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

The impact of technology dependency on device acceptance and quality of life in persons with implantable cardioverter defibrillators

BACKGROUND

The impact of implantable cardioverter defibrillator (ICD) technology on the quality of life (QOL) experienced by recipients has been a major focus of recent research. Numerous studies have found psychological distress to be important in determining QOL in persons receiving ICDs, yet the source of psychological distress is not well understood.

OBJECTIVE

The aim of this study was to determine the impact of technology dependency on psychological outcomes in ICD recipients.

METHODS

With the use of a cross-sectional design, 161 ICD recipients from 1 device clinic were mailed self-administered questionnaires, including the Dependency on Technology Scale, Brief Illness Perception Questionnaire, Florida Shock Anxiety Scale, Florida Patient Acceptance Survey, and Short Form-12 (SF-12). Hierarchical multiple regressions and analyses of variance were performed.

RESULTS

The final sample size was 101 participants. Mean (SD) age was 68 (13) years; 72% of the participants were men, 99% were white, and 30% reported receiving a shock(s). A total of 80% reported positive attitudes toward technology dependency; 14%, neutral; and 6%, negative (Dependency on Technology Scale). Illness perceptions were positive (Brief Illness Perception Questionnaire; mean[SD], 34.5 [12.6]), shock anxiety was elevated (Florida Shock Anxiety Scale; mean [SD], 16.5 [6.7]), and device acceptance was good (Florida Patient Acceptance Survey; mean [SD], 74.9 [17.0]). Physical health QOL was low (SF-12; mean [SD], 38.6 [11.3]) and mental health QOL was moderate (SF-12; mean [SD], 50.6 [10.0]). Attitudes toward technology dependency significantly accounted for the variance seen in device acceptance and mental health QOL beyond age, gender, number of shocks, illness perceptions, and shock anxiety by 5.7% (P = .001) and 3.3% (P = .04), respectively. Significant differences were seen in device acceptance between those with negative and neutral attitudes (P = .001) and those with negative and positive attitudes (P < .001) and in shock anxiety and mental health QOL between those with negative and those with positive attitudes (P < .001).

CONCLUSIONS

Attitudes toward technology dependency is significantly associated with psychological outcomes and may explain the psychological distress in some ICD recipients. Degree of positivity toward technology dependency influences these outcomes. Research evaluating attitudes toward technology dependency and testing of interventions focusing on these attitudes is warranted.

Sudden cardiac death: a critical appraisal of the implantable cardioverter defibrillator

IMPORTANCE

Approximately 350,000 Americans still die of sudden cardiac death each year. This exceeds the number of patients who die annually from stroke, lung cancer, breast cancer and AIDS combined.

OBJECTIVE

This review aims to trace the history of implantable cardioverter defibrillators (ICD) with reference to landmark trials and their influence on the formulation of Medicare guidelines for ICD implantation criteria. This paper will also discuss the cost-effectiveness of ICDs and the quality of life after implantation. The reasons for the disparity between guidelines for implantation and actual clinical practice will be elucidated, with suggestions for improving overall clinical performance.

RESULTS AND CONCLUSION

The ICD has been shown to be cost-effective in reducing sudden cardiac death and all-cause mortality. However, the existing recommendations for ICD implantation have yet to translate completely into clinical practice. Barriers to implementation of existing guidelines include knowledge gaps in the referring physician practices, lack of validated screening tools to assess patient candidacy for the device and patient understanding of the need for the device. Future strategies to increase compliance with the existing guidelines and improve clinical performance are areas of potential research focus.

Implantable cardioverter defibrillator therapy in paediatric practice: a single-centre UK experience with focus on subcutaneous defibrillation

AIMS

Sudden cardiac death (SCD) risk can be managed by implantable cardioverter defibrillators (ICD). Defibrillation shocks can be delivered via ICD generator and/or intracardiac or subcutaneous coil configurations. We present our single-centre use of childhood ICDs.

METHODS AND RESULTS

Twenty-three patients had ICD implantation, with median age and weight of 12.96 years and 41.35 kg. Indications included eight long QT; four hypertrophic cardiomyopathy; three Brugada syndrome; two idiopathic ventricular fibrillation; two post-congenital heart repair; two family history of SCD with abnormal repolarization; one catecholaminergic polymorphic ventricular tachycardia; and one left ventricle non-compaction. Twelve had out of hospital cardiac arrests prior to implantation. Techniques included 13 conventional ICD implants (pre-pectoral device with endocardial leads), 7 with subcutaneous defibrillation coils (sensing via epicardial or endocardial leads tunnelled to the ICD), and 3 with exclusive subcutaneous ICD (sensing and defibrillation via the same subcutaneous lead). Satisfactory defibrillation efficacy and ventricular arrhythmia sensing was confirmed at implantation. Follow-up ranged from 0.17 to 11.08 years. One child died with the ICD in situ. Ten children received appropriate shocks; five on more than one occasion. Five received inappropriate shocks (for inappropriate recognition of sinus tachycardia or supraventricular tachycardia). Five children underwent six further interventions; all had intracardiac leads.

CONCLUSION

Innovative shock delivery systems can be used in children requiring an ICD. The insertion technique and device used need to accommodate the age and weight of the child, and concomitant need for pacing therapy. We have demonstrated effective defibrillation with shocks delivered via configurations employing subcutaneous coils in children.

[Changes in depression, anxiety, and vital exhaustion in patients after ICD implantation. Comparison of clinical subgroups]

BACKGROUND

The psychological strain of an implantable cardioverter-defibrillator (ICD) is infrequently explored in prospective studies, which have until now generally focused on the dimensions anxiety and depression. Furthermore, vital exhaustion (VE; ICD10 F 48.0) is known as a very good predictor for negative outcome in patients with coronary heart disease. The influence of VE on patients with an ICD is presented and analyzed in a prospective study.

METHODS

A total of 249 patients with an ICD completed a set of questionnaires (HADS, EQ-5D, VE) at baseline and at the 1-year follow-up.

RESULTS

The patients with high levels of depression, anxiety, and VE after ICD implantation did not show spontaneous remission after 1 year.

DISCUSSION

As expected, the implanatation of an ICD is associated with high acceptance and increased life quality in about 3/4 of patients. However, there is a subgroup of patients (20-30%) who have difficulties and the measured dimensions remain at elevated levels after implantation, thus, indicating that these patients probably need competent psychological help.

Rationale and design of WEBCARE: a randomized, controlled, web-based behavioral intervention trial in cardioverter-defibrillator patients to reduce anxiety and device concerns and enhance quality of life

Background

The implantable cardioverter defibrillator (ICD) is generally well accepted, but 25-33% of patients experience clinical levels of anxiety, depression, and impaired quality of life (QoL) following implantation. Few trials in ICD patients have investigated whether behavioral intervention may mitigate the development of these adjustment problems. We present the rationale and study design of the WEB-based distress management program for implantable CARdioverter dEfibrillator patients (WEBCARE) trial.

Methods

WEBCARE is a multi-center, multi-disciplinary, randomized, controlled behavioral intervention trial designed to examine the effectiveness of a web-based approach in terms of reducing levels of anxiety and device concerns and enhancing QoL. Consecutive patients hospitalized for the implantation of an ICD will be approached for study participation while in hospital and randomized to the intervention arm (n = 175) versus usual care (n = 175) at baseline (5-10 days post implantation). Patients will complete assessments of patient-centered outcomes at baseline, 14, 26, and 52 weeks after implantation. Patients randomized to the intervention arm will receive a 12-week web-based behavioral intervention starting 2 weeks after implantation. Primary endpoints include (i_i) patient-centered outcomes (i.e., anxiety, depression, ICD acceptance, QoL); (i_ii) health care utilization; and (i_iii) cost-effectiveness. All primary endpoints will be assessed with standardized and validated disease-specific or generic questionnaires. Secondary endpoints include (ii_i) cortisol awakening response; and (ii_ii) ventricular arrhythmias.

Discussion

WEBCARE will show whether a behavioral intervention using a web-based approach is feasible and effective in reducing anxiety and ICD concerns and improving QoL in ICD patients.

Trial Registration

http://www.ClinicalTrials.gov. Identifier: NCT00895700.

Gender differences in anxiety and concerns about the cardioverter defibrillator

BACKGROUND

Little is known about gender differences in the response to implantable cardioverter defibrillator (ICD) therapy. We compared female and male ICD patients on anxiety, depression, health-related quality of life (HRQL), ICD concerns, and ICD acceptance.

METHODS

A cohort of consecutive, surviving patients (n = 535; mean age = 61.5 +/- 14.4, 81.9% male) implanted with an ICD between 1989 and 2006 completed the Hospital Anxiety and Depression Scale, the Short-Form Health Survey (SF-36), the ICD concerns questionnaire, and the Florida Patient Acceptance Survey.

RESULTS

High levels of anxiety (52% vs 34%, P < 0.001) and ICD concerns (34% vs 16%, P = 0.001) were more prevalent in women than men, whereas no significant differences were found on depression and device acceptance (Ps > 0.05). Women were more anxious (odds ratio [OR]: 2.60 [95% confidence interval (CI): 1.46-4.64], P < 0.01) and had more ICD concerns (OR: 1.81 [95% CI: 1.09-3.00], P < 0.05) than men, adjusting for demographic and clinical characteristics. Those ICD patients experiencing shocks were also more anxious (OR: 2.02 [95% CI: 1.20-3.42], P < 0.01) and had higher levels of ICD concerns (OR: 2.70 [95% CI: 1.76-4.16], P < 0.01). In multivariable analysis of variance, significant gender differences were found for only three of the eight subscales of the SF-36 (the physical social functioning and the mental health subscale), with women reporting poorer HRQL on all three subscales.

CONCLUSIONS

Women were more prone to experience anxiety and ICD concerns compared to men regardless of whether they had experienced shocks. In clinical practice, female ICD patients should be closely monitored, and if warranted offered psychosocial intervention, as increased anxiety has been shown to precipitate arrhythmic events in defibrillator patients.

Does ICD indication affect quality of life and levels of distress?

The implantable cardioverter defibrillator (ICD) is the treatment of choice for life-threatening arrhythmias, with ICD indications having recently been extended to include primary prophylaxis. Despite the medical benefits of the ICD, there is an ongoing debate as to the impact of the ICD on patients' lives, particularly whether primary prophylaxis implantation may impact adversely on patient-centered outcomes such as quality of life (QoL) and distress. We examined the evidence for a role of ICD indication on these patient-centered outcomes. A literature search was conducted on PubMed and Web of Science from 2002 to present, focusing on indication for ICD therapy and patient-centered outcomes (i.e., anxiety, depression, disease-specific, or general QoL). We identified five studies (seven articles) concerning the impact of indication on patient-centered outcomes. Sample sizes varied from 91-426 patients across studies, five of seven articles used a prospective design, and follow-up ranged from 2-12 months. No study reported an effect for indication on patient-centered outcomes. There is no evidence to suggest that patients receiving an ICD for primary prophylaxis have subsequent poorer QoL and greater distress than patients receiving an ICD for secondary prophylaxis. This knowledge may help cardiologists in the clinical management of patients, in particular when discussing ICD implantation with patients.

Effect of ischemia on implantable defibrillator intracardiac shock electrograms

INTRODUCTION

Few attempts have been made to extract information from the ventricular electrogram (EGM) recorded by implantable cardioverter defibrillators (ICD) aside from the discrimination of supraventricular tachycardia and ventricular tachycardia. The current study aims to examine the effect of ischemia in the major coronary artery distributions on the shock EGM from ICDs.

METHODS

Domestic crossbred pigs (n = 10, 20-40 kg) were implanted with a dual-coil right ventricular defibrillation system. Through the femoral approach, percutaneous balloon occlusion of the major coronary arteries was performed. The left anterior descending (LAD), left circumflex (LCx), and right coronary (RCA) arteries were occluded in random order for 3-5 minutes with 30-minute periods of reperfusion in between and the shock EGMs were recorded and analyzed.

RESULTS

During peak ischemia, R wave amplitude increased by a mean of 204.3% (P = 0.003), increased by a mean of 73.8% (P = 0.0009), and decreased by a mean of 28.0% (P = 0.109) in the LAD, LCx, and RCA territories, respectively. During peak ischemia ST segments elevated by a mean of 105.3% (P = 0.041), elevated by a mean of 114.9% (P = 0.064), and decreased by a mean of 584.5% (P = 0.006) in the LAD, LCx, and RCA territories, respectively.

CONCLUSIONS

Ischemia affects ICD shock EGMs in a manner that appears to vary depending on the culprit vessel. Our data demonstrate the feasibility of ischemia detection from ICD shock EGMs.

Remodeling of Outward K+Currents in Pressure-Overload Heart Failure

OBJECTIVES

Outward K+ currents are critical determinants of action potential repolarization and the site of action of a number of electrophysiologically active drugs. Further, expression and processing of the channels underlying these currents is altered in heart disease. Here, we investigated the native transmural gradient of outward K+ currents in murine left ventricle (LV) and delineated disease-related remodeling of these currents in heart failure (HF).

METHODS

Pressure-overload heart failure was induced in mice by thoracic aortic constriction. Outward K+ currents were recorded using the whole-cell patch clamp technique in acutely dissociated ventricular myocytes.

RESULTS

Unambiguous gradients of outward K+ current density and Kv4.2 protein abundance were observed across the wall of the LV, with significantly larger current density and protein levels in subepicardial (SEP) myocytes, compared with subendocardial (SEN) myocytes. Voltage dependences of current activation and inactivation were similar in SEP and SEN myocytes. In failing LV, however, outward K+ current density was significantly decreased in SEP but not in SEN cells leading to elimination of the native transmural gradient. In failing LV, the voltage dependences of K+ current activation and inactivation were not altered. However, current inactivation (decay) was significantly accelerated and recovery from inactivation was significantly slowed. Consistent with this, Western blot analysis revealed a decrease in KChIP2 protein abundance in failing LV.

CONCLUSIONS

This is the first report of HF-related remodeling of outward K+ currents in murine LV. Similar to humans, disease-related remodeling occurs differentially across the murine ventricular wall, leading to loss of the native gradient of repolarization. Together with slowed recovery from inactivation, these alterations likely promote abnormal impulse conduction, a major proarrhythmic mechanism.

Heart Rate Turbulence After Short Runs of Nonsustained Ventricular Tachycardia in Chronic Heart Failure

BACKGROUND

Heart rate turbulence (HRT) following isolated premature complexes is a baroreceptor-mediated prognostic marker. Short runs of spontaneous, nonsustained ventricular tachycardia (nsVT) exert a greater hemodynamic effect than extrasystoles and may trigger a more potent turbulence-like response (HRT(VT)), possibly related to other risk-related markers, such as heart rate variability (HRV), left ventricular ejection fraction (EF), and original HRT parameters (turbulence slope [TS] and turbulence onset [TO]).

METHODS

We studied 27 patients with heart failure (HF) and nsVT (4-7 beats) on 24-hour Holter electrocardiographic recordings (mean age 58 +/- 3.6 years, EF 36%+/- 5.0%). Following nsVT, TS(VT) and TO(VT) were measured according to the original definitions. HRV, TS, and TO were also assessed.

RESULTS

HRT(VT) parameters were related to HRV. A significant relation existed between TS(VT) and EF (r= 0.66, P < 0.05). HRT(VT) parameters were related to the originally described (TS and TO), whereas TO(VT) was higher than TO (1.63 +/- 1.6 vs -1.7 +/- 0.65, P < 0.05).

CONCLUSIONS

In mild-to-moderate HF, turbulence is observed following short nsVT runs and is related to prognostically important HRV indexes and EF. HRT(VT) is similar to HRT but TO(VT) is shifted toward more positive values than TO. HRT(VT) might be prognostically significant.