Clinical Predictors of Recurrent Ventricular Arrhythmias in Secondary Prevention Implantable Cardioverter Defibrillator Recipients With Coronary Artery Disease - Lower Left Ventricular Ejection Fraction and Incomplete Revascularization

Revascularization and Left Ventricular Dysfunction for ICD Eligibility

Common triggers for sudden cardiac death (SCD) are transient ischemia, hemodynamic fluctuations, neurocardiovascular influences, and environmental factors. SCD occurs rapidly when sinus rhythm degenerates into ventricular tachycardia (VT) and/or ventricular fibrillation (VF), followed by asystole. Such progressive worsening of the cardiac rhythm is in most cases observed in the setting of ischemic heart disease and often associated with advanced left ventricular (LV) impairment. Revascularization prevents negative outcomes including SCD and heart failure (HF) due to LV dysfunction (LVD). The implantable cardioverter-defibrillator (ICD) on top of medical therapy is superior to antiarrhythmic drugs for patients with LVD and VT/VF. The beneficial effects of ICD have been demonstrated in primary prevention of SCD as well. However, yet debated is the temporal management for patients with LVD who are eligible to ICD prior to revascularization, either through percutaneous or surgical approach. Restoration of coronary blood flow has a dramatic impact on adverse LV remodeling, while it requires aggressive long-term antiplatelet therapy, which might increase complication for eventual ICD procedure when percutaneous strategy is pursued; on the other hand, when LV and/or multiorgan dysfunction is present and coronary artery bypass grafting is chosen, the overall risk is augmented, mostly in HF patients. The aims of this review are to describe the pathophysiologic benefits of revascularization, the studies addressing percutaneous, surgical or no revascularization and ICD implantation, as well as emerging defibrillation strategies for patients deemed at transient risk of SCD and/or at higher risk for transvenous ICD implantation.

Mechanical circulatory support in ventricular arrhythmias

In atrial and ventricular tachyarrhythmias, reduced time for ventricular filling and loss of atrial contribution lead to a significant reduction in cardiac output, resulting in cardiogenic shock. This may also occur during catheter ablation in 11% of overall procedures and is associated with increased mortality. Managing cardiogenic shock and (supra) ventricular arrhythmias is particularly challenging. Inotropic support may exacerbate tachyarrhythmias or accelerate heart rate; antiarrhythmic drugs often come with negative inotropic effects, and electrical reconversions may risk worsening circulatory failure or even cardiac arrest. The drop in native cardiac output during an arrhythmic storm can be partly covered by the insertion of percutaneous mechanical circulatory support (MCS) devices guaranteeing end-organ perfusion. This provides physicians a time window of stability to investigate the underlying cause of arrhythmia and allow proper therapeutic interventions (e.g., percutaneous coronary intervention and catheter ablation). Temporary MCS can be used in the case of overt hemodynamic decompensation or as a “preemptive strategy” to avoid circulatory instability during interventional cardiology procedures in high-risk patients. Despite the increasing use of MCS in cardiogenic shock and during catheter ablation procedures, the recommendation level is still low, considering the lack of large observational studies and randomized clinical trials. Therefore, the evidence on the timing and the kinds of MCS devices has also scarcely been investigated. In the current review, we discuss the available evidence in the literature and gaps in knowledge on the use of MCS devices in the setting of ventricular arrhythmias and arrhythmic storms, including a specific focus on pathophysiology and related therapies.

Clinical management of electrical storm: a current overview

The number of patients affected by electrical storm has been continuously increasing in emergency departments. Patients are often affected by multiple comorbidities requiring multidisciplinary interventions to achieve a clinical stability. Careful reprogramming of cardiac devices, correction of electrolyte imbalance, knowledge of underlying heart disease and antiarrhythmic drugs in the acute phase play a crucial role. The aim of this review is to provide a comprehensive overview of pharmacological treatment, latest transcatheter ablation techniques and advanced management of patients with electrical storm.

Development and Validation of a Risk Prediction Model for Ventricular Arrhythmia in Elderly Patients with Coronary Heart Disease

BACKGROUND

Sudden cardiac death is a leading cause of death from coronary heart disease (CHD). The risk of sudden cardiac death (SCD) increases with age, and sudden arrhythmic death remains a major cause of mortality in elderly individuals, especially ventricular arrhythmias (VA). We developed a risk prediction model by combining ECG and other clinical noninvasive indexes including biomarkers and echocardiology for VA in elderly patients with CHD.

METHOD

In the retrospective study, a total of 2231 consecutive elderly patients (≥60 years old) with CHD hospitalized were investigated, and finally 1983 patients were enrolled as the model group. The occurrence of VA within 12 months was mainly collected. Study parameters included clinical characteristics (age, gender, height, weight, BMI, and past medical history), ECG indexes (QTcd, Tp-e/QT, and HRV indexes), biomarker indexes (NT-proBNP, Myo, cTnT, CK-MB, CRP, K+, and Ca2+), and echocardiology indexes. In the respective study, 406 elderly patients (≥60 years old) with CHD were included as the verification group to verify the model in terms of differentiation and calibration.

RESULTS

In the multiparameter model, seven independent predictors were selected: LVEF, LAV, HLP, QTcd, sex, Tp-e/QT, and age. Increased HLP, Tp-e/QT, QTcd, age, and LAV were risk factors (RR > 1), while female and increased LVEF were protective factors (RR < 1). This model can well predict the occurrence of VA in elderly patients with CHD (for model group, AUC: 0.721, 95% CI: 0.669∼0.772; for verification group, AUC: 0.73, 95% CI: 0.648∼0.818; Hosmer-Lemeshow χ 2 = 13.541, P=0.095). After adjusting the predictors, it was found that the combination of clinical indexes and ECG indexes could predict VA more efficiently than using clinical indexes alone.

CONCLUSIONS

LVEF, LAV, QTcd, Tp-e/QT, gender, age, and HLP were independent predictors of VA risk in elderly patients with CHD. Among these factors, the echocardiology indexes LVEF and LAV had the greatest influence on the predictive efficiency of the model, followed by ECG indexes, QTcd and Tp-e/QT. After verification, the model had a good degree of differentiation and calibration, which can provide a certain reference for clinical prediction of the VA occurrence in elderly patients with CHD.

Reversible Cause of Cardiac Arrest and Secondary Prevention Implantable Cardioverter Defibrillators in Patients With Coronary Artery Disease: Value of Complete Revascularization and LGE-CMR

Background

In survivors of sudden cardiac arrest with obstructive coronary artery disease, it remains challenging to distinguish ischemia as a reversible cause from irreversible scar‐related ventricular arrhythmias. We aimed to evaluate the value of implantable cardioverter‐defibrillator (ICD) implantation in sudden cardiac arrest survivors with presumably reversible ischemia and complete revascularization.

Methods and Results

This multicenter retrospective cohort study included 276 patients (80% men, age 67±10 years) receiving ICD implantation for secondary prevention. Angiography was performed before ICD implantation. A subgroup of 166 (60%) patients underwent cardiac magnetic resonance imaging with late gadolinium enhancement before implantation. Patients were divided in 2 groups, (1) ICD‐per‐guideline, including 228 patients with incomplete revascularization or left ventricular ejection fraction ≤35%, and (2) ICD‐off‐label, including 48 patients with complete revascularization and left ventricular ejection fraction >35%. The primary outcome was time to appropriate device therapy (ADT). During 4.0 years (interquartile range, 3.5–4.6) of follow‐up, ADT developed in 15% of the ICD‐off‐label group versus 43% of the ICD‐per‐guideline group. Time to ADT was comparable in the ICD‐off‐label and ICD‐per‐guideline groups (hazard ratio (HR), 0.46; P=0.08). No difference in mortality was observed (HR, 0.95; P=0.93). Independent predictors of ADT included age (HR, 1.03; P=0.01), left ventricular end‐diastolic volume HR, (1.05 per 10 mL increase; P<0.01) and extent of transmural late gadolinium enhancement (HR, 1.12; P=0.04).

Conclusions

This study demonstrates that sudden cardiac arrest survivors with coronary artery disease remain at high risk of recurrent ventricular arrhythmia, even after complete revascularization and with preserved left ventricular function. Late gadolinium enhancement–cardiac magnetic resonance imaging derived left ventricular volumes and extent of myocardial scar were independently associated with.

Impact of Myocardial Bridge on Life‐Threatening Ventricular Arrhythmia in Patients With Implantable Cardioverter Defibrillator

Background

Myocardial bridge (MB), common anatomic variant, is generally considered benign, while previous studies have shown associations between MB and various cardiovascular pathologies. This study aimed to investigate for the first time possible impact of MB on long‐term outcomes in patients with implantable cardioverter defibrillator, focusing on life‐threatening ventricular arrhythmia (LTVA).

Methods and Results

This retrospective analysis included 140 patients with implantable cardioverter defibrillator implantation for primary (n=23) or secondary (n=117) prevention of sudden cardiac death. Angiographically apparent MB was identified on coronary angiography as systolic milking appearance with significant arterial compression. The primary end point was the first episode(s) of LTVA defined as appropriate implantable cardioverter defibrillator treatments (antitachyarrhythmia pacing and/or shock) or sudden cardiac death, assessed for a median of 4.5 (2.2–7.1) years. During the follow‐up period, LTVA occurred in 37.9% of patients. Angiographically apparent MB was present in 22.1% of patients; this group showed younger age, lower rates of coronary risk factors and ischemic cardiomyopathy, higher prevalence of vasospastic angina and greater left ventricular ejection fraction compared with those without. Despite its lower risk profiles above, Kaplan–Meier analysis revealed significantly lower event‐free rates in patients with versus without angiographically apparent MB. In multivariate analysis, presence of angiographically apparent MB was independently associated with LTVA (hazard ratio, 4.24; 95% CI, 2.39–7.55; P <0.0001).

Conclusions

Angiographically apparent MB was the independent determinant of LTVA in patients with implantable cardioverter defibrillator. Although further studies will need to confirm our findings, assessment of MB appears to enhance identification of high‐risk patients who may benefit from closer follow‐up and targeted therapies.

Secondary prevention of sudden cardiac death

The prevention and treatment of sudden cardiac death (SCD) remains a significant public health challenge. For patients with a history of sudden death attributable to ventricular arrhythmia, implantable cardioverter-defibrillator (ICD) therapy is a mainstay of treatment, although these patients remain at high risk for recurrent ventricular arrhythmia and defibrillator therapies. In this review, we summarize landmark clinical trials evaluating the efficacy of ICD therapy in secondary prevention patients, review clinical outcomes including mode of death in survivors of SCD, and highlight the role for systematic diagnostic evaluation. We additionally discuss the invasive electrophysiological management of these patients, including ICD selection and programming as well as the role and timing of antiarrhythmic drug therapy and catheter ablation. Finally, we frame future challenges and needs to advance the care for secondary prevention patients.

Outcome differences between carotid artery stenting (CAS) and carotid endarterectomy (CEA) in postoperative ventricular arrhythmia, neurological complications, and in-hospital mortality

Objective: We study whether the carotid artery stenting (CAS) and carotid endarterectomy (CEA) differ from each other in postoperative ventricular arrhythmia, along with neurological complications (perioperative stroke and transient ischemic attack), in-hospital mortality, and estimated medical cost. Methods: This study used data of patients with carotid artery stenosis from the National Inpatient Sample (NIS) database (2011-2014) from the United States of America. Based on the procedure that patients received, individuals were categorized into groups of CAS and CEA. Multilevel analyses were conducted to examine the difference in the following outcomes: postoperative ventricular arrhythmia, neurological complications, in-hospital mortality, and medical costs between CAS and CEA. The patient age, gender, race, Charlson Comorbidity Index, primary payer, emergency department service record, bed size of hospital, region of the hospital, and location of the hospital were adjusted in each model. In addition, preexisting cardiovascular diseases (CVDs) were adjusted for when predicting postoperative ventricular arrhythmia; postoperative CVDs were adjusted for in the model of in-hospital mortality. Results: A total of 127,321 carotid artery stenosis hospitalizations were included in our analyses (n = 17,074 in CAS, n = 110,247 in CEA). Multivariate logistic regressions showed that compared with patients underwent CAS, those with CEA had a lower odds of postoperative ventricular arrhythmia (odds ratio [OR] = 0.81, 95% confidence interval [CI]: [0.66-0.98]), less neurological complications (OR = 0.55, 95% CI: [0.51-0.59] in general; OR = 0.63, 95% CI: [0.57-0.69] in ischemic stroke; OR = 0.26, 95% CI: [0.20-0.32] in hemorrhagic stroke; and OR = 0.58, 95% CI: [0.47-0.71] in transient ischemic attack), and in-hospital mortality (OR = 0.52, 95% CI: [0.42-0.64]). Generalized linear model indicated patients undergoing CEA had lower medical cost (β = -4329.99, 95% CI: [-4552.61, -4107.38]) than patients undergoing CAS. Conclusions: In short-term outcomes, CEA was associated with a lower risk of postoperative ventricular arrhythmia, neurological complications, in-hospital mortality, and lower cost as compared with CAS.

Echocardiographic Epicardial Adipose Tissue Thickness for Risk Stratification of Patients With Heart Failure

Background and Aims

Epicardial adipose tissue (EAT) has been shown to be involved in the pathogenesis and progression of heart failure (HF). In this study we aimed to explore the predictive value of echocardiographic EAT thickness on prognosis of a selected population of HF patients.

Methods

The patient population included n. 69 consecutive patients with systolic HF referred to implantable cardioverter defibrillator (ICD) implantation for primary or secondary prevention. At the time of enrolment, echocardiographic EAT thickness was assessed in all patients along with demographic and clinical data. The study had a median follow-up time of 49.8 months. We assessed the prognostic predictive value of EAT thickness on a composite clinical and arrhythmic outcome including HF related deaths, new hospital admissions for HF worsening, and atrial and life threatening ventricular arrhythmic events. Clinical and arrhythmic outcomes were also evaluated separately.

Results

At univariate analysis, EAT thickness significantly predicted all the three outcomes considered. Of interest, at multivariate analysis, after adjusting for known risk factor, EAT remained significantly associated to the composite [HR 1.18 (1.09–1.28); p < 0.001], arrhythmic [HR 1.14 (1.03–1.25); p = 0.008], and clinical [HR 1.14 (1.03–1.27); p = 0.010] outcomes.

Conclusion

Echocardiographic assessment of EAT can predict outcome of HF patients and it is significantly associated with both arrhythmic and clinical events. These preliminary findings pave the way for future and larger studies aimed to definitively recognize the prognostic value of this novel risk marker in HF.