Implantable cardioverter defibrillators in patients with electrical heart disease and hypertrophic cardiomyopathy: data from the German device registry

Global and Temporal Trends in Utilization and Outcomes of Implantable Cardioverter Defibrillators in Hypertrophic Cardiomyopathy

BACKGROUND

Over the past decades, hypertrophic cardiomyopathy has become a contemporary treatable disease. However, limited data exist on the global trends of implantable cardioverter defibrillator (ICD) utilization and its impact on mortality/morbidity burden reduction.

METHODS

Electronic databases were systematically searched up to March 2024 for studies reporting on ICD utilization rates in hypertrophic cardiomyopathy. A random effects model was used to pool study estimates across time-era, geographic region, and age group. Primary outcome was global trends in ICD utilization. Secondary outcomes included trends of sudden cardiac death, appropriate/inappropriate shocks, and ICD-related complications.

RESULTS

In total, 234 studies (N=92 500, 514 748 patient-years) met inclusion criteria. Mean age was 46.2 (12.4) years and 37.49% were women. A total of 12 139 patients (16.43%) received an ICD over 429 766 person-years of follow-up, with an ICD implantation rate of 2.79%/y ([95% CI, 2.35%-3.32%] I²=97.80%). Rates of ICD implantation steadily increased over time from 1990 (1.09%) to 2021 (4.01%; P=0.002), with noticeable geographic variation (P=0.008). The overall rate of appropriate ICD discharges and ICD-related complications was 3.44%/y ([95% CI, 3.08%-3.84%] I²=88.40%) and 1.98%/y ([95% CI, 1.52%-2.59%] I²=90.44%), respectively, with no significant trend over time. The overall rate of inappropriate discharges was 3.58%/y ([95% CI, 3.08%-4.16%] I2=88.03%), and declined significantly over time (P=0.044). There was a significant decline in the rates of sudden cardiac death from 1990 (0.84%/y) to 2020 (0.31%/y).

CONCLUSIONS

Dramatic increases in ICD utilization have occurred, representing a 3.7-fold increase, with appropriate therapies occurring in 3.44%/y. In parallel a significant reduction in sudden cardiac death was observed, but there are insufficient data to demonstrate that a causative relationship exists. Geographic disparities in ICD utilization were evident, highlighting the need to improve access to specialized care for patients with hypertrophic cardiomyopathy. Geographic disparities in ICD utilization were evident, highlighting the need to improve access to specialized care for patients with hypertrophic cardiomyopathy.

REGISTRATION

URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42023407126.

Resting heart rate assessed within clinical practice demonstrates no prognostic relevance for defibrillator recipients in the German DEVICE registry

Resting heart rate (RHR) has prognostic implications in heart failure with reduced ejection fraction, where ≤ 70 bpm is targeted. Whether a RHR > 70 bpm assessed within clinical practice goes along with elevated cardiovascular risk in implantable cardioverter-defibrillator (ICD) / cardiac resynchronization therapy-defibrillator (CRT-D) recipients remains incompletely understood. A total of 1589 patients (ICD n = 1172 / CRT-D n = 417, median age 65 years, 22.6% female) undergoing ICD/CRT-D implantation or revision in the prospective German DEVICE multicenter registry were analyzed. RHR was assessed via a 12-channel electrocardiogram at enrollment. 1-year outcomes (all-cause mortality, major cardio- and cerebrovascular events (MACCE), all-cause hospital admission) were compared between patients with a RHR ≤ 70 bpm and > 70 bpm. 733 patients (46.1%) showed a RHR > 70 bpm. Median RHR was 63 (interquartile range 59; 68) bpm (≤ 70 bpm group) and 80 (75; 89) bpm (> 70 bpm group). Heart failure with reduced ejection fraction was present in 76.3%, a prior myocardial infarction in 32.4% and non-ischemic heart disease in 44.9%. One-year all-cause mortality was similar between RHR groups (≤ 70 bpm 5.4% vs. > 70 bpm 5.4%, p = 0.96), and subgroup analysis regarding patient characteristics and comorbidities revealed only a significantly higher rate of patients with dual chamber ICD in the > 70 bpm group (0.8% vs. 9.2%, p = 0.003). MACCE (5.9% vs. 6.1%, p = 0.87) and defibrillator shock rates (9.9% vs. 9.8%, p = 1.0) were similar. Higher all-cause hospital admission rates were observed in patients with > 70 bpm RHR (23.1% vs. 29.0%, p = 0.027) driven by non-cardiovascular events (6.0% vs. 11.7%, p = 0.001). In conclusion, in ICD and CRT-D recipients a RHR at admission > 70 bpm may indicate patients at increased risk of all-cause hospital admission but not of other adverse cardiovascular events or death at 1-year follow-up.

More than 30 years of Brugada syndrome: a critical appraisal of achievements and open issues

Over the last three decades, what is referred to as Brugada syndrome (BrS) has developed from a clinical observation of initially a few cases of sudden cardiac death (SCD) in the absence of structural heart disease with ECG signs of "atypical right bundle brunch block" to a predominantly electrocardiographic, and to a lesser extent genetic, diagnosis. Today, BrS is diagnosed in patients without overt structural heart disease and a spontaneous Brugada type 1 ECG pattern regardless of symptoms. The diagnosis of BrS is less clear in those with an only transient or drug-induced type 1 Brugada pattern, but should be considered in the presence of an arrhythmic syncope, family history of BrS, or family history of sudden death. In addition to survived cardiac arrest, syncope is probably the single most decisive risk marker for future arrhythmias. For asymptomatic BrS, risk stratification remains challenging. General recommendations to lower the risk in BrS include avoidance of drugs/agents known to induce and/or increase right precordial ST-segment elevation, including treatment of fever with antipyretic drugs. Several ECG markers that have been associated with an increased risk of SCD have been incorporated into a recently published risk score for BrS. The aim of this article is to provide an overview of the status of risk stratification and to illustrate open issues und gaps in evidence in BrS.

Cardiac defibrillator implantation in patients with syncope and inducible ventricular arrhythmia: insights from the German Device Registry

History of syncope is an independent predictor for sudden cardiac death. Programmed stimulation may be considered for risk stratification, but data remain sparse among different populations. Here, we analyzed the prognostic value of inducible ventricular arrhythmia (VA) regarding clinical outcome in patients with syncope undergoing defibrillator implantation. Among 4196 patients enrolled in the prospective, multi-center German Device Registry, patients with syncope and inducible VA (n = 285, 6.8%) vs. those with a secondary preventive indication (n = 1885, 45.2%), defined as previously documented sustained ventricular tachycardia or ventricular fibrillation, serving as a control group were studied regarding demographics, device implantation and post-procedural adverse events. Patients with syncope and inducible VA (64.9 ± 14.4 years, 81.1% male) presented less frequently with congestive heart failure (15.1% vs. 29.1%; p < 0.001) and any structural heart disease (84.9% vs. 89.3%; p = 0.030) than patients with a secondary preventive indication (65.0 ± 13.8 years, 81.0% male). Whereas dilated cardiomyopathy (16.8% vs. 23.8%; p = 0.009) was less common, hypertrophic cardiomyopathy (5.6% vs. 2.8%; p = 0.010) and Brugada syndrome (2.1% vs. 0.3%; p < 0.001) were present more often. During 1-year-follow-up, mortality (5.1% vs. 8.9%; p = 0.036) and the rate of major adverse cardiac or cerebrovascular events (5.8% vs. 10.0%; p = 0.027) were lower in patients with syncope and inducible VA. Among patients with inducible VA, post-procedural adverse events including rehospitalization (27.6% vs. 21.7%; p = 0.37) did not differ between those with vs. without syncope. Taken together, patients with syncope and inducible VA have better clinical outcomes than patients with a secondary preventive defibrillator indication, but comparable outcomes to patients without syncope, which underlines the relevance of VA inducibility, potentially irrespective of a syncope.

Performance evaluation of implantable cardioverter-defibrillators with SmartShock technology in patients with inherited arrhythmogenic diseases

BACKGROUND

Patients with inherited arrhythmogenic diseases (IADs) are often prescribed preventative implantable cardioverter-defibrillators (ICDs) to manage their increased sudden cardiac arrest risk. However, it has been suggested that ICDs in IAD patients may come with additional risk. We aimed to leverage the PainFree SmartShock Technology dataset to compare inappropriate therapies, appropriate therapies, mortality, and complications in patients with and without IAD.

METHODS

This retrospective analysis included extracted, physician-adjudicated, arrhythmic episodes from ICD devices. The incidence of arrhythmic events was estimated with the Kaplan-Meier method using the log-rank test. Cox proportional hazards regression was used to estimate hazard ratios (HRs) with their 95% confidence intervals (CIs).

RESULTS

Of the 1699 ICD patients, 77 patients (4.5%) had IAD. Incidence of inappropriate shock was similar in both patients with (3.2% at 24 months) and without (3.8% at 24 months) IAD (HR: 0.80, CI: 0.19-3.30, p = 0.76). In a multivariable analysis IAD was not significantly associated with reduced mortality (HR: 0.64, CI: 0.08-4.80, p = 0.66). The rates of complications were numerically lower in patients with IAD vs without (8.8% vs 9.6% at 24 months respectively), but not statistically significant (HR: 0.83, CI: 0.20-3.38, p = 0.79).

CONCLUSIONS

IAD patients showed a very low annual rate of inappropriate therapy. This suggests that newer algorithms, such as the SST algorithm, are equally good at identifying and treating life-threatening arrhythmias in patients regardless of whether they have IAD.

Prognostic impact of potassium levels in patients with ventricular tachyarrhythmias

BACKGROUND

The study sought to assess the prognostic impact of potassium levels (K) in patients with ventricular tachyarrhythmias.

METHODS

A large retrospective registry was used including all consecutive patients presenting with ventricular tachyarrhythmias on admission from 2002 to 2016. Patients with hypokalemia (i.e., K < 3.3 mmol/L), normokalemia (i.e., K 3.3-4.5 mmol/L), and hyperkalemia (i.e., K > 4.5 mmol/L) were compared applying multi-variable Cox regression models and propensity-score matching for evaluation of the primary endpoint of all-cause mortality at 3 years. Secondary endpoints were early cardiac death at 24 h, in-hospital death, death at 30 days, as well as the composite endpoint of early cardiac death at 24 h, recurrences of ventricular tachyarrhythmias, and appropriate ICD therapies at 3 years.

RESULTS

In 1990 consecutive patients with ventricular tachyarrhythmias, 63% of the patients presented with normokalemia, 30% with hyperkalemia, and 7% with hypokalemia. After propensity matching, both hypokalemic (HR = 1.545; 95% CI 0.970-2.459; p = 0.067) and hyperkalemic patients (HR = 1.371; 95% CI 1.094-1.718; p = 0.006) were associated with the primary endpoint of all-cause mortality at 3 years compared to normokalemic patients. Hyperkalemia was associated with even worse prognosis directly compared to hypokalemia (HR = 1.496; 95% CI 1.002-2.233; p = 0.049). In contrast, potassium measurements were not associated with the composite endpoint at 3 years.

CONCLUSION

In patients presenting with ventricular tachyarrhythmias, normokalemia was associated with best short- and long-term survival, whereas hyperkalemia and hypokalemia were associated with increased mortality at 30 days and at 3 years.

[Brugada syndrome : Risk stratification and prevention of sudden cardiac death]

Brugada syndrome is ion channelopathy defined by coved type ST-elevation in at least one right precordial ECG lead. Patients may suffer from ventricular tachycardia/fibrillation, which may cause syncope or sudden cardiac death. The majority of patients are likely to remain asymptomatic throughout life. A correct ECG diagnosis remains challenging. The implantable cardioverter/defibrillator (ICD) is the only established therapy to protect against sudden cardiac death. Thus, individual risk stratification is of major clinical relevance in primary prevention. The present article gives an update on current risk stratification and novel therapeutic options apart from ICD therapy.

Single chamber implantable cardioverter defibrillator compared to dual chamber implantable cardioverter defibrillator: less is more! Data from the German Device Registry

BACKGROUND

In patients with high risk for sudden cardiac death the implantation of a defibrillator is an established treatment. However the benefits and risks for patients in accordance to the number of the leads are not clear. Even in the current guidelines a recommendation to this question is missing. We analyzed advantage and disadvantages of single-chamber implantable cardioverter defibrillators (VVI-ICD) versus dual-chamber implantable cardioverter defibrillators (DDD-ICD) in the prospective German Device Registry.

METHODS

The data of 2240 patients who underwent ICD implantation in 45 German Centers between January 2007 and March 2011 were included in a prospective device registry (VVI: n = 1629, male = 1358, EF = 34% ± 13%; DDD: n = 611, male = 491, EF = 35% ± 14%).

RESULTS

The in-hospital complications were significantly higher in the DDD-ICD group with higher revision/device complication rates (3.0% vs. 1.2%; p = 0.003) but also higher mortality rate (1.0% vs. 0.1%; p < 0.001). Regarding the adjusted data at 1-year follow-up DDD-ICD caused more device revisions, but no difference in rehospitalization and mortality.

CONCLUSION

It is still unclear whether DDD-ICD may be beneficial for patients with preserved sinus and atrioventricular nodal function. Our data show that the decision of the operator to choose a DDD-ICD in these patients must be taken very carefully. By choosing a DDD-ICD the patient is exposed to a significantly higher periprocedural complication rate and higher in-hospital mortality. In absence of relevant bradycardias implantation of a DDD-ICD is not justified.

Outcome differences and device performance of the subcutaneous ICD in patients with and without structural heart disease

BACKGROUND

The performance of the subcutaneous ICD (S-ICD™) has been described in different kinds of heart disease and has been proven to be an important advance in prevention of sudden cardiac death (SCD). While positive experiences with the S-ICD™ initially came from collectives of patients without structural heart diseases, positive results have also been collected from cohorts with structural heart disease.

MATERIALS AND METHODS

All S-ICD™ patients with either ischemic cardiomyopathy (ICM), dilated cardiomyopathy (DCM) or hypertrophic cardiomyopathy (HCM) as the main indication for ICD implantation (n = 144 patients) or electrical heart disease/idiopathic ventricular fibrillation (n = 83 patients) in our large-scaled single-center S-ICD™ registry were included in this study. Baseline characteristics, appropriate and inappropriate shocks, and complications were documented in a mean follow-up of 18 ± 15 months.

RESULTS

Baseline characteristics were significantly different between the two groups in most categories. In contrast, there was no difference concerning neither appropriate nor inappropriate shock delivery between the two groups. Also other outcome parameters such as need for surgical revisions and all-cause mortality did not differ. There was a significant difference between the first- and second-generation S-ICDs™ in inadequate shocks mainly driven by patients with HCM.

CONCLUSION

In our study, S-ICD™ performance was similar in patients with and without structural heart disease. Decision pro- or contra-S-ICD™ should be made rather on the basis of expected shock rate and probability of the need for future anti-tachycardia or anti-bradycardia pacing than in dependence of the underlying heart disease.