HRS/ACC/AHA Expert Consensus Statement on the Use of Implantable Cardioverter-Defibrillator Therapy in Patients Who Are Not Included or Not Well Represented in Clinical Trials

Heart involvement in systemic sclerosis: emerging concepts

PURPOSE OF REVIEW

Systemic sclerosis (SSc)-associated heart involvement (SHI) is a significant cause of both morbidity and mortality in individuals with SSc. SHI can take many different forms, and likely is a spectrum of fibroinflammatory cardiac disease. Presenting features include arrhythmia, ventricular systolic or diastolic dysfunction, pericardial disease, and exercise intolerance. Risk of sudden cardiac death in SSc is likely 10-30-fold greater than general population estimates. In this review, we explore what is known about the pathogenesis of SHI, its prevention and management, and discuss available strategies for screening for SHI in light of new recommendations for the routine screening of SHI in all SSc patients.

RECENT FINDINGS

We describe the spectrum, clinical features, and pathogenesis of SHI. Furthermore, we review the new recommendations for screening for SHI in individuals with SSc.

SUMMARY

There is a large, under-recognized burden of SHI in people living with SSc, which likely contributes to the significant increase in sudden cardiac death observed in SSc. However, a broad-based screening approach, including asymptomatic, low-risk patients should be viewed with caution given the lack of evidence-based treatments and interventions for SHI particularly in this group.

The causal effect of Alzheimer's disease and family history of Alzheimer's disease on non-ischemic cardiomyopathy and left ventricular structure and function: a Mendelian randomization study

Background

Previous studies have shown that Alzheimer's disease (AD) can cause myocardial damage. However, whether there is a causal association between AD and non-ischemic cardiomyopathy (NICM) remains unclear. Using a comprehensive two-sample Mendelian randomization (MR) method, we aimed to determine whether AD and family history of AD (FHAD) affect left ventricular (LV) structure and function and lead to NICM, including hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM).

Methods

The summary statistics for exposures [AD, paternal history of AD (PH-AD), and maternal history of AD (MH-AD)] and outcomes (NICM, HCM, DCM, and LV traits) were obtained from the large European genome-wide association studies. The causal effects were estimated using inverse variance weighted, MR-Egger, and weighted median methods. Sensitivity analyses were conducted, including Cochran's Q test, MR-Egger intercept test, MR pleiotropy residual sum and outlier, MR Steiger test, leave-one-out analysis, and the funnel plot.

Results

Genetically predicted AD was associated with a lower risk of NICM [odds ratio (OR) 0.9306, 95% confidence interval (CI) 0.8825-0.9813, p = 0.0078], DCM (OR 0.8666, 95% CI 0.7752-0.9689, p = 0.0119), and LV remodeling index (OR 0.9969, 95% CI 0.9940-0.9998, p = 0.0337). Moreover, genetically predicted PH-AD was associated with a decreased risk of NICM (OR 0.8924, 95% CI 0.8332-0.9557, p = 0.0011). MH-AD was also strongly associated with a decreased risk of NICM (OR 0.8958, 95% CI 0.8449-0.9498, p = 0.0002). Different methods of sensitivity analysis demonstrated the robustness of the results.

Conclusion

Our study revealed that AD and FHAD were associated with a decreased risk of NICM, providing a new genetic perspective on the pathogenesis of NICM.

Outcomes of tricuspid regurgitation after lead extraction

INTRODUCTION

Transvenous leads have been implicated in tricuspid valve (TV) dysfunction, but limited data are available regarding the effect of extracting leads across the TV on valve regurgitation. The aim of this study is to quantify tricuspid regurgitation (TR) before and after lead extraction and identify predictors of worsening TR.

METHODS

We studied 321 patients who had echocardiographic data before and after lead extraction. TR was graded on a scale (0 = none/trivial, 1 = mild, 2 = moderate, 3 = severe). A change of >1 grade following extraction was considered significant.

RESULTS

A total of 321 patients underwent extraction of a total of 338 leads across the TV (1.05 ± 0.31 leads across the TV per patient). There was no significant difference on average TR grade pre- and postextraction (1.18 ± 0.91 vs. 1.15 ± 0.87; p = 0.79). TR severity increased after extraction in 84 patients, but was classified as significantly worse (i.e., >1 grade change in severity) in only 8 patients (2.5%). Use of laser lead extraction was associated with a higher rate of worsening TR postextraction (44.0% vs. 31.6%, p = 0.04).

CONCLUSION

In our single-center analysis, extraction of leads across the TV did not significantly affect the extent of TR in most patients. Laser lead extraction was associated with a higher rate of worsening TR after extraction.

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.

Pre-percutaneous coronary intervention sudden cardiac arrest in ST-elevation myocardial infarction: Incidence, predictors, and related outcomes

Background

ST-segment elevation myocardial infarction (STEMI) is a frequent cause of sudden cardiac arrest (SCA) and early percutaneous coronary intervention (PCI) is associated with increased survival. Despite constant improvements in SCA management, survival remains poor. We aimed to assess pre-PCI SCA incidence and related outcomes in patients admitted with STEMI.

Methods

This was a prospective cohort study of patients admitted with STEMI in a tertiary university hospital over 11  years. All patients were submitted to emergency coronary angiography. Baseline characteristics, details of the procedure, reperfusion strategies, and adverse outcomes were assessed. The primary outcome was in-hospital mortality. The secondary outcome was 1-year mortality after hospital discharge. Predictors of pre-PCI SCA was also assessed.

Results

During the study period 1,493 patients were included; the mean age was 61.1 years (±12), and 65.3% were male. Pre-PCI SCA was present in 133 (8.9%) patients. In-hospital mortality was higher in the pre-PCI SCA group (36.8% vs. 8.8%, p < 0.0001). In multivariate analysis, anterior MI, cardiogenic shock, age, pre-PCI SCA and lower ejection fraction remained significantly associated with in-hospital mortality. When we analyzed the interaction between pre-PCI SCA and cardiogenic shock upon admission there is a further increase in mortality risk when both conditions are present. For predictors of pre-PCI SCA, only younger age and cardiogenic shock remained significantly associated after multivariate analysis. Overall 1-year mortality rates were similar between pre-PCI SCA survivors and non-pre-PCI SCA group.

Conclusion

In a cohort of consecutive patients admitted with STEMI, pre-PCI SCA was associated with higher in-hospital mortality, and its association with cardiogenic shock further increases mortality risk. However, long-term mortality among pre-PCI SCA survivors was similar to non-SCA patients. Understanding characteristics associated with pre-PCI SCA may help to prevent and improve the management of STEMI patients.

Different Phases of Disease in Lymphocytic Myocarditis: Clinical and Electrophysiological Characteristics

BACKGROUND

Endomyocardial biopsy (EMB) is required to make a definite diagnosis of lymphocytic myocarditis (LM), to identify its etiology, and to classify LM into different phases.

OBJECTIVES

This study aims to characterize and compare clinical and electrophysiological characteristics of different biopsy-proven LM phases, namely acute myocarditis (AM), chronic active myocarditis (CAM), and healed myocarditis (HM).

METHODS

All patients with a diagnosis of LM at 3 Italian referral centers were prospectively enrolled. According to EMB findings, LM was classified as AM, CAM, or HM; per-group comparisons of clinical presentations, noninvasive, and invasive findings are reported.

RESULTS

Among the 122 enrolled patients (AM, n = 44; CAM, n = 42; HM, n = 36), complex ventricular arrhythmias were very common overall (n = 109, 89%), but ventricular fibrillation was slightly more prevalent in AM (P = 0.028). Cardiac magnetic resonance imaging showed late gadolinium enhancement in more patients with HM and CAM than AM (94.4% vs 92.9% vs 50%; P < 0.001), whereas edema was more common in AM than in CAM, being absent in HM (90.9% vs 50% vs 0%; P < 0.001). Accordingly, edema was the strongest independent clinical predictor of EMB-proven active inflammation. Electroanatomical mapping revealed a lower prevalence of low-voltage areas in AM than in CAM or HM. We observed a strong association between edema at a specific myocardial segment and normal voltages at that site (odds ratio: 0.24; 95% CI: 0.10-0.54; P < 0.01), as well as between late gadolinium enhancement and low-voltage areas (odds ratio: 2.86; 95% CI: 1.19-6.97; P = 0.019).

CONCLUSIONS

LM is a highly heterogeneous disease, and its different phases are characterized by diverse clinical, morphological, and electrophysiological features. Further research is required to identify electroanatomical markers of inflammation.

Clinical Outcomes of Patients with Coronary Artery Diseases and Moderate Left Ventricular Dysfunction: Percutaneous Coronary Intervention versus Coronary Artery Bypass Graft Surgery

Purpose

Percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) are two revascularization strategies for patients with coronary artery disease (CAD) and left ventricular dysfunction. However, the comparisons of effectiveness between the two strategies are insufficient. This study is aimed to compare the effectiveness between PCI and CABG among patients with moderate left ventricular dysfunction.

Patients and Methods

A total of 1487 CAD patients with moderate reduced ejection fraction (36%≤EF≤40%), who underwent either PCI or CABG, were enrolled in a real-world cohort study (No. ChiCTR2100044378). Clinical outcomes included short- and long-term all-cause mortality, rates of heart failure (HF) hospitalization and repeat revascularization. Propensity score matching was used to balance the two cohorts.

Results

PCI was associated with lower 30-day mortality rate (hazard ratio [HR] [95% CI], 0.35 [0.15–0.83]; P=0.02). At a mean follow-up of 4.5 years, PCI and CABG had similar all-cause death (HR [95% CI], 0.82 [0.56–1.20]; P=0.30) and heart failure (HF) hospitalization (HR [95% CI], 0.93 [0.54–1.60]; P=0.79), but PCI had higher risk of repeat revascularization (HR [95% CI], 8.62 [3.67–20.23]; P<0.001). Improvement in EF measured at 3 months later after revascularization was also similar between PCI and CABG (P for interaction=0.87).

Conclusion

CAD patients with moderate reduced EF who had PCI had lower short-term mortality rate but higher risk of repeat revascularization during follow-up than patients who had CABG. PCI showed comparable long-term survival, HF hospitalization risk, and EF improvement.

Cardiovascular Manifestations From Therapeutic Radiation: A Multidisciplinary Expert Consensus Statement From the International Cardio-Oncology Society

Radiation therapy is a cornerstone of cancer therapy, with >50% of patients undergoing therapeutic radiation. As a result of widespread use and improved survival, there is increasing focus on the potential long-term effects of ionizing radiation, especially cardiovascular toxicity. Radiation therapy can lead to atherosclerosis of the vasculature as well as valvular, myocardial, and pericardial dysfunction. We present a consensus statement from the International Cardio-Oncology Society based on general principles of radiotherapy delivery and cardiovascular risk assessment and risk mitigation in this population. Anatomical-based recommendations for cardiovascular management and follow-up are provided, and a priority is given to the early detection of atherosclerotic vascular disease on imaging to help guide preventive therapy. Unique management considerations in radiation-induced cardiovascular disease are also discussed. Recommendations are based on the most current literature and represent a unanimous consensus by the multidisciplinary expert panel.

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Radiation therapy leads to short- and long-term cardiovascular adverse effects of the vasculature and the heart, including valvular, myocardial, and pericardial disease.

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Computed tomography scans conducted for radiation planning or cancer staging provide an available opportunity to detect asymptomatic atherosclerosis and direct preventive therapies.

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Additional practical screening recommendations for cardiovascular disease based on anatomical exposure are provided.

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There are unique considerations in the management of radiation-induced cardiovascular disease; contemporary percutaneous treatment is often preferred over surgical options.

Right Ventricular Function at Cardiac MRI Predicts Cardiovascular Events in Patients with an Implantable Cardioverter-Defibrillator

Background Right ventricular ejection fraction (RVEF) is an independent predictor of death and adverse cardiovascular outcomes in patients with various cardiac conditions. Purpose To investigate whether RVEF, measured with cardiac MRI, is a predictor of appropriate shock or death in implantable cardioverter-defibrillator (ICD) recipients for primary and secondary prevention of sudden cardiac death. Materials and Methods This retrospective, multicenter, observational study included patients who underwent cardiac MRI before ICD implantation between January 2007 and May 2017. Right ventricular end-diastolic and end-systolic volumes and RVEF were measured with cardiac MRI. The primary end point was a composite of all-cause mortality or appropriate ICD shock. The secondary end point was all-cause mortality. The association between RVEF and primary and secondary outcomes was evaluated by using multivariable Cox regression analysis. Potential interactions were tested between primary prevention, ischemic cause, left ventricular ejection fraction (LVEF), and RVEF. Results Among 411 patients (mean age ± standard deviation, 60 years; 315 men) during a median follow-up of 63 months, 143 (35%) patients experienced an appropriate ICD shock or died. In univariable analysis, lower RVEF was associated with greater risks for appropriate ICD shock or death and for death alone (log-rank trend test, P = .003 and .005 respectively). In multivariable Cox regression analysis adjusting for age at ICD implantation, LVEF, ICD indication (primary vs secondary), ischemic heart disease, and late gadolinium enhancement, RVEF was an independent predictor of the primary outcome (hazard ratio [HR], 1.21 per 10% lower RVEF; 95% CI: 1.04, 1.41; P = .01) and all-cause mortality (HR, 1.25 per 10% lower RVEF; 95% CI: 1.01, 1.55; P = .04). No evidence of significant interactions was found between RVEF and primary or secondary prevention (HR, 1.11 ± 0.17 [standard deviation]; P = .49), ischemic heart disease (HR, 1.02 ± 0.15; P = .78), and LVEF (HR, 0.91 ± 0.8; P = .29). Conclusion Right ventricular ejection fraction measured with cardiac MRI was a predictor of appropriate implantable cardioverter-defibrillator shock or death. © RSNA, 2021 See also the editorial by Nazarian and Zghaib in this issue.

Evaluation and Management of Heart Block After Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR) has developed substantially since its inception. Improvements in valve design, valve deployment technologies, preprocedural imaging and increased operator experience have led to a gradual decline in length of hospitalisation after TAVR. Despite these advances, the need for permanent pacemaker implantation for post-TAVR high-degree atrioventricular block (HAVB) has persisted and has well-established risk factors which can be used to identify patients who are at high risk and advise them accordingly. While most HAVB occurs within 48 hours of the procedure, there is a growing number of patients developing HAVB after initial hospitalisation for TAVR due to the trend for early discharge from hospital. Several observation and management strategies have been proposed. This article reviews major known risk factors for HAVB after TAVR, discusses trends in the timing of HAVB after TAVR and reviews some management strategies for observing transient HAVB after TAVR.

State-of-the-art narrative review: multimodality imaging in electrophysiology and cardiac device therapies

Cardiac electrophysiology procedures have evolved to provide improvement in morbidity and mortality for many patients. Cardiac resynchronization therapy (CRT), implantable cardioverter/defibrillator (ICD) placement and lead extraction procedures are proven procedures, associated with significant reductions in patient morbidity and mortality as well as improved quality of life. The applications and optimization of these therapies are an evolving field. The optimal use and outcomes of cardiac electrophysiology procedures require a multidisciplinary approach to patient selection, device selection, and procedural planning. Cardiac imaging using echocardiography plays a key role in selection of patients for CRT therapy, for guidance of left ventricular (LV) lead placement, and for optimization of atrioventricular pacing delays in patients with CRT. Cardiac computed tomography (CT) is an important tool in assessment of lead perforation, as well as assessing risk of lead extraction and procedural planning. Cardiac magnetic resonance imaging (MRI) is an important adjunct to transthoracic echocardiography for patient selection and risk stratification for defibrillator therapy for multiple disease states including ischemic cardiomyopathy, hypertrophic cardiomyopathy, cardiac sarcoidosis, and arrhythmogenic right ventricular cardiomyopathy (ARVC). Cardiac positron emission tomography (PET) is a useful adjunct to the diagnosis of device infections as well as inflammatory conditions including cardiac sarcoidosis. Our review attempts to summarize the contemporary roles of multimodality imaging in CRT therapy, ICD therapy and lead extraction therapy.

From Hypertrophy to Heart Failure: What Is New in Genetic Cardiomyopathies

PURPOSE

The purpose of this review is to provide an update on the recent advances in the research and clinical care of patients with the major phenotypes of inherited cardiomyopathies-hypertrophic, dilated, and arrhythmogenic. Developments in genetics, risk stratification, therapies, and disease modeling will be discussed.

RECENT

Diagnostic, prognostic, and therapeutic tools which incorporate genetic and genomic data are being steadily incorporated into the routine clinical care of patients with genetic cardiomyopathies. Human pluripotent stem cells are a breakthrough model system for the study of genetic variation associated with inherited cardiovascular disease. Next-generation sequencing technology and molecular-based diagnostics and therapeutics have emerged as valuable tools to improve the recognition and care of patients with hypertrophic, dilated, and arrhythmogenic cardiomyopathies. Improved adjudication of variant pathogenicity and management of genotype-positive/phenotype-negative individuals are imminent challenges in this realm of precision medicine.

Sudden cardiac arrest and ventricular arrhythmias following first type I myocardial infarction in the contemporary era

INTRODUCTION

Myocardial infarction (MI) is associated with an increase in subsequent heart failure (HF), recurrent ischemic events, sudden cardiac arrest, and ventricular arrhythmias (SCA-VA). The primary objective of the study to determine the role of intercurrent HF and ischemic events on the development of SCA-VA following first type I MI.

METHODS AND RESULTS

A retrospective cohort study of patients experiencing first type 1 MI in Olmsted County, Minnesota (2002-2012) was conducted by identifying patients using the medical records linkage system (Rochester epidemiology project). Patients aged ≥18 years were followed from the time of MI till death or 31 July, 2017. Intercurrent HF and ischemic events were the primary exposures following MI and their association with outcome SCA-VA was assessed. Eight hundred and sixty-seven patients (mean age was 63 ± 14.5 years; 69% male; 49.8% ST-elevation myocardial infarction) who had their first type I MI during the study period were included. Majority of acute MI patients were revascularized using percutaneous coronary intervention and bypass surgery (628 [72.43%] and 87 [10.03%] respectively). During a mean follow-up of 7.69 ± 4.17 years, HF, recurrent ischemic events and SCA-VA occurred in 155 (17.9%), 245 (28.3%), and 40 (4.61%) patients respectively. Low ejection fraction (adjusted hazard ratio [HR] 0.95; 95% confidence interval [CI], 0.93-0.98; P < .001), intercurrent HF (adjusted HR 3.11; 95% CI, 1.39-6.95; P = .006) and recurrent ischemic events (adjusted HR 3.47; 95% CI, 1.68-7.18; P < .001) were associated with subsequent SCA-VA.

CONCLUSION

SCA-VA occurred in a small proportion of patients after MI and is associated with intercurrent HF and recurrent ischemic events.

Postoperative Antibiotic Prophylaxis Following Cardiac Implantable Electronic Device Placement

Infections related to cardiac implantable electronic device (CIED) placement are associated with poor clinical outcomes. As such, preprocedural prophylactic antibiotic therapy is indicated for all patients prior to device insertion. However, the available data are less clear on the impact of postprocedural antibiotic therapy on rates of CIED infection when used in addition to preprocedural therapy. This is single-center, retrospective cohort study of 913 patients who underwent CIED-related procedures between October 2010 and August 2014 sought to compare the rate of CIED infections in patients receiving only preprocedural antibiotics with those receiving both preprocedural and postprocedural antibiotics. Univariate analysis was used to detect independent risk factors for CIED infection. After excluding patients receiving concomitant antibiotics for other conditions, those undergoing CIED extraction alone, and those with a lack of follow-up data and/or adequate documentation of clinical encounters, 569 patients were identified for inclusion in the final analysis. The majority of patients who received postprocedural antibiotics received three to five days of therapy, with the most common antibiotic used being cephalexin. There was no statistically significant difference in the incidence of infection between patients who did and did not receive postoperative antibiotics (4.5% versus 6.1%; p = 0.398). In a multivariate analysis, the use of postprocedural antibiotic therapy was not a significant risk factor for infection (adjusted odds ratio: 0.692; 95% confidence interval: 0.314–1.525; p = 0.361). It is therefore reasonable to withhold prescribing postoperative antibiotics in patients following CIED implantation. Individualized risk factor evaluation of patient comorbidities and procedural characteristics may be needed to aid in determining whether postoperative antibiotics are reasonable in different patients. The validity of these findings is contingent on further confirmation via a prospective, randomized clinical trial.

Cognitive performance in patients with implantable cardioverter defibrillators: Associations with objective sleep duration, age and anxiety

Sleep disturbance and anxiety are highly prevalent in patients with implantable cardiac defibrillators (ICDs). There is limited research, however, on the associations between cognitive performance and sleep parameters, age and anxiety. Forty-one patients with ICDs and self-reported sleep disturbance completed 14 days of actigraphy (Mage  = 60.3, SD = 12.3) measuring total sleep time (TST), and a computerized cognitive test battery measuring processing speed and attention (i.e. simple reaction time and symbol digit modality task [SDMT]) and executive function (i.e. flanker task, letter series task and N-back task). Multiple regressions determined whether independent effects of TST, age and anxiety, as well as interactive effects of TST and age, predicted cognitive performance. TST predicted performance on two tasks of executive function (i.e. letter series and N-back task), as well as an attentional vigilance and processing speed task (i.e. SDMT), and this did not depend on patient age. On letter series, N-back and SDMT, longer TST predicted better performance. Increasing age was a predictor of worse performance on SDMT and flanker tasks. No other predictors were associated with task performance. Results show that sleep duration, not anxiety, may be an important predictor of higher-order cognitive functioning and lower-order tasks measuring processing speed and attention in ICD patients, with longer sleep duration showing greater benefit for performance.

Device updates successfully reduce T‑wave oversensing and inappropriate shocks in subcutaneous ICD patients

Aims

To analyse the impact of device and software updates on the prevention of T‑wave oversensing (TWOS) and inappropriate shocks (IS) in subcutaneous ICD (S-ICD) patients.

Background

TWOS is a feared complication after implantation. It may lead to harmful IS. To date, specific strategies to reduce these events are lacking.

Methods

In this retrospective single-centre trial we analysed 146 S‑ICD patients who were implanted between 2010 and 2016. In all eligible consecutive patients (n = 139), follow-up of at least 6 weeks was studied. The incidence of TWOS/IS was analysed in patients receiving a 2^nd generation S‑ICD (Emblem-S-ICD) between 2014 and 2016 (Emblem). Their outcome was compared with a control group (SQ) treated with the SQ1010 device between 2010 and 2014, who were followed up for a maximum of 2 years. Furthermore, to test if the software update SMR8 reduces inappropriate shocks in the SQ1010-S-ICD population, the incidence of TWOS/IS was evaluated before and after update installation.

Results

Basic characteristics and indications for S‑ICD implantation were similar in both groups. However, the cumulative incidence of TWOS/IS was significantly decreased in Emblem vs. SQ (SQ: 15.4%, n = 14/91 vs. Emblem 4.2%, n = 2/48; p = 0.049). Furthermore, with regards to the SQ population we also observed a trend towards a significant reduction of TWOS/IS after installation of the software update SMR8 in 2014 (before update: 13.4%, n = 11/82 vs. after update: 4.6%, 3/65, p = 0.07).

Conclusion

2^nd generation devices but probably also the SMR8 software update reduce the incidence of TWOS/IS in S‑ICD patients.

Comparison of ventricular tachyarrhythmia recurrence between ischemic cardiomyopathy and dilated cardiomyopathy: a retrospective study

Background

The use of an implantable cardioverter-defibrillator (ICD) has been established as an effective secondary prevention strategy for ventricular tachycardia (VT)/ventricular fibrillation (VF). However, few reports discuss the difference in clinical predictors for recurrent VT/VF between patients with ischemic cardiomyopathy (ICM) and patients with dilated cardiomyopathy (DCM).

Methods

From May 2004 to December 2015, 132 consecutive patients who had ICM (n = 94) or DCM (n = 38) and had received ICD implantation for secondary prevention were enrolled in this study. All anti-tachycardia events during follow-up were validated. The clinical characteristics and echocardiographic parameters were obtained for comparison. The incidence of recurrence of VT/VF, cardiovascular mortality, all-cause mortality, the change of left ventricular ejection fraction (LVEF) and LV volume were analyzed.

Results

At a mean follow-up of 3.62 ± 2.93 years, 34 patients (36.2%) in the ICM group and 22 patients (57.9%) in the DCM group had a recurrence of VT/VF episodes (p = 0.032). The DCM group had a lower LVEF (p = 0.019), a larger LV end-diastolic volume (LVEDV) (p = 0.001), a higher prevalence of LVEDV >158 mL (p = 0.010), and a larger LV end-systolic volume (p = 0.010) than the ICM group. LVEDV >158 mL and no use of angiotensin-converting-enzyme inhibitor/angiotensin receptor blocker were independent predictors of recurrences of VT/VF in ICM patients but not in DCM patients. There were no difference in cardiovascular mortality and all-cause mortality between the ICM and DCM patients.

Conclusion

The DCM patients had a higher recurrence rate of VT/VF than did the ICM patients during long-term follow-up. An enlarged LV is an independent predictor of the recurrence of VT/VF in ICM patients receiving ICD for secondary prevention.

Wideband LGE MRI permits unobstructed viewing of myocardial scarring in a patient with an MR-conditional subcutaneous implantable cardioverter-defibrillator

A subcutaneous implantable cardioverter-defibrillator (S-ICD) is an alternative device for prevention of sudden cardiac death, without any leads within the heart. Patients implanted with any type of ICD may need catheter ablation of ventricular tachycardia (VT) to reduce the overall arrhythmia burden (e.g., recurrent monomorphic VT) and lower the incidence of painful shocks induced by the device. Late gadolinium enhancement (LGE) MRI is a useful pre-test for guiding VT ablation, because it can be used to map myocardial scar and produce better outcomes. Growing evidence suggests that MRI can be performed with manageable risks on patients with a cardiac implantable electronic device (CIED). Nonetheless, the diagnostic yield of cardiac MRI is still low because of severe image artifacts, regardless of MR-conditional or non-MR conditional labeling. Image artifacts in the heart induced by an S-ICD is expected to be larger than the artifacts induced by a transvenous ICD, because the former is twice as large in size and implanted closer to the heart. This is the first reported case of successful wideband LGE MRI in a patient implanted with an MR-conditional S-ICD. A 37-year-old man with ischemic cardiomyopathy was referred for a cardiac MRI at 1.5 T ten months after S-ICD implantation, in order to rule out constrictive pericarditis. Clinical standard LGE MRI produced severe image artifacts, rendering it useless. In contrast, wideband LGE MRI provided unobstructed viewing of myocardial scarring. This case illustrates the usefulness of wideband LGE MRI for assessment of myocardial scarring in a patient with an MR-conditional S-ICD.

Physicians' knowledge and attitudes in Saudi Arabia regarding implantable cardiac defibrillators

OBJECTIVES

To evaluate knowledge and attitude of physicians involved in the management of patients with heart failure regarding implantable cardioverter-defibrillator (ICD).

METHODS

We conducted personal interviews with physicians involved in treating patients with heart failure. Between October 2015 and February 2016, the study was conducted in hospitals in the Riyadh region where no cardiac electrophysiology service was available. Every participant was met in person and received an oral questionnaire that aimed to assess basic knowledge regarding ICD indications and benefits.

RESULTS

Sixty-three physicians were met from 13 hospitals (14 consultants and 49 specialists). Forty-one percent of participants use the recommended cut-off level of left ventricular ejection fraction (LVEF) which is ≤35% as the LVEF criterion for ICD referral in patients with cardiomyopathy. Only 50% of the consultants use ≤35% as the LVEF criterion for ICD referral. Seventy percent of the participants thought that ICD may improve heart failure symptoms. Forty-eight percent of physicians have a defined channel to refer patients to higher centers for ICD implant. There was no statistically significant difference between physicians' knowledge when we categorized them according to three different factors: (1) physician's specialty (cardiology vs. internal medicine); (2) physician's degree (consultant vs. specialist); and (3) physician's location (inside vs. outside Riyadh city).

CONCLUSION

There is a lack of knowledge of current clinical guidelines regarding ICD implantation for patients with heart failure at general hospitals in Saudi Arabia. This finding highlights the need to improve the dissemination of guidelines to practitioners involved in managing patients with heart failure in an effort to improve ICD utilization.

Long-term Outcomes Associated With Implantable Cardioverter Defibrillator in Adults With Chronic Kidney Disease

IMPORTANCE

Chronic kidney disease (CKD) is common in adults with heart failure and is associated with an increased risk of sudden cardiac death. Randomized trials of participants without CKD have demonstrated that implantable cardioverter defibrillators (ICDs) decrease the risk of arrhythmic death in selected patients with reduced left ventricular ejection fraction (LVEF) heart failure. However, whether ICDs improve clinical outcomes in patients with CKD is not well elucidated.

OBJECTIVE

To examine the association of primary prevention ICDs with risk of death and hospitalization in a community-based population of potentially ICD-eligible patients who had heart failure with reduced LVEF and CKD.

DESIGN, SETTINGS, AND PARTICIPANTS

This noninterventional cohort study included adults with heart failure and an LVEF of 40% or less and measures of serum creatinine levels available from January 1, 2005, through December 31, 2012, who were enrolled in 4 Kaiser Permanente health care delivery systems. Chronic kidney disease was defined as an estimated glomerular filtration rate of less than 60 mL/min/1.73 m2. Patients who received and did not receive an ICD were matched (1:3) on CKD status, age, and high-dimensional propensity score to receive an ICD. Follow-up was completed on December 31, 2013. Data were analyzed from 2015 to 2017.

EXPOSURES

Placement of an ICD.

MAIN OUTCOMES AND MEASURES

All-cause death, hospitalizations due to heart failure, and any-cause hospitalizations.

RESULTS

A total of 5877 matched eligible adults with CKD (1556 with an ICD and 4321 without an ICD) were identified (4049 men [68.9%] and 1828 women [31.1%]; mean [SD] age, 72.9 [8.2] years). In models adjusted for demographics, comorbidity, and cardiovascular medication use, no difference was found in all-cause mortality between patients with CKD in the ICD vs non-ICD groups (adjusted hazard ratio, 0.96; 95% CI, 0.87-1.06). However, ICD placement was associated with increased risk of subsequent hospitalization due to heart failure (adjusted relative risk, 1.49; 95% CI, 1.33-1.60) and any-cause hospitalization (adjusted relative risk, 1.25; 95% CI, 1.20-1.30) among patients with CKD.

CONCLUSIONS AND RELEVANCE

In a large, contemporary, noninterventional study of community-based patients with heart failure and CKD, ICD placement was not significantly associated with improved survival but was associated with increased risk for subsequent hospitalization due to heart failure and all-cause hospitalization. The potential risks and benefits of ICDs should be carefully considered in patients with heart failure and CKD.

Catheter Ablation of Ventricular Tachycardia in Structural Heart Disease: Indications, Strategies, and Outcomes-Part II

In contrast to ventricular tachycardia (VT) that occurs in the setting of a structurally normal heart, VT that occurs in patients with structural heart disease carries an elevated risk for sudden cardiac death (SCD), and implantable cardioverter-defibrillators (ICDs) are the mainstay of therapy. In these individuals, catheter ablation may be used as adjunctive therapy to treat or prevent repetitive ICD therapies when antiarrhythmic drugs are ineffective or not desired. However, certain patients with frequent premature ventricular contractions (PVCs) or VT and tachycardiomyopathy should be considered for ablation before ICD implantation because left ventricular function may improve, consequently decreasing the risk of SCD and obviating the need for an ICD. The goal of this paper is to review the pathophysiology, mechanism, and management of VT in the setting of structural heart disease and discuss the evolving role of catheter ablation in decreasing ventricular arrhythmia recurrence.

Inappropriate shocks in single-chamber and subcutaneous implantable cardioverter-defibrillators: a systematic review and meta-analysis

AIMS

Single-chamber (VR-ICD) and subcutaneous (S-ICD) implantable cardioverter-defibrillators are effective to protect patients against sudden death but expose them to higher risk of inappropriate shock (IS). We sought to quantify the annual rate and influencing factors of ISs in VR- and S-ICDs from the literature.

METHODS AND RESULTS

PubMed, Embase, and Cochrane Library were searched for full text articles with IS rates. Poisson distribution estimated proportion of patients with ISs; rates were annualized based on follow-up duration. Random effects meta-analysis accounted for study-to-study variation. Out of 3264 articles, 16 qualified for the meta-analysis. Across studies, 6.4% [95% confidence interval (CI) 5.1-7.9%] of patients received an IS per year. Meta-regression analyses demonstrated that IS rates were lower in more recent studies [rate ratio (RR) per year: 0.93, 95% CI: 0.87-0.98; P = 0.01] and trended lower in studies with longer follow-up (RR per year: 0.78, 95% CI: 0.60-1.01; P = 0.06). Use of S-ICDs (RR: 1.81, 95% CI: 0.86-3.81; P = 0.12) and ventricular tachycardia zone programmed on (RR: 1.13, 95% CI: 0.65-1.97; P = 0.66) were not associated with a significantly increased change in risk. The IS rate observed in one of the more recent studies was significantly lower than predicted after accounting for covariates (RR: 0.29, 95% CI: 0.14-0.60; P < 0.001).

CONCLUSIONS

A comprehensive review of the literature shows that 6.4% of patients with ICDs experienced their first IS annually. One of the 16 studies was better than predicted with the lowest reported rate (1.9%) and could not be explained by timing of the study or other covariates.

Opsin spectral sensitivity determines the effectiveness of optogenetic termination of ventricular fibrillation in the human heart: a simulation study

KEY POINTS

Optogenetics-based defibrillation, a theoretical alternative to electrotherapy, involves expression of light-sensitive ion channels in the heart (via gene or cell therapy) and illumination of the cardiac surfaces (via implanted LED arrays) to elicit light-induced activations. We used a biophysically detailed human ventricular model to determine whether such a therapy could terminate fibrillation (VF) and identify which combinations of light-sensitive ion channel properties and illumination configurations would be effective. Defibrillation was successful when a large proportion (> 16.6%) of ventricular tissue was directly stimulated by light that was bright enough to induce an action potential in an uncoupled cell. While illumination with blue light never successfully terminated VF, illumination of red light-sensitive ion channels with dense arrays of implanted red light sources resulted in successful defibrillation. Our results suggest that cardiac expression of red light-sensitive ion channels is necessary for the development of effective optogenetics-based defibrillation therapy using LED arrays.

ABSTRACT

Optogenetics-based defibrillation has been proposed as a novel and potentially pain-free approach to enable cardiomyocyte-selective defibrillation in humans, but the feasibility of such a therapy remains unknown. This study aimed to (1) assess the feasibility of terminating sustained ventricular fibrillation (VF) via light-induced excitation of opsins expressed throughout the myocardium and (2) identify the ideal (theoretically possible) opsin properties and light source configurations that would maximise therapeutic efficacy. We conducted electrophysiological simulations in an MRI-based human ventricular model with VF induced by rapid pacing; light sensitisation via systemic, cardiac-specific gene transfer of channelrhodopsin-2 (ChR2) was simulated. In addition to the widely used blue light-sensitive ChR2-H134R, we also modelled theoretical ChR2 variants with augmented light sensitivity (ChR2+), red-shifted spectral sensitivity (ChR2-RED) or both (ChR2-RED+). Light sources were modelled as synchronously activating LED arrays (LED radius: 1 mm; optical power: 10 mW mm-2 ; array density: 1.15-4.61 cm-2 ). For each unique optogenetic configuration, defibrillation was attempted with two different optical pulse durations (25 and 500 ms). VF termination was only successful for configurations involving ChR2-RED and ChR2-RED+ (for LED arrays with density ≥ 2.30 cm-2 ), suggesting that opsin spectral sensitivity was the most important determinant of optogenetic defibrillation efficacy. This was due to the deeper penetration of red light in cardiac tissue compared with blue light, which resulted in more widespread light-induced propagating wavefronts. Longer pulse duration and higher LED array density were associated with increased optogenetic defibrillation efficacy. In all cases observed, the defibrillation mechanism was light-induced depolarisation of the excitable gap, which led to block of reentrant wavefronts.

The association of serum magnesium and mortality outcomes in heart failure patients: A systematic review and meta-analysis

BACKGROUND

Low serum magnesium (Mg) has been independently shown to increase risk of heart failure (HF), but data on the association between serum Mg concentration and the outcome of patients with HF are conflicting. The purpose of this systematic review and meta-analysis was to estimate the prognostic effects of hypermagnesemia and hypomagnesemia on cardiovascular (CV) mortality and all-cause mortality (ACM) of patients with HF.

METHODS

Relevant studies were identified from Medline and Scopus databases. Included and excluded criteria were defined. Effects (i.e., log [risk ratio [RR]]) of hypomagnesemia and hypermagnesemia versus normomagnesemia were estimated using Poisson regression, and then a multivariate meta-analysis was applied for pooling RRs across studies. Heterogeneity was explored using a meta-regression and subgroup analysis.

RESULTS

On analysis, 7 eligible prospective studies yielded a total of 5172 chronic HF patients with 913 and 1438 deaths from CV and ACM, respectively. Most participants were elderly men with left ventricular (LV) ejection fraction ≤40%. Those patients with baseline hypermagnesemia had a significantly higher risk of CV mortality (RR, 1.38; 95% confidence interval [CI], 1.07-1.78) or ACM (RR, 1.35; 95% CI, 1.18-1.54) than those with baseline normomagnesemia. However, baseline hypomagnesemia was not associated with the risk of CV mortality (RR, 1.11; 95% CI, 0.79-1.57) and ACM (RR, 1.11; 95% CI, 0.87-1.41). A subgroup analysis by Mg cutoff suggested a dose-response trend for hypermagnesemia effects, that is, the pooled RRs for CV mortality were 1.28 (95% CI, 1.05-1.55) and 1.92 (95% CI, 1.00-3.68) for the cutoff of 0.89 to 1.00 and 1.05 to 1.70 mmol/L, respectively.

CONCLUSION

The present systematic review and meta-analysis suggested that, in HF patients, hypermagnesemia with serum Mg ≥ 1.05 mmol/L was associated with an increased risk of CV mortality and ACM but this was not observed for hypomagnesemia. This finding was limited to the elderly patients with chronic HF who had reduced LV systolic function.

The wearable cardioverter-defibrillator in a real-world clinical setting: experience in 102 consecutive patients

BACKGROUND

The wearable cardioverter-defibrillator (WCD) is used for temporary protection of patients deemed to be at high risk for sudden death (SCD) not yet meeting indications for the implantable defibrillator (ICD).

OBJECTIVES

To evaluate the efficacy, safety, and compliance of/to WCD use and subsequent medium-term outcome of patients in a single-center observational study.

METHODS

A total of 102 consecutive patients were fitted with the WCD from 2012 to 2015 and followed for a mean of 11 months (±8 months).

RESULTS

The most common clinical indication for WCD-prescription (63%) was a new diagnosis of severely impaired LV function (LVEF ≤35%). The median wear time of the WCD was 54 days with a daily use of 23 h. Appropriate WCD therapy occurred in four patients (seven shocks for VF, one shock for VT). An ICD was finally implanted in 56 patients (55%). Improvement in LV function was the most common reason not to implant an ICD (HR 0.37; 95% CI 0.19-0.73; p = 0.004). Two patients had inappropriate shocks from their WCD due to atrial fibrillation/flutter. Five patients fitted with an ICD after the end of WCD therapy suffered VT/VF episodes. After wearing the WCD, six patients died (five ICD recipients and one non-ICD recipient).

CONCLUSION

WCD therapy was well accepted by patients and provided temporary protection against ventricular tachyarrhythmias in patients at risk for SCD. The WCD may help to avoid unnecessary ICD implantations in a significant proportion of patients.

Relationship between right and left ventricular function in candidates for implantable cardioverter defibrillator with low left ventricular ejection fraction

Background

Indications for the primary prevention of sudden death using an implantable cardioverter defibrillator (ICD) are based predominantly on left ventricular ejection fraction (LVEF). However, right ventricular ejection fraction (RVEF) is also a known prognostic factor in a variety of structural heart diseases that predispose to sudden cardiac death. We sought to investigate the relationship between right and left ventricular parameters (function and volume) measured by cardiovascular magnetic resonance (CMR) among a broad spectrum of patients considered for an ICD.

Methods

In this retrospective, single tertiary-care center study, consecutive patients considered for ICD implantation who were referred for LVEF assessment by CMR were included. Right and left ventricular function and volumes were measured.

Results

In total, 102 patients (age 62±14 years; 23% women) had a mean LVEF of 28±11% and RVEF of 44±12%. The left ventricular and right ventricular end diastolic volume index was 140±42 mL/m² and 81±27 mL/m², respectively. Eighty-six (84%) patients had a LVEF <35%, and 63 (62%) patients had right ventricular systolic dysfunction. Although there was a significant and moderate correlation between LVEF and RVEF (r=0.40, p<0.001), 32 of 86 patients (37%) with LVEF <35% had preserved RVEF, while 9 of 16 patients (56%) with LVEF ≥35% had right ventricular systolic dysfunction (Kappa=0.041).

Conclusions

Among patients being considered for an ICD, there is a positive but moderate correlation between LVEF and RVEF. A considerable proportion of patients who qualify for an ICD based on low LVEF have preserved RVEF, and vice versa.

Frequency and Implications of Ischemia Prior to Ventricular Tachyarrhythmia in Patients Treated With a Wearable Cardioverter Defibrillator Following Myocardial Infarction

BACKGROUND

Autopsy studies imply that recurrent myocardial infarction (MI) accounts for the majority of sudden death early after acute MI, rather than primary arrhythmia. However, diagnosis of recurrent MI by autopsy is challenging and excludes electrocardiographic data to adjudicate arrhythmic causes. We examined the frequency of ischemia prior to treated ventricular tachycardia/fibrillation (VT/VF) and outcomes in patients using the wearable cardioverter defibrillator (WCD) following acute MI.

HYPOTHESIS

Primary arrhythmia, rather than ischemia, is a frequent contributor to sudden death following MI.

METHODS

All patients treated for VT/VF over a 6-year period while wearing a WCD following acute MI with advanced left ventricular dysfunction (ejection fraction ≤35%) were included. Patients with ST-segment changes ≥0.1 mV before VT/VF were classified ischemic. Demographics and clinical outcomes were compared between those with ischemia-mediated vs primary arrhythmia.

RESULTS

Among 273 patients fulfilling study criteria, 15.4% had ischemia prior to VT/VF. Clinical and WCD use characteristics did not significantly differ between ischemic and primary VT/VF groups. Termination of VT/VF by WCD treatment approximated 96% in both groups. Survival 24 hours post-treatment was 88% and 84% (P = 0.54) for patients with and without ischemic VT/VF, respectively. Furthermore, 30-day cumulative survival for those with and without ischemic VT/VF was 77% and 70%, respectively (P = 0.57).

CONCLUSIONS

Ischemia is an infrequent cause of VT/VF following MI, contradicting previous study conclusions that recurrent MI is responsible for most post-MI sudden death. Etiology of VT/VF, however, did not influence defibrillation success or survival, which was high for both groups.