Use Of Implantable Cardiac Defibrillators Research Articles

Contrasting patterns of symptoms compared to mortality in women and men with Congestive Heart Failure (the G-CHF registry)

Abstract Background There is a paucity of data on the clinical characteristics, management, and outcomes of women compared with men with heart failure, especially in low-and middle-income countries. Purpose In this study from the Global Congestive Heart Failure registry, we examined sex differences in risk factors, clinical characteristics, treatments, and the risk of heart failure hospitalization and mortality by country economic status and by left ventricular ejection fraction (LVEF) category. Methods In the prospective Global-Congestive Heart Failure (G-CHF) study, participants with established heart failure were considered for inclusion from 40 high-, middle-, and low-income countries. We recorded information on the demographic characteristics, medical history, and treatments of participants. We report data on heart failure hospitalization and mortality by sex overall, by country economic status, and by LVEF category. Results From December 2016 to July 2022, 23,000 participants were recruited and followed up. The average age of women in the study was 62 years compared to 64 years in men. Fewer women than men had a LVEF ≤40 (51.7% women vs 66.3% men). By contrast, more women than men had an LVEF≥ 50 (33.2% women vs 18.6% men). Hypertensive heart failure was the most common etiology in women (25.5% women vs 16.8% men), and ischemic heart failure was the most common etiology in men (45.6% men vs 26.6% women). Signs and symptoms of heart failure were more common in women than men: 42.6% of women were NYHA functional class III/IV compared to 37.9% of men. Among participants with a LVEF <35, use of implantable cardiac defibrillator (ICD) was lower in women than men in the overall study (8.7% women vs 17.2% men), and within countries categorized by economic status. However, the use of heart failure medicines and cardiac tests did not differ systematically by sex. Differences by sex were not observed in the adjusted risk of heart failure hospitalization overall (women-to-men adjusted hazard ratio 1.0 (95% CI 0.94 to 1.07)). This pattern was consistent within countries categorized by economic status, geographic region, and by LVEF category. Women had a lower adjusted risk of mortality overall (women-to-men adjusted hazard ratio 0.82 (95% CI 0.77 to 0.87), which was consistently observed within countries categories by economic status, geographic region, and LVEF levels. Conclusions There are differences between women and men in heart failure symptoms, underlying causes, ejection fraction categories, and use of an ICD. However, use heart failure medications, cardiac tests, and hospitalization were similar in women and men; but women had a lower risk of death.

A nationwide 16 year analysis of trends and impact of arrythmias in transplant recipients

Abstract Background Orthotopic heart transplantation is the most effective long-term therapy for end-stage heart disease. Denervation of transplanted heart with the loss of autonomic modulation, vasculopathy, utilization of immunosuppressant drugs, and risk of allograft rejection may result in change in the prevalence of arrhythmias in transplanted hearts. Purpose To describe the trends, distribution and the clinical impact of arrhythmias in transplanted hearts in a large nationwide population. Methods We queried the National Inpatient Sample with administrative codes. Cardiac transplant patients were identified using procedure ICD-9-CM codes 37.5 and 33.6. Common arrhythmias were extracted using appropriate validated ICD-9-CM codes. Statistical Analysis System (SAS) version 9.4 was used for analysis of data. Results There was a total of 30,020 hospitalizations of heart transplant recipients between 1999 and 2014 in the United States and 16342 (54.4%) of these had arrhythmias. The prevalence of total arrhythmias increased from 53.6% (n=1,158) in 1999 to 67.3% (n=1,575) in 2014. The most common arrhythmia was atrial fibrillation (26.83%) followed by ventricular tachycardia (22.86%) and the prevalence of individual arrhythmias is as shown in Figure 1. Cardiogenic shock was higher in transplanted hearts with arrhythmias when compared with patients without arrhythmias (25.96% vs 18.18%; p<0.001). Transplant recipients with arrhythmias were also associated with an increased use of mechanical circulatory device (18.22% vs 12.67%, p<0.001). The use of implantable cardiac defibrillators and permanent pacemaker was also higher in the arrhythmia group (2.19% vs 0.63% and 40.43% vs 30.24% respectively, p<0.0001). However, there was no significant difference in inpatient mortality between transplant recipients with arrhythmias and without arrhythmias (7.72% vs 6.90%, p=0.225). Further, there was no significant difference in frequency of strokes between the groups (4.98% vs 5.08%; p=0.857). The total hospital cost when adjusted for inflation was significantly higher in the arrhythmic patients, with an average cost of about $570,415±9,590 vs $439,707±8362 in patients without arrhythmias (p<0.0001). The mean length of hospitalization was 44.2±0.8 days in patients with arrhythmias compared to 33.9±0.8 days in patients without arrhythmias (p<0.0001). Conclusion A significant proportion of patients with heart transplant have cardiac arrhythmias and are associated with worse in-hospital outcomes of cardiogenic shock, increased length of stay, and cost of hospitalization. However, they are not associated with worse inpatient mortality. Funding Acknowledgement Type of funding source: None

Heart failure management in dialysis patients: Many treatment options with no clear evidence.

Heart failure with reduced ejection fraction (HFrEF) impacts approximately 20% of dialysis patients and is associated with high mortality rates. Key issues discussed in this review of HFrEF management in dialysis include dialysis modality choice, vascular access, dialysate composition, pharmacological therapies, and strategies to reduce sudden cardiac death, including the use of cardiac devices. Peritoneal dialysis and more frequent or longer duration of hemodialysis may be better tolerated due to slower ultrafiltration rates, leading to less intradialytic hypotension and better volume control; dialysate cooling and higher dialysate calcium may also have benefits. While high-quality evidence exists for many drug classes in the non-dialysis population, dialysis patients were excluded from major trials, and only limited data exist for many medications in kidney failure patients. Despite limited evidence, beta blocker and angiotensin-converting enzyme inhibitor or angiotensin receptor blocker use is common in dialysis. Similarly, devices such as implantable cardiac defibrillators (ICDs) and cardiac resynchronization therapy that have proven benefits in non-dialysis HFrEF patients have not consistently been beneficial in the limited dialysis studies. The use of leadless pacemakers and subcutaneous ICDs can mitigate future hemodialysis access limitations. Additional research is critical to address knowledge gaps in treating maintenance dialysis patients with HFrEF.

Heartbeat: When should patients consider implantable cardiac defibrillator deactivation?

The use of implantable cardiac defibrillators (ICDs) has dramatically improved outcomes for patients with many types of heart disease. Yet, the patient with an ICD faces a difficult decision near...

Several reasons explained the variation in the results of 22 meta-analyses addressing the same question

ObjectiveThe objective of this study was to assess and to investigate the reasons for the variations between the results of meta-analyses addressing the same question. Study Design and SettingWe included systematic reviews, and the trials that they included, on the use of implantable cardiac defibrillator (ICD) in patients with nonischemic cardiomyopathy. We assessed the variation between meta-analyses pooled effect estimates by calculating the percentage of absolute difference. We developed a list of 10 reasons for variations between the results of the meta-analyses clustered in four overarching categories. ResultsWe identified 21 systematic reviews including six trials and reporting on 22 eligible meta-analyses. The percentage of absolute difference between each of the 22 pooled effect estimates (included odds ratio, risk ratio, hazard ratio) and their median value had an average of 3.2%. The number of trials for which the following categories of reasons for variations applied were as follows: (1) different decision to include or exclude trials (n = 3); (2) differences in analytical approaches (n = 6); (3) errors in conducting meta-analyses (n = 5); and (4) unclear reason (n = 1). ConclusionFew of the observed variations between the results of the 22 meta-analyses could lead clinicians or guideline development organizations to adopt different courses of actions. Variations were most frequently related to both errors and variations in trial eligibility and analytical approaches.

INCIDENCE OF SUDDEN CARDIAC DEATH IN SPONTANEOUS CORONARY ARTERY DISSECTION AND THE ROLE FOR IMPLANTABLE CARDIAC DEFIBRILLATOR

Spontaneous coronary artery dissection (SCAD) causes acute coronary syndrome among young women and presents as sudden cardiac death (SCD) in 3-11% of patients. There are limited data regarding the use of implantable cardiac defibrillators (ICDs) in this population. Our study aimed to identify

Incidence and predictors of sudden cardiac death after heart transplantation: A systematic review and meta-analysis.

Sudden cardiac death (SCD) is an important post-transplant problem being responsible for ~10% of deaths. We conducted a systematic review and meta-analysis to evaluate incidence and predictors of post-heart transplant SCD and the use of implantable cardiac defibrillator (ICD). Citations were identified in electronic databases and references of included studies. Observational studies on adults reporting on incidence and predictors of post-transplant SCD and ICD use were selected. We meta-analyzed SCD in person-years using random effects models. We qualitatively summarized predictors. This study includes 55 studies encompassing 47901 recipients. The pooled incidence rate of SCD was 1.30 per 100 person-years (95% CI: 1.08-1.52). Cardiac allograft vasculopathy (CAV) was associated with higher SCD risk (2.40 per 100 patient-years, 95% CI: 1.46-3.34). Independent predictors of SCD identified by two moderate-quality studies were older donor age, younger recipient age, non-Caucasian race, reduced left ventricular ejection fraction, rejection, infection, and cancer. Authors rarely reported on ICD use. This meta-analysis found that post-transplant SCD risk in heart transplant recipients is higher than that in the general population. CAV was associated with increased SCD risk. Observational studies reporting on absolute risk of SCD are needed to better identify populations at a clinically significant increased risk.

An unusual presentation of asymptomatic Type 2 Brugada pattern

Patients with asymptomatic Type 2 Brugada ECG patterns are not often associated with the sinister cardiac presentations that are more often related to the Type 1 Brugada pattern. The use of implantable cardiac defibrillators (ICDs) are not recommended in this patient group.We present the case of a 56year old male whom was brought following a witnessed out of hospital cardiac arrest. His background included a drug-induced type 1 Brugada pattern following a flecanide challenge. He has been asymptomatic until this event. In the absence of other causes for a cardiac arrest, he received an implantable cardiac defibrillator.This case highlights an uncommon presentation of a patient with a Drug Induced Type 1 Brugada pattern. These situations pose challenges to clinicians in surveillance of patients, and highlights the need for further research into predictive markers for sudden cardiac death.

RyR2 QQ2958 Genotype and Risk of Malignant Ventricular Arrhythmias.

Ventricular arrhythmias are one of the most common causes of death in developed countries. The use of implantable cardiac defibrillators is the most effective treatment to prevent sudden cardiac death. To date, the ejection fraction is the only approved clinical variable used to determine suitability for defibrillator placement in subjects with heart failure. The purpose of this study was to assess whether genetic polymorphisms found in the ryanodine receptor type 2 (Q2958R) and histidine-rich calcium-binding protein (S96A) might serve as markers for arrhythmias. Genotyping was performed in 235 patients treated with defibrillator for primary and secondary prevention of arrhythmias. No significant association was found between the S96A polymorphism and arrhythmia onset, whereas the QQ2958 genotype in the ryanodine receptor gene was correlated with an increased risk of life-threatening arrhythmias. Concurrent stressor conditions, such as hypertension, seem to increase this effect. Our findings might help to better identify patients who could benefit from defibrillator implantation.

Cardiac arrest: the changing incidence of ventricular fibrillation.

There are more than 300,000 out-of-hospital cardiac arrests (OHCA) in the USA annually, which can be grouped into those presenting with tachyarrhythmic (shockable) rhythms and those presenting with non-tachyarrhythmic rhythms. The incidence of tachyarrhythmic rhythms, which include ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT), has been noted to be progressively decreasing in multiple studies of OHCA. Improved medical and surgical therapies for ischemic heart disease, and the widespread use of implantable cardiac defibrillators (ICDs), have likely contributed to a declining incidence of VF arrest and may result in conversion of an otherwise VF event into a pulseless electrical activity (PEA) arrest. As the incidence of VF has declined, it is unclear if the absolute incidence of non-tachyarrhythmic rhythms has increased or remained largely unchanged. This article discusses the changing rates of presenting rhythms in sudden cardiac arrest, the underlying cellular mechanisms of PEA, the factors contributing to the relative increase in the rate of PEA arrests, and current treatment options.

Shock therapy: psychological impact and patient support

Patients with a history of coronary artery disease, myocardial infarction and poor ventricular function are at high risk of sudden cardiac death and, as such, are candidates for a primary-prevention implantable cardiac defibrillator. The evidence for the use of implantable cardiac defibrillators in the prevention of sudden cardiac death is irrefutable. However, the impact of the implantable cardiac defibrillator on the psychological functioning of a patient is still being investigated. Shock therapy is recognised as being a potent predictor of both mortality and psychological functioning in defibrillator recipients; it is questionable whether patients with implantable cardiac defibrillators are receiving the support they need from current service provision.

How People Die in 2014

How People Die in 2014

Novel and highly lethal NKX2.5 missense mutation in a family with sudden death and ventricular arrhythmia.

To date, several disease-related mutations in NKX2-5, a cardiac-specific homeobox gene, have been documented in patients with a variety of congenital heart diseases (CHDs). The most commonly reported phenotypes are secundum atrial septal defect (ASD) and atrioventricular conduction disease (AVCD). Reports of sudden cardiac death (SCD) have been attributed to progressive conduction disease preventable with pacemaker therapy. A retrospective chart review of individuals from three generations of a family with a novel NKX2-5 mutation associated with CHD, ventricular arrhythmias, and SCD despite pacemaker therapy was conducted. The review documented NKX2-5 Gln181His missense mutation in 11 phenotypically affected members of a single family with a strong family history of SCD, CHD, and AVCD. Before genotyping, four family members died suddenly, two despite pacemaker therapy. The ages at SCD were respectively 23, 29, 44, and 45 years. Observed phenotypic characteristics of genotype-positive patients included ASD, ventricular septal defect, aortic coarctation, tricuspid atresia, supraventricular tachycardia, progressive AVCD, and ventricular tachycardia documented on implantable cardiac defibrillator (ICD) recording. The age at presentation ranged from 5 months to 44 years, and AVCD was seen as early as infancy. Four phenotypically unaffected family members tested negative for the mutation. The findings of this review strongly suggest a new association of this NKX2-5 mutation with SCD from ventricular arrhythmia. This observation has significant implications for the choice of therapy for affected individuals, specifically the use of ICDs, and broadens the observed phenotypic spectrum of NKX2-5 mutations.

Predictors of Mortality in Patients With an Implantable Cardiac Defibrillator: A Systematic Review and Meta-Analysis

Many current predictors of mortality in heart failure (HF) patients were evaluated before the use of implantable cardiac defibrillators (ICD). The aim of this study was to conduct a systematic review and meta-analysis to identify factors associated with mortality in HF patients who have an ICD.

Autonomic Regulation Therapy for the Improvement of Left Ventricular Function and Heart Failure Symptoms: The ANTHEM-HF Study

BackgroundOutcomes of heart failure (HF) have improved dramatically with the use of blockers of the sympathetic and renin-angiotensin-aldosterone systems, as well as with more prevalent use of implantable cardiac defibrillators and cardiac resynchronization therapy. Despite these interventions, however, the overall prognosis of HF patients remains poor. Recently, stimulation of the right cervical vagus nerve in patients with symptomatic heart failure has been evaluated. Results suggest that vagal nerve stimulation provides sustained improvement in left ventricular (LV) function and symptoms associated with HF. However, much remains to be learned about the risks and benefits of therapies that alter autonomic regulatory function for the treatment of heart failure. MethodsThe Autonomic Neural Regulation Therapy to Enhance Myocardial Function in Heart Failure (ANTHEM-HF) study has been designed to address several key clinical questions about the role of autonomic regulation therapy (ART) in patients with LV dysfunction and chronic symptomatic heart failure. ConclusionsANTHEM-HF should provide additional and valuable information regarding the safety and the relationship between the site and intensity of ART and its salutary effects on HF.

Association of left ventricular mechanical dyssynchrony with survival benefit from revascularization: a study of gated positron emission tomography in patients with ischemic LV dysfunction and narrow QRS

LV mechanical dyssynchrony (LVMD) is a risk marker in narrow QRS cardiomyopathy, but its association with treatment outcome is not well defined. We determined the incremental prognostic value of LVMD in ischemic cardiomyopathy, and assessed its interaction with scar, myocardium in jeopardy and subsequent revascularization. Stress and rest (82)Rb gated PET were performed in 486 consecutive patients (66 ± 11 years of age, 82 % men, LV ejection fraction 26 ± 6 %) with ischemic cardiomyopathy and QRS <120 ms. LVMD was determined as the standard deviation (SD) of the regional time to minimum volume on phase analysis of the gated PET scan. A propensity score was determined to adjust for nonrandomized referral after imaging to coronary artery bypass grafting (CABG). In a Cox proportional hazards model used to determine the association between measures of LVMD and survival time, CABG was included as a time-dependent covariate and the use of an implantable cardiac defibrillator (ICD) after imaging was modeled as a stratification factor. Over 1.9 ± 1.4 years, 96 patients (20 %) underwent CABG and 108 (22 %) died. LVMD was a predictor of mortality (HR 1.16. 95 % CI 1.03;1.30, per 10° increase in phase SD, p = 0.02) after adjusting for baseline covariates, prior ICD use, the use of postimaging CABG, and other imaging data. There was a significant interaction between phase SD and CABG. Nested Cox models showed that LVMD carried prognostic information incremental to clinical variables, ejection fraction and CABG. LVMD is an independent predictor of all-cause mortality in ischemic cardiomyopathy, and may identify patients with a differential survival benefit from CABG versus medical therapy.

Abstract 107: Predictors and Frequency of ICD Implantation for Primary Prevention in ICD Eligible Patients: Results from a Prospective Multicenter Registry

Background . The use of implantable cardiac defibrillators has been associated with improved survival in several well-defined patient (pt) subsets. Its utilization for primary prevention in eligible pts, however, is unclear. We sought to examine the frequency of ICD implantation (ICD-IMP) for primary prevention in a cohort prospectively enrolled in a prospective, multicenter registry of ICD candidates. Methods . We identified 961 pts enrolled in the AdreView Myocardial Imaging for Risk Evaluation in Heart Failure (ADMIRE-HF) study, a prospective, multicenter study evaluating the prognostic usefulness of 123I-mIBG scintigraphy in a heart failure population. Inclusion criteria limited patients to those meeting guideline criteria for ICD implantation; these criteria included left ventricular ejection fraction ≤35% and New York Heart Association functional class II-III. We excluded pts with an ICD at the time of enrollment, leaving a study cohort of 934 patients. Pts were followed up for 24 months after enrollment. Pts undergoing ICD-IMP after enrollment for secondary prevention were censored at the time of intervention. The association between ICD-IMP utilization and demographic, clinical, laboratory, and imaging data was examined using Cox proportional hazards analysis (CPH). Results . Of 934 pts, 196 (21%) were referred for ICD-IMP over a mean follow-up of 612±242 days. Implantations occurred 167±164 days after enrollment. Patients referred for ICD were younger (61±12 vs. 63±12), but did not differ with respect to proportion female (17% vs. 21%), African-American race (12% vs. 15%), diabetics (37% vs. 36%) (All p=NS). The frequency of ICD-IMP did not differ as a function of age, race, sex, LVEF, or imaging result (All p=NS). CPH revealed that a model including age, race, sex, diabetes, smoking, BMI, NYHA class, hypertension, heart failure etiology, and prior MI identified none of these as predictive of ICD-IMP. Conclusion: This analysis of prospective registry data reveals that in patients who are guideline-defined candidates for ICD-IMP, only about one in five receive an ICD over a two year follow-up interval. Multivariable modeling failed to identify any factor associated with ICD use.

Abstract 17819: Predicting the Proportional Risk of Sudden Cardiac Death in a Multicenter Heart Failure Cohort

Introduction: Many patients with heart failure die suddenly. Implantable cardiac defibrillators (ICDs) can reduce the rate of sudden death. Strategies that help identify patients who have most to gain from an ICD could reduce morbidity and maximize cost-effectiveness of ICDs. Methods: We used data from 9,885 heart failure patients, of whom 2,549 died during an average follow-up of 2.3 years. Using commonly available baseline clinical and demographic information, we developed a mode-specific multinomial logistic regression model to identify variables associated with a disproportionate fraction of total mortality due to sudden death. Results: In multivariable-adjusted models, we confirmed that commonly utilized variables for ICD implantation decisions, such as lower ejection fraction (OR for sudden death vs. other deaths: 1.15 per 10% decrease, p=0.005) and better New York Heart Association functional class (OR 1.30 for class 2 versus 3/4, p=0.004) were associated with greater proportion of deaths due to sudden death. We also demonstrated that younger age (OR 1.25 per decade younger, p&lt;0.001), male sex (OR 1.40, p=0.002), and higher body mass index (BMI) (OR 1.24 per 5 kg/m 2 , p&lt;0.001) independently increased the chance that if a patient died, it would be due to sudden death. Patients with diabetes (OR 0.75, p=0.001), systolic BP deviating above or below 140mmHg (OR 0.92 per 10mmHg, p=0.005), higher creatinine (OR 0.65 per mg/dL, p&lt;0.001), or lower serum sodium (OR 0.96 per mEq below 138, p=0.029) had a lower proportional risk of sudden death. The use of several heart failure medications, left ventricular end-diastolic dimension, or plasma NT-proBNP levels was not independently associated with risk of sudden versus non-sudden death. Conclusions: Several demographic and clinical variables beyond ejection fraction and functional class are independently associated with higher or lower proportional risk for sudden death. Our findings support the need for further investigation whether this novel predictive model, in the context of absolute mortality rates, can be used to target the use of ICDs and other life-saving therapies to populations who will derive greatest benefit from their application.

Invited Commentary

Invited Commentary

A computer modeling tool for comparing novel ICD electrode orientations in children and adults

Use of implantable cardiac defibrillators (ICDs) in children and patients with congenital heart disease is complicated by body size and anatomy. A variety of creative implantation techniques has been used empirically in these groups on an ad hoc basis. To rationalize ICD placement in special populations, we used subject-specific, image-based finite element models (FEMs) to compare electric fields and expected defibrillation thresholds (DFTs) using standard and novel electrode configurations. FEMs were created by segmenting normal torso computed tomography scans of subjects ages 2, 10, and 29 years and 1 adult with congenital heart disease into tissue compartments, meshing, and assigning tissue conductivities. The FEMs were modified by interactive placement of ICD electrode models in clinically relevant electrode configurations, and metrics of relative defibrillation safety and efficacy were calculated. Predicted DFTs for standard transvenous configurations were comparable with published results. Although transvenous systems generally predicted lower DFTs, a variety of extracardiac orientations were also predicted to be comparably effective in children and adults. Significant trend effects on DFTs were associated with body size and electrode length. In many situations, small alterations in electrode placement and patient anatomy resulted in significant variation of predicted DFT. We also show patient-specific use of this technique for optimization of electrode placement. Image-based FEMs allow predictive modeling of defibrillation scenarios and predict large changes in DFTs with clinically relevant variations of electrode placement. Extracardiac ICDs are predicted to be effective in both children and adults. This approach may aid both ICD development and patient-specific optimization of electrode placement. Further development and validation are needed for clinical or industrial utilization.