Clinical course of hypertrophic cardiomyopathy patients implanted with a transvenous or subcutaneous defibrillator

Subcutaneous Implantable Defibrillators in Young Patients: Arrhythmias, Complications, and Physical Activity

BACKGROUND

The safety of subcutaneous implantable cardioverter defibrillator (S-ICD) recipients who lead active lifestyles and engage in recreational sports is unknown. We aimed to evaluate the association between lifestyle and recreational sports and the occurrence of arrhythmia- and device-related complications, appropriate and inappropriate shocks in S-ICD recipients.

METHODS

We assessed a cohort of young-adult (15-65 years) S-ICD patients, evaluated their physical activity with IPAQ (International Physical Activity Questionnaire), and assessed the association between lifestyle and recreational sports on S-ICD safety and shocks.

RESULTS

We enrolled 602 S-ICD recipients (77% men; age, 46±14 years). According to the IPAQ, patients were categorized as inactive subjects (26.4%), moderately active subjects (45.2%), or highly active subjects (28.4%). Among moderately/highly active subjects, 163 (27.1%) were recreational athletes. During follow-up (47.3 [interquartile range, 27.0-67.6] months), 23 patients (3.8%) reached the safety end point of arrhythmia- or device-related complications, with moderately and highly active subjects showing in multivariate analysis similar incidence compared with inactive subjects (P=0.59 and P=0.83, respectively). Forty-four patients had 87 appropriate shocks. In multivariate analysis, moderately and highly active subjects showed a nonsignificantly lower incidence of appropriate shocks compared with inactive subjects (P=0.12 and P=0.11, respectively). Consistently, there was a nonsignificant lower incidence of appropriate shocks in athletes versus nonathletes (P=0.06). Thirty-nine patients had 46 inappropriate shocks. Moderately and highly active subjects had similar incidence of inappropriate shocks compared with inactive subjects (P=0.92 and P=0.88, respectively).

CONCLUSIONS

Young S-ICD patients often lead active lifestyles and participate in sports. Higher activity levels were not associated with increased implantable cardioverter defibrillator-related complications or increased risk of implantable cardioverter defibrillator shocks.

Substrates of Sudden Cardiac Death in Hypertrophic Cardiomyopathy

Sudden cardiac death (SCD), the most devastating complication of hypertrophic cardiomyopathy (HCM), is primarily triggered by ventricular tachycardia or fibrillation. Despite advances in knowledge, the mechanisms driving ventricular arrhythmia in HCM remain incompletely understood, stemming from an interplay of multiple pro-arrhythmic factors. Myocyte disarray and myocardial fibrosis form a structural substrate favorable to re-entrant arrhythmias by altering myocardial electrophysiological properties, while cellular abnormalities predominate in patients without evident structural remodeling. Traditional SCD risk prediction models rely on clinical risk factors and regression-based risk estimation, often overlooking specific arrhythmic substrates. Emerging techniques now allow for the direct assessment of these substrates, providing deeper insights into the arrhythmogenic mechanisms and paving the way for more personalized SCD risk stratification. This review explores the contribution of cellular, structural, and electrophysiological substrates to arrhythmic risk in HCM, emphasizing their distinct roles. Furthermore, it highlights the potential of substrate-based approaches to refining SCD prevention strategies and improving outcomes for patients with HCM.

Hypertrophic Cardiomyopathy: New Clinical and Therapeutic Perspectives of an "Old" Genetic Myocardial Disease

Since its first pathological description over 65 years ago, hypertrophic cardiomyopathy (HCM), with a worldwide prevalence of 1:500, has emerged as the most common genetically determined cardiac disease. Diagnostic work-up has dramatically improved over the last decades, from clinical suspicion and abnormal electrocardiographic findings to hemodynamic studies, echocardiography, contrast-enhanced cardiac magnetic resonance, and genetic testing. The implementation of screening programs and the use of implantable cardioverter defibrillators (ICDs) for high-risk individuals have notably reduced arrhythmic sudden deaths, altering the disease's mortality profile. Therapeutic breakthroughs, including surgical myectomy, alcohol septal ablation, and the novel introduction of "myosin inhibitors", have revolutionized symptom management and reduced progression to advanced heart failure (HF) and death. Despite this progress, refractory HF-both with preserved and reduced systolic function-has become the predominant cause of HCM-related mortality. While most patients with HCM experience a favorable clinical course with low morbidity and mortality, timely identification and targeted treatment of high-risk subgroups progressing toward progressive HF remain a pressing challenge, even for expert clinicians.

Fifteen years of subcutaneous implantable cardioverter-defibrillator therapy: Where do we stand, and what will the future hold?

The subcutaneous implantable cardioverter-defibrillator (S-ICD) has emerged as a feasible alternative to the transvenous ICD in the treatment of ventricular tachyarrhythmias in patients without indications for pacing or cardiac resynchronization therapy. Since its introduction, numerous innovations have been made and clinical experience has been gained, leading to its adoption in current practice and preference in certain populations. Moreover, emerging technologies like the extravascular ICD and the combination of the S-ICD with the leadless pacemaker offer new possibilities for the future. These advancements underscore the evolving role of the S-ICD in management of ventricular tachyarrhythmias. This review outlines implantation considerations, patient selection, and troubleshooting advancements in the last 15 years and provides insights into future perspectives.

Cardiac implantable electronic device infection awareness - A European survey amongst implanting physicians

BACKGROUND AND AIMS

Cardiac Implantable Electronic Device (CIED) infections pose significant mortality and morbidity despite optimal treatment. This survey aimed to understand whether and how the risk of CIED infection is assessed and mitigated in clinical practice in Europe, and to detect gaps with respect to EHRA recommendations.

METHODS

An Expert Group of 8 European cardiologists with specific expertise across CIED therapy designed and distributed electronically a survey to a number of European Cardiologists.

RESULTS

302 physicians from 18 European countries responded to the survey. 288/302 (95%) physicians agreed that CIED-related infections represent a burden on healthcare resources and are associated with significant morbidity and mortality. 285/302 respondents (94%) primarily assess the risk of CIED infections by only evaluating the patient's clinical profile (137/302, 46%) or with the support of a risk score (148/302, 49%). Intravenous antibiotic prophylaxis is used by 282/302 (93%), followed by the implantation of the lowest number of leads possible (182/302, 60%), and by the use of an antibacterial envelope (173/302, 57%). 230/302 respondents (76%) declared that there is need for clear and concise guidelines and more sensitive risk-scores for CIED infection, to maximize the chances of preventative strategies.

CONCLUSIONS

This survey demonstrates a high level of awareness about the multifaceted issue of CIED infection, however, it also highlights an incomplete penetration of scoring systems for risk stratification owing to their perceived limitations, and detects a strong commitment to increase the effectiveness of preventative strategies.

Candidacy and long-term outcomes of subcutaneous implantable cardioverter-defibrillators in current practice in patients with hypertrophic cardiomyopathy

BACKGROUND

In patients with Hypertrophic Cardiomyopathy (HCM) S-ICD is usually the preferred option as pacing is generally not indicated. However, limited data are available on its current practice adoption and long-term follow-up.

METHODS

Consecutive HCM patients with S-ICD implanted between 2013 and 2021 in 3 international centers were enrolled in this observational study. Baseline, procedural and follow-up data were regularly collected. Efficacy and safety were compared with a cohort of HCM patients implanted with a tv-ICD.

RESULTS

Seventy patients (64% males) were implanted with S-ICD at 41 ± 15 years, whereas 168 patients with tv-ICD at 49 ± 16 years. For S-ICD patients, mean ESC SCD risk score was 4,5 ± 1.9%: 25 (40%) at low-risk, 17 (27%) at intermediate and 20 (33%) at high-risk. Patients were followed-up for 5.1 ± 2.3 years. Two patients (0.6 per 100-person-years, vs 0.4 per 100 person-years with tv-ICD, p = 0.45) received an appropriate shock on VF, 17 (24%) were diagnosed with de-novo AF. Inappropriate shocks occurred in 4 patients (1.2 per 100-person-years, vs 0.9 per 100 person-years with tv-ICD, p = 0.74), all before Smart-Pass algorithm implementation. Four patients experienced device-related adverse events (1.2 per 100-person-years, vs 1 per 100 person-years with tv-ICD, p = 0.35%).

CONCLUSIONS

S-ICDs were often implanted in patients with an overall low-intermediate ESC SCD risk, reflecting both the inclusion of additional risk markers and a lower decision threshold. S-ICDs in HCM patients followed for over 5 years showed to be effective in conversion of VF and safe. Greater scrutiny may be required to avoid overtreatment in patients with milder risk profiles.

Subcutaneous versus transvenous implantable cardioverter defibrillator in hypertrophic cardiomyopathy: a systematic review and meta-analysis

Background

A subcutaneous implantable cardioverter-defibrillator (S-ICD) is an alternative to a transvenous implantable cardio defibrillator (TV-ICD). An S-ICD reduces the risk of transvenous lead placement. However, further research is required to determine how S-ICDs affect patients with hypertrophic cardiomyopathy (HCM). In this study, we investigated the comparative efficacy and safety of S-ICDs versus TV-ICDs in HCM.

Methods

On December 6th, 2023, we performed a comprehensive search of the PubMed, Embase, Scopus, and Cochrane databases to identify randomized clinical trials (RCTs) and observational studies comparing S-ICDs with TV-ICDs in HCM patients published from 2004 until 2023. No language restrictions were applied. The primary outcome was appropriate shocks (AS), with inappropriate shocks (IAS), and device-related complications considered as secondary outcomes. Odds ratios (ORs) and 95% confidence intervals (CIs) were pooled using a random effects model. The ROBINS-I tool was used to assess the risk of bias of the studies.

Results

The search yielded 1,114 records. Seven studies comprising 4,347 HCM patients were included, of whom 3,325 (76.0%) had TV-ICDs, and 1,022 (22.6%) had S-ICDs. There were 2,564 males (58.9%). The age range was from 39.1 to 49.4 years. Compared with the TV-ICD group, the S-ICD cohort had a significantly lower incidence of device-related complications (OR 0.52; 95% CI: 0.30-0.89; P=0.02; I2=4%). Contrastingly, there were no statistically significant differences in the occurrences of AS (OR 0.49; 95% CI: 0.22-1.08; P=0.08; I2=75%) and IAS (OR 1.03; 95% CI: 0.57-1.84; P=0.93; I2=65%) between the two device modalities. In the analysis of the overall risk of bias in the studies, we found 42% of them with several, 28% with moderate, and 14% with low risk of bias.

Conclusions

In HCM patients, S-ICDs were associated with a lower incidence of device-associated problems than TV-ICDs. AS and IAS incidence rates were similar between groups. These findings may assist clinicians in determining the most suitable device for treating patients with HCM.

Differences in underlying cardiac substrate among S-ICD recipients and its impact on long-term device-related outcomes: Real-world insights from the iSUSI registry

BACKGROUND

Outcome comparisons among subcutaneous implantable cardioverter-defibrillator (S-ICD) recipients with nonischemic cardiomyopathies are scarce.

OBJECTIVE

The aim of this study was to evaluate differences in device-related outcomes among S-ICD recipients with different structural substrates.

METHODS

Patients enrolled in the i-SUSI (International SUbcutaneouS Implantable cardioverter defibrillator registry) project were grouped according to the underlying substrate (ischemic vs nonischemic) and subgrouped into dilated cardiomyopathy, hypertrophic cardiomyopathy, Brugada syndrome (BrS), arrhythmogenic right ventricular cardiomyopathy (ARVC). The main outcome of our study was to compare the rates of appropriate and inappropriate shocks and device-related complications.

RESULTS

Among 1698 patients, the most common underlying substrate was ischemic (31.7%), followed by dilated cardiomyopathy (20.5%), BrS (10.8%), hypertrophic cardiomyopathy (8.5%), and ARVC (4.4%). S-ICD for primary prevention was more common in the nonischemic cohort (70.9% vs 65.4%; P = .037). Over a median (interquartile range) follow-up of 26.5 (12.6-42.8) months, no differences were observed in appropriate shocks between ischemic and nonischemic patients (4.8%/y vs 3.9%/y; log-rank, P = .282). ARVC (9.0%/y; hazard ratio [HR] 2.492; P = .001) and BrS (1.8%/y; HR 0.396; P = .008) constituted the groups with the highest and lowest rates of appropriate shocks, respectively. Device-related complications did not differ between groups (ischemic: 6.4%/y vs nonischemic: 6.1%/y; log-rank, P = .666), nor among underlying substrates (log-rank, P = .089). Nonischemic patients experienced higher rates of inappropriate shocks than did ischemic S-ICD recipients (4.4%/y vs 3.0%/y; log-rank, P = .043), with patients with ARVC (9.9%/y; P = .001) having the highest risk, even after controlling for confounders (adjusted HR 2.243; confidence interval 1.338-4.267; P = .002).

CONCLUSION

Most S-ICD recipients were primary prevention nonischemic cardiomyopathy patients. Among those, patients with ARVC tend to receive the most frequent appropriate and inappropriate shocks and patients with BrS the least frequent appropriate shocks.

Left ventricular assist device in the presence of subcutaneous implantable cardioverter defibrillator: Data from a multicenter experience

BACKGROUND

Left ventricular assist devices (LVADs) are an increasingly used strategy for the management of patients with advanced heart failure (HF). Subcutaneous implantable cardioverter defibrillator (S-ICD) might be a viable alternative to conventional ICDs with a lower risk of short- and long-term of device-related complications and infections.The aim of this multicenter study was to evaluate the outcomes and management of S-ICD recipients who underwent LVAD implantation.

METHODS

The study population included patients with a preexisting S-ICD who underwent LVAD implantation for advanced HF despite optimal medical therapy.

RESULTS

The study population included 30 patients (25 male; median age 45 [38-52] years).The HeartMate III was the most common LVAD type. Median follow-up in the setting of concomitant use of S-ICDs and LVADs was 7 months (1-20).There were no reports of inability to interrogate S-ICD systems in this population. Electromagnetic interference (EMI) occurred in 21 (70%) patients. The primary sensing vector was the one most significantly involved in determining EMI. Twenty-seven patients (90%) remained eligible for S-ICD implantation with at least one optimal sensing vector. The remaining 3 patients (10%) were ineligible for S-ICD after attempts of reprogramming of sensing vectors. Six patients (20%) experienced inappropriate shocks (IS) due to EMI. Six patients (20%) experienced appropriate shocks. No S-ICD extraction because of need for antitachycardia pacing, ineffective therapy or infection was reported.

CONCLUSIONS

Concomitant use of LVAD and S-ICD is feasible in most patients. However, the potential risk of EMI oversensing, IS and undersensing in the post-operative period following LVAD implantation should be considered. Careful screening for EMI should be performed in all sensing vectors after LVAD implantation.