Long-term outcome of pharmacological and nonpharmacological treatment for ventricular arrhythmias

Recent advances of nonpharmacological therapy such as catheter ablation and implantable cardioverter defibrillator and lessons from the Cardiac Arrhythmia Suppression Trial(CAST) have changed the strategy for ventricular arrhythmias. The safety and efficacy of radiofrequency catheter ablation of symptomatic sustained monomorphic ventricular tachycardia without structural heart disease has made ablation the firstline curative therapy. In idiopathic ventricular fibrillation such as Brugada syndrome, an implantable cardioverter defibrillator is the most effective treatment to prevent sudden cardiac death. In patients with asymptomatic ventricular tachyarrhythmias in heart failure, class I antiarrhythmic drugs should be avoided due to proarrhythmic and negative inotropic effects that may be responsible for increased mortality in some trials. In such patients, amiodarone and beta-blocker may reduce sudden cardiac death. For patients with sustained ventricular tachycardia or ventricular fibrillation in heart failure, amiodarone or implantable cardioverter defibrillator should be considered. In comparison with amiodarone, implantable cardioverter defibrillator markedly reduced sudden death in ventricular tachycardia and ventricular fibrillation survivors in Antiarrhythmics Versus Implantable Defibriltors(AVID). Although better patient selection and clarification of mapping criteria improved the successful ablation rate in patients with structural heart disease, candidates of ablation are few. In patients with extensive structural heart disease, multiple ventricular tachycardias are often present. Catheter ablation of a single ventricular tachycardia may be only palliative. Therefore, implantable cardioverter defibrillator is the most effective treatment to prevent sudden cardiac death, with amiodarone and ablation as the adjunctive therapy to prevent frequent ventricular tachycardia. Furthermore, an implantable cardioverter defibrillator improved survival in selected patients with depressed ventricular function after myocardial infarction, who also have nonsustained and inducible sustained ventricular tachycardia in Multicenter Automatic Defibrillator Implantation Trial(MADIT) and Multicenter Unsustained Tachycardia Trial(MUSTT).     

Ventricular arrhythmias in the athlete

Life-threatening ventricular arrhythmias in the athlete nearly always occur in the presence of structural heart disease. In the last few years, 2 new causes of life-threatening arrhythmias have been described in patients with normal hearts-that of the Brugada syndrome and that of commotio cordis. Non-life-threatening premature ventricular beats and even nonsustained ventricular tachycardia are not rare, and although usually benign, can be secondary to cardiomyopathies. Athletes with symptoms of syncope, especially if exertional, warrant a complete evaluation. The treatment of athletes and other individuals with life-threatening ventricular arrhythmias has been revolutionized by the implantable cardioverter defibrillator, a device that affords excellent protection from sudden death. Defining those athletes who would benefit from the implantable defibrillator is not always clear. Furthermore, participation in competitive athletics for athletes with life-threatening arrhythmias or structural heart disease known to put the athlete at risk for life-threatening arrhythmias is usually prohibited.     

Update of implantable cardioverter/defibrillator and cardiac resynchronization therapy in heart failure

PURPOSE OF REVIEW: Heart failure prevalence is reaching epidemic proportion in the United States and is associated with significant morbidity and mortality. A large proportion of the mortality is the result of sudden cardiac death (SCD). Clinical trials have demonstrated the superiority of the implantable cardioverter/defibrillator (ICD) compared with antiarrhythmic drugs for secondary prevention of sudden cardiac death. RECENT FINDINGS: Recently, several clinical trials in primary prevention of sudden cardiac death in both ischemic and nonischemic heart failure have been completed. The 2002 guidelines for implantable cardioverter/defibrillator implantation were recently released as well. Adjunct therapy consisting of antiarrhythmic drugs or radiofrequency ablation is necessary in the subset of patients with implantable cardioverter/defibrillator that have frequent or intractable ventricular arrhythmias. An emerging new therapy in the heart failure population is cardiac resynchronization therapy, which coordinates right and left ventricular pacing in a subset of patients with interventricular conduction delay. SUMMARY: Several randomized clinical trials have demonstrated improvements in heart failure-related symptoms, exercise tolerance, and reversal of ventricular remodeling. Meta-analysis of these trials has also demonstrated mortality benefit. Patient selection, left ventricular pacing site, and optimal device programming are issues that need further investigation. Recent trials have also studied the compatibility between cardiac resynchronization therapy and implantable cardioverter/defibrillator as a single device. Finally, the DAVID trial has raised concerns of conventional right ventricular pacing and the risk of heart failure in a subset of patients.     

Adverse interaction between a left ventricular assist device and an implantable cardioverter defibrillator

An increasing number of patients have a coexisting implantable cardioverter defibrillator (ICD) and left ventricular assist device (LVAD) to treat ventricular arrhythmias and refractory heart failure, respectively. To date, there have been no published reports of negative interactions between these devices that have impacted appropriate ICD or LVAD function. In this case report, we describe a patient with an LVAD-ICD interaction that necessitated replacement of the implantable defibrillator.     

The role of invasive electrophysiology in the management of patients with chronic heart failure

It is well known that both atrial and ventricular arrhythmias play a key role in morbidity and overall mortality among patients with heart failure. In addition to pharmacological treatment, up-to-date and evidence-based use of invasive electrophysiology, including implantable cardioverter defibrillator implantation, is recommended in the global management of patients with heart failure. This article will review current clinical indications for invasive electrophysiology, either acknowledged or under evaluation, focusing on the scientific background and some technical and practical aspects. The discussion is organized in an arrhythmia-based manner so that ventricular-, atrial-, and heart transplant-related arrhythmias will be discussed separately.     

Ventricular arrhythmias in congestive heart failure

Despite advances in the treatment of congestive heart failure (CHF), the mortality rate continues to be high. A large number of the deaths are sudden, presumably due to ventricular arrhythmias. Complex ventricular arrhythmias are recorded in as many as 80% of patients with CHF, with nonsustained ventricular tachycardia occurring in 40%. The latter appears to be an independent predictor of mortality. Chronic structural abnormalities responsible for CHF may be the basis for the capability of a ventricle to support life-threatening arrhythmias, which are triggered by premature ventricular contractions. The pathogenesis of arrhythmias is multifactorial. Electrolyte abnormalities, ischemia, catecholamines, inotropic and antiarrhythmic drugs may worsen arrhythmias and increase susceptibility of a ventricle to sustained arrhythmias. Beta-adrenergic blockers and angiotensin-converting enzyme inhibitors have a beneficial effect. The role of various drugs in the pathogenesis and treatment of ventricular arrhythmias is discussed. The efficacy of antiarrhythmic therapy targeted to asymptomatic nonsustained ventricular tachycardia, in order to prevent sudden death, is controversial. Pharmacotherapy guided by electrophysiologic testing is the treatment of choice for patients who have manifest sustained ventricular tachycardia, but patients resuscitated from ventricular fibrillation may require automatic implantable cardioverter defibrillator.     

Implantable cardioverter-defibrillators

Implantable defibrillators have become the dominant therapeutic modality for patients with life-threatening ventricular arrhythmias. Current defibrillators are small (<60 mL) and implanted with techniques similar to standard pacemakers. They provide high-energy shocks for ventricular fibrillation and rapid ventricular tachycardia, antitachycardia pacing for monomorphic ventricular tachycardia, as well as antibradycardia pacing. Newer devices incorporating an atrial lead allow dual-chamber pacing and better discrimination between ventricular and supraventricular tachyarrhythmias. Randomized controlled trials have shown superior survival with implantable defibrillators than with antiarrhythmic drugs in survivors of life-threatening ventricular tachyarrhythmias and in high-risk patients with coronary artery disease. Complications associated with implantable defibrillator therapy include infection, lead failure, and spurious shocks for supraventricular tachyarrhythmias. Most patients adapt well to living with an implantable defibrillator, although driving often has to be restricted. Limited evidence suggests that implantable defibrillator therapy is cost-effective when compared with other widely accepted treatments. The use of implantable defibrillators is likely to continue to expand in the future. Ongoing clinical trials will define further prophylactic indications of the implantable defibrillator and clarify its cost-effectiveness ratio in different clinical settings.     

Assessment of cardiac sympathetic activity by MIBG imaging in patients with heart failure: a clinical appraisal

Cardiac sympathetic activity can be assessed by (123)I-labelled meta-iodobenzylguanidine (MIBG) scintigraphy. Abnormalities of sympathetic cardiac activity have been shown in patients with heart failure, resulting in reduced MIBG uptake. Abnormal MIBG uptake predicts cardiac death, arrhythmias and all-cause mortality in patients with heart failure with a prognostic power incremental to that of conventional risk markers, and may identify patients at low risk of arrhythmias despite current guideline indications for implantable cardioverter defibrillator or patients at high risk for arrhythmias not fulfilling implantable cardioverter defibrillator indications. Prospective outcome studies are needed to assess whether MIBG imaging will have an impact on the mortality and morbidity of patients with heart failure.     

Devices for the management of ventricular arrhythmias in cardiac failure

Heart failure is a common clinical syndrome with a high morbidity and mortality. Despite advances in medical treatment, death from dangerous ventricular arrhythmias is frequently implicated. Emerging evidence supports the use of the implantable cardioverter defibrillator for selected patients. This includes secondary prevention indications for patients who have survived life-threatening ventricular arrhythmias. In addition, patients who have not suffered spontaneous sustained ventricular arrhythmias, but who are at high risk for sudden arrhythmic death are starting to be recognized as candidates for ICD therapy. At present the only primary prevention indication with a good evidence base is the presence of inducible ventricular arrhythmias at electrophysiologic testing in patients with prior myocardial infarction, impaired left ventricular systolic function and non-sustained ventricular tachycardia on Holter monitoring. Studies planned or in progress are likely to expand further the role of device therapy in the treatment of patients with cardiac failure.     

Statins, ventricular arrhythmias and heart rate variability in patients with implantable cardioverter defibrillators and coronary heart disease

The aim of this study was to evaluate whether the incidence of ventricular arrhythmias and heart rate variability were influenced by statin treatment and lipid levels in patients treated with an implantable cardioverter defibrillator (ICD). Heart rate variability measurements were performed in 86 patients with coronary heart disease and an ICD implant. The number of events with ventricular fibrillation and ventricular tachycardia were recorded during a 12-month period. This study lends little support for an antiarrhythmic effect of statins or any relation between plasma lipids and lipoproteins and malignant ventricular arrhythmias in patients with an ICD.     

Kommentar zu den „ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death – executive summary“

The purpose of this document is to translate and to comment on the previously published“ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death”. The aim is to update the recommendations for clinical practice in Germany. We address the diagnostic procedures (e.g. ECG, imaging, electrophysiological studies etc.) and therapeutic options (e.g. medical treatment, catheter ablation, implantable cardioverter defibrillator – ICD etc.). Special emphasis was put on management of acute ventricular arrhythmias and on the different treatment modalities for various conditions (e.g. ischemic cardiomyopathy, valvular heart disease, congenital heart disease, non-ischemic cardiomyopathies, congestive heart failure, genetic arrhythmia syndromes etc.). Comments are given in each chapter, including the ongoing debate about ICD indications in primary prophylaxis.     

Circadian variation of malignant ventricular arrhythmias in patients with ischemic and nonischemic heart disease after cardioverter defibrillator implantation. European 7219 Jewel Investigators.

OBJECTIVES: The purpose of this study was to examine the circadian variation of ventricular arrhythmias detected by an implantable cardioverter defibrillator in patients with and without ischemic heart disease. BACKGROUND: Previous studies have shown a circadian variation of ventricular arrhythmias, sudden death and myocardial infarction with a peak occurrence in the morning hours. The circadian pattern, which is similar for both arrhythmic and ischemic events, suggests that ischemia may play a critical role in the genesis of ventricular arrhythmias and sudden death. We hypothesized that, if ischemia plays an important role in the triggering of ventricular arrhythmias, the circadian pattern should be different in patients with ischemic heart disease compared with patients with nonischemic heart disease. METHODS: The circadian variation of ventricular arrhythmias recorded by an implantable cardioverter defibrillator was studied in 310 patients during a mean follow-up of 181 +/- 163 days. Two hundred four patients had a history of ischemic heart disease and 106 patients had nonischemic heart disease. The times of the episodes of ventricular arrhythmias were retrieved from the data log of each device during follow-up, and the circadian pattern was compared between the two groups. RESULTS: During follow-up, 1,061 episodes of ventricular arrhythmias were recorded by the device in the 310 patients. Six hundred eighty-two episodes occurred in the group of patients with ischemic heart disease and 379 occurred in the nonischemic heart disease group. The circadian variation of the episodes showed a typical pattern with a morning and afternoon peak in both groups of patients with ischemic and nonischemic heart disease, but there was no significant difference between the two groups. CONCLUSIONS: The circadian rhythm of ventricular arrhythmias in patients with ischemic heart disease is similar to patients with nonischemic heart disease, suggesting that the trigger mechanisms of the initiation of ventricular tachyarrhythmias may be similar, irrespective of the underlying heart disease.     

Evidence-based medicine and the implantable defibrillator

Evidence from recent randomized clinical trials now strongly supports the use of the implantable defibrillator, as treatment of first choice, in patients who have experienced symptomatic, sustained ventricular tachyarrhythmias. Little or no controversy remains on this question, either among physicians or third-party players. The evidence-based use of the defibrillator as primary preventative therapy (that is, for patients who have an increased risk for lethal arrhythmias, but who have not yet experienced them) is far more limited. Two randomized trials have now demonstrated a survival benefit with the defibrillator in patients who have ichemic heart disease; reduced left ventricular ejection fraction; documented nonsustained ventricular tachycardia; and inducible sustained ventricular tachycardia during electrophysiologic testing that is not suppressed by at least one drug trial. Based on the strength of this recently available information, the screening of appropriate patients, while admittedly inconvenient, ought to be strongly considered. The broader use of the implantable defibrillator in the primary prophylaxis of arrhythmic sudden death will have to await the results of future trials.     

Automatic Implantable Cardiac Defibrillators

Opinion statement Since its first human application in 1980, the automatic implantable cardioverter defibrillator (ICD) has undergone remarkable advances leading to expanded acceptance. Originally indicated only for patients who had survived two cardiac arrests, the devices have recently been shown to improve survival in all patients with prior myocardial infarction and an ejection fraction of 30% or less. The devices have been miniaturized and are now implanted transvenously, often with hospital discharge within 24 hours of surgery. The ICD is now considered standard therapy for the prevention of life-threatening arrhythmias. Current versions not only treat ventricular arrhythmias with pacing and shock therapy, but some versions also have the capability to treat and suppress atrial arrhythmias, resynchronize the ventricles to manage heart failure symptoms, or pace the heart with all the features of a dual chamber pacemaker. Technologic advances have dramatically expanded the indications for ICD implantation.     

Radiofrequency catheter ablation of ventricular tachycardia in patients with an implantable defibrillator. Long-term follow-up

INTRODUCTION AND OBJECTIVES: The frequent occurrence of ventricular tachycardia can be a serious problem for patients with an implantable defibrillator, and may necessitate adjuvant antiarrhythmic therapy or radiofrequency catheter ablation. We analyzed the long-term results obtained with this latter therapy in patients suffering from frequent or continuous ventricular tachycardia. PATIENTS AND METHOD: Eighteen ablation procedures were performed in 11 patients who had a defibrillator implanted because of previous syncopal ventricular tachycardia. All were men, aged 67.64 (5.87) years; 10 patients had had a myocardial infarction 15.50 (5.08) years earlier, and one suffered from arrhythmogenic right ventricular dysplasia. RESULTS: Electrophysiologically, treatment was initially successful in 8 patients (72.73%). After a follow-up period of 39.10 (24.70) months, the number of defibrillator discharges decreased significantly in all patients, from 52.82 (35.73) to 0.64 (1.03) (P=.001). During follow-up, ventricular tachycardia occurred in nine patients. In five, it took the same form as the ablated ventricular tachycardia. Six patients needed additional ablation procedures: two because of initial failure, three because of recurrence, and one because a different ventricular tachycardia occurred. In addition to the good electrophysiological results obtained, long-term clinical evolution was favorable in all patients. CONCLUSIONS: Radiofrequency ablation successfully disrupts frequent or continuous ventricular tachycardias and significantly reduces the defibrillator discharge rate even when ablation has failed electrophysiologically. It is particularly useful in these latter critical situations, in which other therapies are not sufficiently effective. Because our patients mainly had ischemic heart disease and were highly susceptible to new arrhythmias during follow-up, ablation complemented rather than replaced the implantable defibrillator.     

How to evaluate sudden cardiac death risk after myocardial infarction?

Sudden cardiac death is the mode of death of more than half of coronary heart disease patients. Preventing sudden cardiac death involves prevention of ventricular arrhythmias occurrence as well as the treatment by an implantable cardioverter defibrillator. The evaluation of sudden cardiac death risk should consider the underlying cardiopathy, the associated coronary risk factors and all pharmacological treatment efficient to reduce ventricular remodeling and myocardial ischemia. Only significant low ejection fraction and positive ventricular testing in some cases are now considered are now considered by the current French recommendations for cardioverter defibrillator implantation in primary prevention. However, other noninvasive markers such as heart rate variability and T wave alternans are of interest in sudden cardiac death risk stratification after myocardial infarction.     

Management of arrythmias

The management of arrhythmias in elderly patients with congestive heart failure, including atrial fibrillation, ventricular tachyarrhythmias, and bradyarrhythmias, is described. Patients with atrial fibrillation can be treated with rate control anticoagulation for stroke prevention or by attempt at cardioversion and maintenance of sinus rhythm. Elderly patients remaining in atrial fibrillation benefit from anticoagulation provided that no contraindication exists. In patients surviving malignant ventricular arrhythmias, defibrillator implantation is beneficial in elderly patients with heart failure. Prognosis and treatment of nonsustained arrhythmias depends on the presence of underlying cardiac abnormalities. In the healthy elderly population, treatment is not indicated. In patients with coronary artery disease, decreased ejection fraction, and nonsustained ventricular tachycardia, electrophysiology can further stratify risk, and defibrillator implantation can improve survival if arrhythmias are induced. This benefit is as great in elderly patients as in younger patients. Symptomatic bradycardias are increasingly common with advancing age. Symptoms are improved with pacing, with maximum benefit from physiologic rather than ventricular pacing. Although the elderly population poses a unique challenge when faced with arrhythmias, an active approach not only saves lives but also reduces morbidity.     

Arrhythmias in heart failure: current concepts of mechanisms and therapy

About one half of deaths in patients with heart failure are sudden, mostly due to ventricular tachycardia (VT) degenerating to ventricular fibrillation or immediate ventricular fibrillation. In severe heart failure, sudden cardiac death also may occur due to bradyarrhythmias. Other dysrhythmias complicating heart failure include atrial and ventricular extrasystoles, atrial fibrillation (AF), and sustained and nonsustained ventricular tachyarrhythmias. The exact mechanism of the increased vulnerability to arrhythmias is not known. Depending on the etiology of heart failure, different preconditions, including ischemia or structural alterations such as fibrosis or myocardial scarring, may be prominent. Reentrant mechanisms around scar tissue, afterdepolarizations, and triggered activity due to changes in calcium metabolism significantly contribute to arrhythmogenesis. Furthermore, alterations in potassium currents leading to action potential prolongation and an increase in dispersion of repolarization play a significant role. Treatment of arrhythmias is necessary either because patients are symptomatic or to reduce the risk for sudden cardiac death. The individual history, left ventricular function, electrophysiologic testing, and the signal-averaged ECG give useful information for identifying patients at risk for sudden cardiac death. The implantable cardioverter defibrillator (ICD) has evolved as a promising therapy for life-threatening arrhythmias. A potential role may exist for antiarrhythmic drugs, mainly amiodarone. There is growing evidence that patients with sustained VT or a history of resuscitation have the best outcome with ICD therapy regardless of the degree of heart failure. Many of these patients require additional antiarrhythmic therapy because of AF or nonsustained VTs that may activate the device. Catheter ablation or map-guided endocardial resection are additional options in selected patients but seldom represent the only therapeutic strategy.     

Isolated noncompaction cardiomyopathy presenting with paroxysmal supraventricular tachycardia--case report and literature review

Isolated noncompaction cardiomyopathy is an exceedingly rare congenital cardiomyopathy. A case of isolated noncompaction cardiomyopathy is reported and the literature on the subject collected through a comprehensive literature search is reviewed. Fewer than 100 cases of this condition have been reported. Isolated noncompaction cardiomyopathy is caused by a defect in cardiac morphogenesis resulting in an arrest of compaction of loose interwoven meshwork of myocardial fibers during intrauterine life, which results in severe systolic dysfunction as well as undue hypertrophy of the involved walls of the ventricles. Although the most frequent sites involved are left ventricular apex and inferior wall, involvement of other left ventricular walls and right ventricle has also been reported. Etiology of the isolated noncompaction of myocardium is not clear. Familial cases have been reported and the mode of inheritance is heterogeneous. In X-linked form of the disease, a locus has been found on Xq28, and mutations have been reported in G4.5 gene. The age of onset of symptoms ranges from infancy to the geriatric age. Patients with isolated noncompaction cardiomyopathy have a high incidence of heart failure, arrhythmias, and thromboembolism. The most common presentation is congestive heart failure. Arrhythmias include atrial arrhythmias, ventricular tachycardia, and sudden cardiac death. The patient reported in this article presented with paroxysmal supraventricular tachycardia. Echocardiography is the procedure of choice to establish diagnosis. Due to the lack of associated cardiac anomalies, antenatal detection is difficult. The treatment is that for congestive heart failure, arrhythmias, and thromboembolism. The end-stage congestive heart failure is managed with heart transplantation and potential life-threatening ventricular tachyarrhythmias with an implantable cardioverter defibrillator. Prognosis is poor and the common causes of death are intractable heart failure and sudden cardiac death.     

Catheter-based Ablation for Ventricular Arrhythmias

Catheter ablation for patients with recurrent ventricular arrhythmias has emerged as an important and effective treatment option. The approach to ablation, and the risks and likely efficacy are determined by the nature of the severity and type of underlying heart disease. Although implantable defibrillators remain the corner stone for prevention of sudden cardiac death, ablation successfully reduces tachycardia recurrences and storms of ventricular arrhythmias triggering defibrillator shocks in patients with structural heart disease. Our understanding of idiopathic ventricular tachycardia (VT) has grown substantially with several new sites of VT origin recognized in recent years. Ablation is often curative for idiopathic VT. This review discusses common mechanisms and clues to diagnosis of the various VTs, and current advances in ablation options. In particular, endocardial ablation techniques have been complemented by newer approaches such as percutaneous epicardial ablation. In rare cases, transcoronary alcohol ablation can be effective for life-threatening arrhythmia.