Late Gadolinium Enhancement in Patients with Nonischemic Dilated Cardiomyopathy

One‐third of all patients with heart failure have nonischemic dilated cardiomyopathy (NIDM). Five‐year mortality from NIDM is as high as 20% with sudden cardiac death (SCD) as the cause in 30% of the deaths. Currently, the left ventricular ejection fraction (LVEF) is used as the main criteria to risk stratify patients requiring an implantable cardioverter defibrillator (ICD) to prevent SCD. However, LVEF does not necessarily reflect myocardial propensity for electrical instability leading to ventricular tachycardia (VT) or ventricular fibrillation (VF). Due to the differential risk in various subgroups of patients for arrhythmic death, it is important to identify appropriate patients for ICD implantation so that we can optimize healthcare resources and avoid the complications of ICDs in individuals who are unlikely to benefit. We performed a systematic search and review of clinical trials of NIDM and the use of ICDs and cardiac magnetic resonance imaging with late gadolinium enhancement (LGE) for risk stratification. LGE identifies patients with NIDM who are at high risk for SCD and enables optimized patient selection for ICD placement, while the absence of LGE may reduce the need for ICD implantation in patients with NIDM who are at low risk for future VF/VT or SCD.     

Sudden Death Mortality in Implantable Cardioverter Defibrillator Patients

Implanfable Cardioverter defibrillator (ICD) prevention of sudden cardiac death (SCD) is not absolute and our experience was reviewed to determine the frequency and nature of SCO in this population. The incidence and cause of mortality in 56 consecutive patients, who underwent ICD implantation beginning May 1982 with follow-up through May 19, 1990 were analyzed. Twenty-one patients died, 33% of the mortality was due to SCD, and 52% of deaths may be considered arrhythmic. The cumulative 1, 3, and 5 year SCD survivals were 93%, 89%, and 75%. All seven patients dying of SCD presented initially with SCD, all received previous shocks prior to SCD, and two of the seven patients had devices that were probably inactive at the time of death. We conclude that ICDs reduce but by no means eliminate arrhythmic death, particularly in those at highest risk for SCD. Arrhythmic death remained the most common cause of death in this population.     

Brugada.

The Brugada syndrome was first described in 1992. Palpitations and/or syncope are usually experienced during rest and increased vagal activity. [table: see text] However, in 15% of patients with Brugada syndrome, symptoms occur during physical activity. The syndrome is further characterized by a pattern of RBBB and ST-segment elevation in V1 to V2/V3 (see Table). One major and one minor criterion from the Table can serve to establish a diagnosis of Brugada syndrome. The patient presented in this report described symptoms only during physical activity. EPS confirmed the diagnosis of the Brugada syndrome, and an ICD was implanted. The clinical importance of the Brugada syndrome is that it calls attention to patients at risk for SCD. The syndrome is genetically determined and caused by mutations in the cardiac ion channels. Signal averaging that reveals late potentials can help identify persons who may be at high risk for SCD and who would thus be candidates for EPS, which can identify those at risk of SCD. The ICD is the only therapy known to help prevent SCD in patients with Brugada syndrome.     

The clinical challenge of preventing sudden cardiac death immediately after acute ST-elevation myocardial infarction

Unfortunately, of all patients experiencing acute myocardial infarction (MI), usually in the form of ST-elevation MI, 25–35% will die of sudden cardiac death (SCD) before receiving medical attention, most often from ventricular fibrillation. For patients who reach the hospital, prognosis is considerably better and has improved over the years. Reperfusion therapy, best attained with primary percutaneous coronary intervention compared to thrombolysis, has made a big difference in reducing the risk of SCD early and late after ST-elevation MI. In-hospital SCD due to ventricular tachyarrhythmias is manageable, with either preventive measures or drugs or electrical cardioversion. There is general agreement for secondary prevention of SCD post-MI with implantation of a cardioverter defibrillator (ICD) when malignant ventricular arrhythmias occur late (>48 h) after an MI, and are not due to reversible or correctable causes. The major challenge remains that of primary prevention, that is, how to prevent SCD during the first 1–3 months after ST-elevation MI for patients who have low left ventricular ejection fraction and are not candidates for an ICD according to current guidelines, due to the results of two studies, which did not show any benefits of early (<40 days after an MI) ICD implantation. Two recent documents may provide direction as to how to bridge the gap for this early post-MI period. Both recommend an electrophysiology study to guide implantation of an ICD, at least for those developing syncope or non-sustained ventricular tachycardia, who have an inducible sustained ventricular tachycardia at the electrophysiology study. An ICD is also recommended for patients with indication for a permanent pacemaker due to bradyarrhythmias, who also meet primary prevention criteria for SCD.     

T-Wave Variability as a Risk Stratifier in Patients with Dilated Cardiomyopathy

Background: T-wave alternans is an important identifier of patients at risk of sudden cardiac death (SCD), but the procedure usually requires stress testing. In this study, the variability of T-wave amplitude (TVAR) was evaluated at rest, as a risk stratifier for SCD.
Methods: This study included 57 patients in sinus rhythm and with a left ventricular ejection fraction ≤40%, of whom 34 (60%) received an implantable cardioverter-defibrillator (ICD) after surviving SCD, and 23 (40%) presented with ischemic or nonischemic cardiomyopathy and no history of SCD. A 20-minute high-resolution electrocardiographic recording for TVAR assessment was performed during supine rest. The vector magnitude was used as a primary lead for TVAR analysis.
Results: The mean, median, and maximum (max) values of TVAR were measured. The patients with ICD had a lower max TVAR than the patients without ICD (67 vs 95 μV; P = 0.045), though the mean and median TVAR values were similar. By multivariate logistic analysis, max TVAR remained a predictor of SCD, after adjustments for potentially confounding factors (P = 0.044).
Conclusion: Max TVAR was a predictor of arrhythmic events in patients with dilated cardiomyopathy at rest.     

The Effect of Coronary Bypass Graft Surgery for the Prevention of Sudden Cardiac Death: Recurrent Episodes After ICD Implantation and Review of Literature

Sudden cardiac death (SCD) accounts for at least 50% of the mortality of patients with ischemic heart failure. Ventricular arrhythmias are responsible for most cases of sudden cardiac death. There is some evidence that coronary artery bypass graft (CABG) surgery may reduce the incidence of recurrent episodes of SCD by prevention of myocardial ischemia. To test the hypothesis that CABG surgery is effective in the prevention of SCD, we compared the recordings of implantable cardioverter defibrillators (ICD) in patients who underwent ICD implantation alone (n = 64) or ICD implantation and concomitant CABG surgery respectively (n = 11). All patients had experienced out of hospital cardiac arrest. ICD recordings were obtained every 3 months and the number of recurrent episodes of ventricular tachycardia (VT) for each time period was noted. Three months foilowing ICD implantation patients in the surgically treated group had an average of one episode of VT per patient as compared to 2.7 episodes in the nonsurgical group. This difference was observed during the following months as well. However, at nlo time (up to 18 months of follow-up) this difference reached statistical significance. There were no deaths in the surgically treated group. Although we could not demonstrate a statistical significant difference between the two groups, there was a tendency in the surgically treated group to have less episodes of recurrent VT than in the medically treated group. We, therefore, conclude that survivors of SCD presenting with multivessel coronary artery disease (CAD) should undergo coronary artery bypass grafting to prevent myocardial ischemia as the triggering event for lethal ventricular arrhythmias.     

Sudden cardiac death and implantable cardioverter-defibrillators

Sudden cardiac death is a major public health problem, affecting 500,000 patients in the United States annually. An implantable cardioverter-defibrillator (ICD) can terminate malignant ventricular arrhythmias and has been shown to improve survival in high-risk populations. Although sudden cardiac death is a heterogeneous condition, left ventricular ejection fraction of 35 percent or less remains the single best factor to stratify patients for prophylactic ICD implantation, and randomized trials have shown mortality benefit in this population. Therefore, in patients with heart disease, assessment of ejection fraction remains the most important step to identify patients at risk of sudden cardiac death who would benefit from ICD implantation. Physician understanding of each patient's ICD type, indication, etiology of heart disease, and cardiovascular status is essential for optimal care. If the ICD was placed for secondary prevention, the circumstances relating to the index event should be explored. Evaluation of defibrillator shocks merits careful assessment of the patient's cardiovascular status. Consultation with a subspecialist and interrogation of the ICD can determine if shocks were appropriate or inappropriate and can facilitate management.     

Implantable Cardioverter Defibrillator for Prevention of Sudden Cardiac Deatb in Patients with Ventricular Tachycardia and Ventricular Fibrillation: ICD Therapy In Sudden Cardiac Death

Among the various therapy options for survivors of ventricular tachycardia-ventricular fibrillation (VT-VF), the implantable cardioverter defibrillator (ICD) seems most promising. It reliably terminates VT-VF and thus significantly impacts sudden cardiac death (SCD) survival. It is more effective than any of the known antiarrhythmic drugs in prevention of SCD, particularly among survivors of cardiac arrest. Compared to VT surgery, the ICD therapy can be offered to a larger pool of patients and can be placed at a lower surgical risk. With proper patient selection, ICD therapy is of major benefits to its recipients since it markedly reduces the chances of VT-VF relaled mortality; the main cause of premature death in this population. The ICD therapy is cost effective when compared to other medical interventions and could be more so if the implant is carried out early in the course of VT-VF management.     

Cardiac defibrillation and resynchronization therapies: principles, therapies, and management implications

Patients with heart failure remain at high risk for sudden cardiac death (SCD) and death due to heart failure progression, despite the incorporation of pharmacologic agents into clinical practice that have been shown to decrease mortality in clinical trials. Most patients experience SCD as their first dysrrhythmic event. The implantable cardioverter defibrillator (ICD) effectively terminates ventricular tachycardia/fibrillation (VT/VF) aborting SCD. Cardiac resynchronization therapy (CRT) complements pharmacologic therapy improving cardiac performance, quality of life, functional status, and exercise capacity in patients with systolic dysfunction despite optimal medical therapy who have a prolonged QRS duration; furthermore, it decreases mortality when compared with optimal medical therapy alone. Implantation of a combination CRT and ICD device, a CRT-D, reduces mortality by aborting SCD and providing the functional benefits of CRT. This article discusses the evolution of CRT-D therapy, the mechanism of operation of a CRT-D device, and nursing implications.     

Sudden cardiac death

Sudden cardiac death (SCD) due to ventricular tachyarrhythmias is a leading cause of death in the United States. Various etiologies, including ischemic and nonischemic cardiomyopathies, hypertrophic cardiomyopathy, valvular or congenital heart diseases and other less common disorders, may result in SCD. Beta blockers are the only class of medications that have been shown to be beneficial in the primary prevention of SCD. However, recently, aldosterone antagonism early after myocardial infarction has also been shown to significantly reduce the risk of SCD. Multiple trials have elaborated on the potential benefits of implantable cardioverter defibrillators (ICD) in appropriately selected patients. However, there is still some controversy regarding the optimum period for ICD implantation, and its cost-effectiveness. An evidence-based approach to primary and secondary prevention of SCD is presented. Management of out-of-hospital cardiac arrest is briefly discussed.     

Prediction of arrhythmic events with positron emission tomography: PAREPET study design and methods

BACKGROUND: In medically-treated patients with ischemic cardiomyopathy, myocardial viability is associated with a worse prognosis than scar. The risk is especially great with hibernating myocardium (chronic regional dysfunction with reduced resting flow), and the excess mortality appears to be due to sudden cardiac death (SCD). Hibernating myocardium also results in sympathetic nerve dysfunction, which has been independently associated with risk of SCD. OBJECTIVES: PAREPET is a prospective, observational cohort study funded by NHLBI. It is designed to determine whether hibernating myocardium and/or inhomogeneity of sympathetic innervation by positron emission tomography imaging identifies patients with ischemic cardiomyopathy who are at high risk for SCD and cardiovascular mortality. METHODS: Patients with documented ischemic cardiomyopathy, an ejection fraction of 相似文献   

Arrhythmias in Hypertrophic Cardiomyopathy

Supraventricular and ventncular arrhythmias, particularly nonsustained ventricular tachycardia, and ventricular premature beats are a common finding in patients with hypertrophic cardiomyopathy. Several investigations have demonstrated that nonsustained ventricular tachycardia on Holter monitoring is associated with an increased risk of sudden cardiac death. It has been a long lasting controversial discussion whether suppression of these arrhythmias with drugs, such as amiodarone is capable to reduce the incidence of sudden cardiac death. While recent studies have indicated that nonsustained ventricular tachycardia in asymptomatic patients without additional risk factors, such as a positive family history of sudden cardiac death or syncope should not be treated prophylactically with amiodarone. Symptomatic patients with sustained ventricular tachycardias and/or syncope related to ventricular arrhythmias should undergo ICD implantation. The implantation of an ICD in asymptomatic patients should be limited to those who have several risk factors for sudden cardiac death. It is questionable whether other risk stratifiers, such as programmed electrical stimulation may be helpful to identify asymptomatic patients who are at risk to die suddenly. Moreover, whether the demonstration of electrocardiogram fractionation during electrophysiological study is superior to the induction of sustained ventricular arrhythmias for risk stratification, needs further investigation.     

Implantable cardioverter-defibrillator in patients with chronic heart failure

Sudden cardiac death (SCD) is a major cause of death in patients with chronic heart failure. The implantable cardioverter-defibrillator (ICD) effectively treats malignant ventricular tachyarrhythmias and reduces significantly the total mortality as well as the incidence of SCD in heart failure patients. It is evident that ICD is indicated for the secondary prevention of SCD. There is growing evidence for the use of the ICD for the primary prevention of SCD in patients with LV systolic dysfunction without documented arrhythmia. However, the efficacy of ICD seems to be modest in patients with advanced heart failure. Individualized combined therapies such as ICD plus amiodarone and ICD plus cardiac resynchronization therapy are necessary for advanced heart failure patients. It is doubtful whether ICD is indicated for MADIT II and SCD -HeFT population in Japan, where the incidence of SCD is thought to be lower than the Western countries.     

Ventricular fibrillation and sudden cardiac arrest in apical hypertrophic cardiomyopathy: Two case reports

BACKGROUNDApical hypertrophic cardiomyopathy (HCM) is considered to have a benign prognosis in terms of cardiovascular mortality. This serial case report aimed to raise awareness of ventricular fibrillation (VF) and sudden cardiac death (SCD) in apical HCM. CASE SUMMARYHere we describe two rare cases of apical HCM that presented with documented VF and sudden cardiac collapse. These patients were previously not recommended for primary prevention using implantable cardioverter-defibrillator (ICD) therapy based on current guidelines. However, both received ICD therapy for the secondary prevention of SCD.CONCLUSIONThese cases illustrate serious complications including VF and aborted sudden cardiac arrest in apical HCM patients who are initially not candidates for primary prevention using ICD implantation based on current guidelines.     

植入型心律转复除颤器在心脏性猝死一级预防中的应用

目的随访观察植入型心律转复除颤器（ICD）／心室再同步心律转复除颤器（CRT．D）在中国单中心心脏性猝死（SCD）高危患者一级预防中的临床应用。方法入选2009年1月至2011年12月入住浙江大学医学院附属第一医院心内科符合一级预防适应证并植入ICD／CRT．D的患者共80例,其中33例植入单腔／双腔ICD,47例植入CRT．D。基础病因主要为扩张性心肌病（55．0％）和冠状动脉性心脏病（27．5％）。植入ICD／CRT．D后第1个月末和第3个月末各随访1次,以后每6个月随访1次,若患者发生电击等ICD治疗事件,则即时进行检查。结果80例患者平均随访（23±7）个月,非计划性再入院11例（13．7％）,死亡4例（5．0％）。记录ICD治疗事件共38次,其中有26次（68．4％）为ICD识别持续性VT／VF发作而进行的适当治疗,12次（31．6％）为由于心房颤动而进行的不适当治疗事件。结论ICD,CRT—D能在短时间内对发生恶性快速性心律失常的患者进行识别及实施治疗,在SCD一级预防中疗效明确,可使SCD的高危患者获益。     

Sudden Cardiac Death in Dilated Cardiomyopathies

Dilated cardiomyopathy (DCM) is the most prevalent form of cardiomyopathy, and sudden cardiac death (SCD) remains a common event in young patients. The disorder is highly heterogeneous and pediatric DCM often differs from adult DCM in etiologies, risk factors, and prognosis. Prognosis may be improving, likely secondary to specialized management. Both traditional and novel markers of risk have been studied in adults and are beginning to be applied to children with DCM. The major therapy for patients considered at risk remains implantable cardioverter-defibrillator ( ICD) placement, although frequently this functions as a bridge to eventual transplantation.     

Psychosocial impact of the implantable cardioverter defibrillator: nursing implications

Sudden cardiac death (SCD) remains a significant problem despite an overall reduction in other cardiac related deaths in recent years. Research supports the use of the implantable cardioverter defibrillator (ICD) as an effective means of treating dangerous ventricular tachydysrhythmias to prevent SCD. The issue that demands increasing attention is the psychologic experience of ICD recipients. Although the ICD is clearly a technological success, there is evidence that recipients experience strong physical and emotional reactions to the device. Such quality of life issues are worthy of a multidisciplinary effort directed at facilitating patient acceptance and adaptation to technology that although potentially life-saving, may also be unpredictable and anxiety provoking.     

Rhythm disorders in isolated left ventricular noncompaction

Both supraventricular and ventricular rhythm disorders are frequently observed in patients with isolated left ventricular noncompaction (IVNC). Most importantly, these patients are prone to develop life-threatening ventricular arrhythmias, which are amongst their most frequent causes of death. Data regarding risk stratification of ventricular arrhythmias, however, are scarce due to the rareness of the disease. Indeed, even invasive electrophysiological studies may be of limited value in this regard in the majority of patients. Implantable cardioverter defibrillators (ICDs) have been demonstrated to be highly effective for the prevention of sudden arrhythmic death in IVNC and should be considered in patients who are clinically judged to be at high risk for ventricular tachyarrhythmias. These include patients with a severely reduced ejection fraction as well as those with a prior history of sustained ventricular tachycardia or fibrillation, recurrent syncope of unknown etiology, or a family history of ventricular tachyarrhythmias or sudden cardiac death. This review summarizes the electrocardiographic and electrophysiological findings in patients with IVNC and discusses possibilities for risk stratification as well as the rationale for ICD implantation for the prevention of sudden cardiac death.     

Rhythm disorders in isolated left ventricular noncompaction

Abstract

Both supraventricular and ventricular rhythm disorders are frequently observed in patients with isolated left ventricular noncompaction (IVNC). Most importantly, these patients are prone to develop life-threatening ventricular arrhythmias, which are amongst their most frequent causes of death. Data regarding risk stratification of ventricular arrhythmias, however, are scarce due to the rareness of the disease. Indeed, even invasive electrophysiological studies may be of limited value in this regard in the majority of patients. Implantable cardioverter defibrillators (ICDs) have been demonstrated to be highly effective for the prevention of sudden arrhythmic death in IVNC and should be considered in patients who are clinically judged to be at high risk for ventricular tachyarrhythmias. These include patients with a severely reduced ejection fraction as well as those with a prior history of sustained ventricular tachycardia or fibrillation, recurrent syncope of unknown etiology, or a family history of ventricular tachyarrhythmias or sudden cardiac death. This review summarizes the electrocardiographic and electrophysiological findings in patients with IVNC and discusses possibilities for risk stratification as well as the rationale for ICD implantation for the prevention of sudden cardiac death.