Heart Failure and the Risk of Shocks in Patients With Implantable Cardioverter Defibrillators

Hospitalization for Heart Failure and Subsequent Ventricular Tachyarrhythmias in Patients With Left Ventricular Dysfunction

OBJECTIVES

This study aimed to evaluate the risk of sustained life-threatening ventricular tachyarrhythmias (VTAs) after hospitalization for heart failure (HHF).

BACKGROUND

HHF is common among patients with an implantable cardioverter-defibrillator (ICD).

METHODS

We analyzed all 5,511 ICD patients enrolled in the landmark MADIT and RAID trials. Multivariate Cox regression was used to evaluate the association of in-trial HHF occurrence with the risk of subsequent VTA and the composite end point of VTA or cardiac death.

RESULTS

Mean age was 64 ± 11 years, 23% were women, 62% were ischemic, and 40% had cardiac resynchronization therapy with defibrillators. The 3-year cumulative rate of VTA subsequent to HHF was significantly higher than the corresponding rate without HHF (44% vs. 24%, respectively; p < 0.001). After multivariable adjustment, time-dependent HHF was shown to be associated with a 79% increased risk for VTA and a 2.9-fold increased risk for VTA/cardiac death (p < 0.001 for both). In-trial development of atrial tachyarrhythmia (ATA) was also identified as an independent risk factor for the VTA and VTA/cardiac death end points (hazard ratios [HRs]: 1.59 and 1.43, respectively; p ≤ 0.001 for both) but did not affect the association of HHF with VTA. Subgroup analysis demonstrated that the association of HHF with the risk of subsequent VTA was maintained among risk subsets categorized by age, sex, history of ATA, and implantation indication, but was significantly more pronounced among patients with nonischemic versus ischemic cardiomyopathy (HRs: 2.54 and 1.43, respectively; p value for interaction: 0.017).

CONCLUSIONS

HHF is a powerful risk factor for subsequent VTA in patients implanted with an ICD. These data may be used for improved risk stratification in this population.

The impact of implantable cardioverter-defibrillator implantation on health-related quality of life in the DANISH trial

AIM

The Danish Study to Assess the Efficacy of Implantable Cardioverter-Defibrillators (ICD) in Patients with Non-ischaemic Systolic Heart Failure (HF) on Mortality (DANISH) found no overall effect on all-cause mortality. The effect of ICD implantation on health-related quality of life (HRQoL) remains to be established as previous trials have demonstrated conflicting results. We investigated the impact of ICD implantation on HRQoL in patients with non-ischaemic systolic HF, a prespecified secondary endpoint in DANISH.

METHODS AND RESULTS

In DANISH, a total of 1116 patients with non-ischaemic systolic HF were randomly assigned (1:1) to ICD implantation or usual clinical care (control). Patients completed disease-specific HRQoL as assessed by Minnesota Living with Heart Failure Questionnaire (MLHFQ; 0-105, high indicating worse). Changes in HRQoL 8 months after randomization were assessed with a mixed-effects model. At randomization, MLHFQ was completed by 935 (84%) patients (n = 472 in the ICD group and n = 463 in the control group) and was reassessed in 274 (58%) and 292 (63%) patients, respectively after 8 months for the primary analysis. Patients in the ICD group vs. the control group had similar improvements in MLHFQ after 8 months [least square mean -7.0 vs. -4.2 (P = 0.13)]. A clinically relevant improvement (decrease ≥5) in the MLHFQ overall score at 8 months was observed in 151 patients in the ICD group and 148 patients in the control group [55% vs. 51%, respectively (P = 0.25)].

CONCLUSION

Implantable cardioverter-defibrillator implantation in patients with non-ischaemic systolic HF did not significantly alter HRQoL compared with patients randomized to usual clinical care.

Fitness to Drive After Syncope and/or in Cardiovascular Disease - An Overview and Practical Advice

The risk of syncope occurring while driving has implications for personal and public safety. Little is thought about the medical considerations related to the driving of motor vehicles. Physicians treating patients with cardiovascular disease need to acquire basic competences to be able to advise them about their fitness to drive. Current knowledge, governmental regulations, and recommendations concerning fitness to drive in patients with syncope and/or cardiovascular disease are presented. Narrative review with educational and clinical advice. Cardiovascular disease can make a driver lose control of a vehicle without warning and thereby lead to an accident. The main pathophysiological mechanisms of sudden loss of control are disturbances of brain perfusion (eg, syncope with or without cardiac arrhythmia, sudden cardiac death due to ventricular fibrillation or asystole, stroke, etc.) and marked general weakness (eg, after major surgery or in heart failure). Patients with syncope and/or cardiovascular disease should be properly advised by their physicians about their fitness to drive, and restrictions should be documented.

[Electrical storm : Recognition and management]

The electrical storm (ES) defined as ≥3 sustained episodes of ventricular tachycardia within a 24 h period comprises a wide spectrum of clinical entities. Mostly patients suffer from severe heart insufficiency and comorbidities making an immediate transfer into a heart center with multidisciplinary expertise in the treatment of ES mandatory. As these patients are often traumatized by ongoing tachycardia despite multiple cardioversions, early deep sedation and β‑blockade to break the vicious circle of sympathico-adrenergic hyperactivation is very effective. Multiple ICD discharges suggesting the diagnosis of ES are inadequate in one third of cases. Pharmacological suppression, frequency control or ablation of supraventricular tachycardias (SVT) help in most cases. In some cases "oversensing" demands optimization of ICD programming. Even so not all adequate ICD discharges, however, are necessary. Since every ICD discharge worsens the patient's prognosis, any kind of ICD discharge should be prevented as far as hemodynamically feasible. After clinical stabilization of the patient with simultaneous acquisition of ECG and testing for reversible causes of ES, ES should be terminated by external or internal cardioversion followed by urgent but elective therapy. Some cases of ES, however, may require immediate escalation of therapy with emergency ablation or revascularization sometimes with circulatory support systems. If ES still persists, a further step in escalation may be taken by cardiac sympathetic denervation. Due to the poor prognosis of patients after ES, close monitoring of the patient, preferably with telemedicine, is indicated.

Incidence, Predictors, and Outcomes of Implantable Cardioverter-Defibrillator Discharge Among People Living With HIV

Background

People living with HIV (PHIV) are at an increased risk for sudden cardiac death, and implantable cardioverter‐defibrillators (ICDs) prevent SCD. There are no data on the incidence, predictors, and effects of ICD therapies among PHIV.

Methods and Results

We compared ICD discharge rates between 59 PHIV and 267 uninfected controls. For PHIV, we tested the association of traditional cardiovascular risk factors and HIV‐specific parameters with an ICD discharge and then tested whether an ICD discharge among PHIV was associated with cardiovascular mortality or an admission for heart failure. The indication for ICD insertion was similar among groups. Compared with controls, PHIV with an ICD were more likely to have coronary artery disease and to use cocaine. In follow‐up, PHIV had a higher ICD discharge rate (39% versus 20%; P=0.001; median follow‐up period, 19 months). Among PHIV, cocaine use, coronary artery disease, QRS duration, and higher New York Heart Association class were associated with an ICD discharge. An ICD discharge had a prognostic effect, with a subsequent 1.7‐fold increase in heart failure admission and a 2‐fold increase in cardiovascular mortality, an effect consistent across racial/ethnic and sex categories.

Conclusions

ICD discharge rates are higher among PHIV compared with uninfected controls. Among PHIV, cocaine use and New York Heart Association class are associated with increased ICD discharge, and an ICD discharge is associated with a subsequent increase in admission for heart failure and cardiovascular mortality.

Heart failure as a substrate and trigger for ventricular tachycardia

Heart failure (HF) is a major cause of morbidity and mortality with more than 5.1 million individuals affected in the USA. Ventricular tachyarrhythmias (VAs) including ventricular tachycardia and ventricular fibrillation are common in patients with heart failure. The pathophysiology of these mechanisms as well as the contribution of heart failure to the genesis of these arrhythmias is complex and multifaceted. Myocardial hypertrophy and stretch with increased preload and afterload lead to shortening of the action potential at early repolarization and lengthening of the action potential at final repolarization which can result in re-entrant ventricular tachycardia. Myocardial fibrosis and scar can create the substrate for re-entrant ventricular tachycardia. Altered calcium handling in the failing heart can lead to the development of proarrhythmic early and delayed after depolarizations. Various medications used in the treatment of HF such as loop diuretics and angiotensin converting enzyme inhibitors have not demonstrated a reduction in sudden cardiac death (SCD); however, beta-blockers (BB) are effective in reducing mortality and SCD. Amongst patients who have HF with reduced ejection fraction, the angiotensin receptor-neprilysin inhibitor (sacubitril/valsartan) has been shown to reduce cardiovascular mortality, specifically by reducing SCD, as well as death due to worsening HF. Implantable cardioverter-defibrillator (ICD) implantation in HF patients reduces the risk of SCD; however, subsequent mortality is increased in those who receive ICD shocks. Prophylactic ICD implantation reduces death from arrhythmia but does not reduce overall mortality during the acute post-myocardial infarction (MI) period (less than 40 days), for those with reduced ejection fraction and impaired autonomic dysfunction. Furthermore, although death from arrhythmias is reduced, this is offset by an increase in the mortality from non-arrhythmic causes. This article provides a review of the aforementioned mechanisms of arrhythmogenesis in heart failure; the role and impact of HF therapy such as cardiac resynchronization therapy (CRT), including the role, if any, of CRT-P and CRT-D in preventing VAs; the utility of both non-invasive parameters as well as multiple implant-based parameters for telemonitoring in HF; and the effect of left ventricular assist device implantation on VAs.

Prognostic Impact of Atrial Fibrillation in Electrical Storm

BACKGROUND

Data regarding the prognostic impact of atrial fibrillation (AF) in patients with electrical storm (ES) is rare.

OBJECTIVES

This study sought to assess the prognostic impact of AF in patients with ES on mortality, rehospitalization, major adverse cardiovascular events (MACE) and recurrence of ES (ES-R).

METHODS

All consecutive implantable cardioverter defibrillator (ICD) patients presenting with ES were included retrospectively from 2002 to 2016. Patients with AF were compared to non-AF patients. The primary prognostic endpoint was all-cause mortality. Secondary endpoints were in-hospital mortality, rehospitalization rates, MACE and ES-R.

RESULTS

A total of 87 ES patients with ICD were included and followed up to 2.5 years; 43% suffered from AF. The presence of AF was associated with increased all-cause mortality (47 vs. 29%, log-rank p = 0.052; hazard ratio [HR] 1.969, 95% confidence interval [CI] 0.981-3.952, p = 0.057), which was no longer present after multivariable adjustment for age, diabetes and dilated cardiomyopathy. Furthermore, AF was associated with increased rates of overall rehospitalization (61 vs. 31%, log-rank p = 0.013; HR 2.381, 95% CI 1.247-4.547, p = 0.009), especially due to AF (14 vs. 0%, p = 0.001) and acute heart failure (AHF) (28 vs. 10%, p = 0.018; HR 3.754, 95% CI 1.277-11.038, p = 0.016). Notably, AF was not associated with differences in MACE (55 vs. 37%, log rank p = 0.339) and ES-R (28 vs. 25%, log rank p = 0.704).

CONCLUSION

In ES patients, presence of AF was univariably associated with increased rates of all-cause mortality at 2.5 years. Furthermore, AF was multivariably associated with overall rehospitalization, especially due to AF and AHF.

Clinical predictors of antitachycardia pacing response in implantable cardioverter defibrillator patients

BACKGROUND

Antitachycardia pacing (ATP) provides safe and painless termination of reentrant ventricular arrhythmias in patients with implantable cardioverter defibrillator (ICDs), improving their quality of life. Established predictors of ATP responsiveness are not well known; only longer ventricular tachycardia (VT) cycle length and higher ejection fraction have been found to predict ATP success.

OBJECTIVE

To investigate clinical and ECG predictors of ATP response in ICD patients with monomorphic VT.

METHODS

The ICD clinic database was searched for monomorphic VT events requiring ICD therapy in patients with ischemic or non-ischemic cardiomyopathy. Each patient's first ICD encounter for VT was assessed. Patient demographics, clinical characteristics, VT rate, and ATP responsiveness (always, sometimes, and never successful) were recorded. An ECG was analyzed for QRS morphology and duration. Data was assessed for predictors of ATP responsiveness.

RESULTS

In 527 patients, characteristics associated with always successful ATP included ACE-I/ARB therapy and slower VT rate (never successful ATP 197 ± 28 bpm, sometimes successful ATP 190 ± 27 bpm, always successful ATP 183 ± 22 bpm, P < .0001). Secondary prevention indication, amiodarone therapy, and longer QRS duration were associated with ATP failure. After multivariate analysis, only faster VT rate and amiodarone therapy were predictive of ATP failure.

CONCLUSIONS

Neither QRS morphology nor duration was predictive of ATP success. Slower VT rate was predictive of repeated ATP responsiveness. Amiodarone therapy, which is known to increase VT cycle length, interestingly was associated with ATP failure for unclear reasons. More individualized and possibly more aggressive ATP programming may be warranted in patients on amiodarone.

Prognostic significance of ventricular tachycardia clustering after catheter ablation in non-ischemic dilated cardiomyopathy

BACKGROUND

Ventricular tachycardia clustering (VTc) is associated with a worse clinical outcome in patients with non-ischemic dilated cardiomyopathy (NI-DCM) and implantable cardioverter defibrillator (ICD); however, its role after catheter ablation (CA) has still not been investigated. Aim of this study was to evaluate the prognostic significance of VTc after CA.

METHODS

96 consecutive patients (59 ± 13 years, 82% males) with NI-DCM underwent CA for drug-refractory VT. After CA, patients with VT recurrence were divided into two groups: (1) patients that presented with VTc defined as the occurrence of three or more appropriate ICD interventions within 2 weeks, and (2) patients without VTc.

RESULTS

At 56-months follow-up after ablation 52/96 (54%) patients had recurrent VT, 28/52 (54%) patients experienced VTc and 24/52 (46%) no VTc. When comparing patients with VTc after CA with those without, no differences in terms of age, sex, ejection fraction and cardiovascular risk factors were found. However, patients with VTc showed higher mortality rates at follow-up (54% vs 21% p = 0.04; log-rank p ≤ 0.01). No survival differences were found between patients without VT recurrence and those with VT recurrence but without VTc (29% vs 21% p = 0.77). Predictors of VTc were LVEF < 30% at follow-up and endo-epicardial scar at 3D voltage mapping. At stepwise multivariate analysis VTc and NHYA class were the only independent predictors of death (respectively, RR 3.4, CI 95% 1.16-10.3, p = 0.02; RR 4.18, CI 95% 1.3-12.6, p = 0.01).

CONCLUSIONS

VTc after CA is an independent predictor of survival and is associated with reduced LVEF at follow-up and endo-epicardial scar at 3D voltage mapping.

Prevalence and prognosis of ventricular tachycardia/ventricular fibrillation in patients with post-infarction left ventricular aneurysm: Analysis of 575 cases

BACKGROUND

We investigated the prevalence of ventricular tachycardia/ventricular fibrillation (VT/VF) in Post-infarction left ventricular aneurysm (PI-LVA) patients and analyze clinical outcomes in patients presenting with VT/VF.

METHODS

575 PI-LVA patients were enrolled and investigated by logistic regression analysis. Patients with VT/VF were followed up, the composite primary endpoint was cardiac death and appropriate ICD/external shocks.

RESULTS

The incidence of sustained VT/VF was 11%. Logistical regression analysis showed male gender, enlarged LV end diastolic diameter (LVEDD) and higher NYHA class were correlated with VT/VF development. During follow up of 46 ± 15 months, 19 out of 62(31%) patients reached study end point. Multivariate Cox regression analysis revealed that enlarged LVEDD and moderate/severe mitral regurgitation (MR) were independently predictive of clinical outcome.

CONCLUSIONS

Male gender, enlarged LVEDD and higher NYHA class associated with risk of sustained VT/VF in PI-LVA patients. Among VT/VF positive patients, enlarged LVEDD and moderate/severe MR independently predicted poor clinical prognosis.

Predicting appropriate shocks in patients with heart failure: Patient level meta-analysis from SCD-HeFT and MADIT II

BACKGROUND

No precise tools exist to predict appropriate shocks in patients with a primary prevention ICD. We sought to identify characteristics predictive of appropriate shocks in patients with a primary prevention implantable cardioverter defibrillator (ICD).

METHODS

Using patient-level data from the Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT), we identified patients with any appropriate shock. Clinical and demographic variables were included in a logistic regression model to predict appropriate shocks.

RESULTS

There were 1,463 patients randomized to an ICD, and 285 (19%) had ≥1 appropriate shock over a median follow-up of 2.59 years. Compared with patients without appropriate ICD shocks, patients who received any appropriate shock tended to have more severe heart failure. In a multiple logistic regression model, predictors of appropriate shocks included NYHA class (NYHA II vs. I: OR 1.65, 95% CI 1.07-2.55; NYHA III vs. I: OR 1.74, 95% CI 1.10-2.76), lower LVEF (per 1% change) (OR 1.04, 95% CI 1.02-1.06), absence of beta-blocker therapy (OR 1.61, 95% CI 1.23-2.12), and single chamber ICD (OR 1.67, 95% CI 1.13-2.45).

CONCLUSION

In this meta-analysis of patient level data from MADIT-II and SCD-HeFT, higher NYHA class, lower LVEF, no beta-blocker therapy, and single chamber ICD (vs. dual chamber) were significant predictors of appropriate shocks.

High incidence of ventricular arrhythmias in patients with left ventricular enlargement and moderate left ventricular dysfunction

BACKGROUND

Left ventricular ejection fraction (LVEF) ≤35% is the cutoff value used to identify patients at high risk of sudden cardiac death. However, whether patients who have moderate left ventricular dysfunction and left ventricular enlargement (LVE) have a high risk of ventricular arrhythmias (VAs) and cardiac death is unclear.

HYPOTHESIS

Patients with moderate left ventricular dysfunction and LVE may have a high risk of VAs.

METHODS

This study retrospectively analyzed the data of 853 patients who have an implantable cardioverter-defibrillator/cardiac resynchronization therapy cardioverter-defibrillator equipped with home monitoring. The patients were divided into 4 groups: group A, 35% < LVEF ≤ 45% and left ventricular end-diastolic dimension (LVEDD) ≥60 mm; group B, LVEF ≤35% and LVEDD <60 mm; group C, 35% < LVEF ≤ 45% and LVEDD <60 mm; and group D, LVEF ≤35% and LVEDD ≥60 mm.

RESULTS

During a mean follow-up period of 30 ± 13 months, 324 patients (38%) experienced VAs and 125 patients (14.7%) experienced cardiac death. Based on multivariate Cox regression modeling, group A had an increased risk of VAs (A vs B, hazard ratio [HR]: 1.563, 95% confidence interval [CI]: 1.029-2.375, P = 0.036; A vs C, HR: 1.661, 95% CI: 1.204-2.294, P = 0.002) and cardiac death (A vs B, HR: 1.845, 95% CI: 1.013-3.356; A vs C, HR: 2.041, 95% CI: 1.136-3.731, P = 0.021).

CONCLUSIONS

Patients with moderate left ventricular dysfunction and LVE have a high risk of VAs and cardiac death.

Effect of Levosimendan and Milrinone on Regional Myocardial Ischemia/Reperfusion-Induced Arrhythmias in Dogs

Phosphodiesterase inhibitors as inodilators in heart failure are associated with promotion of arrhythmias. Calcium sensitizers have been proposed for the treatment of severe decompensated heart failure. The effect of levosimendan, a calcium sensitizer, and milrinone, a phosphodiesterase inhibitor, on ventricular arrhythmias was compared in a model of acute regional myocardial ischemia and reperfusion. The left anterior descending coronary artery in dogs was occluded for 25 minutes, followed by reperfusion. The 2 drugs were administered in a hemodynamically equieffective dose (0.1 μmol/kg) 10 minutes before coronary occlusion. Levosimendan, but not milrinone, significantly attenuated the pronounced increase in the number of ventricular premature beats (-63%), tachycardia (-50%), fibrillation (-70%), and inhomogeneity of ventricular electrical activation. Levosimendan significantly improved the overall survival rate. Levosimendan has a more beneficial profile than milrinone regarding the development of ventricular arrhythmias during and after regional myocardial ischemia

Association of Implantable Cardioverter Defibrillator Therapy with All-Cause Mortality-A Systematic Review and Meta-Analysis

BACKGROUND

Implantable cardioverter defibrillators (ICDs) have become the standard approach for prevention of sudden cardiac death. Whether ICD therapy is an independent predictor of all-cause mortality is controversial. We made the systematic review and meta-analysis to estimate the impact of ICD therapy on mortality.

METHODS

We searched the PubMed and Embase databases for studies evaluating the effect of ICD shocks or antitachycardia pacing (ATP) on mortality. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated using random effects models.

RESULTS

Thirteen cohort studies were identified. Mean ejection fraction of the population was 23-35%; 68.0% had ischemic etiology, and 74.5% received a primary prevention ICD implantation. Appropriate shocks were an independent predictor of increased mortality compared with no-shock or no-therapy patients (HR 2.07, 2.76, respectively). In contrast, inconsistent results were obtained during inappropriate-shock analyses: when compared with no-shock patients, inappropriate shocks were associated with an increased risk of death (HR 1.54, 95% CI: 1.25-1.89, P < 0.0001); however, when compared to no-therapy patients, there was no relationship between inappropriate shocks and mortality (HR 1.20, 95% CI: 0.90-1.61, P = 0.22). Subgroup analysis in heart failure patients also did not find any difference in mortality between inappropriate-shock and no-therapy patients. No increased risk of mortality was found in the patients who experienced appropriate or inappropriate ATP only.

CONCLUSION

Appropriate shocks were associated with an increased mortality in ICD patients. However, whether inappropriate shocks worsened the clinical outcome was controversial, and larger prospective trials are needed to clarify the issue.

Safety of symptom-limited exercise testing in a big cohort of a modern ICD population

BACKGROUND

Exercise may predispose to ventricular arrhythmias especially in patients with congestive heart failure. As therapy with implanted cardioverter-defibrillators (ICDs) has become standard medical care, there is an emerging number of exercise tests that need to be performed in patients with ICDs. In contrast, little is known about the safety of symptom-limited exercise testing in these patients.

METHODS AND RESULTS

400 ICD patients performed symptom-limited exercise treadmill testing. 200 patients performed a ramp protocol with an initial workload of 0 W increased by 15 W every minute. Another 200 ICD patients did a slightly modified ramp protocol with again an initial workload of 0 W but with an increased capacity of 15 W every 2 min. The study population consists mainly of patients with ischemic (63%) and non-ischemic (34%) heart disease. Atrial fibrillation was present in 16% of the subjects. The mean ejection fraction was 28 ± 8, and 78% of the patients had an ejection fraction below 30%. In this cohort of patients, no sustained ventricular arrhythmias and no deaths occurred during or after exercise testing. No inappropriate shock delivery was observed. The modified ramp protocol resulted in a prolonged exercise time with equal exercise capacity but does not result in an enhanced susceptibility for ventricular arrhythmias.

CONCLUSIONS

Symptom-limited exercise treadmill testing in heart failure patients with ICDs is a safe procedure. The use of a ramp protocol is sufficient in terms of safety and is easy to perform in general practice. The exercise duration in heart failure patients with ICDs does not predict serious adverse events.

[Electrical storm in ICD patients: prevention and treatment]

Medical progress and demographic changes cause a continuous increase in patients with implantable cardioverter-defibrillators (ICD). Up to one third of patients with ICDs for secondary prevention and half of the patients with previous electrical storm (ES) will suffer from (further) ESs. When multiple ICD shocks are reported by patients (ICD storm), appropriate, inappropriate and phantom shocks have to be distinguished. Reported shocks without clinical correlates (phantom) often affect patients suffering from posttraumatic stress syndrome after an ICD storm. Approximately one third of all ICD shocks are inappropriate, most often due to supraventricular tachycardia with fast atrioventricular (AV) nodal conduction or lead failure. Within 10 years after implantation lead failure can be detected in up to 20 % of cases and approximately one third of these failures are only seen after inappropriate ICD shocks. Furthermore, inappropriate shocks are due to oversensing of far field atrial electrograms, T-waves, diaphragmatic potentials and electrical noise.Appropriate ICD shocks can rarely also be stimulated by the proarrhythmogenicity of lead implantation or ICD programming. Modifications of the waiting period to therapy, time to detection, detection window, antitachycardia pacing (ATP) stimulation and supraventricular discrimination algorithms may minimize ICD shocks. Some stimulation algorithms may improve the hemodynamic stability during ES. In addition to ventricular ablation, blockade of the sympathetic autonomic nervous system and antiarrhythmic treatment are the main pillars of ES treatment. The best ES prevention, however, is optimized heart failure treatment, especially when a cardiac resynchronization with defibrillator (CRT-D) system is implanted.

Deactivation of implantable cardioverter-defibrillators at end of life

It is inevitable that all patients with implantable cardioverter-defibrillators (ICDs) will die during extended follow-up. End-of-life care planning may become appropriate as a patient's condition deteriorates. There is concern about multiple futile shocks in the final hours of life, although the incidence of this problem has been estimated at only 8-16%. Despite broad consensus that ICD deactivation should be discussed as part of end-of-life care planning, the effect of ICD deactivation, in particular whether life expectancy is altered, is uncertain. Many clinicians are reluctant to discuss ICD deactivation. Many patients have misconceptions regarding ICD function and value longevity above quality of life. As such, ICD deactivation is often discussed late or not at all. The management of ICDs in patients approaching death is likely to become a major problem in the coming years. This article will discuss directions in which clinical practice might develop and areas for future research.

Clinical characteristics, mortality, cardiac hospitalization, and ventricular arrhythmias in patients undergoing CRT-D implantation: results of the ACTION-HF study

INTRODUCTION

The characteristics and outcomes of patients who undergo cardiac resynchronization therapy (CRT) device implantation in current clinical practice may differ from those of reference trial populations. Study objectives were to assess 2-year outcomes in a population implanted with a CRT plus defibrillator device in accordance with the standard of care and to evaluate any independent association between clinical variables and outcome.

METHODS AND RESULTS

A total of 406 patients enrolled at 35 centers in Italy were followed up prospectively for 2 years. All patient management decisions were left to the treating physician's discretion, in accordance with clinical practice. ACTION-HF patients had a better baseline clinical status than patients enrolled in the COMPANION study: shorter HF history (1 vs 3.5 years, P < 0.01), less advanced NYHA functional class (III-IV: 73% vs 100%, P < 0.01), higher LVEF (26% vs 21%, P < 0.01), higher SBP (122 vs 112 mmHg, P < 0.01), and less diabetes (27% vs 41%, P < 0.01). This status was reflected in lower mortality (11.5% vs 26%) and a lower incidence of appropriate ICD shocks (12.1% vs 19.3%). AF history was an independent predictor of the combination of all-cause mortality and cardiac-cause hospitalization (HR: 3.31; P < 0.001). Recurrent or new atrial arrhythmias were independently associated with the development of ventricular arrhythmias (HR: 3.4; P < 0.001).

CONCLUSIONS

This population appears clinically less compromised and had a lower incidence of adverse clinical outcomes than those of reference trials. However, we recorded a substantial burden of atrial arrhythmias, which was independently associated with a higher incidence of ventricular arrhythmias.

Cardiac Resynchronization Therapy With and Without Defibrillator in a Commercial Truck Driver with Ischemic Cardiomyopathy and New York Heart Association Class III Heart Failure

Commercial drivers warrant tighter restrictions to their driving privileges than private drivers. Patients with cardiac disease who are at risk of consciousness-impairing arrhythmias are not allowed to drive commercially. Patients with left ventricular systolic dysfunction and/or heart failure symptoms are permanently disqualified from commercial driving. A biventricular pacemaker without defibrillator can improve symptoms and mortality in selected patients with heart failure. Biventricular pacing may have antiarrhythmic effects that may reduce the added benefit of a defibrillator. Motor vehicle collisions resulting from arrhythmic events are infrequent. The interests of public safety must outweigh individual liberties when driving safety is in question.

Ventricular tachycardia or ventricular fibrillation occurs less often in patients with left bundle branch block and combined resynchronization and defibrillators than in patients with narrow QRS and conventional defibrillators

AIMS

Mortality in chronic heart failure (CHF) patients with left bundle branch block (LBBB) is high. Cardiac resynchronization therapy (CRT) reduces symptoms and mortality in CHF patients with LBBB. Whether CRT promotes or prevents ventricular tachycardia (VT)/ventricular fibrillation (VF) remains controversial, however. Therefore, we aimed to analyse arrhythmia-related CRT effects and characterized the VT/VF incidence in CRT-defibrillator patients and matched controls with conventional implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden cardiac death.

METHODS AND RESULTS

We enrolled 134 patients [110 men, left ventricular ejection fraction (LVEF) 24 ± 8%, 71 coronary artery disease, CRT-ICD 67, conventional ICD matched controls 67, follow-up 31 ± 17 months] and monitored overall survival and the time to a first VT/VF episode. Controls did not have LBBB. They were otherwise matched for age, LVEF, and follow-up duration. Gender and underlying disease did not differ between the groups. Kaplan-Meier analysis revealed more favourable arrhythmia-free survival in CRT-ICD vs. conventional ICD patients [hazard ratio (HR) 2.26, confidence interval (CI) 1.09-4.67, log rank P = 0.023]. The difference persisted in the multivariate Cox regression analysis (HR 3.25, CI 1.18-8.93, P= 0.022). Overall survival was similar in both groups (HR 1.45, CI 0.55-3.82, P = 0.45).

CONCLUSIONS

Chronic heart failure patients with LBBB treated with CRT-ICD, experience less and delayed VT/VF episodes compared with matched controls without LBBB receiving conventional ICD. In the long-term, CRT appears to exert antiarrhythmic effects and to attenuate the particularly high arrhythmia-related risk of CHF patients with LBBB. The incremental benefit of adding the ICD option to CRT pacing in LBBB patients appears questionable.

Intrathoracic impedance preceding ventricular tachyarrhythmia episodes

BACKGROUND

Heart failure is associated with ventricular tachyarrhythmias (VT/VF). Fluid accumulation during worsened heart failure may trigger VT/VF. Increased intrathoracic impedance has been correlated with fluid accumulation during heart failure. Implanted defibrillators capable of daily measures of intrathoracic impedance allow correlation of impedance with occurrence of VT/VF. We hypothesized that VT/VF episodes are preceded by decreases in intrathoracic impedance. The goal was to identify the relationship of intrathoracic impedance measured by implanted cardioverter defibrillators to the occurrence of VT/VF.

METHOD

Implanted defibrillator follow-up data were obtained retrospectively. Those with Medtronic OptiVol (Medtronic Inc., Minneapolis, MN, USA), storing averaged daily and reference impedance values, were reviewed for VT/VF episodes. Impedance changes in the week leading up to VT/VF were analyzed.

RESULTS

A total of 317 VT/VF episodes in a cohort of 121 patients' follow-up data were evaluated. Averaged daily intrathoracic impedance declined preceding 64% of VT/VF episodes, with an average decline of 0.46 +/- 0.35 Ohms from the day before the VT/VF episodes. However, the mean values of the averaged daily and reference impedance did not change significantly. A novel measure, DeltaTI, the sum of the daily differences between the averaged daily and reference impedance, was negative preceding 66% of VT/VF episodes (P < 0.001). The mean DeltaTI was -4.0 +/- 1.3 Ohms, which was significantly lower than the theoretically expected value of zero Ohms (P < 0.01).

CONCLUSION

(1) Averaged daily impedance declined preceding 64% of VT/VF episodes, but the overall decline was of small magnitude; (2) a novel measure, DeltaTI, was negative preceding 66% of VT/VF episodes, and significantly below zero.

Left ventricular ejection fraction and absence of ACE inhibitor/angiotensin II receptor blocker predicts appropriate defibrillator therapy in the primary prevention population

INTRODUCTION

Implantable cardioverter defibrillators (ICD) significantly reduce mortality in patients with left ventricular (LV) dysfunction. However, little is known of the predictors of appropriate device activation in the primary prevention population. The aim of the present study was to determine predictors of appropriate device therapy in patients receiving ICDs for primary prevention.

METHODS & RESULTS

One hundred twenty-six patients with a left ventricular ejection fraction (LVEF) of < 35% and no prior documented ventricular arrhythmias underwent ICD implantation. The ICD implanted was single chamber in 60 (48%), dual chamber in 10 (8%), and biventricular in 56 (44%) patients and programmed with a single ventricular fibrillation (VF) zone at >180 beats per minute. Mean age was 58 +/- 13 years and mean LVEF was 23 +/- 7%. Fifty-two percent had ischemic cardiomyopathy and 66% were New York Heart Association heart failure class II/III. During a mean follow-up period of 589 +/- 353 days, 17 (13%) patients received appropriate device therapy and three (4%) received inappropriate shocks. Appropriate ICD therapy was associated with reduced LVEF (mean 19.9% vs 23.7%, P = 0.02) and the patients were less likely to have received angiotensin-converting enzyme inhibitor (ACEI) or angiotensin II receptor blockers (AIIRB) (65% vs 90%, P = 0.04). Multivariate analysis revealed lack of ACEI/AIIRB (odds ratio [OR]= 0.06, 95% confidence interval [CI]= 0.01-0.37, P = <0.01) and lower LVEF (OR = 0.88, 95% CI 0.79-0.98, P = 0.02) predicted appropriate device activation. There was no difference in transplant-free survival between the appropriate therapy and no/inappropriate therapy groups, LVEF <20% and LVEF >20% group, and lack of ACEI/AIIRB and ACEI/AIIRB group.

CONCLUSION

Appropriate device activation occurred in 13% of patients in a primary prevention population. LVEF and absence of ACEI/AIIRB predicted appropriate ICD therapy.

Prediction of appropriate defibrillator therapy in heart failure patients treated with cardiac resynchronization therapy

The necessity of implantable cardioverter-defibrillator (ICD) implantation in patients with systolic heart failure (HF) who undergo cardiac resynchronization therapy (CRT) may be questioned. The aim of this study was to identify patients at low risk for sustained ventricular arrhythmia. One hundred sixty-nine consecutive patients with HF (mean age 60 +/- 12 years, 125 men, 73% in New York Heart Association class III) referred for CRT and prophylactic, primary prevention ICD implantation underwent baseline clinical and echocardiographic assessment and regular device follow-up. The primary study end point was appropriate ICD therapy. During a mean follow-up period of 654 +/- 394 days, 35 patients (21%) had sustained ventricular arrhythmias requiring appropriate ICD therapy. Of the 3 patients who experienced sudden cardiac death, 2 had been treated with appropriate ICD therapy before sudden cardiac death. In a multivariate model, only history of nonsustained ventricular tachycardia (p = 0.001), a severely (<20%) decreased left ventricular ejection fraction (p = 0.001), and digitalis therapy (p = 0.08) independently predicted appropriate ICD therapy. Patients with 0 (n = 46), 1 (n = 36), 2 (n = 73), and 3 (n = 14) risk factors for appropriate ICD therapy had a 7%, 14%, 27%, and 64% and 0%, 6%, 10%, and 43% incidence of appropriate ICD therapy for ventricular arrhythmias and for rapid ventricular tachycardia or ventricular fibrillation, respectively. In conclusion, apart from commonsense considerations (age and significant co-morbidities), ICD addition seems ineffective in CRT patients without nonsustained ventricular tachycardia, digoxin therapy, and severely reduced left ventricular systolic function.

Risk of ventricular arrhythmia after implantable defibrillator treatment in anxious type D patients

OBJECTIVES

We sought to examine the combination of adverse psychological factors (anxiety, depression, and distressed or Type D personality) as a predictor of ventricular arrhythmias in patients with implantable cardioverter-defibrillators (ICDs).

BACKGROUND

Little is known about the role of psychological factors and their clustering in the occurrence of life-threatening arrhythmias.

METHODS

In this prospective study, 391 patients with an ICD (81% men, age 62.3 +/- 10.4 years) completed anxiety, depression, and Type D personality scales at the time of implantation. The end point was occurrence of ventricular arrhythmia, defined as appropriate ICD therapies, in the first year after implantation.

RESULTS

Ventricular arrhythmias occurred in 19% (n = 75) of patients. Increased symptoms of depression (p = 0.81) or anxiety (p = 0.31) did not predict arrhythmias. However, anxious patients with a Type D personality had a significantly increased rate of ventricular arrhythmias (21 of 71; 29.6%) as compared with other ICD patients (54 of 320; 16.9%; hazard ratio [HR]: 1.89; 95% confidence interval [CI]: 1.14 to 3.13; p = 0.013). When controlled for the effects of sex, age, ischemic etiology, left ventricular dysfunction, prolonged QRS duration, and medication, anxious Type D patients (HR: 1.72; 95% CI: 1.03 to 2.89; p = 0.039) and secondary prevention patients (HR: 1.91; 95% CI: 1.14 to 3.20; p = 0.014) were at increased risk of ventricular arrhythmias.

CONCLUSIONS

Personality modulated the effect of emotional distress; anxiety predicted a 70% increase in risk of arrhythmia in Type D patients but not in other patients. Anxious Type D patients may be identified and offered additional behavioral support after ICD implantation.

Rates and predictors of appropriate implantable cardioverter-defibrillator therapy delivery: results from the EVADEF cohort study

BACKGROUND

The implantable cardioverter defibrillator (ICD) is the therapy of choice in patients at risk for sudden cardiac death in both primary and secondary prevention indication. There are no recent data concerning the delivery rate and etiology of appropriate ICD therapies in routine medical care.

METHODS

The EVADEF study was a French multicenter, prospective, observational cohort study of ICD patients with a 2-year follow-up. Every 6 months we recorded patients' survival status and evaluated appropriate ICD therapies-antitachycardia pacing or shocks. Causes of ICD activation were also recorded from among ventricular tachycardia (VT), fast VT and ventricular fibrillation (VF).

RESULTS

From 2001 to 2003, 2296 unselected patients were implanted and followed until 2005. During a mean follow-up of 20.5 months, 274 deaths occurred. In 2009 patients with cardiopathy, 22 patients per 100 person-years had at least one appropriate therapy. Twenty-four and 11 patients per 100 person-years had at least one therapy in secondary and primary prevention, respectively. Age >65 years, left ventricular ejection fraction <30% and secondary prevention were independently associated with appropriate therapy. Besides, 5 patients per 100 person-years had at least 1 episode of life-threatening arrhythmia (fast VT or VF). Left ventricular ejection fraction <30% and secondary prevention were independently associated with life-threatening arrhythmia. In 287 patients without cardiopathy, the rate of appropriate therapy was twice as less, whereas the rate of life-threatening arrhythmia was similar.

CONCLUSION

Over a 24-month follow-up, the rate of appropriate therapy was substantial while few patients had life-threatening arrhythmia. Appropriate therapies and life-threatening arrhythmia were more frequent in patients with secondary prevention indication.

Effect of cardiac resynchronization therapy on the incidence of electrical storm

BACKGROUND

Hemodynamic improvement from biventricular pacing is well documented; however, its electrophysiologic effects have not been systematically studied. In this study, incidence and risk factors for electrical storm (ES) were investigated in 729 ICD and biventricular defibrillator (CRT-D) heart failure patients.

METHODS

168 consecutive CRT-D and 561 ICD patients were retrospectively analyzed for the occurrence of VT/VF and predisposing factors. Electrical storm was defined as ventricular tachycardia or fibrillation ≥3 times during 24 h. Mean follow-up was 41 months.

RESULTS

In 168 CRT-D patients only one patient experienced electrical storm compared to 39 patients out of 561 ICD patients (0.6% vs. 7%, p<0.01). 33% of the patients with electrical storm died within one year. In the CRT-D group 81 patients (48%) developed VT or VF and received at least one appropriate therapy, compared to 281 patients (50%) in the ICD group. Mean ejection fraction was 21.7% in the CRT-D group and 34.7% (p<0.01) in the ICD group. Stratifying the patients according to primary or secondary prevention and ejection fraction demonstrated that VT/VF clusters were significantly associated with ICD indication for secondary prevention, previous myocardial infarction and LVEF<30%.

CONCLUSION

The development of electrical storm is accompanied with a highly increased mortality risk even if an ICD/CRT-D is implanted. In CRT-D patients electrical storm is much less common than in ICD patients. Secondary prevention and ejection fraction<30% are predictors of electrical storm. Beside hemodynamic improvements cardiac resynchronization therapy may reduce the arrhythmia burden in heart failure patients.

B-type natruiretic peptide levels stratify the risk for arrhythmia among implantable cardioverter defibrillator patients

BACKGROUND

We sought to study the association between brain natriuretic peptide (BNP) levels and the occurrence of ventricular arrhythmias in patients with left ventricular dysfunction (LVD) and an implantable cardioverter defibrillator (ICD).

METHODS

This was a prospective study of consecutive, stable, ambulatory patients with moderate and severe ischemic LVD and an ICD. A plasma BNP level was obtained at recruitment. Patients were evaluated every 3-6 mo for a minimum of 1 y. The primary end point was the occurrence of malignant ventricular arrhythmia or sudden cardiac death (SCD).

RESULTS

The cohort consisted of 94 subjects (6 women) with a mean +/- standard deviation (SD) age of 69 +/- 10 y. The ICD implantation indication was primary and secondary prevention of SCD in 49% and 51% of subjects, respectively. A primary end point occurred in 27 patients (29%), and was more frequent in symptomatic heart failure patients and those implanted for secondary prevention of SCD. The median BNP level was significantly higher among patients who experienced an end point (191 pg/ml versus 142 pg/ml, p = 0.03). After controlling for New York Heart Association heart failure class and ICD implantation indication, the odds ratio (OR) for experiencing an adverse outcome among the upper BNP quartile versus all others was 3.5 (95% confidence interval [CI]: 1.2-10.2). Among patients implanted for primary prevention of SCD, none of the patients in the lower BNP quartile (BNP < 91 pg/ml) experienced an adverse outcome.

CONCLUSIONS

These results suggest that abnormally high BNP levels not only predict cardiac death, but also arrhythmic death in this patient population, and a low BNP level can serve to identify low risk patients. (c)

Risk stratification for sudden cardiac death

Recent advances in pharmacological and device-based therapies have provided a range of management options for patients at risk of sudden cardiac death (SCD). Since all such interventions come with their attendant risks, however, stratification procedures aimed at identifying those who stand to benefit overall have gained a new degree of importance. This review assesses the value of risk stratification measures currently available in clinical practice, as well as of others that may soon enter the market. Parameters that may be obtained only by performing invasive cardiac catheterisation procedures are considered separately from those that may be derived using more readily available non-invasive techniques. It is concluded that effective stratification is likely to require the use of composite parameters and that invasive procedures might only be justified in specific sub-groups of patients.