First implantable cardiac defibrillator insertions in New South Wales, 2005-2020: an analysis of linked administrative data

OBJECTIVES

To determine the annual numbers of first ICD insertions in New South Wales during 2005-2020; to examine health outcomes for people who first received ICDs during this period.

STUDY DESIGN

Retrospective cohort study; analysis of linked administrative health data.

SETTING, PARTICIPANTS

All first insertions of ICDs in NSW, 2005-2020.

MAIN OUTCOME MEASURES

Annual numbers of first ICD insertions, and of emergency department presentations and hospital re-admissions 30 days, 90 days, 365 days after first ICD insertions; all-cause and disease-specific mortality (to ten years after ICD insertion).

RESULTS

During 2005-2020, ICDs were first inserted into 16 867 people (18.5 per 100 000 population); their mean age was 65.7 years (standard deviation, 13.5 years; 7376 aged 70 years or older, 43.7%), 13 214 were men (78.3%). The annual number of insertions increased from 791 in 2005 to 1256 in 2016; the first ICD insertion rate increased from 15.5 in 2005 to 18.9 per 100 000 population in 2010, after which the rate was stable until 2019 (19.8 per 100 000 population). Of the 16 778 people discharged alive from hospital after first ICD insertions, 54.4% presented to emergency departments within twelve months, including 1236 with cardiac arrhythmias (7.4%) and 434 with device-related problems (2.6%); 56% were re-admitted to hospital, including 1944 with cardiac arrhythmias (11.5%) and 2045 with device-related problems (12.1%). A total of 5624 people who received first ICDs during 2005-2020 (33.3%) died during follow-up (6.7 deaths per 100 person-years); the survival rate was 94.4% at one year, 76.5% at five years, and 54.2% at ten years.

CONCLUSIONS

The annual number of new ICDs inserted in NSW has increased since 2005. A substantial proportion of recipients experience device-related problems that require re-admission to hospital. The potential harms of ICD insertion should be considered when assessing the likelihood of preventing fatal ventricular arrhythmia.

Outcomes Following Implantable Cardioverter-Defibrillator Insertion in Patients 80 Years of Age or Older: A Statewide Population Cohort Study

BACKGROUND

Patients ≥ 80 years of age are underrepresented in major implantable cardioverter-defibrillator (ICD) trials, and real-world data are lacking. In this study, we sought to assess ICD utilisation, outcomes, and their predictors, in an unselected statewide population including patients ≥ 80 years old.

METHODS

We extracted details of ICDs implanted from 2009 to 2018 in New South Wales (NSW), Australia from the Centre for Health Record Linkage administrative data sets. Analysis was stratified into age groups of < 60 years, 60-79 years, and ≥ 80 years.

RESULTS

A total of 9304 patients (mean age 66.1 ± 13.1 years; 12.1% ≥ 80 years) had de novo ICD placement at an average rate of 1163 ± 122 patients per annum, with more implants in men in all age groups. After adjusting for NSW population size by sex, age group, and calendar year, mean implantation rates were 5.5 ± 0.6, 63.2 ± 8.6, and 52.7 ± 10.8 per 100,000 persons per annum in patients aged < 60 years, 60-79 years, and ≥ 80 years, respectively. In-hospital mortality was 0.4% and did not differ among age groups. However, 1-year mortality was 2.1%, 5.9%, and 10.7%, in those < 60 years, 60-79 years, and ≥ 80 years of age, respectively (P < 0.001), with hazard ratios for those aged ≥ 80 years of 4.3 (95% confidence interval [CI] 3.1-6.0) and those aged 60-79 years of 2.6 (95% CI 1.9-3.5) relative to those aged < 60 years (both P < 0.001) after adjusting for ICD indications, sex, implantation year, referral source, and comorbidities. In those aged ≥ 80 years, age > 83 years, congestive cardiac failure, chronic renal failure, neurodegenerative disease, and a higher Charlson comorbidity index score were each independent predictors of 1-year mortality.

CONCLUSIONS

ICD use in patients aged ≥ 80 years and 60-79 years was 10-fold that in patients aged < 60 years, and perioperative outcomes were good in all ages, but there was substantially increased 1-year mortality in those aged ≥ 80 years. Careful selection based on age and comorbidity may further reduce 1-year mortality in patients ≥ 80 years old receiving ICDs.

Transvenous versus subcutaneous implantable cardioverter defibrillators in young cardiac arrest survivors

Secondary prevention implantable cardioverter defibrillators (ICDs) are indicated in young patients presenting with aborted sudden cardiac death (SCD) because of ventricular arrhythmias. Transvenous-ICDs (TV-ICDs) are effective, established therapies supported by evidence. The significant morbidity associated with transvenous leads led to the development of the newer subcutaneous-ICD (S-ICD). This review discusses the clinical considerations when selecting an ICD for the young patient presenting with out-of-hospital cardiac arrest. The major benefits of TV-ICDs are their ability to pace (antitachycardia pacing [ATP], bradycardia support and cardiac resynchronisation therapy [CRT]) and the robust evidence base supporting their use. Other benefits include a longer battery life. Significant complications associated with transvenous leads include pneumothorax and tamponade during insertion and infection and lead failure in the long term. Comparatively, S-ICDs, by virtue of having no intravascular leads, prevent these complications. S-ICDs have been associated with a higher incidence of inappropriate shocks. Patients with an indication for bradycardia pacing, CRT or ATP (documented ventricular tachycardia) are seen as unsuitable for a S-ICD. If venous access is unsuitable or undesirable, S-ICDs should be considered given the patient is appropriately screened. There is a need for further randomised controlled trials to directly compare the two devices. TV-ICDs are an effective therapy for preventing SCD limited by significant lead-related complications. S-ICDs are an important development hindered largely by an inability to pace. Young patients stand to gain the most from a S-ICD as the cumulative risk of lead-related complications is high. A clinical framework to aid decision-making is presented.

Burden of mood symptoms and disorders in implantable cardioverter defibrillator patients: a systematic review and meta-analysis of 39 954 patients

AIMS

Implantable cardioverter defibrillators (ICDs) prevent sudden cardiac death. Anxiety, depression, and post-traumatic stress disorder (PTSD) are underappreciated symptoms. We aimed to systematically synthesize prevalence estimates of mood disorders and symptom severities, pre- and post-ICD insertions. Comparisons were made with control groups, as well as within ICD patients by indication (primary vs. secondary), sex, shock status, and over time.

METHODS

Databases (Medline, PsycINFO, PubMed, and Embase) were searched without limits from inception to 31 August 2022; 4661 articles were identified, 109 (39 954 patients) of which met criteria.

RESULTS

Random-effects meta-analyses revealed clinically relevant anxiety in 22.58% (95%CI 18.26-26.91%) of ICD patients across all timepoints following insertion and depression in 15.42% (95%CI 11.90-18.94%). Post-traumatic stress disorder was seen in 12.43% (95%CI 6.90-17.96%). Rates did not vary relative to indication group. Clinically relevant anxiety and depression were more likely in ICD patients who experienced shocks [anxiety odds ratio (OR) = 3.92 (95%CI 1.67-9.19); depression OR = 1.87 (95%CI 1.34-2.59)]. Higher symptoms of anxiety were seen in females than males post-insertion [Hedges' g = 0.39 (95%CI 0.15-0.62)]. Depression symptoms decreased in the first 5 months post-insertion [Hedges' g = 0.13 (95%CI 0.03-0.23)] and anxiety symptoms after 6 months [Hedges' g = 0.07 (95%CI 0-0.14)].

CONCLUSION

Depression and anxiety are highly prevalent in ICD patients, especially in those who experience shocks. Of particular concern is the prevalence of PTSD following ICD implantation. Psychological assessment, monitoring, and therapy should be offered to ICD patients and their partners as part of routine care.

Communication regarding the deactivation of implantable cardioverter-defibrillators: A scoping review and narrative summary of current interventions

OBJECTIVES

Communication about deactivation of implantable cardioverter-defibrillator (ICD) therapy at end-of-life (EoL) is a recognised issue within clinical practice. The aim of this scoping review was to explore and map the current literature in this field, with a focus on papers which implemented interventional studies.

METHODS

Systematic searches of six major databases were conducted. Citations were included by four researchers according to selection criteria. Key demographic data and prespecified themes in relation to communication of ICD deactivation at EoL were extracted.

RESULTS

The search found 6197 texts of which 63 were included: 39 quantitative, 14 qualitative and 10 mixed-methods. Surveys were predominantly used to gather data (n = 34), followed by interviews (n = 18) and retrospective reviews of patient records (n = 18).

CONCLUSIONS

Several key gaps in the literature warrant further research. These include who is responsible for initiating ICD deactivation discussions, how clinicians should initiate and conduct these discussions, when ICD deactivations should be occurring, and family perspectives. Adequately explored themes include patient and clinician knowledge and attitudes regarding ICD deactivation at EoL.

PRACTICAL IMPLICATIONS

Facilities treating patients with ICDs at EoL should consider ongoing quality improvement projects aimed at clinician education and protocol changes to improve communication surrounding EoL ICD deactivation.

Cognitive Function of Recipients of Primary or Secondary Defibrillator Therapy: A Comparative Study Involving Nondefibrillator Patients With Systolic Heart Failure

BACKGROUND

The extent to which cognitive function differs between patients who receive implantable cardioverter-defibrillator (ICD) therapy and patients with heart failure (HF) who do not receive ICD therapy remains to be elucidated.

OBJECTIVES

The aim of this study was to compare the cognitive function between patients with primary or secondary ICDs and patients with HF without an ICD.

METHODS

This descriptive, comparative study included 116 patients who received ICDs and 74 patients with HF who did not receive ICDs. Patients underwent neuropsychological assessment for general cognition, memory, and executive function.

RESULTS

Immediate recall memory loss (18.9%) occurred more often in patients with HF without an ICD than in patients with primary (3.1%) and secondary (7.1%) ICDs (P = .018). After adjusting for age and education, delayed recall memory of patients with HF without ICDs was significantly worse than that of patients with primary ICDs (4.0 vs 6.5; P < .001), whereas delayed recall memory of patients with primary ICDs was better than that of patients with secondary ICDs (6.0 vs 6.5; P = .006). Executive function of patients with HF without ICDs was significantly worse than that of patients with primary (35 vs 58 seconds; P < .001) and secondary (28 vs 58 seconds; P = .0012) ICDs.

CONCLUSIONS

Patients with ICDs, regardless of primary or secondary indication, had less impairment of memory and executive function than patients with HF without ICDs, implying that ICD therapy did not interfere with cognitive performance. Cognitive screening as a part of routine care could be helpful for identifying impairment and implementing early cognitive training, especially in patients with HF.

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 Hypertrophic Cardiomyopathy: Interaction With Genetics and Environment

Purpose of Review

We explore the sex-specific interaction of genetics and the environment on the clinical course and outcomes of hypertrophic cardiomyopathy (HCM).

Recent Findings

Women account for approximately one-third of patients in specialist HCM centres and reported in observational studies. As a result, evidence informing clinical guideline recommendations is based predominantly on risk factors and outcomes seen in men. However, disease progression appears to be different between the sexes. Women present at a more advanced stage of disease, are older at diagnosis, have higher symptom burden, carry greater risk for heart failure and are at greater risk of mortality compared to men. Women are more likely to be gene-positive, while men are more likely to be gene-negative. The risk of sudden cardiac death and access to specialised care do not differ between the sexes.

Summary

Reporting sex-disaggregated results is essential to identify the mechanisms leading to sex differences in HCM.

Sex Disparities in Sudden Cardiac Death

The overall incidence of sudden cardiac death is considerably lower among women than men, reflecting significant and often under-recognized sex differences. Women are older at time of sudden cardiac death, less likely to have a prior cardiac diagnosis, and less likely to have coronary artery disease identified on postmortem examination. They are more likely to experience their death at home, during sleep, and less likely witnessed. Women are also more likely to present in pulseless electrical activity or systole rather than ventricular fibrillation or ventricular tachycardia. Conversely, women are less likely to receive bystander cardiopulmonary resuscitation or receive cardiac intervention post-arrest. Underpinning sex disparities in sudden cardiac death is a paucity of women recruited to clinical trials, coupled with an overall lack of prespecified sex-disaggregated evidence. Thus, predominantly male-derived data form the basis of clinical guidelines. This review outlines the critical sex differences concerning epidemiology, cause, risk factors, prevention, and outcomes. We propose 4 broad areas of importance to consider: physiological, personal, community, and professional factors.

Clinical Profile and Health Disparities in a Multiethnic Cohort of Patients With Hypertrophic Cardiomyopathy

BACKGROUND

Clinical studies of hypertrophic cardiomyopathy are over-represented by individuals of European ethnicity, with less known about other ethnic groups. We investigated differences between patients in a multiethnic Australian hypertrophic cardiomyopathy population.

METHODS

We performed a retrospective cohort study of 836 unrelated hypertrophic cardiomyopathy probands attending a specialized clinic between 2002 and 2020. Major ethnic groups were European (n=611), East Asian (n=75), South Asian (n=58), and Middle Eastern and North African (n=68). The minor ethnicity groups were Oceanian (n=9), People of the Americas (n=7), and African (n=8). One-way ANOVA with Dunnett post hoc test and Bonferroni adjustment were performed.

RESULTS

Mean age of the major ethnic groups was 54.9±16.9 years, and 527 (65%) were male. Using the European group as the control, East Asian patients had a lower body mass index (29 versus 25 kg/m², P<0.0001). South Asians had a lower prevalence of atrial fibrillation (10% versus 31%, P=0.024). East Asians were more likely to have apical hypertrophy (23% versus 6%, P<0.0001) and Middle Eastern and North African patients more likely to present with left ventricular outflow tract obstruction (46% versus 34%, P=0.0003). East Asians were less likely to undergo genetic testing (55% versus 85%, P<0.0001) or have an implantable cardioverter-defibrillator implanted (19% versus 36%, P=0.037). East Asians were more likely to have a causative variant in a gene other than MYBPC3 or MYH7, whereas Middle Eastern and North African and South Asians had the highest rates of variants of uncertain significance (27% and 21%, P<0.0001).

CONCLUSIONS

There are few clinical differences based on ethnicity, but importantly, we identify health disparities relating to access to genetic testing and implantable cardioverter-defibrillator use. Unless addressed, these gaps will likely widen as we move towards precision-medicine-based care of individuals with hypertrophic cardiomyopathy.

Primary Prevention Implantable Cardiac Defibrillators: A Townsville District Perspective

Background: Despite major advances in treating patients with severe heart failure, deciding who should receive an implantable cardiac defibrillator (ICD) remains challenging.

Objective: To study the risk factors and mortality in patients after receiving an ICD (January 2008–December 2015) in a regional hospital in Australia.

Methods: Eighty-two primary prevention patients received an ICD for ischemic cardiomyopathy (ICM, n = 41) and non-ischemic cardiomyopathy (NICM, n = 40) with 4.8-yrs follow-up. One patient had mixed ICM/NICM indications. Ventricular arrhythmias were assessed using intracardiac electrograms. Statistical analysis compared the total population and ICM and NICM groups using Kaplan-Meier for survival, Cox regression for mortality predictors, and binary logistic regression for predictors of ventricular arrhythmias (p < 0.05).

Results: Major risk factors were hypercholesterolemia (70.7%), hypertension (47.6%), and obesity (41.5%). Severe obstructive sleep apnea (OSA) was found exclusively in NICM patients (23.7%, p = 0.001). Mortality was 30.5% after 4.8-yrs. The majority of patients (n=67) had no sustained ventricular arrhythmias yet 28% received therapy (n = 23), 18.51% were appropriate (n = 15), and 13.9% inappropriate (n = 11). Patients receiving ≥2 incidences of inappropriate shocks were 18-times more likely to die (p = 0.013). Three sudden cardiac deaths (SCD) (3.7%) were prevented by the ICD.

Conclusion: Patients implanted with an ICD in Townsville had 30.5% all-cause mortality after 4.8-yrs. Only 28% of patients received ICD therapy and 13.9% were inappropriate. OSA may have contributed to the fourfold increase in inappropriate therapy in NICM patients. Our study raises important efficacy, ethical and healthcare cost questions about who should receive an ICD, and possible regional and urban center disparities.

Effect of physical and psychocognitive function and perceived health status on 12-month adverse cardiac events among implantable cardioverter-defibrillator recipients

BACKGROUND

Post-implant recovery in patients with implantable cardioverter-defibrillators (ICDs) is often compromised because of reduced physical and psycho-cognitive function and poor health perception, leading to short event-free survival.

OBJECTIVES

To examine the effects of psychocognitive function, health perception, and ICD-related factors on 12-month cardiac events among ICD patients.

METHODS

Using a prospective study design, ICD patients underwent baseline assessment and were followed for 12 months to assess cardiac events.

RESULTS

Cardiac events occurred in 14 patients (18.9%) (N = 74: age, 58 years; primary ICDs, 45.9%). Time after ICD implant (odds ratio [OR] = 1.002; p = .028) and executive function (OR = 1.021; p = .027) were significant predictors of 12-month cardiac events, while other physical and psychological indices were not.

CONCLUSIONS

Reduced executive function and longer time after implant predicted the events. Healthcare professionals need to assess executive function and provide treatment and support to improve executive function.

Changes in the Physical Function and Psychological Distress from Pre-Implant to 1, 6, and 12 Months Post-Implant in Patients Undergoing Implantable Cardioverter Defibrillator Therapy

Recipients of implantable cardioverter-defibrillator (ICD) therapy in Western countries often experience distressful physical and psychological adjustments. Sociocultural influences on post-implant recovery are likely; however, evidence from other ethnic/cultural backgrounds is lacking. This study aimed to examine the changes in physical function and psychological distress (anxiety and depressive symptoms) from pre-implant to one, six, and 12 months post-implant in Korean patients undergoing ICD therapy. A total of 34 patients underwent pre- to post-implant longitudinal assessments of physical and psychological function using mixed modeling procedures. Physical function significantly declined from pre-implant to one month post-implant (B = -10.05, p = 0.004) and then nearly returned to the pre-implant level at six months post-implant (B = 8.34, p = 0.028). This level of improvement continued through 12 months post-implant. In psychological distress, significant improvements were observed from pre-implant to one month (anxiety (B = -1.20, p = 0.020) and in depressive symptoms (B = -1.15, p = 0.037)), which then plateaued without significant changes from one to 12 months. We concluded that physical function recovery occurred six months post-implant, but function remained poor until 12 months post-implant. Psychological distress improved one month post-implant and it was maintained. Clinicians must provide more intensive interventions to improve long-term physical function after ICD therapy.

Ten-year trends in catheter ablation for ventricular tachycardia vs other interventional procedures in Australia

AIMS

Major technological and procedural advancements have reinvigorated catheter ablation as adjunctive therapy for drug-refractory ventricular tachycardia (VT). We examined temporal trends in VT ablations as compared to other interventional cardiovascular procedures namely, percutaneous coronary intervention (PCI) and atrial fibrillation (AF) ablation in Australia.

METHODS AND RESULTS

A retrospective review of procedural numbers for VT ablations, AF ablations, and PCI was performed from 2008/09-2016/17 the Australian Institute of Health, Welfare and Aging (AIHW), and Medicare Australia (MA) databases. Linear regression models were fitted to compare the trends in population-adjusted procedural numbers over the 10-year period. Data from the AIHW and MA sources respectively showed that (a) PCI had a 1.3% (AIHW data P = .15) and 1.8% (MA data P < .001) population-adjusted increment per year, (b) AF ablations had a 12.7% (P < .001) and 11.7% (P < .001) per year population-adjusted increment, and (c) VT ablations showed an 18% (P < .001) and 12.7% (P < .001) per year population-adjusted increment. Growth of PCI was increasing at a lower rate than AF ablations (P < .001 for both AIHW and MA sources). Growth of VT ablation was significantly higher than AF ablations and PCI (AIHW: 18% vs 12.7% [P = .004] and 1.3% per year [P < .001]).

CONCLUSION

Catheter-based VT ablation has increased significantly in Australia over the last decade, consistent with worldwide trends, and now surpassing all ablation procedures, including AF ablation and PCI for CAD. This data highlight the provision of additional resources to match the increasing demand for VT ablation procedures in Australia.

Sex Differences in Electrophysiology, Ventricular Tachyarrhythmia, Cardiac Arrest and Sudden Cardiac Death Following Acute Myocardial Infarction

BACKGROUND

Women experience less appropriate implantable cardioverter-defibrillator (ICD) interventions and are underrepresented in randomised ICD trials. Sex-differences in inducible and spontaneous ventricular tachycardia/fibrillation (VT/VF), cardiac arrest and sudden cardiac death (SCD) early post-myocardial infarction (MI) require further study.

METHODS

Consecutive ST-elevation MI patients with left ventricular ejection fraction (LVEF)≤40% underwent electrophysiology study (EPS) to target early prevention of SCD. An ICD was implanted for a positive (inducible monomorphic VT) but not a negative (no arrhythmia or inducible VF) EPS. The combined primary endpoint of VT/VF (spontaneous or ICD-treated), cardiac arrest or SCD was assessed using competing risk survival analysis in women versus men with adjustment for confounders. Logistic regression was used to determine independent predictors of inducible VT at EPS.

RESULTS

A total of 403 patients (16.9% female) underwent EPS. Women were significantly older than men but with similar LVEF (31.5 ± 6.3 versus 31.6 ± 6.4%, p = 0.91). Electrophysiology study was positive for inducible VT in 22.1% and 33.4% (p = 0.066) and an ICD implanted in 25.0% and 33.4% (p = 0.356) of women versus men. Appropriate ICD activations (VT/VF) occurred in 5.9% of women and 36.6% of men (p = 0.012). The adjusted cumulative primary endpoint incidence was significantly lower in women than men (1.6% versus 26.5%, p = 0.03). Female sex was not an independent predictor of inducible VT at EPS (HR 0.63, 95% CI 0.33-1.23, p = 0.178).

CONCLUSIONS

Women with early post-MI cardiomyopathy had lower VT/VF, cardiac arrest and SCD, compared to men. In ICD recipients the rate of appropriate activations was six-fold less in women compared to men.