Benefits of Implantable Cardioverter-Defibrillator for Secondary Prevention in Patients With Organic Heart Disease.

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 …

Sudden cardiac death (SCD) is a major public health problem in North America, responsible for approximately 400 000 deaths annually.1,2 Most episodes of SCD in ambulatory populations result from ventricular tachyarrhythmias,3 whereas bradyarrhythmias may be important in some populations, notably hospitalized patients with advanced heart failure4 (Figure 1). A prior article in this series by Zipes and Wellens2 provides a detailed review of the pathogenesis of SCD, its underlying causes, and treatment strategies. Figure 1. Mechanisms of SCD in ambulatory persons. Most SCDs result from ventricular fibrillation. VT, bradyarrhythmias, and other mechanisms account for the remainder. ### ICD Therapy The availability of a therapy that reliably terminates the vast majority of life-threatening tachyarrhythmic and bradyarrhythmic events has tremendous clinical appeal. The implantable cardioverter defibrillator (ICD) represents such a therapy. Despite its appeal, the ICD is imperfect. Currently, systems are costly, have a limited life expectancy, and are subject to complications in the long term.5,6 Furthermore, many patients at risk for SCD are at risk of dying from causes that the ICD would not alter. The impact of ICD shocks also merits consideration. Evidence links multiple shocks with myocardial injury7 and fibrosis,8 and sporadic shocks are associated with significant, independent reductions in quality of life. Compared with patients not having shocks, patients in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial who had ≥1 shocks in the initial year of follow-up had significant declines in self-perceived physical functioning and mental well-being, independent of ejection fraction (EF), social circumstances, and medication use. The reduction in quality of life associated with shocks was of a magnitude similar to clinically important adverse effects from amiodarone.9 Cost-efficacy is a vital issue in settings of limited or restricted health care resources6 and is particularly relevant as ICD use is expanded to …

POSTER PRESENTATIONS

Detached from the 'Gentleman's Magazine', October-November, 1801. In volume lettered: Miscellaneous on China.

ORAL PRESENTATION

Trials comparing implantable cardioverter-defibrillator (ICD) therapy with cardiac resynchronization therapy with a defibrillator (CRT-D) are limited to selected patients treated at centers with extensive experience. To compare outcomes after CRT-D versus ICD therapy in contemporary practice. Retrospective cohort study using the National Cardiovascular Data Registry's ICD Registry linked with Medicare claims. 780 U.S. hospitals implanting both CRT-D and ICD devices. 7090 propensity-matched patients older than 65 years with reduced left ventricular ejection fraction (<0.35) and prolonged QRS duration on electrocardiography (≥120 ms) having CRT-D or ICD implantation between 1 April 2006 and 31 December 2009. Risks for death, readmission, and device-related complications over 3 years. Compared with ICD therapy, CRT-D was associated with lower risks for mortality (cumulative incidence, 25.7% vs. 29.8%; adjusted hazard ratio [HR], 0.82 [99% CI, 0.73 to 0.93]), all-cause readmission (cumulative incidence, 68.6% vs. 72.8%; adjusted HR, 0.86 [CI, 0.81 to 0.93]), cardiovascular readmission (cumulative incidence, 45.0% vs. 52.4%; adjusted HR, 0.80 [CI, 0.73 to 0.88]), and heart failure readmission (cumulative incidence, 24.3% vs. 29.4%; adjusted HR, 0.78 [CI, 0.69 to 0.88]). It was also associated with greater risks for device-related infection (cumulative incidence, 1.9% vs. 1.0%; adjusted HR, 1.90 [CI, 1.07 to 3.37]). The lower risks for heart failure readmission associated with CRT-D compared with ICD therapy were most pronounced among patients with left bundle branch block or a QRS duration at least 150 ms and in women. Patients were not randomly assigned to treatment groups, and few patients could be propensity-matched. The findings may not extend to younger patients or those outside of fee-for-service Medicare. In older patients with reduced left ventricular ejection fraction and prolonged QRS duration, CRT-D was associated with lower risks for death and readmission than ICD therapy alone. Agency for Healthcare Research and Quality.

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 …

Mitral annular disjunction (MAD) carries an increased risk of complex ventricular arrhythmias, which can lead to sudden cardiac death. Many of these patients undergo implantable cardioverter defibrillator (ICD) implantation, but their ICD outcomes are not known. The aim of this study was to assess the outcomes of ICD implantation and the predictors of appropriate ICD therapies in patients with MAD. The study included patients with MAD who underwent ICD implantation. Clinical, electrocardiographic, cardiac imaging, and device therapy data were collected. Forty-nine patients with MAD and ICD were included. Median age was 49 (21) years, and 29 (59%) were female. 13 (27%) patients underwent ICD implantation for primary prevention and 36 (73%) patients for secondary prevention. Over a median follow-up of 27.3 (35.3) months, 23 (47%) patients received ICD therapies. 18 (37%) patients had appropriate ICD therapies, and 5 (10%) patients had inappropriate ICD shocks. Median time to first appropriate therapy was 22.3 (63.3) months. In patients with a secondary prevention ICD indication, the rate of appropriate ICD therapies was 44%, while in patients with a primary prevention ICD indication, it was 15%. Among patients with appropriate ICD therapies, the first therapies were delivered for monomorphic ventricular tachycardia (VT) in 7 (39%) patients and polymorphic VT or ventricular fibrillation (VF) in 11 (61%) patients. Patients with appropriate ICD therapies were more likely to have a history of SCA (p = 0.003) and/or low left ventricular ejection fraction (LVEF) (p = 0.022) before ICD implantation as compared to patients without appropriate ICD therapies. In our cohort of patients with MAD and ICD, appropriate ICD therapies were common. Most appropriate ICD therapies were delivered for polymorphic VT or VF. Larger studies are needed to elucidate the mechanisms of VAs and refine risk stratification in MAD.

Introduction Cardiac sarcoidosis (CS) is an inflammatory cardiomyopathy that manifests as heart failure and fatal arrhythmia, resulting in increased risk of sudden cardiac death. Implantable cardioverter-defibrillator (ICD) therapy plays a vital role in correcting life-threatening ventricular arrhythmias in these patients. However, there is currently no standardized ICD therapy guidelines for primary prevention in CS. In a recent study based on the Netherlands population, independent predictors of ICD therapy in patients with CS were identified. Purpose This study aims to identify predictors of appropriate ICD therapy in a large heterogeneous metropolitan population and to compare these to the predictors in the Netherlands study, which had a homogenous population, in an effort to refine the indications for ICD implantation in those with CS. Methods A single-center retrospective study of patients was performed on patients with ICD implantation after CS diagnosis. ICD implant was classified as primary or secondary prevention. Primary prevention (PP) indications were a reduced ejection fraction with other causes excluded, second or third-degree AV block, extensive late gadolinium enhancement (LGE) on CMR, or atrial arrhythmia. Secondary prevention (SP) indications included sudden cardiac arrest, history of sustained ventricular tachycardia/fibrillation (VT/VF), or syncope of probable arrhythmic origin. Primary outcome was appropriate ICD therapy. Appropriate ICD therapy included sustained VT/VF terminated by shock or ATP. Secondary outcome parameters included inappropriate ICD therapy. Inappropriate ICD therapy included shock or ATP delivered for any rhythm outside of VT/VF. Statistical analysis was performed using RStudio. Results Among 94 patients with clinically diagnosed cardiac sarcoidosis, 66 patients received an ICD. Of these, 41 patients received ICD implant as PP (62.1%), of which 13 patients received appropriate therapy at least once (31.7%). Of the 25 SP patients, 10 patients received appropriate therapy (40.0%). LGE of right ventricle was identified as the only predictor of appropriate shock therapy (p = 0.049). Obesity with BMI > 30 was identified as a predictor of appropriate ATP therapy (p = 0.048). 4 patients were identified with inappropriate ICD therapy secondary to atrial fibrillation or supraventricular tachycardia, where 3 of them belonged to PP. No statistically significant predictors were identified for inappropriate ICD therapy. Conclusion LGE of right ventricle was identified as a predictor of appropriate ICD therapy, which was more common in SP patients. These findings were similar to those seen in the homogenous Netherlands population. The findings of our study emphasize the need for further evaluation of the ICD indications in CS. Further exploration of additional factors could refine patient selection and optimize prevention strategies for life-threatening arrhythmias in CS patients.

The implantable cardioverter defibrillator (ICD) has proved effective in preventing sudden death and decreasing mortality in randomised secondary prevention trials. Some nonrandomized studies have reported different incidences and predictors of appropriate ICD therapy in patients with idiopathic dilated cardiomyopathy (DCM). The antiarrhythmic and other medical therapies were different between the published studies and it was reported that not using beta-blockers was a predictor of appropriate ICD therapy. In the present study, we report on our long-term experience with ICD therapy in patients with DCM, the majority of whom were treated with beta-blockers and amiodarone. The study population consisted of 25 patients with DCM who underwent initial transvenous ICD implantation between December 1995 and May 2005. Indications for ICD implantation were monomorphic sustained ventricular tachycardia (VT) in 16 patients (64%), cardiac arrest in 8 patients (32%), and syncope plus inducible VT in one patient. Twenty-four patients underwent an electrophysiologic study (EPS). In 18 patients, the ICDs were programmed to only shocks and in 7 patients an additional antitachycardia pacing program was performed. One patient was lost to follow-up and 24 patients were followed-up primarily in our ICD pacemaker outpatient clinic. Appropriate ICD therapy was defined as antitachycardia pacing therapy or shock for tachyarrhythmia determined by evaluation of the clinical information and by device diagnostics to be either ventricular fibrillation or ventricular tachycardia. The mean follow-up was 39.29 +/- 30.59 months after ICD implantation. At follow-up, 17 patients were using a beta-blocker and 16 patients amiodarone. Appropriate ICD therapy was observed in 14 patients (58%). The detected arrhythmias were VT in 12 patients, ventricular fibrillation (VF) in one, and VT and VF in one patient. The time to first ICD therapy was 15.93 +/- 18.45 (range, 1-74) months. Using the Kaplan-Meier method, the percent survival free of appropriate ICD therapy was 82%, 72%, 66%, and 55% at 1, 2, 3, and 4 years follow-up, respectively. The clinical, echocardiographic, and electrophysiologic characteristics did not differ between those who did and did not receive appropriate ICD therapy. However, the mean QRS duration was significantly longer in patients who received appropriate ICD therapies. Cox regression analysis did not reveal any factors that predicted appropriate ICD therapy. Five patients (21%) died during follow-up. Four deaths were classified as cardiac and one as noncardiac. The cumulative survival from total death was 94%, 82%, 82%, and 69%, and the cumulative survival from cardiac death was 94%, 82%, 82%, and 76% during 1, 2, 3, and 4 years of follow-up, respectively. In summary, in this selected patient population with DCM, the majority of patients were unresponsive to beta-blocker and antiarrhythmic therapy. Most of these patients received appropriate ICD therapy during follow-up. Cox regression analysis did not identify any factors that predicted appropriate ICD therapy. Additional trials with larger patient populations are needed to detect the predictors of appropriate ICD therapy in patients with DCM.

Who benefits from implantable cardioverter defibrillator therapy, and who pays the price?

Although the efficacy of an implantable cardioverter defibrillator (ICD) in preventing sudden cardiac death is well established, the incidence and predictors of appropriate ICD therapy in Japanese ischemic heart disease (IHD) patients remain unclear. We retrospectively studied Japanese 141 IHD patients undergoing transvenous ICD or cardiac resynchronization therapy with a defibrillator (CRT-D) implantation for primary or secondary prevention at Hirosaki University Hospital. Over a mean (±SD) follow-up period of 5.5±2.8 years, the incidence of appropriate ICD therapy was similar in the primary and secondary prevention groups, although it was relatively more frequent in the first 2 years in the secondary prevention group. Four patients died due to sustained ventricular tachycardia (VT) or ventricular fibrillation (VF), mainly due to post-shock pulseless electrical activity. Once patients had received their first appropriate ICD therapy, 49.2% received second appropriate ICD therapy within 6 months. Cox proportional hazard analysis revealed that sustained VT as an index life-threatening ventricular tachyarrhythmia before ICD/CRT-D implantation was an independent predictor of appropriate ICD therapy, but VF was not. The incidence of appropriate ICD therapy was comparable in primary and secondary prevention among Japanese IHD patients. We need to recognize the high-risk period for second appropriate ICD therapy after the first therapy and sustained VT as index life-threatening ventricular tachyarrhythmia as a risk factor for appropriate ICD therapy.

The Implantable Cardioverter/Defibrillator (ICD) represents the therapy of choice for patients at risk of malignant ventricular arrhythmias. The survival benefit of the ICD vs antiarrhythmic therapy in patients with coronary artery disease and ventricular tachycardia has been proven. Recently, the ICD therapy has also been established for primary prevention in high risk patients. We report about the incidence of adequate ICD therapies in patients with coronary artery disease, who underwent ICD implantation at the University Hospital Zurich. 104 consecutive patients (97 men, 7 women, mean age of 67 +/- 10 years) with coronary artery disease, who underwent ICD implantation in accordance with the AHA/ACC/NASPE guidelines between January 2000 and July 2003 were included in the study. Follow-up was performed every three to six months, when all ICD therapies were documented. This documentation was used for analysis of adequate or inadequate ICD therapies. The mean follow-up time was 383 +/- 195 days. The time to the first adequate therapy was 201 +/- 283 days. The cumulative incidence for the first adequate therapy was 21% at six months, 39% at two years and 59% at four years. In 64% of patients, who experienced adequate ICD therapies, antitachycardia pacing (ATP) and in 36% an initial shock was delivered. ATP was successful in 83% of adequately delivered episodes. In the follow-up period 12 patients died. The benefit of the ICD was apparent in patients at risk for ventricular arrhythmias and coronary artery disease after a relatively short period of time, which underlines the important role of the ICD in primary and secondary prevention.

Heart failure patients unresponsive to implantable cardioverter-defibrillator therapy: a neglected problem.

Although highly effective in preventing arrhythmic death, there is a high prevalence of anxiety, depression and reduced quality of life among patients who have received an implantable cardioverter defibrillator (ICD). Whether mortality, ICD shock and readmission are predicted by patient-reported outcomes is unknown. The aim of this study was to describe patient-reported outcomes among patients with ICDs compared by: ICD indication and generator type (ICD or cardiac resynchronisation therapy ICD), and to determine whether patient-reported outcomes at discharge predict mortality, ICD therapy and readmission. A national cross-sectional survey at hospital discharge ( n=998) with register follow-up. Patient-reported outcomes included the Hospital Anxiety and Depression Scale, Short Form-12, HeartQoL, EQ-5D and Edmonton Symptom Assessment Scale. Register data: ICD therapy, readmissions and mortality within one year following discharge. Patients with primary prevention ICDs had significantly worse patient-reported outcomes at discharge than patients with secondary prevention ICDs. Likewise, patients with cardiac resynchronisation therapy ICDs had significantly worse patient-reported outcomes at discharge than patients without cardiac resynchronisation therapy. One-year mortality was predicted by patient-reported outcomes, with the highest hazard ratio (HR) being anxiety (HR 2.02; 1.06-3.86), but was not predicted by indication or cardiac resynchronisation therapy. ICD therapy and ventricular tachycardia/ventricular fibrillation were not predicted by patient-reported outcomes, indication or cardiac resynchronisation therapy. Overall, patient-reported outcomes predicted readmissions, e.g. symptoms of anxiety and depression predicted all readmissions within 3 months (HR 1.50; 1.13-1.98) and 1.47 (1.07-2.03), respectively). Patients with primary indication ICDs and cardiac resynchronisation therapy ICDs report worse patient-reported outcomes than patients with secondary indication and no cardiac resynchronisation therapy. Patient-reported outcomes such as mental health, quality of life and symptom burden predict one-year mortality and acute and planned hospital readmissions.