Prophylactic Implantable Cardioverter-defibrillator Therapy Research Articles

Do patients at high risk of nonsudden cardiac death benefit from prophylactic ICD therapy?

Randomized controlled trials have established that prophylactic implantable cardioverter defibrillator (ICD) therapy improves survival in patients with reduced left ventricular ejection fraction (LVEF). However, mortality reduction is not uniform across the implanted population and recent data have highlighted the importance of nonsudden cardiac death (non-SCD) risk in predicting benefit from ICD therapy. This review explores the importance of non-SCD risk in patient selection for prophylactic ICD therapy, as well as the proposed approaches to identify potential ICD recipients at high risk of non-SCD. Data from randomized controlled trials have demonstrated that patients at high risk of non-SCD do not gain significant survival benefit from prophylactic ICD therapy irrespective of their risk of SCD. A variety of strategies to identify low LVEF patients at high risk of non-SCD have been proposed. These include the use of individual risk markers, such as advanced age and renal dysfunction, the presence of cardiac and noncardiac comorbidities, and the use of more complex risk scores. Non-SCD risk is an important issue in patient selection for prophylactic ICD therapy. However, the optimal strategy to identify patients at high non-SCD risk is unclear and further research is needed.

Comparison of Ventricular Tachyarrhythmia Characteristics in Patients With Idiopathic Dilated or Ischemic Cardiomyopathy and Defibrillators Implanted for Primary Prevention

Implantable cardioverter-defibrillator (ICD) therapy for primary prevention is well established in ischemic cardiomyopathy (ICM). Data on the role of ICDs in patients with dilated cardiomyopathy (DCM) and no history of ventricular tachyarrhythmia (VT/VF) are more limited. DCM patients with an impaired left ventricular ejection fraction (LVEF) still represent a low arrhythmic risk subgroup in clinical practice. ICD stored data of DCM patients with an LVEF ≤35% was compared to data of ICM patients meeting Multicenter Automatic Defibrillator Implantation Trial (MADIT) eligibility criteria. VT/VF occurrences and electrical storm (ES) events were analyzed. There were 652 patients followed for 50.9 ± 33.9 months. There were 1978 VT and 241 VF episodes analyzed in 66 out of 203 patients (32.5%) with DCM and in 118 out of 449 patients (26.3%, P = 0.209) with ICM. Freedom of appropriate ICD treatment due to VT/VF or ES events did not differ in both patient populations (log-rank, P>0.05). In patients presenting with VT/VF episodes, mean event rates were comparable in both patient populations (3.2 ± 14.1 for DCM and VT vs 3 ± 13.9 for ICM and VT [P = 0.855], 0.4 ± 1.3 for DCM and VF vs 0.4 ± 1.8 for ICM and VF [P = 0.763], and 0.2 ± 0.7 for DCM and ES vs 0.2 ± 1 for ICM and ES [P = 0.666]). DCM patients with prophylactic ICDs implanted due to heart failure and patients fulfilling MADIT criteria reveal comparable patterns of VT/VF/ES events during long-term follow-up. Incidence, mean number of events, and time to first event did not differ significantly. Findings support the current guidelines for prophylactic ICD therapy in DCM patients with heart failure.

Age and Effectiveness of Implantable Cardioverter-Defibrillators

Letters2 August 2011Age and Effectiveness of Implantable Cardioverter-DefibrillatorsFrieder Braunschweig, MD, PhD and Hans Wedel, PhDFrieder Braunschweig, MD, PhDFrom Karolinska University Hospital, SE-17 176 Stockholm, Sweden, and Nordic School of Public Health, SE-402 02 Göteborg, Sweden.Search for more papers by this author and Hans Wedel, PhDFrom Karolinska University Hospital, SE-17 176 Stockholm, Sweden, and Nordic School of Public Health, SE-402 02 Göteborg, Sweden.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-155-3-201108020-00013 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail TO THE EDITOR:Although some studies suggest that patients aged 75 years or older derive benefit from primary prophylactic implantable cardioverter-defibrillator (ICD) therapy similar to that of their younger counterparts (1), consideration of age and noncardiac comorbid conditions is critical in the decision to implant a device. Santangeli and colleagues' meta-analysis (2) adds an intriguing observation to the ongoing debate on ICD therapy in elderly persons.On the basis of their primary analysis of 3 major randomized trials of prophylactic ICD therapy in patients with severe left ventricular dysfunction (DEFINITE [Defibrillators in Non-Ischemic Cardiomyopathy Treatment Evaluation], MADIT-II [Multicenter Automatic Defibrillator ...

Meta-analysis: Age and Effectiveness of Prophylactic Implantable Cardioverter-Defibrillators

Implantable cardioverter-defibrillators (ICDs) for the primary prevention of sudden cardiac death have been proven effective in several clinical trials. To summarize evidence about the effectiveness of ICDs versus standard medical therapy for the primary prevention of sudden cardiac death in different age groups of patients with severe left ventricular dysfunction. MEDLINE, Embase, CENTRAL, BioMed Central, Cardiosource, ClinicalTrials.gov, and ISI Web of Science (January 1970 to April 2010) were searched with no language restrictions. Two independent reviewers screened titles and abstracts to identify randomized, controlled trials of prophylactic ICD versus medical therapy in patients with severe left ventricular dysfunction that provided data about mortality outcomes for different age groups. Two independent reviewers assessed risk for bias of trials and extracted patient and study characteristics and hazard ratios (HRs) relevant to all-cause mortality. Five trials (MADIT-II, DEFINITE, DINAMIT, SCD-HeFT, and IRIS) that enrolled 5783 patients (44% were elderly) were included. The primary analysis, which excluded the 2 trials enrolling patients early after acute myocardial infarction (DINAMIT and IRIS), found that prophylactic ICD therapy reduced mortality in younger patients (HR, 0.65 [95% CI, 0.50 to 0.83]; P < 0.001). A smaller survival benefit was found in elderly patients (HR, 0.75 [95% CI, 0.61 to 0.91]) that was not confirmed when MADIT-II patients older than 70 years were excluded or when data from DINAMIT and IRIS were included [corrected]. Four potentially eligible trials were not included in the meta-analysis because mortality data by age group were not available. Adjustment for differences in comorbid conditions and medical therapies among patients enrolled in the trials was not possible. Available data suggest that prophylactic ICD therapy may be less beneficial for elderly patients with severe left ventricular dysfunction than for younger patients [corrected]. None.

Prophylactic Implantation of Cardioverter Defibrillators in Idiopathic Nonischemic Cardiomyopathy for the Primary Prevention of Death: A Narrative Review

Implantable cardioverter defibrillator (ICD) therapy reduces sudden cardiac death rates and reduces mortality in patients with ischemic heart disease and low ejection fractions. One-third of the deaths in patients with nonischemic cardiomyopathy are sudden. However, the efficacy of ICDs in the primary prevention of death in these patients is less clear. The most common cause of mortality in patients treated with ICDs is heart failure progression. ICD shocks can cause direct myocardial injury, fibrosis, inflammation, and adverse psychological outcomes, and these changes may contribute to the ventricular dysfunction in patients who already have a significantly depressed ejection fraction. We have reviewed the published randomized controlled trials and meta-analysis of prophylactic ICD therapy in the primary prevention of death in patients with nonischemic cardiomyopathy. The individual randomized controlled trials do not report a statistically significant reduction of mortality unless the ICD treatment is added to cardiac resynchronization therapy, but the meta-analysis did show a significant mortality reduction and favored ICD therapy in these patients. Medical management of many study participants was suboptimal, at least based on current guidelines. The patients with non-ischemic cardiomyopathy have good outcomes with medical therapy, and ICD therapy in this relatively low-risk population needs better selection criteria.

Risk Stratification and Role of Implantable Defibrillators for Prevention of Sudden Death in Patients With Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death (SCD) in young people, including trained athletes. It is now 30 years since the introduction of implantable cardioverter-defibrillators (ICDs) to clinical cardiovascular practice and coronary artery disease, and now device therapy represents the most significant therapeutic innovation and the only definitive strategy for prolonging the life of HCM patients. ICDs have proved effective in preventing SCD in young HCM patients with appropriate intervention rates of 11% for secondary and 4% for primary prevention, despite massive left ventricular (LV) hypertrophy, LV outflow obstruction, diastolic dysfunction or microvascular ischemia. Targeting candidates for prophylactic ICD therapy can be complex, compounded by the unpredictability of the arrhythmogenic substrate, the absence of a dominant risk factor, and difficulty in assembling randomized trials. However, a single major risk factor is often sufficient to justify an ICD, although additional markers and other disease features can resolve ambiguous decision-making. Nevertheless, the absence of all risk factors does not convey absolute immunity to SCD. The current risk factor algorithm, when combined with a measure of individual physician judgment (and patient autonomy considerations), is an effective guide to identifying high-risk HCM patients. ICDs have altered the natural history of HCM for many patients and provided an opportunity to achieve many decades of productive life, and the potential for normal or near-normal longevity. Indeed, prevention of SCD has now become a new paradigm in the management of HCM.

Defibrillator Implantation Early after Myocardial Infarction

The rate of death, including sudden cardiac death, is highest early after a myocardial infarction. Yet current guidelines do not recommend the use of an implantable cardioverter-defibrillator (ICD) within 40 days after a myocardial infarction for the prevention of sudden cardiac death. We tested the hypothesis that patients at increased risk who are treated early with an ICD will live longer than those who receive optimal medical therapy alone. This randomized, prospective, open-label, investigator-initiated, multicenter trial registered 62,944 unselected patients with myocardial infarction. Of this total, 898 patients were enrolled 5 to 31 days after the event if they met certain clinical criteria: a reduced left ventricular ejection fraction (< or = 40%) and a heart rate of 90 or more beats per minute on the first available electrocardiogram (ECG) (criterion 1: 602 patients), nonsustained ventricular tachycardia (> or = 150 beats per minute) during Holter monitoring (criterion 2: 208 patients), or both criteria (88 patients). Of the 898 patients, 445 were randomly assigned to treatment with an ICD and 453 to medical therapy alone. During a mean follow-up of 37 months, 233 patients died: 116 patients in the ICD group and 117 patients in the control group. Overall mortality was not reduced in the ICD group (hazard ratio, 1.04; 95% confidence interval [CI], 0.81 to 1.35; P=0.78). There were fewer sudden cardiac deaths in the ICD group than in the control group (27 vs. 60; hazard ratio, 0.55; 95% CI, 0.31 to 1.00; P=0.049), but the number of nonsudden cardiac deaths was higher (68 vs. 39; hazard ratio, 1.92; 95% CI, 1.29 to 2.84; P=0.001). Hazard ratios were similar among the three groups of patients categorized according to the enrollment criteria they met (criterion 1, criterion 2, or both). Prophylactic ICD therapy did not reduce overall mortality among patients with acute myocardial infarction and clinical features that placed them at increased risk. (ClinicalTrials.gov number, NCT00157768.)

Pitfalls in health-economic evaluations: the case of cost-effectiveness of prophylactic implantable cardioverter-defibrillator therapy in Belgium

Variations in the medical therapy directed at the underlying disease among the trials also play a role. In the MADIT I trial, 65% of patients took an ACE-inhibitor, and only 14% of patients were on b-blocking therapy by the end of the study. In MADIT II, 70% of patients took an ACE-inhibitor, and 70% took a b-blocker, whereas in SCD-HeFT, 94% took an ACE-inhibitor or an angiotensin-II-receptor blocker, and 69% took a b-blocker. Apart from medical treatment of acute myocardial infarction (AMI), there is evidence from clinical trials that early reperfusion reduces the risk of sudden cardiac death (SCD) in selected AMI patients. This may have influenced the occurrence of sudden cardiac arrest in the trials and could have inflated the perceived efficacy of the ICD in the older studies. Pooling the results from trials that also considered asymptomatic patients with nonischaemic disease is inconsistent. The clinical effectiveness of ICD therapy in primary prevention of death seems best reflected by the results of the SCD-HeFT trial. In a German series of 3000 ambulatory patients with heart failure and a low ejection fraction, 17.0 and 71.1% of patients fulfilled MADIT II and SCD-HeFT criteria, respectively. 4 SCD-HeFT is the most recent and the largest randomized trial that has been published, with the longest follow-up duration, and enrolling heart failure patients with ischaemic or non-ischaemic cardiomyopathy who were receiving up-to-date medical treatment for the underlying disease.

Editorial: The economical challenge in the treatment of chronic heart failure: is primary prophylactic implantable cardioverter defibrillator therapy cost-effective in Europe?

We read with interest the editorial commenting on our modelling of the cost-effectiveness of primary prophylactic implantable cardioverter defibrillator (ICD) implantation according to the current European guidelines in a European population,1 claiming that our analysis overstated the likely cost-effectiveness of such therapy due to inappropriate assumptions around key determinants of cost and efficacy. Meine et al. mistakenly suggest that the results of our analysis2 were materially different from those from the MADIT II3 and SCD-HeFT4 trials. Our analysis had a life-time model time horizon (as recommended in most recent national and international guidelines for health economic analyses5–7), whereas the two US cost-effectiveness analyses took a (rather arbitrary) 12-year time horizon. If we had taken this time horizon, the incremental cost-effectiveness ratio (ICER) at that point in our analysis would have been €43 752 ($61 253 per QALY at exchange rate of €1: $1.40), similar to the MADIT II ($78 600–$114 000 per life year) and SCD-HeFT analyses ($58 510 per QALY). The more appropriate life-time horizon in our analysis gave an ICER of €31 717 per QALY gained ($44 404). The editorial also suggests that there is a lack of a treatment effect for ICDs in …

Risk stratification for sudden cardiac death: Is there a clinical role for T wave alternans?

The proportion of cardiovascular deaths attributable to sudden cardiac death (SCD) is on the rise. Herein lies the rationale for developing risk stratification strategies to predict who will benefit from prophylactic implantable cardioverter-defibrillator (ICD) implantation. Current guidelines recommend prophylactic ICD therapy in patients with reduced left ventricular ejection fraction (LVEF). However, there are clear limitations in using LVEF alone to decide who should receive an ICD. There is mounting evidence that microvolt-level T-wave alternans (TWA) is an important marker of arrhythmic risk. TWA is appealing because it noninvasively probes the underlying electrophysiological substrate and has been linked to cellular mechanisms for arrhythmias. This review considers the clinical role of TWA for risk stratification of SCD.

Noninvasive risk stratification after myocardial infarction: Rationale, current evidence and the need for definitive trials

Despite advances in therapies for myocardial infarction (MI), death attributed to a cardiac arrest from ventricular tachycardia (VT) or ventricular fibrillation (VF) remains an important problem. The implantable cardioverter defibrillator (ICD) is effective in preventing death from VT/VF, but reliably identifying which post-MI patients would benefit from an ICD remains a major challenge. Beyond the initial post-MI period, the presence of significant left ventricular (LV) dysfunction, alone or in combination with the induction of sustained VT/VF during invasive testing, is the only proven means of selecting patients for a prophylactic ICD. However, these approaches identify only a fraction of those at risk. Furthermore, most patients with significant LV dysfunction after MI have a low, near-term risk of VT/VF. Noninvasive risk stratification tools have been developed to better identify patients likely to benefit from an ICD. To date, none of these tools has been proven useful in this regard. The factors leading to a cardiac arrest are complex, and a single test is unlikely to reliably predict risk. Noninvasive assessment of cardiac structure, conduction and repolarization along with autonomic modulation appear to be useful in predicting the risk of a cardiac arrest after MI, particularly when assessed in combination. However, randomized trials assessing the efficacy of ICD therapy in patients identified as being at risk are required. Until such data are available, significant LV dysfunction alone and in combination with the induction of VT/VF during invasive testing in the nonacute post-MI period remain the only proven methods to guide prophylactic ICD therapy.

Electrocardiographic Evaluation of Cardiovascular Status

The electrocardiogram (ECG) is indispensable for the diagnosis and management of patients with a wide variety of cardiac and noncardiac diseases. The purpose of this paper is focused on recent research that used ECG, specifically the long-QT interval and microvolt T wave alternans, for the evaluation of life-threatening ventricular arrhythmias. Although remaining to be validated, QT prolongation along with other emerging electrocardiographic indices such as T wave morphology, T peak-to-T end time, or beat-to-beat QT variability may be sensitive indicators of malignant polymorphic ventricular tachyarrhythmia, torsade de pointes. Microvolt T wave alternans may provide important information in identifying a low-risk group with left ventricular dysfunction who is unlikely to benefit from unnecessary prophylactic implantable cardioverter defibrillator therapy. These ECG markers have the potential to aid in the safe administration of individualized medications, avoidance of sudden cardiac death, and provision of a noninvasive strategy to identify patients who are most and least likely to benefit from expensive prophylactic implantable cardioverter defibrillator placement.

Long-term follow-up of primary prophylactic implantable cardioverter-defibrillator therapy in Brugada syndrome

Aims To analyse the follow-up data of implantable cardioverter-defibrillator (ICD) therapy in Brugada syndrome (BS). Methods and results We conducted a retrospective, single centre study of 47 patients (mean age: 44.5 ± 15 years) with BS, who underwent primary prophylactic ICD implantation. All patients had baseline spontaneous (23 patients) or drug-induced (24 patients) coved type I ECG pattern. All patients were judged to be at high risk because of syncope (26 patients) and/or a positive family history of sudden death (26 patients). During a median follow-up of 47.5 months, seven patients had appropriate shocks. The presence of spontaneous type I ECG and non-sustained ventricular tachyarrhythmia in the ICD datalog suggested a trend towards shorter appropriate shock-free survival by Kaplan–Meier analysis ( P = 0.037 and P = 0.012, respectively). Seventeen patients received inappropriate shocks (IS); eight patients for sinus tachycardia; six patients for new onset atrial arrhythmias; and five patients for noise oversensing. In multivariable Cox-regression analysis, new onset atrial fibrillation (AF) and less than 50 years of age were independent predictors of significantly shorter IS-free survival ( P = 0.04 and P = 0.036, respectively). Conclusion In high-risk patients with BS, primary prophylactic ICD therapy is an effective treatment. In this, young and otherwise healthy patient population, the IS rate is high.

Long-term follow-up of primary prophylactic implantable cardioverter-defibrillator therapy in Brugada syndrome: reply

Long-term follow-up of primary prophylactic implantable cardioverter-defibrillator therapy in Brugada syndrome: reply

Potential demographic and baselines variables for risk stratification of high-risk post-myocardial infarction patients in the era of implantable cardioverter-defibrillator — A prognostic indicator

Background Risk stratification after myocardial infarction (MI) remains expensive and disappointing. We designed a prognostic indicator using demographic information to select patients at risk of dying after MI. Method and results We combined individual patient data from the placebo arms of EMIAT, CAMIAT, TRACE and DIAMOND-MI with LVEF ≤ 40% or ventricular arrhythmias (i.e. > 10 ventricular premature beats/hour or a run of ventricular tachycardia). Risk factors for mortality beginning at day 45 post-MI up to 2 years were examined using Cox regression analysis. Risk scores were derived from the equation of a Cox regression model containing only significant variables. The prognostic index was the sum of the individual contribution from the risk factors. 2707 patients were pooled (age: 66 (23–92) years, 78.8% M) with 480 deaths at 2-years (44% arrhythmic and 35.6% non-arrhythmic cardiac deaths). Variables predicting mortality were age, sex, previous MI or angina, hypertension, diabetes, systolic blood pressure, heart rate, NYHA functional class and non-Q wave infarct on electrocardiogram. Distinct survival curves were obtained for 3 risk groups based on the median and inter-quartile range for the prognostic index. In the high-risk group, up to 40% of patients died (all-cause mortality), 19.1% died of arrhythmic and 18.2% died of non-arrhythmic cardiac causes at 2-years. Conclusion In post-MI patients with LVEF ≤ 40% or frequent ventricular premature beats, the additional use of a simple prognostic indicator based on demographic information was able to provide clinically meaningful risk stratification on patients that were at high risk of dying and may be used to identify patients for prophylactic implantable cardioverter-defibrillator therapy.

Long-term follow-up of primary prophylactic implantable cardioverter-defibrillator therapy in Brugada syndrome

To analyse the follow-up data of implantable cardioverter-defibrillator (ICD) therapy in Brugada syndrome (BS). We conducted a retrospective, single centre study of 47 patients (mean age: 44.5 +/- 15 years) with BS, who underwent primary prophylactic ICD implantation. All patients had baseline spontaneous (23 patients) or drug-induced (24 patients) coved type I ECG pattern. All patients were judged to be at high risk because of syncope (26 patients) and/or a positive family history of sudden death (26 patients). During a median follow-up of 47.5 months, seven patients had appropriate shocks. The presence of spontaneous type I ECG and non-sustained ventricular tachyarrhythmia in the ICD datalog suggested a trend towards shorter appropriate shock-free survival by Kaplan-Meier analysis (P = 0.037 and P = 0.012, respectively). Seventeen patients received inappropriate shocks (IS); eight patients for sinus tachycardia; six patients for new onset atrial arrhythmias; and five patients for noise oversensing. In multivariable Cox-regression analysis, new onset atrial fibrillation (AF) and less than 50 years of age were independent predictors of significantly shorter IS-free survival (P = 0.04 and P = 0.036, respectively). In high-risk patients with BS, primary prophylactic ICD therapy is an effective treatment. In this, young and otherwise healthy patient population, the IS rate is high.

Utility of microvolt T-wave alternans to predict sudden cardiac death in patients with cardiomyopathy

Sudden cardiac death remains a major cause of mortality among patients with cardiomyopathy and implantable cardioverter-defibrillator therapy has been shown to improve survival in these patients. Effective use of prophylactic implantable cardioverter-defibrillator therapy requires accurate risk stratification beyond assessment of ejection fraction, however. Repolarization alternans is a harbinger of ventricular arrhythmias and its measurement from body-surface recordings, also known as microvolt T-wave alternans, is emerging as an effective prognostic tool in these patients based on recent clinical trials. We review the pathogenesis and determinants of repolarization alternans. The current techniques for measuring T-wave alternans from the body surface are compared, including the spectral and modified moving average methods. Recent clinical trials evaluating the prognostic utility of T-wave alternans in patients with ischemic and nonischemic cardiomyopathy and no prior arrhythmic events are summarized. The findings of these studies are discussed in the context of implantable cardioverter-defibrillator prophylaxis. Body-surface T-wave alternans is an evolving technique and its limitations are presented along with approaches to improve its predictive accuracy. Risk stratification with T-wave alternans has the potential to guide prophylactic implantable cardioverter-defibrillator therapy in a growing population of patients with cardiomyopathy.

The Microvolt T-Wave Alternans Test

Sudden cardiac death (SCD) still remains a major cause of mortality among patients with ischaemic and nonischaemic cardiomyopathy, and implantable cardioverter-defibrillator (ICD) therapy has been shown to improve survival in these patients. However, the use of a prophylactic ICD therapy in clinical practice needs accurate identification of patients likely to benefit from it, considering the high incidence of device-related complications, the psychological consequences of ICD implantation and social costs. Current risk stratification for SCD is mainly based on assessment of ejection fraction and it is strongly influenced by the largest clinical trials on primary prevention: the MADIT II and SCD-HeFT studies. In recent years, the microvolt T-wave alternans test (MTWA) is emerging as a powerful non-invasive tool for risk stratification of SCD. MWTA is a beat-to-beat alternation in the amplitude of the T wave on the order of microvolts, which can be assessed during an exercise test, pharmacological stress or atrial pacing. MTWA has been associated with unidirectional block, re-entry and initiation of ventricular fibrillation in animal studies. There is strong evidence that intracellular calcium cycling plays a key role in the mechanism of MTWA. Several large clinical trials have shown that MTWA is comparable or superior to other noninvasive markers and to electrophysiological study in risk stratification of SCD. The very high negative predictive value of MTWA may provide a better selection of patients who would be likely or not likely to benefit from ICD implantation. Broad evidence-based data suggest that non-invasive MTWA may improve the accuracy of primary prevention of SCD in patients with ischaemic and non-ischaemic cardiomyopathy. Further studies are needed to evaluate the role of MTWA testing as an integral part of risk stratification, in combination with additional risk markers.

Are women worldwide under-treated with regard to cardiac resynchronization and sudden death prevention?

Implantable cardioverter defibrillators (ICDs) have been demonstrated to improve survival in patients with serious structural heart disease. Likewise, cardiac resynchronization therapy (CRT) has assumed an important role in the treatment of patients with symptomatic heart failure because of its demonstrated value in improving functional class, quality of life, exercise capacity, and survival. However, these clinical trials have all primarily enrolled Caucasian males, raising the question as to whether other important subgroups benefit in a comparable way. Women have lower rates of sudden cardiac death (SCD) compared to men, and event rates lag 10-20 years behind those in men. Among patients with known coronary artery disease, women have one-fourth the risk of SCD found in men. Women with heart failure tend to present at an older age than men, and women more often have heart failure with preserved systolic function, a group in whom prophylactic ICD therapy for the prevention of SCD has not been studied. Despite these differences, analysis of clinical trial results shows that women have similar outcomes with ICD and CRT therapy compared to men. There is a lower percentage of women among device therapy patients both in clinical trials and in practice for reasons that are not clear, but at least some of the difference is likely due to differences in age at presentation and co-morbidities. In fact, device therapy overall appears to be under-utilized in both men and women, when implantation rates are compared to the prevalence of heart failure in the population as a whole.

Impact of Implantable Defibrillators and Resynchronization Therapy on Outcome in Patients with Left Ventricular Dysfunction – A Meta-Analysis

Background: The clinical benefits of cardiac resynchronization therapy (CRT) and primary prophylactic implantable cardioverter defibrillator (ICD) in patients with left ventricular systolic dysfunction (LVSD) are debated. Objective: To evaluate by a meta-analysis the effect of CRT and prophylactic ICD therapy in patients with LVSD. Methods: Eligible trials evaluating the effect of CRT vs. no-CRT, ICD vs. no-ICD and adding ICD to CRT vs. no-ICD were selected and meta-analyzed. The outcomes were: all cause mortality, cardiac mortality, hospitalization for heart failure and change in exercise tolerance and New York Heart Association class. Results: Implantation of CRT reduced all cause mortality odds ratio (OR) = 0.73 (0.60–0.89) p = 0.002 and hospitalization for heart failure OR = 0.60 (0.45, 0.80) p = 0.001, increased peak oxygen consumption by 1.77 (0.32–3.22) ml/kg/min p = 0.017 and improved New York Heart Association class by at least one class with OR = 1.52 (1.30, 1.77) p < 0.0001. Implantation of ICD reduced all-cause mortality OR = 0.75 (0.59–0.96) p = 0.025 and cardiac mortality OR = 0.63 (0.48, 0.82) p = 0.001. Adding ICD to CRT reduced all cause mortality OR = 0.69 (0.53–0.91) p = 0.008. Conclusion: Selective patients with LVSD benefit from CRT, ICD or both. Further investigations are necessary to clarify which patients benefit most from a single or combined device implantation.