS Economic Evaluation Database, and from March 2015 to October 2018 on MEDLINE and Embase.

SELECTION CRITERIA

We included randomised controlled trials involving adults with chronic non-ischaemic cardiomyopathy due to a left ventricular systolic dysfunction with an ejection fraction of 35% or less (New York Heart Association (NYHA) type I-IV). Participants in the intervention arm should have received ICD in addition to optimal medical therapy, while those in the control arm received optimal medical therapy alone. We included studies with cardiac resynchronisation therapy when it was appropriately balanced in the experimental and control groups.

DATA COLLECTION AND ANALYSIS

The primary outcomes were all-cause mortality, cardiovascular mortality, sudden cardiac death, and adverse events associated with the intervention. The secondary outcomes were non-cardiovascular death, health-related quality of life, hospitalisation for heart failure, first ICD-related hospitalisation, and cost. We abstracted the log (hazard ratio) and its variance from trial reports for time-to-event survival data. We extracted the raw data necessary to calculate the risk ratio. We summarised data on quality of life and cost-effectiveness narratively. We assessed the certainty of evidence for all outcomes using GRADE.

MAIN RESULTS

We identified six eligible randomised trials with a total of 3128 participants. The use of ICD plus optimal medical therapy versus optimal medical therapy alone decreases the risk of all-cause mortality (hazard ratio (HR) 0.78, 95% confidence interval (CI) 0.66 to 0.92; participants = 3128; studies = 6; high-certainty evidence). An average of 24 patients need to be treated with ICD to prevent one additional death from any cause (number needed to treat for an additional beneficial outcome (NNTB) = 24). Individuals younger than 65 derive more benefit than individuals older than 65 (HR 0.51, 95% CI 0.29 to 0.91; participants = 348; studies = 1) (NNTB = 10). When added to medical therapy, ICDs probably decrease cardiovascular mortality compared to not adding them (risk ratio (RR) 0.75, 95% CI 0.46 to 1.21; participants = 1781; studies = 4; moderate-certainty evidence) (possibility of both plausible benefit and no effect). Implantable cardioverter-defibrillator was also found to decrease sudden cardiac deaths (HR 0.45, 95% CI 0.29 to 0.70; participants = 1677; studies = 3; high-certainty evidence). An average of 25 patients need to be treated with an ICD to prevent one additional sudden cardiac death (NNTB = 25). We found that ICDs probably increase adverse events (possibility of both plausible harm and benefit), but likely have little or no effect on non-cardiovascular mortality (RR 1.17, 95% CI 0.81 to 1.68; participants = 1781; studies = 4; moderate-certainty evidence) (possibility of both plausible benefit and no effect). Finally, using ICD therapy probably has little or no effect on quality of life, however shocks from the device cause a deterioration in quality of life. No study reported the outcome of first ICD-related hospitalisations.

AUTHORS' CONCLUSIONS

The use of ICD in addition to medical therapy in people with non-ischaemic cardiomyopathy decreases all-cause mortality and sudden cardiac deaths and probably decreases mortality from cardiovascular causes compared to medical therapy alone. Their use probably increases the risk for adverse events. However, these devices come at a high cost, and shocks from ICDs cause a deterioration in quality of life.

Advances in Cardiovascular Health in Women over the Past Decade: Guideline Recommendations for Practice

Cardiovascular disease (CVD) remains the number one cause of death in women. It is estimated that 44 million women in the United States are either living with or at risk for heart disease. This article highlights the recent significant progress made in improving care, clinical decision-making, and policy implications for women with CVD. We provide our perspective supported by evidence-based advances in cardiovascular research and clinical care guidelines in seven areas: (1) primary CVD prevention and community heart care, (2) secondary prevention of CVD, (3) stroke, (4) heart failure and cardiomyopathies, (5) ischemia with nonobstructive coronary artery disease, (6) spontaneous coronary artery dissection, and (7) arrhythmias and device therapies. Advances in these fields have improved the lives of women living with and at risk for heart disease. With increase awareness, partnership with national organizations, sex-specific research, and changes in policy, the morbidity and mortality of CVD in women can be further reduced.

Sex Differences in Heart Failure

Heart failure (HF) represents a global pandemic health problem with a high impact on health-care costs, affecting about 26 million adults worldwide. The overall HF prevalence and incidence are ~2% and ~0.2% per year, respectively, in Western countries, with half of the HF population with reduced ejection fraction (HFpEF) and half with preserved (HFpEF) or mid-range ejection fraction (HFmrEF). Sex differences may exist in HF. More males have HFrEF or HFmrEF and an ischemic etiology, whereas more females have HFpEF and hypertension, diastolic dysfunction, and valvular pathologies as HF etiologies. Females are generally older, have a higher EF, higher frequency of HF-related symptoms, and lower NYHA functional status. Generally, it is observed that female HF patients tend to have more comorbidities such as atrial fibrillation, diabetes, hypertension, anemia, iron deficiency, renal disease, arthritis, frailty, depression, and thyroid abnormalities. However, overall, females have better prognosis in terms of mortality and hospitalization risk compared with men, regardless of EF. Potential sex differences in HF characteristics may be underestimated because of the underrepresentation of females in cardiovascular research and, in particular, the sex imbalance in clinical trial enrollment may avoid to identify sex-specific differences in treatments' benefit.

Atrial Fibrillation and Ventricular Arrhythmias: Sex Differences in Electrophysiology, Epidemiology, Clinical Presentation, and Clinical Outcomes

Sex-specific differences in the epidemiology, pathophysiology, clinical presentation, clinical treatment, and clinical outcomes of atrial fibrillation (AF), sustained ventricular arrhythmias, and sudden cardiac death are recognized. Sex hormones cause differences in cardiac electrophysiological parameters between men and women that may affect the risk for arrhythmias. The incidence and prevalence of AF is lower in women than in men. However, because women live longer and AF prevalence increases with age, the absolute number of women with AF exceeds that of men. Women with AF are more symptomatic, present with more atypical symptoms, and report worse quality of life in comparison with men. Female sex is an independent risk factor for death or stroke attributable to AF. Oral anticoagulation therapy for stroke prevention has similar efficacy for men and women, but older women treated with warfarin have a higher residual risk of stroke in comparison with men. Women with AF are less likely to receive rhythm control antiarrhythmic drug therapy, electric cardioversion, or catheter ablation in comparison with men. The incidence and prevalence of sustained ventricular arrhythmias and sudden cardiac death are lower in women than in men. Women receiving implantable cardioverter defibrillators for primary prevention of sudden cardiac death are less likely to experience sustained ventricular arrhythmias in comparison with men. In contrast, women receiving a cardiac resynchronization therapy implantable cardioverter defibrillator for the treatment of heart failure are more likely to benefit than men. Women are less likely to be referred for implantable cardioverter defibrillator therapy despite current guideline recommendations. Women are more likely to experience a significant complication related to implantable cardioverter defibrillator implantation in comparison with men. Whether sex differences in treatment decisions reflect patient preferences or treatment biases requires further study.

Analysis of ECG Measures of Cardiac Repolarization in Relation to Arrhythmic Events in an Implantable Cardioverter Defibrillator Population

BACKGROUND

ECG-derived measures of cardiac repolarization may have utility in risk prediction of future ventricular arrhythmia, and a range of different measures have been proposed. We compared time-based, vectorcardiographic, and singular value decomposition (SVD) derived measures of repolarization to determine which was most predictive of appropriate therapy in an ICD population.

METHODS

We examined the independent prognostic value of a range of repolarization measures derived from 60 second 12-lead ECG recordings in 150 patients receiving new ICD implants in relation to the occurrence of appropriate therapy during follow-up.

RESULTS

Over an average follow-up of 2.15 ± 0.87 years, male gender, presence of premature ventricular complex (PVC), relative T wave residuum (TWR-rel, measures regional repolarization heterogeneity), and TCRT (the total cosine R-to-T, describes the global angle between repolarization and depolarization wavefronts) were the only independent predictors of appropriate therapy. With every 0.01% increase in TWR-rel, there was 2% increased risk of appropriate therapy (HR = 1.02, 95% CI 1.006-1.034, P < 0.001). With every 1° decrease in TCRT, there was an increase in arrhythmic risk of 0.9% (HR 1.009, 95% CI 1.003-1.015, P = 0.003).

CONCLUSIONS

The use of advanced analytic ECG techniques to derive measures of repolarization abnormality might shave utility in risk stratification in an ICD population.

Sex difference in appropriate shocks but not mortality during long-term follow-up in patients with implantable cardioverter-defibrillators

AIMS

Implantable cardioverter-defibrillators (ICDs) have been shown to improve survival, although a considerable number of patients never receive therapy. Implantable cardioverter-defibrillators are routinely implanted regardless of sex. There is continuing controversy whether major outcomes differ between men and women.

METHODS AND RESULTS

In this retrospective single-centre study, 1151 consecutive patients (19% women) undergoing ICD implantation between 1998 and 2010 were followed for mortality and first appropriate ICD shock over 4.9 ± 2.7 years. Sex-related differences were investigated using multivariable Cox models adjusting for potential confounders. During follow-up, 318 patients died, a rate of 5.9% per year among men and 4.6% among women (uncorrected P = 0.08); 266 patients received a first appropriate ICD shock (6.3% per year among men vs. 3.6% among women, P = 0.002). After multivariate correction, independent predictors of all-cause mortality were age (hazard ratio, HR = 1.04 per year of age, 95% confidence interval (CI) [1.03-1.06], P < 0.001), left ventricular ejection fraction (HR = 0.98 per %, 95% CI [0.97-1.00], P = 0.025), renal function (HR = 0.99 per mL/min/1.73 m(2), 95% CI [0.99-1.00], P = 0.009), use of diuretics (HR = 1.81, 95% CI [1.29-2.54], P = 0.0023), peripheral arterial disease (HR = 2.21, 95% CI [1.62-3.00], P < 0.001), and chronic obstructive pulmonary disease (HR = 1.48, 95% CI [1.13-1.94], P = 0.029), but not sex. Female sex (HR = 0.51, 95% CI [0.33-0.81], P = 0.013), older age (HR = 0.98, 95% CI [0.97-0.99], P < 0.001), and primary prophylactic ICD indication (HR = 0.69, 95% CI [0.52-0.93], P = 0.043) were independent predictors for less appropriate shocks.

CONCLUSION

Women receive 50% less appropriate shocks than men having similar mortality in this large single-centre population. These data may pertain to individually improved selection of defibrillator candidates using risk factors, e.g. sex as demonstrated in this study.

Gender and outcomes after primary prevention implantable cardioverter-defibrillator implantation: Findings from the National Cardiovascular Data Registry (NCDR)

BACKGROUND

Clinical trials have demonstrated the benefit of implantable cardioverter-defibrillators (ICDs) for the primary prevention of sudden cardiac death in selected high-risk individuals. Because of small numbers of women enrolled in these trials, outcomes for women after hospital discharge have not been well described. We compared procedure-related complications and outcomes after hospital discharge between men and women undergoing single- or dual-chamber ICD implantation for primary prevention.

METHODS

In patients 65 years or older with Medicare fee-for-service coverage, we identified 38,912 initial implants (25% women) who received single- or dual-chamber ICDs for primary prevention between January 2006 and December 2009 in the NCDR and evaluated gender differences in outcomes.

RESULTS

Women had greater comorbidity and more advanced heart failure (HF) at the time of ICD implantation than did men. Device-related complications, death at 6 months, all-cause readmissions, and HF readmissions at 6 months were significantly more common in women (7.2% vs 4.8%, 6.5% vs 5.6%, 37.2% vs 31.7%, and 14.0% vs 10.0% respectively; P < .001 for all). Women continued to have higher odds of procedural complications (odds ratio [OR] 1.39, 95% CI 1.26-1.53, P < .001), 6-month all-cause readmission (OR 1.22, 95% CI 1.16-1.28, P < .001), and 6-month HF readmission (OR 1.32, 95% CI 1.23-1.42, P < .001), with a trend toward higher 6-month mortality (OR 1.08, 95% CI 0.98-1.20, P = .123), compared with men, after adjusting for differences in baseline characteristics and device type (single vs dual chamber).

CONCLUSIONS

Among older patients receiving ICDs for primary prevention in clinical practice, women experience worse outcomes than do men. Reasons for gender differences in outcomes are poorly understood and require further investigation.

Use of Implantable Cardioverter Defibrillators in Heart Failure Patients and Risk of Mortality: A Meta-Analysis

BACKGROUND

The purpose of this study was to evaluate the effect of implantable cardioverter defibrillators (ICD) in heart failure (HF) patients compared to pharmacologic/conventional management.

MATERIAL AND METHODS

We searched PubMed, Embase, and Springer Link Library databases up to February 10th, 2014. Pooled risk ratio (RR) and 95% confidence interval (CI) for the mortality of the patients with HF were collected and calculated in a fixed-effects model or a random-effects model, as appropriate. Summary effect estimates were also stratified by sex and follow-up time. Egger's regression asymmetry tests were utilized for publication bias detection.

RESULTS

A total of 7 separate studies including 15 520 patients (10 801 ICD cases and 4719 controls) with HF were considered in the meta-analysis. The overall estimates showed that ICD could statistically significantly reduce the mortality of male (RR=0.73, 95% CI: 0.66-0.80) and female (RR=0.75, 95% CI: 0.63-0.90) patients. In addition, the further stratification subgroup analysis indicated that ICD presented a significant reduction (male: RR=0.72, 95% CI: 0.64-0.81; female: RR=0.69, 95% CI: 0.56-0.85) of mortality after 2-3 years of ICD therapy. The RR (95% CI) effects of mortality after 4-5 years of ICD therapy for males and females were 0.76 (0.51-1.14) and 0.96 (0.68-1.37), respectively.

CONCLUSIONS

This meta-analysis suggests that ICD could reduce HF patient mortality despite the sex difference.

Age and sex differences in long-term outcomes following implantable cardioverter-defibrillator placement in contemporary clinical practice: findings from the Cardiovascular Research Network

Background

Patient sex and age may influence rates of death after receiving an implantable cardioverter-defibrillator for primary prevention. Differences in outcomes other than mortality and whether these differences vary by heart failure symptoms, etiology, and left ventricular ejection fraction are not well characterized.

Methods and Results

We studied 2954 patients with left ventricular ejection fraction ≤0.35 undergoing first-time implantable cardioverter-defibrillator for primary prevention within the Cardiovascular Research Network; 769 patients (26%) were women, and 2827 (62%) were aged >65 years. In a median follow-up of 2.4 years, outcome rates per 1000 patient-years were 109 for death, 438 for hospitalization, and 111 for heart failure hospitalizations. Procedure-related complications occurred in 8.36%. In multivariable models, women had significantly lower risks of death (hazard ratio 0.67, 95% CI 0.56 to 0.80) and heart failure hospitalization (hazard ratio 0.82, 95% CI 0.68 to 0.98) and higher risks for complications (hazard ratio 1.38, 95% CI 1.01 to 1.90) than men; patients aged >65 years had higher risks of death (hazard ratio 1.55, 95% CI 1.30 to 1.86) and heart failure hospitalization (hazard ratio 1.25, 95% CI 1.05 to 1.49) than younger patients. Age and sex differences were generally consistent in strata according to symptoms, etiology, and severity of left ventricular systolic dysfunction, except the higher risk of complications in women, which differed by New York Heart Association classification (P=0.03 for sex–New York Heart Association interaction), and the risk of heart failure hospitalization in older patients, which differed by etiology of heart failure (P=0.05 for age–etiology interaction).

Conclusions

The burden of adverse outcomes after receipt of an implantable cardioverter-defibrillator for primary prevention is substantial and varies according to patient age and sex. These differences in outcome generally do not vary according to baseline heart failure characteristics.

ICD and CRT use in ischemic heart disease in women

Although the role of implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy (CRT) in improving outcomes in ischemic cardiomyopathy (ICM) has been described, the data regarding gender-based survival outcomes are limited. There is a higher preponderance of non-ischemic cardiomyopathy (NICM) in women, and most of the ICM literature is derived from sub-study analysis. This review summarizes the current body of literature on prognosis, pathophysiology, and the present clinical practice for device implantation in women with ICM.

Outcomes of implantable cardioverter-defibrillator use in patients with comorbidities: results from a combined analysis of 4 randomized clinical trials

OBJECTIVES

The aim of this study was to determine if the benefit of implantable cardioverter-defibrillators (ICDs) is modulated by medical comorbidity.

BACKGROUND

Primary prevention ICDs improve survival in patients at risk for sudden cardiac death. Their benefit in patients with significant comorbid illness has not been demonstrated.

METHODS

Original, patient-level datasets from MADIT I (Multicenter Automatic Defibrillator Implantation Trial I), MADIT II, DEFINITE (Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation), and SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) were combined. Patients in the combined population (N = 3,348) were assessed with respect to the following comorbidities: smoking, pulmonary disease, diabetes, peripheral vascular disease, atrial fibrillation, ischemic heart disease, and chronic kidney disease. The primary outcome was overall mortality, using the hazard ratio (HR) of time to death for patients receiving an ICD versus no ICD by extent of medical comorbidity, and adjusted for age, sex, race, left ventricular ejection fraction, use of antiarrhythmic drugs, beta-blockers, and angiotensin-converting enzyme inhibitors.

RESULTS

Overall, 25% of patients (n = 830) had <2 comorbid conditions versus 75% (n = 2,518) with significant comorbidity (≥2). The unadjusted hazard of death for patients with an ICD versus no ICD was significantly lower, but this effect was less for patients with ≥2 comorbidities (unadjusted HR: 0.71; 95% confidence interval: 0.61 to 0.84) compared with those with <2 comorbidities (unadjusted HR: 0.59; 95% confidence interval: 0.40 to 0.87). After adjustment, the benefit of an ICD decreased with increasing number of comorbidities (p = 0.004).

CONCLUSIONS

Patients with extensive comorbid medical illnesses may experience less benefit from primary prevention ICDs than those with less comorbidity; implantation should be carefully considered in sick patients. Further study of ICDs in medically complex patients is warranted.

Primary prevention implantable cardioverter-defibrillators and survival in older women

OBJECTIVES

The purpose of this study was to assess the benefit of primary prevention implantable cardioverter defibrillators (ICDs) in women.

BACKGROUND

Clinical trials of primary prevention ICDs enrolled a limited number of women.

METHODS

Using a propensity score method, we matched 490 women ≥65 years of age who received an ICD during a hospitalization for heart failure in the National Cardiovascular Data Registry ICD Registry from January 1, 2006, through December 31, 2007, to 490 ICD-eligible women without an ICD hospitalized for heart failure in the Get With The Guidelines for Heart Failure database from January 1, 2006, through December 31, 2009. The primary endpoint was all-cause mortality obtained from the Medicare Claims Database. An identical analysis was conducted in men.

RESULTS

Median follow-up for patients with an ICD was 4.6 years versus 3.2 years for patients with no ICD. Compared with women with no ICD, those with an ICD were younger and less frequently white. In the matched cohorts, the survival of women with an ICD was significantly longer than that of women without an ICD (adjusted hazard ratio: 0.79, 95% confidence interval: 0.66 to 0.95; p = 0.013). Similarly, men with an ICD had longer survival than men without an ICD (adjusted hazard ratio: 0.73, 95% confidence interval: 0.65 to 0.83; p < 0.0001). There was no interaction between sex and the presence of an ICD with respect to survival (p = 0.44).

CONCLUSIONS

Among older women with left ventricular dysfunction, a primary prevention ICD was associated with a significant survival benefit that was nearly identical to that seen in men. These findings support the use of primary prevention ICDs in eligible patients regardless of sex.

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.

Clinical Effectiveness of Cardiac Resynchronization and Implantable Cardioverter-Defibrillator Therapy in Men and Women With Heart Failure

Background—

Many clinical trials have demonstrated a benefit for cardiac resynchronization (CRT) and implantable cardioverter-defibrillator (ICD) therapies in patients with heart failure and reduced ejection fraction, yet questions have been raised with regard to the benefit of ICDs for women. The purpose of this study was to determine the clinical effectiveness of CRT and ICD therapy as a function of sex in outpatients with heart failure and reduced ejection fraction (≤35%).

Methods and Results—

Data from the Registry to Improve the Use of Evidence-Based Heart Failure Therapies in the Outpatient Setting (IMPROVE HF) were analyzed by device status and sex among guideline-eligible patients for vital status (alive/dead) at 24 months. Multivariate generalized estimating equation analyses were conducted adjusting for baseline patient and practice characteristics. In the ICD/CRT-defibrillator (CRT-D) eligible cohort (n=7748), there were 5485 (71%) men and 2261 (29%) women. In the CRT-pacemaker (CRT-P)/CRT-D eligible cohort (n=1188), there were 824 (69%) men and 364 (31%) women. The clinical benefit associated with ICD/CRT-D therapy was similar in both men and women (men adjusted odds ratio, 0.71; 95% confidence interval, 0.57–0.87; P =0.0012; and women adjusted odds ratio, 0.65; 95% confidence interval, 0.49–0.85; P =0.0019). For CRT-P/CRT-D, the associated benefits showed no significant heterogeneity (men adjusted odds ratio, 0.59; 95% confidence interval, 0.33–1.06; P =0.0793; and women adjusted odds ratio, 0.44; 95% confidence interval, 0.22–0.90; P =0.0243). The device-by-sex interactions were not significant ( P =0.4441 for CRT-P/CRT-D and P =0.5966 for ICD/CRT-D).

Conclusions—

The use of guideline-directed CRT and ICD therapy was associated with substantially reduced 24-month mortality in eligible men and women with heart failure and reduced ejection fraction. Device therapies should be offered to all eligible patients with heart failure, without modification based on sex.

Gender-specific differences in clinical outcome of primary prevention implantable cardioverter defibrillator recipients

OBJECTIVE

To assess differences in clinical outcome of implantable cardioverter-defibrillator (ICD) treatment in men and women.

DESIGN

Prospective cohort study.

SETTING

University Medical Center.

PATIENTS

1946 primary prevention ICD recipients (1528 (79%) men and 418 (21%) women). Patients with congenital heart disease were excluded for this analysis.

MAIN OUTCOME MEASURES

All-cause mortality, ICD therapy (antitachycardia pacing and shock) and ICD shock.

RESULTS

During a median follow-up of 3.3 years (25th-75th percentile 1.4-5.4), 387 (25%) men and 76 (18%) women died. The estimated 5-year cumulative incidence for all-cause mortality was 20% (95% CI 18% to 23%) for men and 14% (95% CI 9% to 19%) for women (log rank p<0.01). After adjustment for potential confounding covariates all-cause mortality was lower in women (HR 0.65; 95% CI 0.49 to 0.84; p<0.01). The 5-year cumulative incidence for appropriate therapy in men was 24% (95% CI 21% to 28%) as compared with 20% (95% CI 14% to 26%) in women (log rank p=0.07). After adjustment, a non-significant trend remained (HR 0.82; 95% CI 0.64 to 1.06; p=0.13).

CONCLUSIONS

In clinical practice, 21% of primary prevention ICD recipients are women. Women have lower mortality and tend to experience less appropriate ICD therapy as compared with their male peers.

Gender differences in the pathophysiology, clinical presentation, and outcomes of ischemic heart failure

Despite advances in the treatment of acute myocardial infarction (MI), heart failure (HF) remains a frequent acute and long-term outcome of ischemic heart disease (IHD). In response to acute coronary ischemia, women are relatively protected from apoptosis, and experience less adverse cardiac remodeling than men, frequently resulting in preservation of left ventricular size and ejection fraction. Despite these advantages, women are at increased risk for HF- complicating acute MI when compared with men. However, women with HF retain a survival advantage over men with HF, including a decreased risk of sudden death. Sex-specific treatment of HF has been hindered by historical under-representation of women in clinical trials, though recent work has suggested that women may have a differential response to some therapies such as cardiac resynchronization. This review highlights the sex differences in the pathophysiology, clinical presentation and outcomes of ischemic heart failure and discusses key areas worthy of further investigation.

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.

Sex Difference in Clinical Outcome of Patients With Implantable Cardioverter-defibrillator

BACKGROUND

Indications for the use of the Implantable Cardioverter-Defibrillator (ICD) have been greatly expanded in recent years, but the influence of sex on the efficacy of the ICD in eligible patients has still been remained unknown.

OBJECTIVES

The aim of this study was to determine the impact of sex on the effectiveness of the ICD intervention for mortality and appropriate events.

MATERIALS AND METHODS

This retrospective study was conducted on the outcome of the ICD therapy in 443 patients, including 341 men with a mean age of 55 ± 16 years and 102 women with a mean age of 54 ± 17 years, in our center between April 2001 and February 2007. Sex-specific cumulative probabilities of outcomes concerning mortality and appropriate ICD intervention were evaluated for the patients.

RESULTS

Among the 443 patients, enrolled in this study, the women and men had a mean left ventricular ejection fraction of 35 ± 14.8% and 30 ± 13.5%, respectively (P = 0.03). Ischemic heart disease was more frequent in the men than the women (P = 0.0001).The average follow-up period was 3 years. Test for an interaction between sex and the ICD treatment regarding total mortality was not significant (23 men and 6 women). Additionally, there was no significant difference in appropriate events between the women and men (129 men and 33 women).

CONCLUSIONS

While women were significantly less likely than the men to receive the ICD therapy, no conclusive evidence could be found for the impact of sex factor on the effectiveness of the ICD intervention with respect to mortality and appropriate events.

Use of implantable cardioverter-defibrillators

The implantable cardioverter-defibrillator (ICD) is the most effective treatment for patients with life-threatening ventricular tachycardia or ventricular fibrillation not due to reversible causes. The American College of Cardiology/American Heart Association class I and IIa indications for an ICD are discussed. Patients with ICDs who need pacing should be treated with biventricular pacing, not with dual-chamber rate-responsive pacing, at a rate of 70/min. Patients with ICDs should be treated with β-blockers, statins and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers.