Antiarrhythmics Versus Implantable Defibrillators Research Articles

Abstract 11665: Does the Benefit of Secondary Prevention Implantable Cardioverter-Defibrillators Vary Based on the Estimated Proportional Risk of Sudden Death?

Introduction: The Seattle Proportional Risk Model (SPRM) is a validated model developed in systolic heart failure patients without implantable cardioverter-defibrillators (ICDs) to estimate the proportion of all-cause mortality (ACM) due to sudden death. This study aims to ascertain if SPRM has utility in risk stratification for secondary prevention ICD. Methods: The AVID (Antiarrhythmics Versus Implantable Defibrillators) trial was a multicenter, randomized clinical trial in which 1,016 patients presenting with ventricular fibrillation or sustained, symptomatic ventricular tachycardia were randomized to ICD or antiarrhythmic (AA) drug therapy. Using routine clinical variables, we applied the SPRM to patient-level data (n=995 with complete data) and assessed if the ICD benefit for ACM varied with SPRM-predicted probability of sudden death. Results: SPRM was predictive of sudden death vs. non-sudden death in patients without an ICD (logistic regression p=0.005). The ICD hazard ratio for ACM was 0.59. ICD survival benefit varied with SPRM for ACM (p=0.013) with benefit (ICD HR≤0.80) seen in patients with SPRM>40%. ICD benefit trended higher in patients with a history of heart failure (HF) vs no HF (HR=0.52 vs. 0.81, interaction p=0.13) (Figure 1). In comparison to the AA group, patients with either HF or SPRM>51% (median) had a meaningful ICD benefit (HR=0.60, p=0.017), and patients with both HF and SPRM>51% had the greatest ICD benefit (HR=0.38, p<0.001). There was no ICD benefit if no HF and SPRM<51% (HR=1.17). Conclusions: In a population of patients with VF or sustained VT, secondary prevention ICDs decreased ACM by 41%. ICD survival benefit varied with SPRM-predicted proportion of sudden death, and trended higher in patients with HF. SPRM may therefore provide a useful tool for risk stratifying patients for secondary prevention ICD. Figure 1: Survival benefit for ICD therapy varies with SPRM-estimated proportion of sudden death, and HF versus no HF.

Information provision, satisfaction and emotional distress in patients with an implantable cardioverter-defibrillator

The implantable cardioverter-defibrillator (ICD) is the treatment of choice for primary and secondary prevention of sudden cardiac death due to ventricular arrhythmias [ 1 Moss A. Hall W. Cannom D. et al. Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia. N Engl J Med. 1996; 335: 1933-1940 Crossref PubMed Scopus (3569) Google Scholar , 2 Bardy G.H. Lee K.L. Mark D.B. et al. Amiodarone or an implantable cardioverter-defibrillator for congestive heart failure. N Engl J Med. 2005; 352: 225-237 Crossref PubMed Scopus (5302) Google Scholar , 3 The Antiarrhythmics versus Implantable Defibrillators (AVID) Investigators A comparison of antiarrhythmic-drug therapy with implantable defibrillators in patients resuscitated from near-fatal ventricular arrhythmias. N Engl J Med. 1997; 337: 1576-1584 Crossref PubMed Scopus (3004) Google Scholar ]. Although the majority of patients adapts well to living with an ICD, 1 in 4 patients report anxiety and depression [ [4] Sears S.F. Conti J.B. Quality of life and psychological functioning of ICD patients. Heart. 2002; 87: 488-493 Crossref PubMed Google Scholar ]. Sufficient understanding of the reasons for ICD implantation, its benefits, side effects, and impact on daily life plays a major role in adaptation. Adequate information provision and psycho-education may facilitate adaptation and reduce emotional distress [ 5 Vazquez L.D. Conti J.B. Sears S.F. Female-specific education, management, and lifestyle enhancement for implantable cardioverter defibrillator patients: the FEMALE-ICD study. Pacing Clin Electrophysiol. 2010; 33: 1131-1140 Crossref PubMed Scopus (38) Google Scholar , 6 Dunbar S.B. Dougherty C.M. Sears S.F. et al. Educational and psychological interventions to improve outcomes for recipients of implantable cardioverter defibrillators and their families: a scientific statement from the American Heart Association. Circulation. 2012; 126: 2146-2172 Crossref PubMed Scopus (158) Google Scholar , 7 Dunbar S.B. Langberg J.J. Reilly C.M. et al. Effect of a psychoeducational intervention on depression, anxiety, and health resource use in implantable cardioverter defibrillator patients. Pacing Clin Electrophysiol. 2009; 32: 1259-1271 Crossref PubMed Scopus (81) Google Scholar , 8 Eads A.S. Sears S.F.J. Sotile W.M. Conti J.B. Supportive communication with implantable cardioverter defibrillator patients: seven principles to facilitate psychosocial adjustment. J Cardiopulm Rehabil Prev. 2000; 20: 109-114 Crossref Scopus (22) Google Scholar ]. Paradoxically, recent surveys indicate that many patients have insufficient knowledge about their ICD and associated challenges [ 9 Cinar F.I. Tosun N. Kose S. Evaluation of an education and follow-up programme for implantable cardioverter defibrillator-implanted patients. J Clin Nurs. 2013; 22: 2474-2486 Crossref PubMed Scopus (15) Google Scholar , 10 Groarke J. Beirne A. Buckley U.N.A. et al. Deficiencies in patients' comprehension of implantable cardioverter defibrillator therapy. Pacing Clin Electrophysiol. 2012; 35: 1097-1102 Crossref PubMed Scopus (23) Google Scholar ].

Current Evidence Base for Use of the Implantable Cardioverter–Defibrillator

Almost 4 decades after its conception the implantable cardioverter–defibrillator (ICD) has emerged as a widely accepted treatment modality for the prevention of sudden cardiac death (SCD). The indications for ICD therapy have rapidly expanded over the past 10 years, and, today, >100 000 ICDs are implanted annually in the United States. More recently, however, some have raised words of caution as to the potential overestimation of ICD-associated benefits and hazards in individual patients.1,2 Therefore, this review summarizes the current scientific basis for ICD indications, puts it in context with recent guidelines, and discusses areas where additional trial evidence is needed to clarify pending issues regarding the optimal use of device therapy. The term secondary prevention refers to the prevention of SCD in patients who have survived previous cardiac arrest or an episode of sustained ventricular tachycardia (VT). The term primary prevention of SCD describes patient populations known to be at high risk for cardiac arrest because of preexisting cardiovascular disease but who have not yet experienced sustained VT or ventricular fibrillation (VF).3 ### Secondary Prevention Trials The secondary prevention strategy that emerged from observations indicating a high recurrence rate of VT or VF in survivors of cardiac arrest4,5 was the first to be tested in randomized clinical trials (Table 1). There are 3 secondary prevention ICD trials, the Antiarrhythmics Versus Implantable Defibrillator (AVID) trial, the Canadian Implantable Defibrillator (CIDS) trial, and the Cardiac Arrest Study Hamburg (CASH) trial, all initiated between the late 1980s and early 1990s.6–8 The AVID trial was the first to report its results and showed a statistically significant survival benefit over antiarrhythmic drugs (mostly amiodarone), with an absolute risk reduction of 7% over 2 years.6 After publication of AVID, the CIDS trial was prematurely stopped owing to the similarities between …

Modes of death in defibrillator patients: Learning from clinical experience

Historically, mortality rates from trials with implantable cardioverter-defibrillator (ICD) treatment arms for primary and secondary prevention have ranged from 6% to 8%. 1 Moss A.J. Hall W.J. Cannom D.S. et al. Multicenter Automatic Defibrillator Implantation Trial InvestigatorsImproved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia. N Engl J Med. 1996; 335: 1933-1940 Crossref PubMed Scopus (3537) Google Scholar , 2 Moss A.J. Zareba W. Hall W.J. et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med. 2002; 346: 877-883 Crossref PubMed Scopus (5558) Google Scholar , 3 Connolly S.J. Gent M. Roberts R.S. et al. Canadian Implantable Defibrillator Study (CIDS): a randomized trial of the implantable cardioverter defibrillator against amiodarone. Circulation. 2000; 101: 1297-1302 Crossref PubMed Scopus (1357) Google Scholar , 4 The AVID InvestigatorsCauses of death in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial. J Am Coll Cardiol. 1999; 34: 1552-1559 Abstract Full Text Full Text PDF PubMed Scopus (89) Google Scholar Mortality rates for cardiac resynchronization therapy with defibrillators (CRT-D) have ranged from 9% to 12%. 5 Bristow M.R. Saxon L.A. Boehmer J. et al. Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure. N Engl J Med. 2004; 350: 2140-2150 Crossref PubMed Scopus (4734) Google Scholar , 6 Cleland J.G. Daubert J.C. Erdmann E. et al. The effect of cardiac resynchronization on morbidity and mortality in heart failure. N Engl J Med. 2005; 352: 1539-1549 Crossref PubMed Scopus (5130) Google Scholar Annual heart failure mortality rates have been reported at ∼3% 4 The AVID InvestigatorsCauses of death in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial. J Am Coll Cardiol. 1999; 34: 1552-1559 Abstract Full Text Full Text PDF PubMed Scopus (89) Google Scholar , with sudden cardiac death rates at 20%–27% in primary prevention trials (MADIT-I, MADIT-II) and 30%–36% in secondary prevention trials (AVID, CIDS). The mode of death in implantable cardioverter-defibrillator and cardiac resynchronization therapy with defibrillator patients: Results from routine clinical practiceHeart RhythmVol. 9Issue 10PreviewAlthough data on the mode of death of implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy with defibrillator (CRT-D) patients have been examined in randomized clinical trials, in routine clinical practice data are scarce. To provide reasonable expectations and prognosis for patients and physicians, this study assessed the mode of death in routine clinical practice. Full-Text PDF

Analysis of large databases in vascular surgery

Large databases can be a rich source of clinical and administrative information on broad populations. These datasets are characterized by demographic and clinical data for over 1000 patients from multiple institutions. Since they are often collected and funded for other purposes, their use for secondary analysis increases their utility at relatively low costs. Advantages of large databases as a source include the very large numbers of available patients and their related medical information. Disadvantages include lack of detailed clinical information and absence of causal descriptions. Researchers working with large databases should also be mindful of data structure design and inherent limitations to large databases, such as treatment bias and systemic sampling errors. Withstanding these limitations, several important studies have been published in vascular care using large databases. They represent timely, "real-world" analyses of questions that may be too difficult or costly to address using prospective randomized methods. Large databases will be an increasingly important analytical resource as we focus on improving national health care efficacy in the setting of limited resources.

Prevention of sudden cardiac death.

It is often unclear why some patients suffer sudden cardiac death (SCD), or even what risk factors correlate best with the syndrome. This review describes current thinking on the prevention of SCD. Most studies have focused on the prevention of potentially fatal ventricular arrhythmias in patients post myocardial infarction (MI). While pharmacotherapy has a role in the prevention of SCD in patients post MI, the interpretation of drug trials can be problematic. This is because not all patients participating in such trials received optimized medical therapy by today's standards. As a result, trial outcomes for new therapies may not reflect their true efficacy when they are added to a background of best medical care. The two principal prophylactic modalities for SCD studied to date are antiarrhythmic drug therapy and use of an implantable cardioverter defibrillator (ICD). At the present time, antiarrhythmic drugs, such as the class III agent amiodarone, seem to display relatively limited efficacy for the primary prevention of sudden death in most patients post MI. Most clinical trials have found that ICD therapy has a significant mortality benefit in patients at high risk for ventricular arrhythmias. This has been demonstrated in primary prevention trials, and in secondary prevention trials such as Antiarrhythmics Versus Implantable Defibrillators (AVID), which studied patients who survived a near-fatal ventricular arrhythmia. Based on an analysis of secondary prevention trials, the single patient characteristic that best predicted an advantage of ICD therapy over antiarrhythmic drug therapy was a left ventricular (LV) ejection fraction < or = 35%. Cardiac resynchronization therapy has been established as having a mortality benefit in patients with dyssynchronous LV contraction associated with dilated cardiomyopathy.

Clinical criteria for predicting benefit of ICD/PM in post myocardial infarction patients: an AVID and CAST analysis

Three clinical factors from the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial-heart failure, left ventricular dysfunction and certain historical features defined a subgroup in which an implantable cardioverter defibrillator (ICD/PM) has a mortality advantage over amiodarone. These three factors were jointly evaluated in the AVID cohort with ischemic heart disease (IHD) and the results applied in placebo-treated post-infarction patients in the cardiac arrhythmia suppression trial (CAST). Similar predictive power was noted in AVID patients with IHD. In CAST the factors defined three groups; one group (5.8%), corresponding to AVID patients that had high risk and benefited from an ICD/PM and another group (17.2%) corresponding to patients in AVID where the risk was moderate and ICD/PM and amiodarone had equal efficacy, demonstrated a two-fold higher risk of sudden arrhythmic than non-arrhythmic death and hence would be expected to benefit from antiarrhythmia therapy. The third group, corresponding to AVID patients with low risk of arrhythmia, demonstrated similar and low risks of sudden arrhythmic and non-arrhythmic death. Thus this group (77%) is unlikely to benefit from indiscriminate antiarrhythmia therapy. Onset of risk of death in CAST patients was offset from randomization by 3 to 6 months. Readily available clinical criteria identify a small group likely to benefit from an ICD/PM after recent myocardial infarction (MI) and the remainder unlikely to benefit from nonselective ICD/PM therapy. Additional risk stratification should focus on the latter patients and be timed to allow ICD/PM implantation between 2 and 6 months after MI.

Implantable Cardioverter-Defibrillator Lead Performance

Implantable cardioverter-defibrillators (ICDs) have revolutionized the treatment of patients at risk for sudden cardiac death. In the nearly 3 decades since the first human ICD implant,1 millions of devices have been implanted worldwide and innumerable lives have been saved. Successful resuscitation of a potentially lethal ventricular arrhythmia by an ICD system depends on successful arrhythmia detection and timely delivery of therapy. Both the ICD generator and the ICD lead are critical components of this system. The lead, in particular, is literally a lifeline whose purpose is to convey critical information about the heart’s rhythm to the ICD generator and, in turn, to deliver life-sustaining therapy when needed. Failure of an ICD lead may result in significant clinical events, including failure to pace, failure to defibrillate, inappropriate shocks, and even death. Article p 2727 ICD leads, like many medical technologies, have undergone a remarkable transformation. Epicardial leads, which necessitated a thoracotomy for lead placement, have given way to transvenous leads, which are easier to implant, less costly, and associated with decreased morbidity and mortality.2 Important advances in transvenous lead technology, such as the development of steroid elution, smaller diameter leads, novel insulations, and multipolar leads, have translated into meaningful clinical benefits for patients. Although modern ICD leads consist primarily of electrodes, conductors, insulation, and a fixation mechanism to attach the lead to the myocardium, lead design and performance vary from model to model. Indeed, monitoring of performance is critical not only to identify products with increased failure rates but also to provide physicians and patients with realistic expectations of device performance. In the current issue of Circulation , Eckstein et al add to our understanding of ICD lead performance.3 The investigators conducted a retrospective analysis of 1317 consecutive patients who received ICD systems (including 38 different ICD lead …

Invited Commentary

Invited Commentary

Psychosocial status predicts mortality in patients with life-threatening ventricular arrhythmias

Quality-of-life (QoL) instruments evaluate various aspects of physical, mental, and emotional health, but how these psychosocial characteristics impact long-term outcome after cardiac arrest and ventricular tachycardia (VT) is unknown. The purpose of this study was to evaluate the relationship of baseline QoL scores with long-term survival of patients enrolled in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial. Formal QoL measures included SF-36 mental and physical components, Patient Concerns Checklist, and Ferrans and Powers Quality-of-Life Index-Cardiac Version. Multivariate Cox regression was used to assess the association of survival and these measures, adjusting for index arrhythmia type, gender, race, age, ejection fraction, history of congestive heart failure, antiarrhythmic therapy, and beta-blocker use. During mean follow-up of 546 +/- 356 days, 129 deaths occurred among 740 patients. Higher baseline SF-36 physical summary scores (P <.001), higher baseline QoL Index summary scores (P = .015), and lower baseline Patient Concerns Checklist summary scores (P = .047) were associated with longer survival, even after adjustment for clinical variables. When QoL measures were examined simultaneously, only the SF-36 physical summary score remained significant (P = .002). During recovery after sustained VT or cardiac arrest, formal baseline QoL assessment provides important prognostic information independent of traditional clinical data.

Partner Quality of Life in the Antiarrhythmics Versus Implantable Defibrillators Trial

The quality of life (QOL) of patients with ventricular dysrhythmias is well studied, but less is known about the QOL of their partners. This study describes the QOL of partners of patients with serious ventricular dysrhythmias enrolled in the Antiarrhythmics Versus Implantable Defibrillators trial. A convenience sample of 124 partners of patients randomized to antiarrhythmic drugs (n = 59) or an implantable cardioverter defibrillator (n = 65) in the Antiarrhythmics versus Implantable Defibrillators trial was obtained. The Short Form-36 and Quality of Life Index were assessed at baseline (postrandomization) and at 3-, 6-, and 12-month follow-up. The mean age of the partners was 62 years. Most were white and female. Their mean Short Form-36 scores were comparable to a normative age group. Partner and participant mean Short Form-36 and Quality of Life Index scores correlated modestly (range 0.25-0.36). The physical summary scores of partners using the Short Form-36 declined over time, whereas their mental summary scores remained stable. Partner concerns related to death, dysrhythmia recurrence, and the impact of dysrhythmias on enjoyment of life lessened from baseline to 12 months. Concern about implantable cardioverter defibrillator function remained stable over time. Although the sample size of this study was relatively small and limited by missing data for some assessments, it is the largest prospective study of QOL in partners of patients with serious dysrhythmias. The results offer a foundation for future research of the partners of patients with serious dysrhythmias in terms of identifying their needs, offering support, and maximizing QOL.

All Patients With Hemodynamically Tolerated Postinfarction Ventricular Tachycardia Do Not Require an Implantable Cardioverter-Defibrillator

Several randomized clinical trials have been published in the last decade to evaluate the clinical efficacy of the implantable cardioverter-defibrillator (ICD) for secondary prevention of sudden cardiac arrest.1–4 However, none of those trials included patients with hemodynamically tolerated ventricular tachycardia (VT). In the largest of these trials, the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial, patients with VT were included only if the VT produced syncope or if the “ejection fraction was 0.40 or less and symptoms suggesting severe hemodynamic compromise” were present.1 The Canadian Implantable Defibrillator Study (CIDS) trial included patients with VT if it produced syncope or caused presyncope or angina.2 The other 2 trials included only cardiac arrest survivors.3,4 Thus, no information is available from randomized clinical trials about outcome in patients with hemodynamically tolerated VT. Response by Callans p 1212 Despite decades of active research focused on post–myocardial infarction (MI) VT, information on the clinical outcome of sustained monomorphic VT patients is limited. Several reasons account for the limited information. First, because post-MI VT has always been considered a life-threatening condition, it has been considered unethical to leave these patients without specific antiarrhythmic therapy for group comparisons. Second, VT recurrences during follow-up have been considered in some studies together with sudden cardiac death (SCD)5 despite the fact that both events are distinctly different; the recurrence of a well-tolerated VT may require medical attention, but in most instances, the patient leaves the hospital alive and without any sequelae. Third, because ICD and catheter ablation therapy have been used increasingly in recent years, outcome information is likely to be more homogeneous in relatively old studies. Fourth, several outcome studies have included patients with a variety of sustained ventricular arrhythmias, but the prognosis of patients with ventricular fibrillation (VF) may not be the same as …

Sudden Death Prevention With Implantable Devices

The “modern” era of the treatment of ventricular tachyarrhythmias with device-based therapy may have begun in 1899, when Prevost and Battelli noted, almost as an afterthought, that direct current shock could terminate ventricular fibrillation (VF) in dogs.1 Three decades later, pioneering work in the field of defibrillation concluded that the passage of electrical current across the heart can both initiate and terminate VF.2,3 Still, little attention was paid to this phenomenon, as evidenced by Paul Dudley White’s Heart Disease , which devoted less than half a page to VF and characterized the arrhythmia as “a condition of little importance so far as we know now.”4 In 1947, the thoracic surgeon Claude Beck saved the first human life by the successful use of cardiac defibrillation in a 14-year-old boy who developed VF during a thoracic surgical procedure and went on to achieve a full recovery.5 These early accomplishments provided the foundation for the landmark work of Mirowski and Mower that ultimately led to the development of the implantable cardioverter-defibrillator (ICD) and its introduction in humans in 1980.6 Pacing may prevent sudden cardiac death due to bradyarrhythmias and in certain circumstances such as torsade de pointes associated with congenital long-QT syndrome (LQTS) and pause-dependent ventricular tachycardia (VT). Although no controlled studies exist, retrospective analyses suggest that recurrent torsade de pointes in patients with LQTS may be prevented by continuous pacing.7 Early clinical data on small numbers of patients suggested that the combination of β-adrenergic blockade plus continuous pacing reduced the number of syncopal events and the anticipated rate of sudden death in high-risk LQTS patients.8 The beneficial effects of pacing may be limited to patients with LQT2 and LQT3, in which the transmural dispersion of repolarization worsens steeply during bradycardia.9 Genotype-phenotype correlation confirms that …

Review Article

Review Article

A Comparison of the AVID and DAVID Trials of Implantable Defibrillators

We compared 2 studies of implantable cardiac defibrillators (ICDs) to determine the effects of device mode on outcomes. The Antiarrhythmics Versus Implantable Defibrillators (AVID) trial (1993 to 1997) demonstrated improved survival with the ICD compared with antiarrhythmic drug therapy. The Dual-chamber And VVI Implantable Defibrillator (DAVID) trial (2000 to 2002) showed that VVI pacing at 40 beats/min in patients with ICDs reduced the combined end point of death and hospitalization for congestive heart failure compared with DDDR pacing at 70 beats/min. Patients in the AVID trial (631 of 1,016) and the DAVID trial (221 of 506) meeting common inclusion and all exclusion criteria were studied. The major end points were the time to death, and the composite end point of time to death or hospitalization for congestive heart failure. Patients in the AVID and DAVID trials were similar, but more AVID patients had coronary artery disease (p = 0.04), history of myocardial infarction (p = 0.005), and previous ventricular arrhythmias (p = 0.03). DAVID patients underwent more previous revascularization procedures (coronary artery bypass surgery, p = 0.03; percutaneous coronary intervention, p = 0.001), and were more often taking beta-blocking drugs at hospital discharge (p <0.001). The backup VVI ICD groups in both studies had similar outcomes (p = 0.4), even when corrected for the previous demographic differences. The time-to- composite end point was similar in AVID patients treated with antiarrhythmic drugs and DAVID patients treated with DDDR ICDs (p = 0.6). Despite improved pharmacologic therapy and revascularization, outcomes have not improved with backup VVI pacing ICDs. If DDDR ICDs had been used in the AVID trial, benefit from ICDs for patients with serious ventricular arrhythmias could have been missed.

Seasonal variation of mortality in the Antiarrhythmics Versus Implantable Defibrillators (AVID) study registry

We postulated that the pattern of death would be nonrandom with respect to temporal variables. Previous studies have demonstrated increased sudden death is associated with periods of relative stress, and overall mortality is associated with temporal variables. In the Antiarrhythmics Versus Implantable Defibrillators (AVID) registry, vital status was obtained for 4,450 patients (who had a recent episode of sustained ventricular arrhythmias or unexplained syncope and inducible ventricular tachycardia) through the National Death Index Service as of December 31, 1997 (follow-up 25.5 +/- 13.7 months). Mortality was not associated with the day of the week or with holidays but was associated with season (P = .033). Seasonal variation was present both in northern and southern sites. Mortality was higher during the winter months compared to the remaining months (111.2% in winter vs 96.5% in other months, P = .036). In addition, increased mortality was associated with a high-risk season variable defined (prior to evaluation of treatment arm associations) as spring in the north and winter in the south (P < .001). The hazard ratio for death associated with this "high-risk season" measured 1.25 (P = .001) compared to the other seasons in each region. A test of interaction between "high-risk" season and implantable cardioverter-defibrillator (ICD) status suggested that the group with ICDs experienced reduced mortality during the "high-risk season" compared to the group without ICDs (P = .047). Mortality was higher in the winter months and in the respective regional "high-risk" seasons. Furthermore, seasonal variation in mortality may have been due to variation in sudden arrhythmic death, and associated increases in mortality were reduced by ICD therapy.

Implantable defibrillators and sudden cardiac death.

Sudden cardiac death (SCD) is among the most common causes of death in developed countries throughout the world. It is estimated that more than 3 million people die yearly from SCD, with a survival rate of less than 1%. In the United States, the Center for Disease Control recently estimated an annual incidence of 450 000 sudden deaths,1 with a survival rate of approximately 5%, although this probably is an overestimation. Although there has been a reduction in total cardiac mortality from 728 115 in 1989 to 719 456 in 1999, the percentage of deaths that are sudden has actually increased from 38% to 47%. The increase was greatest in women older than 65 years of age, from 56.3% to 63.9%. This has resulted primarily from an increase in out-of-hospital sudden deaths. There is a comparable incidence of SCD and survival rate in Western Europe.2 The magnitude of this problem can be understood by noting that SCD accounts for more deaths each year than the total number of deaths from AIDS, breast cancer, lung cancer, and stroke (Figure 1). Unfortunately, it is the first presentation of cardiac disease in 33% to 50% of patients and is 3 times as common in men than in women. Figure 1. Magnitude of the problem of sudden cardiac arrest. Coronary artery disease, with or without myocardial infarction, is by far the most common underlying disease for SCD in the western world, being responsible for approximately 75% of all SCDs.3,4 Cardiomyopathies (dilated and hypertrophic) and primary electrical heart disease account for most of the remainder. The two most important risk factors for SCD (ie, those with highest predictive value) are left ventricular ejection fraction (LVEF) less than 40% and clinical congestive heart failure.3,4 These are followed by significant ventricular arrhythmias (particularly …

Subanalyses of secondary prevention implantable cardioverter-defibrillator trials: antiarrhythmics versus implantable defibrillators (AVID), Canadian Implantable Defibrillator Study (CIDS), and Cardiac Arrest Study Hamburg (CASH).

Controlled trials for secondary prevention of sudden death--Antiarrhythmics Versus Implantable Defibrillators (AVID), Canadian Implantable Defibrillator Study (CIDS), and Cardiac Arrest Study Hamburg (CASH)--have been published and subanalyses of them provide useful clinical information on the outcome during the follow-up of this population. Results from a meta-analysis showed a significant risk reduction (RR) of 25 to 27% of total mortality (P < 0.001) and 50 to 52% of arrhythmic death (P < 0.001). Compared with amiodarone, patients treated with an implantable cardioverter-defibrillator (ICD) in AVID had a maximal benefit in survival when the ejection fraction (EF) was between 20 and 34%. In CIDS, the group of higher risk (older than 70 years, EF less than 3.5%, and New York Heart Association class III-IV) presented a 50% RR of mortality. It has been demonstrated that the imbalance in beta-blocker use cannot explain the better survival in the ICD patients. After 3 years the recurrence of arrhythmia was 64% in the ICD group of the AVID trial. Patients enrolled after an episode of ventricular tachycardia were more likely to have appropriate therapy during follow-up. Older age, lower blood pressure, history of atrial fibrillation, diabetes, congestive heart failure, and prior pacemaker were parameters used for high-risk stratification. Conversely, inducibility of ventricular tachyarrhythmias on electrophysiology did not predict death. Patients with ICD after ventricular tachyarrhythmias have a 28% RR in total mortality. Individuals with EF between 20 to 34% received the highest benefit with ICD therapy.

Are lipid-lowering drugs also antiarrhythmic drugs? an analysis of the antiarrhythmics vs. implantable defibrillators (AVID) trial

Are lipid-lowering drugs also antiarrhythmic drugs? an analysis of the antiarrhythmics vs. implantable defibrillators (AVID) trial

Are lipid-lowering drugs also antiarrhythmic drugs?: an analysis of the antiarrhythmics versus implantable defibrillators (AVID) trial

ObjectivesThis study sought to evaluate the antiarrhythmic effects of lipid-lowering drug therapy as assessed by ventricular tachyarrhythmia (ventricular tachycardia [VT]/ventricular fibrillation [VF]) recurrences recorded by an implantable cardioverter defibrillator (ICD) in patients with atherosclerotic heart disease (ASHD). BackgroundRandomized trials of lipid-lowering drugs suggest reduction of sudden death (SD) in patients with ASHD. Because SD is usually secondary to VT/VF, this observation suggests that lipid-lowering therapy has antiarrhythmic effects. MethodsThe probability of VT/VF recurrence in patients with ASHD treated with an ICD in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial who did not receive lipid-lowering drug therapy (n = 279) was compared with that in patients who received early and consistent lipid-lowering therapy (n = 83). In addition, all-cause mortality and cardiac mortality of all patients in the AVID trial with ASHD who did not receive lipid-lowering therapy (n = 564) were compared with that of those who received early and consistent lipid-lowering therapy (n = 149). ResultsUsing multivariate analyses, lipid-lowering therapy was associated with a reduction in the relative hazard for VT/VF recurrence of 0.40 (95% confidence interval [CI] 0.15 to 0.58) (adjusted p = 0.003) in the ICD subgroup. Lipid-lowering therapy was also associated with a reduction in the relative hazard for all-cause mortality of 0.36 (95% CI 0.15 to 0.68) (adjusted p = 0.03) and a reduction in the relative hazard for cardiac mortality of 0.39 (95% CI 0.16 to 0.78) (adjusted p = 0.04) in the larger study population. ConclusionsIn patients with ASHD who have received an ICD, lipid-lowering therapy is associated with reduction in the probability of VT/VF recurrence, suggesting that part of the benefit of lipid-lowering therapy may be due to an antiarrhythmic effect.