Use Of Implantable Cardioverter-defibrillator In Patients Research Articles

Implantable cardioverter defibrillators in left ventricular assist device patients: Α systematic review and meta-analysis

Implantable cardioverter-defibrillators (ICDs) remain the standard of care in advanced heart failure with reduced ejection fraction patients for the prevention of sudden cardiac death. However, current guidelines remain conflicting with respect to the use of ICDs in patients supported with a continuous flow left ventricular assist device (CF-LVAD). The current review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies comparing the use of ICD in patients with CF-LVADs were included. The 2 primary outcomes studied were all-cause mortality, and a successful bridge to heart transplantation. We calculated pooled odds ratios (ORs) with 95% confidence intervals (CIs). We also compared baseline characteristics between US and European studies, for CF-LVAD patients with an ICD. Among all studies, the use of an ICD was not associated with all-cause mortality in patients with CF-LVADs (OR: 0.85, 95% CIs: 0.64-1.12, p=0.24). The presence of an ICD was associated with a trend towards increased likelihood of successful bridge to heart transplantation (OR: 1.12, 95% CI: 1.0-1.3, p=0.06). A subgroup analysis of studies published by European centers revealed a significant decrease in pooled mortality (OR: 0.58, 95% CI: 0.4-0.83, p=0.003) with the use of ICD, contrary to an increase in pooled mortality among studies published by US centers (OR: 1.2, 95% CI 1.02-1.33, p=0.025). Moreover, we identified significant differences in baseline characteristics such as bridge to transplantation rate, Interagency Registry for Mechanically Assisted Circulatory Support profiles, and use of an intra-aortic balloon pump or extracorporeal membrane oxygenation preoperatively, between the US and European populations. While this meta-analysis did not show an overall survival benefit with the use of an ICD in CF-LVAD patients, it revealed significant differences in the derived benefit, in distinct patient populations. This might reflect differences in baseline patient characteristics and warrants further investigation.

Implantable Cardioverter Defibrillator Therapy in Patients with Acute Decompensated Heart Failure with Reduced Ejection Fraction: An Observation from the KCHF Registry

It remains unclear the clinical characteristics and prognosis of implantable cardioverter defibrillator (ICD) on prevention for sudden cardiac death (SCD) in Japanese patients with acute decompensated heart failure (ADHF) and reduced left ventricular ejection fraction (LVEF). We investigated the prevalence, clinical characteristics, and clinical outcomes in a contemporary large-scale Japanese ADHF registry. Among the consecutive 3785 patients hospitalized for ADHF and discharged alive in the Kyoto Congestive Heart Failure registry, we identified 1409 patients with reduced LVEF (ICD: N = 115, non-ICD: N = 1294). Patients in the ICD group were younger (69.3 ± 12.9/74.2 ± 13.6 years; p < 0.001), more likely to be men (84%/65%), and more often had a history of heart failure hospitalization (70%/36%; p = 0.001), cardiomyopathy as the underlying heart disease (51%/27%; p < 0.001), and previous serious ventricular arrhythmia (57%/3.8%; p < 0.001), and had lower LVEF (25.4±7.4%/29.5±6.9%; p < 0.001), and estimated glomerular filtration rate (43.0±19.7/47.8±23.4 mL/min/1.73m2; p = 0.04) than those in the non-ICD group. The cumulative 1-year incidence of the primary arrhythmic composite endpoint of SCD, arrhythmic death, or resuscitated cardiac arrest trended to be lower in the ICD group than in the non-ICD group (0.0% versus 3.4%, p = 0.053), and the lower adjusted risk of the ICD group relative to the non-ICD group was significant for the primary arrhythmic endpoint (HR 0.10, 95% CI, 0.01-0.53; p = 0.003). However, there were no differences in the cumulative incidences of all-cause death between the ICD and non-ICD groups (17.3% versus 17.5%, p = 0.68), and the adjusted risk of the ICD group relative to the non-ICD group remained insignificant for all-cause death (HR, 0.85; 95%CI, 0.52-1.36, p = 0.51). This study elucidated the real-world features of ADHF patients between those with ICD and those without. ICD use in patients with ADHF and reduced LVEF as compared with non-ICD use was associated with significant risk reduction for arrhythmic events, but not for mortality.

Effect of ICD implantation on cardiovascular outcomes in patients with cardiac amyloidosis: A systematic review and meta‐anaylsis

Cardiac amyloidosis is associated with a high rate of sudden cardiac death (SCD). Whether implantable cardioverter-defibrillator (ICD) use in such patients prevents SCD is uncertain. This study assesses outcomes of ICD use in patients with cardiac amyloidosis. A systematic review and meta-analysis of data were performed after searching multiple databases and scientific sites pertaining to ICD use and cardiac amyloidosis. Of 8260 citations identified, six studies comprising 194 patients met inclusion criteria. Mean values and frequencies of patient characteristics were as follows: mean NT-proBNP: 6867.9 pg/mL, mean left ventricular ejection fraction: 48.1%, heart failure: 67%, nonsustained ventricular tachycardia: 51%, syncope: 21%, and secondary prevention: 33%. During the mean follow-up period of 18.21 months, 18% of patients received appropriate ICD treatment and 5% received inappropriate ICD treatment. The mortality rate was 31%. Two studies assessed the difference between patients with appropriate ICD treatment and patients with absence of appropriate ICD treatment. There was no difference between the two groups when stratified on multiple selected third variables except for two subgroups. Male gender was associated with a higher rate of appropriate ICD treatment, whereas New York Heart Association class III or IV heart failure patients was associated with a lower rate of appropriate ICD treatment. The frequency of appropriate ICD treatment in cardiac amyloidosis is low and is not predicted by nonsustained ventricular tachycardia. Male gender is associated with appropriate ICD treatment. New York Heart Association class III or IV heart failure is associated with lower rate of appropriate ICD treatment.

Implantable Cardioverter Defibrillator Use in Males with Duchenne Muscular Dystrophy and Severe Left Ventricular Dysfunction

Purpose Duchenne muscular dystrophy (DMD) is characterized by myocardial fibrosis and left ventricular (LV) dysfunction. Implantable cardioverter defibrillator (ICD) use has not been characterized in this population but is generally considered for patients with severe LV dysfunction receiving goal directed medical therapy (GDMT), including a beta blocker plus an angiotensin converting enzyme inhibitor. We evaluated utilization and efficacy of ICD use in patients with DMD. Methods Retrospective cohort study of DMD patients followed at 17 centers across the US and Canada from January 2, 2005-January 1, 2018. ICD use and its effect on survival was evaluated in those patients with severe LV dysfunction (shortening fraction (SF) Results Severe LV dysfunction was present in 57/436 (13.1%) patients, of which 11 (19.3%) died during the study period, as compared to 17/379 (4.5%) who died without severe LV dysfunction (p Conclusion ICD use may be associated with improved survival and minimal complications in DMD cardiomyopathy with severe LV dysfunction. However, inconsistent utilization of GDMT may be a significant confounder.Future studies are needed to define optimal ICD use in patients with DMD related cardiomyopathy.

Systematic Review for the 2017 AHA/ACC/HRS Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society.

Although large randomized clinical trials have found that primary prevention use of an implantable cardioverter-defibrillator (ICD) improves survival in patients with cardiomyopathy and heart failure symptoms, patients who receive ICDs in practice are often older and have more comorbidities than patients who were enrolled in the clinical trials. In addition, there is a debate among clinicians on the usefulness of electrophysiological study for risk stratification of asymptomatic patients with Brugada syndrome. Our analysis has 2 objectives. First, to evaluate whether ventricular arrhythmias (VAs) induced with programmed electrostimulation in asymptomatic patients with Brugada syndrome identify a higher risk group that may require additional testing or therapies. Second, to evaluate whether implantation of an ICD is associated with a clinical benefit in older patients and patients with comorbidities who would otherwise benefit on the basis of left ventricular ejection fraction and heart failure symptoms. Traditional statistical approaches were used to address 1) whether programmed ventricular stimulation identifies a higher-risk group in asymptomatic patients with Brugada syndrome and 2) whether ICD implantation for primary prevention is associated with improved outcomes in older patients (>75 years of age) and patients with significant comorbidities who would otherwise meet criteria for ICD implantation on the basis of symptoms or left ventricular function. Evidence from 6 studies of 1138 asymptomatic patients were identified. Brugada syndrome with inducible VA on electrophysiological study was identified in 390 (34.3%) patients. To minimize patient overlap, the primary analysis used 5 of the 6 studies and found an odds ratio of 2.3 (95% CI: 0.63-8.66; P=0.2) for major arrhythmic events (sustained VAs, sudden cardiac death, or appropriate ICD therapy) in asymptomatic patients with Brugada syndrome and inducible VA on electrophysiological study versus those without inducible VA. Ten studies were reviewed that evaluated ICD use in older patients and 4 studies that evaluated unique patient populations were identified. In our analysis, ICD implantation was associated with improved survival (overall hazard ratio: 0.75; 95% confidence interval: 0.67-0.83; P<0.001). Ten studies were identified that evaluated ICD use in patients with various comorbidities including renal disease, chronic obstructive pulmonary disease, atrial fibrillation, heart disease, and others. A random effects model demonstrated that ICD use was associated with reduced all-cause mortality (overall hazard ratio: 0.72; 95% confidence interval: 0.65-0.79; P<0.0001), and a second "minimal overlap" analysis also found that ICD use was associated with reduced all-cause mortality (overall hazard ratio: 0.71; 95% confidence interval: 0.61-0.82; P<0.0001). In 5 studies that included data on renal dysfunction, ICD implantation was associated with reduced all-cause mortality (overall hazard ratio: 0.71; 95% confidence interval: 0.60-0.85; P<0.001).

The Use of Implantable Cardioverter-defibrillators in the Prevention of Sudden Cardiac Death: A Focus on Congenital Heart Disease and Inherited Arrhythmia Syndromes.

Some congenital heart diseases (CHDs) and inherited arrhythmia syndromes are associated with an increased risk of sudden cardiac death (SCD). Appropriate selection criteria for implantable cardioverter-defibrillator (ICD) implantation in these patients are poorly defined due to a paucity of data available from randomized clinical trials, leading to current guidelines relying more on non-randomized studies and expert opinions to make their recommendations. This review describes available evidence-based risk stratification methods for identifying patients at risk for SCD, as well as current guideline-driven management strategies for the use of ICDs in patients with CHD and inherited arrhythmia syndromes.

Implantable cardioverter defibrillator therapy in hypertrophic cardiomyopathy: an updated systematic review and meta-analysis of outcomes and complications.

Since the introduction of the implantable cardioverter-defibrillator (ICD) in patients with hypertrophic cardiomyopathy (HCM), the incidence of sudden cardiac death (SCD) has been significantly reduced. Given its widespread use, it is important to identify the outcomes associated with ICD use in patients with HCM. The present paper is a systematic review and meta-analysis of the rates of appropriate and inappropriate interventions, mortality, and device complications in HCM patients with an ICD. We conducted a systematic review and meta-analysis on 27 studies reporting outcomes and complications after ICD implantation in patients with HCM. ICD interventions, device complications, and mortality were extracted for analysis. A total of 3,797 patients with HCM and ICD implantation were included (mean age, 44.5 years; 63% male), of which 83% of patients had an ICD for primary prevention of SCD. The cardiac mortality was 0.9% (95% CI: 0.7-1.3) per year and non-cardiac mortality was 0.8% (95% CI: 0.6-1.2) per year. Annualized appropriate intervention rate was 4.8% and annualized inappropriate intervention was 4.9%. The annual incidence of lead malfunction, lead displacement and infection was 1.4%, 1.3%, and 1.1%, respectively. ICD use in patients with HCM produces low rates of cardiac and non-cardiac mortality, and an appropriate intervention rate of 4.8% per year. However, moderate rates of inappropriate intervention and device complications warrant careful patient selection in order to optimize the risk to benefit ratio in this select group of patients.

Implantable Cardioverter-defibrillator for Primary Prevention of Sudden Cardiac Death in Non-ischemic Cardiomyopathy

The insertion of implantable cardioverter-defibrillators (ICD) in patients with non-ischemic cardiomyopathy (NICM) has been recommended by recent guidelines. However, current evidence shows limited benefits to inserting ICDs in patients with NICM. Recently, the defibrillator implantation in patients with non-ischemic systolic heart failure (DANISH) trial, a large randomized trial of more than 1,100 patients with NICM, was conducted to compare the primary prevention of all-cause mortality between optimal medical therapy, cardiac resynchronization therapy, and ICD implantation. The DANISH trial revealed no differences in all-cause mortality between the groups after 5 years. However, in patients younger than 68 years of age, the rate of death from any cause was significantly lower in the ICD group compared to the control group. In addition, the rate of sudden cardiac death was lower in the ICD group compared to the control group in patients under 68 years. The results of DANISH will likely change guidelines about the insertion of ICD in patients with NICM, and encourage the use of ICD in patients with NICM. Keywords: Implantable cardioverter-defibrillator; Non-ischemic cardiomyopathy; Sudden cardiac death; Primary prevention 중심 단어: ì‚½ìž í˜• ì œì„¸ë™ê¸°; 비허혈성 심근병증; 심장돌연사; ì¼ì°¨ì  예방

Risk stratification for sudden cardiac death in North America – current perspectives

Sudden cardiac death (SCD) accounts for approximately 360,000 deaths annually in the United States, and is the cause of half of all cardiovascular deaths. In patients with severely depressed left ventricular ejection fraction (LVEF), implantable cardioverter-defibrillators (ICDs) have been shown to significantly reduce total mortality, but many factors beyond LVEF influence the relative benefit afforded by ICD implantation. In fact, among patients with prior myocardial infarction, approximately half of all SCDs occur in patients without severe LV dysfunction, and in analyses of large ICD trials, certain patient subgroups derive no benefit to ICD implantation despite having low LVEF, often due to competing non-arrhythmic mortality. Improved risk stratification tools to help select patients who are likely to derive the most benefit from ICD implantation are therefore needed. This manuscript will review studies evaluating use of ICDs in patients with mild LV systolic dysfunction and LVEF >35%, currently available ICD risk stratification models, and the rationale for designing a cohort study to prospectively validate use of an ICD risk stratification score.

Implantable Cardioverter-Defibrillator and Cardiac Resynchronization Therapy

The use of an implantable cardioverter-defibrillator (ICD) is an effective treatment strategy for patients with aborted sudden cardiac death (SCD) and ventricular tachyarrhythmias. Primary prevention of SCD is a strategy involving the use of ICDs in patients who are at high risk for but who have not had any previous events of ventricular arrhythmias or cardiac arrest. Cardiac resynchronization therapy (CRT) improves symptoms of heart failure and left ventricular systolic function when used in patients with severe heart failure symptoms, reduced left ventricular ejection, and a wide QRS complex. CRT has also been proven to reduce the rate of hospitalization due to heart failure as well as the rate of death from any cause. In this review, we discuss the clinical trials and current clinical indications for the ICD and CRT. Keywords: Defibrillators, Implantable; Cardiac resynchronization therapy; Heart failure 중심 단어: ì‚½ìž í˜• ì œì„¸ë™ê¸°; 심장재동기화 치료; ì‹¬ë¶€ì „

Implantable Cardioverter-Defibrillators for Primary Prevention of Sudden Cardiac Death

Implantable cardioverter-defibrillators (ICDs) are an effective treatment strategy for patients with aborted sudden cardiac death (SCD) and ventricular tachyarrhythmias. rimary prevention of SCD is a strategy involving the use of ICDs in patients who are at high risk for, but have not had, any previous events of ventricular arrhythmias or cardiac arrest. Several randomized clinical trials have demonstrated the efficacy of ICDs in the primary prevention of SCD. Therefore, ICD implantation is recommended as a standard of care by the guidelines in patients who have ischemic or nonischemic cardiomyopathy and a low left ventricular ejection fraction. However, the rates of ICD implantation as a primary prevention in Korea is quite low compared to western countries. In this review, we will summarize the results and efficacy of ICDs in the clinical trials about primary prevention of SCD, the current treatment guidelines, and the reimbursement policy of Korean health insurance. We hope that this review will help broaden the recognition of importance of ICD implantation for the primary prevention of SCD. Keywords: Implantable cardioverter-defibrillator; Sudden cardiac death; Primary prevention 중심 단어: ì‚½ìž í˜• ì œì„¸ë™ê¸°; 돌연사; ì¼ì°¨ì  예방

Remarks on polyparametric assessment of sudden death risk for primary prevention ICD implantation in patients with left ventricular dysfunction of ischemic and non ischemic etiology. Italian Association of Hospital Cardiologists (ANMCO) Experts Position Paper

It is generally recognized that current guidelines, based on ejection fraction criteria, do not allow appropriate selection of patients for implantable cardioverter-defibrillator (ICD) therapy in the primary prevention of sudden death, thus hindering the optimal use of ICD in patients with left ventricular dysfunction of ischemic and nonischemic etiology. Ejection fraction alone has limitations in both sensitivity and specificity. Assessment of the risk for sudden death using a combination of multiple tests (ejection fraction associated with one or more different arrhythmic risk markers) could partially compensate for these limitations. In this position paper, the potential usefulness of a polyparametric assessment using some of the most investigated risk markers of sudden death is discussed, including late gadolinium enhancement cardiac magnetic resonance, programmed ventricular stimulation, T-wave alternans, autonomic tone, biomarkers, and genetic testing.

Outcomes of Implantable Cardioverter-Defibrillator Use in Patients With Comorbidities: Results From a Combined Analysis of 4 Randomized Clinical Trials

ObjectivesThe aim of this study was to determine if the benefit of implantable cardioverter-defibrillators (ICDs) is modulated by medical comorbidity. BackgroundPrimary prevention ICDs improve survival in patients at risk for sudden cardiac death. Their benefit in patients with significant comorbid illness has not been demonstrated. MethodsOriginal, patient-level datasets from MADIT I (Multicenter Automatic Defibrillator Implantation Trial I), MADIT II, DEFINITE (Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation), and SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) were combined. Patients in the combined population (N = 3,348) were assessed with respect to the following comorbidities: smoking, pulmonary disease, diabetes, peripheral vascular disease, atrial fibrillation, ischemic heart disease, and chronic kidney disease. The primary outcome was overall mortality, using the hazard ratio (HR) of time to death for patients receiving an ICD versus no ICD by extent of medical comorbidity, and adjusted for age, sex, race, left ventricular ejection fraction, use of antiarrhythmic drugs, beta-blockers, and angiotensin-converting enzyme inhibitors. ResultsOverall, 25% of patients (n = 830) had <2 comorbid conditions versus 75% (n = 2,518) with significant comorbidity (≥2). The unadjusted hazard of death for patients with an ICD versus no ICD was significantly lower, but this effect was less for patients with ≥2 comorbidities (unadjusted HR: 0.71; 95% confidence interval: 0.61 to 0.84) compared with those with <2 comorbidities (unadjusted HR: 0.59; 95% confidence interval: 0.40 to 0.87). After adjustment, the benefit of an ICD decreased with increasing number of comorbidities (p = 0.004). ConclusionsPatients with extensive comorbid medical illnesses may experience less benefit from primary prevention ICDs than those with less comorbidity; implantation should be carefully considered in sick patients. Further study of ICDs in medically complex patients is warranted.

Most Important Outcomes Research Papers on Device Therapies for Cardiomyopathies

Disorders of the cardiac muscle or cardiomyopathies are a broad, yet collectively common, group of conditions. Despite the heterogeneous etiologies, mode of death from these conditions is remarkably similar - progressive decline in cardiac function leading to intractable heart failure (HF) and sustained ventricular arrhythmias resulting in sudden cardiac death (SCD). Nearly 50% of patients die within 5 years of a HF diagnosis.1 Indeed, in the United States, HF alone is thought to cause 55,000 deaths per year2 and further contribute to 1 in 9 deaths overall.1 However, while advanced HF and the risk of SCD were once thought to be untreatable, technological advances has seen the emergence of device therapies as viable treatment options. Specifically, implantable cardioverter-defibrillator (ICD) therapy for treatment of ventricular arrhythmias, cardiac resynchronization therapy (CRT) for restoring cardiac synchrony and mechanical efficiency, and ventricular assist device (VAD) therapy to temporarily or permanently replace the function of the failing heart, have all emerged as highly efficacious therapies. The expanding use of device therapies, however, poses many challenges. First, while the indications for these devices are well summarized in clinical guidelines,3,4 considerable hurdles remain in ensuring eligible patients receive these therapies.5 By the same token, establishing the safety and effectiveness of these therapies in populations that are found in clinical practice, yet commonly excluded from trials, such as the elderly6 and uncommon forms of cardiomyopathies,7 is a high priority. Second, rapid dissemination of technologies frequently results in disparities in care. Indeed, age, gender, and racial disparities, in both receipt of these devices and outcomes following implantation, have been well documented. Whether these disparities have persisted, and the potential causative mechanisms underlying these disparities, however, are uncertain.8,9 Third, these devices are not without significant untoward effects; understanding …

ORAL PRESENTATION

ORAL PRESENTATION

Use of a Screening Tool Improves Appropriate Referral to an Electrophysiologist for Implantable Cardioverter-Defibrillators for Primary Prevention of Sudden Cardiac Death

Despite data showing the benefits of implantable cardioverter-defibrillator (ICD) insertion for primary prevention in populations at risk for sudden death, professional society guidelines recommending primary prevention, and recognition by payers of the clinical value of ICDs in these populations, ICDs for primary prevention remain underused. We sought to determine whether implementing a screening tool would increase appropriate identification of patients showing clinical evidence of ICD benefit and prompt referral to an electrophysiologist for ICD implantation. Screening tools were affixed to medical records for patients seen in 2 outpatient cardiology offices that queried ejection fraction and whether referral to an electrophysiologist was made (N=6632). The number of appropriate referrals in the screening period were compared with analogous data collected before implementation of the screening tool (control period) through retrospective record review (n=3606). Significantly more eligible patients were offered referral during the screening period than during the control period at both sites, 80% (8/10 eligible) versus 33% (5/15) at site 1 (P<0.02) and 100% (44/44) versus 60% (21/35) at site 2 (P<0.001). Of all patients offered referral, 41% (32/78) accepted. The use of a screening tool increases referral to electrophysiology for patients in whom placement of an ICD confers the benefit of sudden cardiac death primary prevention. Barriers to referral include both physician and patient factors. Verification of these findings on a larger scale as well as studies defining the foundation of these barriers may further improve use of ICDs in patients for whom their mortality benefit is well described.

Hospital Variation and Characteristics of Implantable Cardioverter-Defibrillator Use in Patients With Heart Failure: Data From the GWTG-HF (Get With The Guidelines–Heart Failure) Registry

The aim of this study was to describe hospital variation and factors associated with adherence to guidelines for implantable cardioverter-defibrillator (ICD) therapy. Studies have shown incomplete application of ICD therapy in eligible heart failure (HF) patients. New or discharge prescription rates for ICD therapy (ejection fraction <or=30% without documented ICD contraindications) for hospitals were calculated from participants in the GWTG-HF (Get With The Guidelines-Heart Failure) registry during January 2005 to June 2007. With hierarchical modeling, hospitals' patient case-mix adjusted ICD rate and hospital factors associated with ICD use were determined. The association of ICD rate and other quality of care indicators and procedure use was determined. Overall use of ICD in-hospital or planned implantation rate was 20%. This rate ranged widely among hospitals, from 1% among the lowest tertile to 35% among the top tertile (p < 0.01). After adjusting for patient case mix, independent hospital characteristics associated with higher ICD use were percutaneous coronary intervention, coronary artery bypass grafting, and heart transplant capability as well as larger hospital bed size (p < 0.01). Hospital Centers for Medicare and Medicaid Services/Joint Commission on the Accreditation of Healthcare Organizations performance measures (discharge instructions, angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker use, smoking cessation; p >or= 0.05) were similar across ICD, whereas higher ICD-rate hospitals had higher adherence to GWTG-HF performance measures (beta-blocker use, evidence-based beta-blocker use, aldosterone-antagonist, hydralazine/nitrate; p < 0.05) except warfarin in patients with atrial fibrillation (p = 0.18). There is significant unexplained hospital variation in the use of ICD therapy among potentially eligible HF patients. However, hospitals that use ICD therapy more often also have more rapidly adopted other newer evidence-based HF therapies.

The Use of Implantable Cardioverter Defibrillators for the Prevention of Sudden Cardiac Death: A Review of the Evidence and Implications

Sudden cardiac death (SCD) claims approximately 460,000 lives per year in the United States, and half of these deaths occur in people with a history of coronary artery disease. Patients with left ventricular dysfunction and a history of myocardial infarction are at especially high risk. There is now strong evidence from multiple well-designed randomized controlled trials that implantable cardioverter defibrillators (ICDs) save lives when used for both primary and secondary prevention. As indications for ICD implantation have broadened, considerable debate has taken place because of the substantial cost involved in widespread ICD utilization. This article summarizes the epidemiology of SCD, reviews the evidence supporting the use of ICDs in patients with ischemic cardiomyopathy, and explores some of the controversy surrounding ICD utilization that has arisen in the wake of recent trials that have utilized ICDs for the primary prevention of SCD.

Implantable cardioverter-defibrillator therapy in patients with congenital long-QT syndrome: A long-term follow-up

The purpose of this study was to evaluate retrospectively a single-center experience with the use of ICDs in patients with long QT syndrome (LQTS) concerning outcome, complications, and optimal programming. Use of implantable cardioverter-defibrillator (ICD) in patients with congenital LQTS is controversial but is generally accepted in high-risk patients. We enrolled 27 symptomatic patients with LQTS undergoing ICD therapy (QTc 540 +/- 64 ms(1/2); 85% female, 63% cardiac arrest; 33% syncope despite beta-blockers; 4% with severe phenotype) and 81 genotyped patients with LQTS undergoing conventional drug therapy (28 LQT1, 39 LQT2, 1 LQT3, 13 LQT5). During a mean follow-up of 65 +/- 34 months, one death occurred in the ICD group that was not LQTS related. A total of 178 appropriate shocks were observed in 10/27 patients (37%), mostly in survivors of cardiac arrest (in 58% of cardiac arrest patients vs. in 20% of non-cardiac arrest patients). In a logistic regression analysis, only QTc interval (121/178 shocks (68%) for QTc > 500 ms(1/2)) and "survived cardiac arrest" were prognostic for ICD shocks. In 30% of patients in the ICD group, multiple shocks occurred and could be reduced after increase of antibradycardia pacing rate, adding beta-blocker therapy, or starting the rate-smoothing algorithm (average 7.1 shocks before to 0.75 shocks after additional intervention annually). ICD therapy is a safe and useful tool in high-risk patients with LQTS. QTc interval and cardiac arrest survivors were prognostic factors for appropriate ICD shocks. The results of this large single-center experience suggest that beta-blockers should always be added to ICD therapy. In addition, some patients might benefit from additional antibradycardia pacing, prolonged detection time, and a rate-smoothing algorithm to prevent recurrent episodes.

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 …