ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: Executive Summary

Primary Electrical Heart Disease-Principles of Pathophysiology and Genetics

Primary electrical heart diseases, often considered channelopathies, are inherited genetic abnormalities of cardiomyocyte electrical behavior carrying the risk of malignant arrhythmias leading to sudden cardiac death (SCD). Approximately 54% of sudden, unexpected deaths in individuals under the age of 35 do not exhibit signs of structural heart disease during autopsy, suggesting the potential significance of channelopathies in this group of age. Channelopathies constitute a highly heterogenous group comprising various diseases such as long QT syndrome (LQTS), short QT syndrome (SQTS), idiopathic ventricular fibrillation (IVF), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and early repolarization syndromes (ERS). Although new advances in the diagnostic process of channelopathies have been made, the link between a disease and sudden cardiac death remains not fully explained. Evolving data in electrophysiology and genetic testing suggest previously described diseases as complex with multiple underlying genes and a high variety of factors associated with SCD in channelopathies. This review summarizes available, well-established information about channelopathy pathogenesis, genetic basics, and molecular aspects relative to principles of the pathophysiology of arrhythmia. In addition, general information about diagnostic approaches and management is presented. Analyzing principles of channelopathies and their underlying causes improves the understanding of genetic and molecular basics that may assist general research and improve SCD prevention.

Sinus node dysfunction and related permanent pacemaker implantation after major cardiac surgeries, systematic review, and meta-analysis

Background

There is no concise evidence or clinical guidelines regarding the incidence of sinus node dysfunction (SND) and permanent pacemaker (PPM) implantation following cardiac surgeries and their management approaches.

Objective

We aim to systematically review current evidence on the prevalence of SND, PPM implantation concerning it, and its risk factors in patients undergoing cardiac surgery.

Method

Four electronic databases (Cochrane Library, Medline, SCOPUS, and Web of Science) were systematically searched for articles regarding SND after cardiovascular surgeries and reviewed by two independent researchers, and a third review in case of discrepancies. Using the random-effects model, a proportion meta-analysis was performed on data regarding PPM implantation. Subgroup analysis was performed for different interventions, and the possible effect of different covariates was evaluated using meta-regression.

Results

From the initial 2012 unique records, 87 were included in the study, and results were extracted. Pooled data from 38,519 patients indicated that the overall prevalence of PPM implantation due to SND after cardiac surgery was 2.87% (95% CI [2.09; 3.76]). The incidence of PPM implantation in the first post-surgical month was 2.707% (95% CI [1.657; 3.952]). Among the four main intervention groups, including valve, maze, valve-maze, and combined surgeries, maze surgery was associated with the highest prevalence (4.93%; CI [3.24; 6.92]). The pooled prevalence of SND among studies was 13.71% (95% CI [8.13; 20.33]). No significant relationship was observed between PPM implantation and age, gender, cardiopulmonary bypass time, or aortic cross-clamp time.

Conclusion

Based on the present report, patients undergoing the maze and maze-valve procedures are at higher risk of post-op SND, whereas lone valve surgery had the lowest prevalence of PPM implantation.

Systematic Review Registration

PROSPERO (CRD42022341896).

Implantable Cardiac Device Infections Prevalence: Diagnostic and Therapeutic Implications

Background:  It has been demonstrated that the use of cardiac implanted electronic devices (CIED) improve mortality and survivability in a variety of patient populations. Nevertheless, CIED related infection is a serious complication characterized by a high rate of mortality and morbidity. Objectives: To evaluate the prevalence of CIED related infections, risk factors, clinical and demographic characteristics, causative organisms, and the management and outcome of patients presented in the Critical Care Department, Cairo University. Methods: A retrospective analysis was conducted in 1871 individuals who had been implanted with a cardiac device with a total number of devices of 1968 and 2270 procedures performed from January 2007 to December 2017. Results: 59 infectious episodes were identified with an estimated incidence of 2.99% of inserted devices and 2.6% of total procedures.  The infection rate was considerably higher in patients with multiple procedures than those who had a single procedure (9.27% vs. 1.18%; P<0.001). The individuals with a dual-chamber implantable cardiac defibrillator (ICD) and cardiac resynchronization therapy devices (CRTD) had the highest infection rate of 6.25% & 6.85%, respectively. The rate of pocket infection (PI) and CIED related endocarditis (CDE) was 1.54% & 1.06% of total devices respectively.  Numerous risk factors have been found; the most significant of those are diabetes mellitus, recurrent procedures, the device's complexity, and the existence of more than one lead. Gram-positive cocci were the most isolated organisms in all positive cultures (69.23%). Echocardiography revealed lead vegetations and valvular vegetations in 22 patients and 2 patients respectively.  In 53 cases (89.83%), the devices were removed; in 41 cases, the entire system was removed; and in 12 cases, only the generator was removed. The mortality rate was found to be 10.17%, having a considerably higher prevalence in CDE individuals than in pocket infection individuals (20.83% vs. 2.86%; P=0.025). Conclusion: In our center, while the rate of CIED implantation continues to increase, the incidence rate of CIED-related infection continues to decline. Until now, the infection burden associated with secondary intervention is still significantly high.  The management strategy of selection is to eliminate the entire system for patients presented with infection especially those with CDE. However, the mortality rate is still high.

Social cognitive intervention following an initial implantable cardioverter defibrillator: Better treatment response for secondary versus primary prevention

BACKGROUND

The patient + partner (P+P) is a patient/partner-focused social cognitive intervention with demonstrated efficacy to improve outcomes following an initial implantable cardioverter defibrillator (ICD). Little is known about how the patient response may differ by ICD implant indication. The aim of this study was to examine the response to intervention for patients with an initial ICD by reasons for primary versus secondary ICD indication.

METHOD

A longitudinal secondary analysis of data from a randomized clinical trial testing the P+P intervention examined patient health outcomes over 12 months, stratified by the indication for the ICD: primary prevention without cardiac resynchronization therapy (CRT) (1o No CRT, n = 100), primary prevention with CRT (1o CRT, n = 78), secondary prevention after cardiac arrest (2° Cardiac Arrest, n = 66), and secondary prevention for other arrhythmias (2o Other, n = 57). Outcomes included physical and mental health status (Short-Form-36 Physical Component Summary and Mental Component Summary), physical symptoms (Patient Concerns Assessment), depression (Patient-Health-Questionniare-9), and anxiety (State-Trait Anxiety Inventory).

RESULTS

Participants (n = 301) were on average 64 years old, primarily male (73.7%) and Caucasian (91%) with reduced ejection fraction (34%). There were no baseline differences between ICD groups for all outcomes (P > .05). Patients in the 2° Cardiac Arrest group showed greater improvement from baseline to 3 months in physical and mental health outcomes. The 2° Cardiac Arrest group had better physical (F = 11.48, P = .004) and mental health (F = 4.34, P = .038) and less severe physical (z = 2.24, P = 0.013) and depressive symptoms (z = 2.71, P = .003) at 12 months compared to the 1o No CRT group.

CONCLUSION

The P+P intervention was more effective for promoting physical and psychological health outcomes for individuals receiving an ICD for 2o prevention after cardiac arrest.

Tachyarrhythmia discriminator for implantable cardioverter-defibrillators in bundle branch block

BACKGROUND

Inaccurate arrhythmia classification by implantable cardioverter-defibrillators (ICDs) contributes to inappropriate shocks and increased health care utilization.

OBJECTIVE

The purpose of this study was to evaluate the ability of a novel discriminator using far-field (FF) and near-field (NF) right ventricular lead electrograms (EGMs) to differentiate ventricular tachycardia (VT) from supraventricular tachycardia (SVT) in patients with underlying conducted narrow QRS, right bundle branch block (RBBB), and left bundle branch block (LBBB).

METHODS

ICD interrogations were reviewed, identifying subjects with tachycardia events at least 5 beats in duration with stable morphology and cycle length. FF to NF (FF-NF) EGM intervals during tachycardia and baseline conducted rhythm were measured using digital calipers. Events with uncertain tachycardia rhythm mechanism were excluded.

RESULTS

Ninety-five subjects were included. Mean FF-NF interval during tachycardia was significantly lower during SVT than VT (25.8 ± 12.0 ms vs 91.0 ± 37.2 ms; P <.001). Participants with LBBB (n = 22) and RBBB (n = 21) had significantly lower mean FF-NF intervals during SVT compared with VT (LBBB 25.6 ± 7.26 ms vs 93.1 ± 41.5 ms; P <.001; RBBB 30.0 ± 16.6 ms vs 101.7 ± 34.3 ms; P <.001). In this cohort, FF-NF interval cutoff of 100 ms was 100% specific for VT discrimination regardless of underlying QRS morphology, with sensitivity of 46%, 50%, and 38% for LBBB, RBBB, and narrow QRS, respectively.

CONCLUSION

Prolonged FF-NF interval on intracardiac EGM during tachycardia is a highly specific discriminator for VT, regardless of baseline QRS morphology.

Antibiotic envelope is associated with reduction in cardiac implantable electronic devices infections especially for high-power device-Systematic review and meta-analysis

BACKGROUND

Infections after cardiac implantable electronic device (CIED) placement are associated with significant morbidity and mortality. The incidence of CIED is increasing overtime despite the optimal use of antimicrobial agents. This systematic review and meta-analysis will address the latest evidence on the use of AE to mitigate the risk of CIED infection, and which subset of patients will they benefit the most.

METHODS

We performed a comprehensive search on topics that assesses antibiotic envelope and implantable cardiac electronic device up until August 2019.

RESULTS

There were a total of 32,329 subjects from six studies. Antibiotic envelope was associated with a lower risk of major infection with OR 0.42 [0.19, 0.97], P = .04; I2: 58% and HR 0.52 [0.32, 0.85], P = .009; I2: 80%. Upon sensitivity analysis by removing a study, the OR became 0.40 [0.27, 0.59], P < .001; I2: 46%. Subgroup analysis for 12 months' infection was OR 0.65 [0.43, 0.99], P = .04; I2: 49%. Meta-analysis of propensity-matched cohort showed a reduced risk of infection with AE (OR of 0.14 [0.05, 0.41], P < .001; I2:0%). Mortality was similar in both AE and control groups. Antibiotic envelope reduced the incidence of infection in patients receiving high-power device (OR 0.44 [0.27, 0.73], P = .001; I2:0%) but not low-power device.

CONCLUSION

Antibiotic envelope (TYRX) was found to be safe and effective in reducing the risk of major infections in high-risk patients receiving CIED implantation, especially in those receiving high-power CIED.

Cardioneuroablation: Catheter Vagal Denervation as a New Therapy for Cardioinhibitory Syncope

The vasovagal syncope is the most frequent cause of transient loss of consciousness, especially in young people without significant heart disease. The malignant cardioinhibitory form is caused by abrupt and intense vagal reflex with or without defined triggers. Refractory cases to preventive measures and pharmacological handling has been treated with definitive pacemaker implantation. Besides showing questionable results, pacemaker implantation is highly rejected by young patients. In the late 1990s, we proposed specific vagal denervation by catheter ablation and spectral mapping, for paroxysmal AF, functional bradyarrhythmias and severe cases of malignant cardioinhibitory syncope giving rise to cardioneuroablation. Recently, many authors worldwide have been reproducing the cardioneuroablation results where elimination or significant reduction of the vagal response were observed, which abolished symptoms in more than 75% of patients followed up to 14 years, without complications. Therefore, cardioneuroablation has shown to be a real therapeutic option in malignant syncope cardioinhibitory and in any exclusive vagal mediated bradyarrhythmia without the need for pacemaker implantation.

Cardioneuroablação: A Denervação Vagal por Cateter Como Nova Terapia para Síncope Cardioinibitória

A síncope vasovagal é a causa mais frequente de perda transitória de consciência, especialmente em jovens sem doença cardíaca significativa. A forma cardioinibitória maligna é causada por reflexo vagal abrupto e intenso com ou sem gatilhos definidos. Casos refratários a medidas preventivas e manuseio farmacológico foram tratados com implante definitivo de marcapasso. Além de apresentar resultados questionáveis, o implante de marcapasso é altamente rejeitado por pacientes jovens. No final dos anos 1990, propusemos uma denervação vagal específica por ablação do cateter e mapeamento espectral para FA paroxística, bradiarritmias funcionais e casos graves de síncope cardioinibitória maligna dando origem à cardioneuroablação. Recentemente, muitos autores em todo o mundo vêm reproduzindo os resultados da cardioneuroablação, onde se observou eliminação ou redução significativa da resposta vagal, o que aboliu sintomas em mais de 75% dos pacientes acompanhados por até 14 anos, sem complicações. Portanto a cardioneuroablação tem se mostrado uma verdadeira opção terapêutica na síncope cardioinibitória maligna e em qualquer bradiarritmia vagal exclusiva mediada sem a necessidade de implante de marcapasso.

The role of implantable cardioverter-defibrillators and sudden cardiac death prevention: indications, device selection, and outcome

Multiple randomized multicentre clinical trials have established the role of the implantable cardioverter-defibrillator (ICD) as the mainstay in the treatment of ventricular tachyarrhythmias and sudden cardiac death (SCD) prevention. These trials have focused mainly on heart failure patients with advanced left ventricular dysfunction and were mostly conducted two decades ago, whereas a more recent trial has provided conflicting results. Therefore, much remains to be determined on how best to balance the identification of patients at high risk of SCD together with who would benefit most from ICD implantation in a contemporary setting. Implantable cardioverter-defibrillators have also evolved from the simple, defibrillation-only devices implanted surgically to more advanced technologies of multi-chamber devices, with physiologic bradycardic pacing, including cardiac resynchronization therapy, atrial and ventricular therapeutic pacing algorithms, and subcutaneous ICDs. These multiple options necessitate individualized approach to device selection and programming. This review will focus on the current knowledge on selection of patients for ICD treatment, device selection and programming, and future directions of implantable device therapy for SCD prevention.

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Permanent pacing and conduction recovery in patients undergoing cardiac surgery for active infective endocarditis in an Australian Tertiary Center

BACKGROUND

Postoperative heart block is common among patients undergoing surgery for infective endocarditis (IE). Limited data exists allowing cardiologists to predict who will require permanent pacemaker (PPM) implantation postoperatively. We aimed to determine the rate of postoperative PPM insertion, predictors for postoperative PPM, and describe PPM utilization and rates of device-related infection during follow-up.

MATERIALS AND METHODS

A retrospective analysis was performed of 191 consecutive patients from a single institution who underwent cardiac surgery for IE between 2001 and 2017. Preoperative and operative predictors for postoperative PPM were evaluated using univariate and multivariate logistic regression.

RESULTS

The rate of postoperative PPM implantation was 11% (17/154). The PPM group had more preoperative prolonged PR interval alone (33% vs 12%; P = .03), coexistent prolonged PR and QRS durations (13% vs 2%; P = .01), infection beyond the valve leaflets (82% vs 41%; P = .001), aortic root debridement (65% vs 23%; P = <.001), patch repair (47% vs 20%; P = .01), postoperative prolonged PR interval (50% vs 24%; P = .01), and prolonged QRS duration (47% vs 15%; P = .001). On multivariate analysis, infection beyond the valve leaflets emerged as an independent predictor for postoperative PPM (odds ratio, 1.94, 95% confidence interval, 1.14-3.28; P = .014). A reduction in PPM utilization was observed in five patients while eight patients continued to show significant ventricular pacing with no underlying rhythm at 12 months. There were no device-related infections.

CONCLUSION

Postoperative PPM was required in 11% of patients undergoing surgery for IE over a 16-year period. Infection beyond the valve leaflet was an independent predictor for postoperative PPM insertion.

Association of body mass index with cardiac resynchronization therapy intention and left ventricular lead implantation failure: insights from the NCDR implantable cardioverter-defibrillator registry

BACKGROUND

Cardiac resynchronization therapy with defibrillator (CRT-D) implantation involves left ventricular (LV) lead placement for biventricular pacing and is more complex than implantable cardioverter-defibrillator (ICD)-only implantation. Differences in the prescription of CRT-D versus ICD may result from clinician biases based on patient body habitus, and body habitus may be associated with LV lead implantation failure.

OBJECTIVE

We sought to evaluate whether patient body mass index (BMI) was associated with planned use and implantation failure of CRT-D therapy.

METHODS

We studied all patients enrolled in the National Cardiovascular Data Registry ICD Registry who met standard CRT-D criteria and received either an ICD or CRT-D between 2010 and 2012. BMI was categorized based on World Health Organization classification. Using hierarchical logistic regression, two multivariate models adjusted for patient demographic and clinical characteristics were fit based on the following outcome variables: (1) planned implantation with CRT-D versus ICD and (2) failed versus successful LV lead placement.

RESULTS

Of 337,547 patients, 41,872 met inclusion criteria for the first analysis and 35,186 met criteria for the second analysis. After multivariable adjustment, patients with extreme (BMI > 40 kg/m²) obesity were less likely to receive guideline-concordant CRT-D compared with patients with normal weight (adjusted odds ratio (AOR), 0.86; 95% confidence interval (CI), 0.75-0.99; p = 0.04). Extreme (BMI > 40 kg/m²) obesity was associated with higher odds of failed LV lead placement (AOR, 1.35; 95% CI, 1.07-1.72, p = 0.01).

CONCLUSIONS

Compared with normal weight patients, extremely obese (BMI > 40 kg/m²) CRT-D eligible patients were less likely to be prescribed CRT-D and were at higher odds for failed LV lead placement.

Primary prevention with the implantable cardioverter-defibrillator in high-risk long-QT syndrome patients

AIMS

Prospective data regarding the role of implantable cardioverter-defibrillator (ICD) for the primary prevention of sudden cardiac death in patients with long QT syndrome (LQTS) is scarce. Herein, we explore the prospective Rochester LQTS ICD registry to assess the risk for appropriate shock in primary prevention in a real-world setting.

METHODS AND RESULTS

We studied 212 LQTS patients that had ICD implantation for primary prevention. Best-subsets proportional-hazards regression analysis was used to identify clinical variables that were associated with the first appropriate shock. Conditional models of Prentice, Williams, and Peterson were utilized for the analysis of recurrent appropriate shocks. During a median follow-up of 9.2 ± 4.9 years, there were 42 patients who experienced at least one appropriate shock and the cumulative probability of appropriate shock at 8 years was 22%. QTc ≥ 550 ms [hazard ratio (HR) 3.94, confidence interval (CI) 2.08-7.46; P < 0.001) and prior syncope on β-blockers (HR 1.92, CI 1.01-3.65; P = 0.047) were associated with increased risk of appropriate shock. History of syncope while on β-blocker treatment (HR 1.87, CI 1.28-2.72; P = 0.001), QTc 500-549 ms (HR 1.68, CI 1.10-2.81; P = 0.048), and QTc ≥ 550 ms (HR 3.66, CI 2.34-5.72; P < 0.001) were associated with increased risk for recurrent appropriate shocks, while β-blockers were not protective (HR 1.03, CI 0.63-1.68, P = 0.917). LQT2 (HR 2.10, CI 1.22-3.61; P = 0.008) and multiple mutations (HR 2.87, CI 1.49-5.53; P = 0.002) were associated with higher risk for recurrent shocks as compared with LQT1.

CONCLUSION

In this prospective ICD registry, we identified clinical and genetic variables that were associated appropriate shock risk. These data can be used for risk stratification in high-risk patients evaluated for primary prevention with ICD.

The Wearable Cardioverter Defibrillator: A Case Study Illustrating Physical Therapy Implications and Management in the Inpatient Setting

BACKGROUND AND PURPOSE

Sudden cardiac death causes an estimated 200,000 to 450,000 deaths per year in the USA. Although permanent implantation of an internal cardiac defibrillator offers a preventive intervention, the required assessment period for determining need creates vulnerability for patients who will benefit from this protection. The use of a wearable cardioverter defibrillator (WCD) for interim protection is rapidly increasing. There are no rehabilitation guidelines for patients wearing a WCD. This article reviews the WCD's purpose, considers implications and current challenges for use during rehabilitation, and illustrates this with a case report.

CASE DESCRIPTION

A 51-year-old male with coronary artery disease following prolonged hospitalization was fitted with a WCD during evaluation for an internal cardiac defibrillator. During inpatient rehabilitation, the therapy plan required unique considerations because of the presence of the WCD.

OUTCOMES

Recapitulating the patient's rehabilitation course illustrates the WCD's challenges, the benefits to exercise progression, and the safety measures used. The patient gained functional independence, with uninterrupted care, in the presence of the WCD.

DISCUSSION

Knowledgeable clinicians, attention to safety, and sufficient patient/caregiver education are essential for uninterrupted and successful rehabilitative care for WCD-wearing patients. Because of increasing clinical prevalence of WCDs in rehabilitation, it is critically important to share clinical experience and eventually conduct a systematic assessment.

Syncope and the risk of sudden cardiac death: Evaluation, management, and prevention

Syncope is a clinical syndrome defined as a relatively brief self-limited transient loss of consciousness (TLOC) caused by a period of inadequate cerebral nutrient flow. Most often the trigger is an abrupt drop of systemic blood pressure. True syncope must be distinguished from other common non-syncope conditions in which real or apparent TLOC may occur such as seizures, concussions, or accidental falls. The causes of syncope are diverse, but in most instances, are relatively benign (e.g., reflex and orthostatic faints) with the main risks being accidents and/or injury. However, in some instances, syncope may be due to more worrisome conditions (particularly those associated with cardiac structural disease or channelopathies); in such circumstances, syncope may be an indicator of increased morbidity and mortality risk, including sudden cardiac death (SCD). Establishing an accurate basis for the etiology of syncope is crucial in order to initiate effective therapy. In this review, we focus primarily on the causes of syncope that are associated with increased SCD risk (i.e., sudden arrhythmic cardiac death), and the management of these patients. In addition, we discuss the limitations of our understanding of SCD in relation to syncope, and propose future studies that may ultimately address how to improve outcomes of syncope patients and reduce SCD risk.

Predictors of sudden cardiac death in atrial fibrillation: The Atherosclerosis Risk in Communities (ARIC) study

We previously reported that incident atrial fibrillation (AF) is associated with an increased risk of sudden cardiac death (SCD) in the general population. We now aimed to identify predictors of SCD in persons with AF from the Atherosclerosis Risk in Communities (ARIC) study, a community-based cohort study. We included all participants who attended visit 1 (1987-89) and had no prior AF (n = 14,836). Incident AF was identified from study electrocardiograms and hospitalization discharge codes through 2012. SCD was physician-adjudicated. We used cause-specific Cox proportional hazards models, followed by stepwise selection (backwards elimination, removing all variables with p>0.10) to identify predictors of SCD in participants with AF. AF occurred in 2321 (15.6%) participants (age 45-64 years, 58% male, 18% black). Over a median of 3.3 years, SCD occurred in 110 of those with AF (4.7%). Predictors of SCD in AF included higher age, body mass index (BMI), coronary heart disease, hypertension, diabetes, current smoker, left ventricular hypertrophy, increased heart rate, and decreased albumin. Predictors associated only with SCD and not other cardiovascular (CV) death included increased BMI (HR per 5-unit increase, 1.15, 95% CI, 0.97-1.36, p = 0.10), increased heart rate (HR per SD increase, 1.18, 95% CI 0.99-1.41, p = 0.07), and low albumin (HR per SD decrease 1.23, 95% CI 1.02-1.48, p = 0.03). In the ARIC study, predictors of SCD in AF that are not associated with non-sudden CV death included increased BMI, increased heart rate, and low albumin. Further research to confirm these findings in larger community-based cohorts and to elucidate the underlying mechanisms to facilitate prevention is warranted.

Implantable cardioverter defibrillator and survival after out-of-hospital cardiac arrest due to acute myocardial infarction in Denmark in the years 2001-2012, a nationwide study

AIM

The purpose of this study was to describe the implantation of implantable cardioverter defibrillator after out-of-hospital cardiac arrest caused by myocardial infarction in Denmark 2001-2012 and subsequent survival.

METHODS

The Danish Cardiac Arrest Registry was used to identify patients ⩾18 years surviving to discharge without prior implantable cardioverter defibrillator. Information on cardioverter defibrillator implantation was obtained from the National Patient Registry.

RESULTS

We identified 974 myocardial infarction-out-of-hospital cardiac arrest patients surviving to hospital discharge, 130 of these patients (13%) had a cardioverter defibrillator implanted early (⩽40 days post-out-of-hospital cardiac arrest), 58 patients (6%) had late implantable cardioverter defibrillator (41-365 days post-out-of-hospital cardiac arrest). Odds of implantable cardioverter defibrillator implantation within one year were higher in patients receiving cardiopulmonary resuscitation (odds ratio (OR)_CPR: 1.99, confidence interval (CI): 1.23-3.22, p=0.01), and Charlson Comorbidity Index level 1, (OR_CCI1: 2.10, CI:1.25-3.49, p<0.01). Odds of a late implantable cardioverter defibrillator was higher in patients undergoing percutaneous coronary intervention (PCI) (OR_PCI: 3.67, CI: 1.35-9.97, p=0. 01). An early, but not late implantable cardioverter defibrillator was associated with increased survival (event time ratio_{Early ICD}: 1.45, CI: 1.11-1.90, p=0.01). Chronic heart failure, higher age groups, Charlson Comorbidity Index levels 1 to ⩾3 and male sex were associated with lower survival. Highest income was associated with higher survival.

CONCLUSION

Cardioverter defibrillator implantation rates in patients surviving an myocardial infarction-out-of-hospital cardiac arrest increased from 14% to 19% over the period. Of the total patient population, 13% had implantation earlier than recommended by guidelines, presumably as primary prevention of sudden cardiac death. Acute PCI and arrest later in the study period (increase one year) were predictors of late cardioverter defibrillator implantation. Early cardioverter defibrillator implantation was significantly associated with a long-term survival benefit, later implantation was not.

Deceleration capacity: A novel predictor for total mortality in patients with non-ischemic dilated cardiomyopathy

OBJECTIVES

We hypothesized that deceleration capacity (DC), a novel marker of cardiac autonomic modulation, is an independent predictor for mortality in patients with non-ischemic dilated cardiomyopathy (NICM).

BACKGROUND

NICM is associated with a high risk for sudden cardiac death (SCD). However there are no clinically established parameters available for risk stratification beyond LVEF. DC has been previously shown to be a strong independent predictor for total mortality in patients after myocardial infarction.

METHODS

Holter-ECG recordings of 201 patients NICM (83.1% male, mean age: 61.4years, mean LVEF: 33.3%) were analyzed by the method of phase-rectified-signal-averaging (PRSA) to obtain DC.

RESULTS

During a minimum follow-up of 40month 59 patients died. Kaplan Meyer Analysis showed a significantly higher mortality in patients with a DC below 4.5ms (log rank p=0.012) irrespective to the presence of atrial fibrillation.

CONCLUSIONS

Impaired DC is a powerful independent predictor for mortality in patients with NICM.

Symptomatic Trifascicular Block in Steinert's Disease: Is It Too Soon for a Pacemaker?

We report a case of a 62-year-old male with Steinert's disease who presented with progressive intermittent episodes of lightheadedness five years after he was diagnosed with the disease. On evaluation, he developed a new onset trifascicular block (first degree atrioventricular block, new onset right bundle branch block, and left anterior fascicular block). A dual chamber pacemaker was inserted and lightheadedness improved significantly.

Improve the prevention of sudden cardiac arrest in emerging countries: the Improve SCA clinical study design

AIMS

This study aims to demonstrate that primary prevention (PP) patients with one or more additional risk factors are at a similar risk of life-threatening ventricular arrhythmias when compared with secondary prevention (SP) patients, and would receive similar benefit from an implantable cardioverter defibrillator (ICD), or cardiac resynchronization therapy-defibrillator (CRT-D) implant. The study evaluates the benefits of therapy for high-risk patients in countries where defibrillation therapy for PP of SCA is underutilized.

METHODS

Enrolment will consist of 4800 ICD-eligible patients from Asia, Latin America, Eastern Europe, the Middle East, and Africa. Upon enrolment, patients will be categorized as SP or PP. Primary prevention patients will be assessed for additional risk factors: syncope/pre-syncope, non-sustained ventricular tachycardia, frequent premature ventricular contractions, and low left ventricular ejection fraction. Those PP patients with one or more risk factors will be categorized as '1.5' patients. Implant of an ICD/CRT-D will be left to the patient and/or physician's discretion. The primary endpoint will compare the appropriate ICD therapy rate between SP and 1.5 patients. The secondary endpoint compares mortality between 1.5 implanted and non-implanted patients.

CONCLUSION

The Improve SCA study will investigate a subset of PP patients, believed to be at similar risk of life-threatening ventricular arrhythmias as SP patients. Results may help clinicians identify and refer the highest risk PP patients for ICDs, help local societies expand guidelines to include PP of SCA utilizing ICDs, and provide additional geographical-relevant evidence to allow patients to make an informed decision whether to receive an ICD.

TRIAL REGISTRATION

NCT02099721.

Implantation of a defibrillator in a patient with an upper airway stimulation device

The patient is a 62-year-old man with continuous positive airway pressure-intolerant obstructive sleep apnea who was enrolled in a study for a hypoglossal nerve upper airway stimulation device (UAS). Nearly 2.5 years later, he was admitted to the hospital for unstable angina. Diagnostic workup revealed a prior myocardial infarction, an ejection fraction of 30% on maximal medical therapy, and episodes of nonsustained ventricular tachycardia. During hospitalization, the patient received an implantable cardioverter defibrillator (ICD). This is the first reported case of simultaneous use of a UAS and an ICD, and we report no untoward device interference between the two implantable devices.

Device therapy for acute systolic heart failure and atrial fibrillation

Patients with newly diagnosed cardiomyopathy require careful assessment of cause and initiation of treatment before the decision is made to implant an internal cardiac defibrillator. In patients with medicine-refractory atrial fibrillation and cardiomyopathy, atrioventricular node ablation and implantation of a biventricular pacemaker is the therapy of choice when tachycardia-induced cardiomyopathy is suspected and curative therapy is not possible.

Cost-effectiveness analysis of alternative cooling strategies following cardiac arrest

OBJECTIVES

Using survival and neurologic outcome as endpoints , this study explored the incremental cost effectiveness of three mutually exclusive cooling strategies employed after resuscitated out-of-hospital cardiac arrests.

DESIGN

Economic analysis based on retrospective data collection and Markov modeling.

SETTING

Modeling based on patients housed in a tertiary ICU setting.

PATIENTS

Patients >18 years following resuscitation from out-of-hospital cardiac arrest.

INTERVENTIONS

Therapeutic cooling vs. conventional care.

MEASUREMENTS AND MAIN RESULTS

Using societal-based analytic decision modeling with a lifetime study horizon, incremental cost effectiveness ratios (ICERs) for blanket, peritoneal lavage, and V-V ECMO cooling strategies were compared with conventional care. Comprehensive cost data were obtained from available literature, national and local databases; health utility data were abstracted from previous publications and converted to quality-adjusted life years (QALYs)/person and stratified by neurologic outcome state. Future costs were discounted using a standard 3% discount rate. Cooling blankets produced better overall health outcomes at a lower cost than conventional care and V-V ECMO. Peritoneal lavage added an additional 0.67 QALYs at an ICER of $58,329/QALY. Monte-Carlo simulations incorporating uncertainty in all parameters showed that peritoneal lavage was 70% likely to be the preferred, cost-effective therapy if one were willing to pay (WTP) $100,000/QALY.

CONCLUSIONS

This analysis suggests that blankets are the most cost effective cooling strategy for post-ROSC therapeutic hypothermia, with peritoneal lavage as an acceptable alternative at higher WTP thresholds. Though uncertainty about the optimal therapy could be reduced with additional research, these results can inform policy-makers and healthcare providers about cost effectiveness of alternative cooling modalities designed to improve neurologic outcome for this expanding patient population. This may be particularly relevant as societal-based cost effectiveness analyses become more widely incorporated into studies evaluating treatment for frequently encountered diseases.

Cardiac sarcoidosis and consequent arrhythmias

Myocardial involvement in patients with sarcoidosis can be difficult to diagnose, and requires a high index of suspicion and low threshold for screening. The presentation of cardiac sarcoidosis is variable, and can range from asymptomatic electrocardiographic changes to sudden cardiac death. This review provides an overview of the arrhythmic consequences of cardiac sarcoidosis, with emphasis on the electrophysiologist's role in recognition, diagnostic testing, and management of this rare disease.

Wall Thickness, Pulmonary Hypertension, and Diastolic Filling Abnormalities Predict Response to Postoperative Biventricular Pacing

OBJECTIVE

Post-cardiopulmonary bypass biventricular pacing improves hemodynamics but without clearly defined predictors of response. Based on preclinical studies and prior observations, it was suspected that diastolic dysfunction or pulmonary hypertension is predictive of hemodynamic benefit.

DESIGN

Randomized controlled study of temporary biventricular pacing after cardiopulmonary bypass.

SETTING

Single-center study at university-affiliated tertiary care hospital.

INTERVENTIONS

Patients who underwent bypass with preoperative ejection fraction ≤40% and QRS duration ≥100 ms or double-valve surgery were enrolled. At 3 time points between separation from bypass and postoperative day 1, pacing delays were varied to optimize hemodynamics.

PARTICIPANTS

Data from 43 patients were analyzed.

MEASUREMENTS AND MAIN RESULTS

Cardiac output and arterial pressure were measured under no pacing, atrial pacing, and biventricular pacing. Preoperative echocardiograms and pulmonary artery catheterizations were reviewed, and measures of both systolic and diastolic function were compared to hemodynamic response. Early after separation, improvement in cardiac output was positively correlated with pulmonary vascular resistance (R(2) = 0.97, p<0.001), ventricle wall thickness (R(2) = 0.72, p = 0.002)), and E/e', a measure of abnormal diastolic ventricular filling velocity (R(2) = 0.56, p = 0.04). Similar trends were seen with mean arterial pressure. QRS duration and ejection fraction did not correlate significantly with improvements in hemodynamics.

CONCLUSIONS

There may be an effect of biventricular pacing related to amelioration of abnormal diastolic filling patterns rather than electrical resynchronization in the postoperative state.

Lower omega-3 index is a marker of increased propensity of hypertensive rat heart to malignant arrhythmias

Polyunsaturated omega-3 fatty acids (omega-3 PUFA) are important components of cell membrane affecting its function and their deficiency is deleterious to health. We have previously shown that spontaneously hypertensive rats (SHR) are prone to life-threatening arrhythmias that are reduced by omega-3 PUFA intake. Purpose of this study was to explore plasma and red blood cells (RBC) profile of omega-3 and omega-6 PUFA as well as to determine omega-3 index, a risk factor for sudden cardiac death, in aged SHR and the effect of omega-3 PUFA intake. Male and female 12-month-old SHR and age-matched Wistar rats fed with omega-3 PUFA (200 mg/kg BW/day/2 month) were compared with untreated rats. Composition of omega-3 PUFA: alpha linolenic acid, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as well as omega-6 PUFA: linoleic acid and arachidonic acid was analyzed by gas chromatography. Results showed sex- and strain-related differences of basal omega-3 and omega-6 PUFA levels in plasma and RBC as well as in response to omega-3 PUFA intake. Comparing to Wistar rats omega-3 index, expressed as a percentage of EPA+DHA of total fatty acids, was lower in SHR and it increased due to consumption of omega-3 PUFA. Findings support our hypothesis that lower omega-3 index may be also a marker of increased propensity of the hypertensive rat heart to malignant arrhythmias.

Arrhythmogenic right ventricular cardiomyopathy in pregnancy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is predominantly a genetically determined heart muscle disorder that is characterized by fibro-fatty replacement of the right ventricular (RV) myocardium.(1)) The clinical spectrum of ARVC may represent from asymptomatic premature ventricular complexes to ventricular tachycardia (VT) and sudden cardiac death (SCD). It is a well-known leading cause of SCD in young adults.(2,3))There is no general consensus on the management of ARVC in pregnancy, and the preferred mode of delivery is uncertain. Herein, we report a case of ARVC diagnosed at 20 weeks of gestation following a sustained VT and treated with an implantable cardiac defibrillator (ICD). We also reviewed the current knowledge and approach to ARVC in pregnancy since the literature on this condition is based on case reports.

A novel algorithm to assess risk of heart failure exacerbation using ICD diagnostics: validation from RAFT

BACKGROUND

The integrated diagnostics (ID) algorithm is an implantable device-based tool that collates data pertaining to heart rhythm, heart rate, intrathoracic fluid status, and activity, producing a risk score that correlates with 30-day risk of heart failure (HF) hospitalization.

OBJECTIVE

We sought to validate the ID algorithm using the Resynchronization-Defibrillation for Ambulatory Heart Failure Trial.

METHODS

Diagnostic measures of the algorithm include OptiVol fluid index, nighttime heart rate, minutes of patient activity, heart rate variability, and combined measure of cardiac rhythm and biventricular pacing. Monthly evaluations of ID parameters were assessed for the development of HF symptoms and hospitalization for HF.

RESULTS

A total of 1224 patients were included: 741 (61%) with cardiac resynchronization therapy with defibrillator devices and 483 (39%) with implanted cardioverter-defibrillator only. The mean age was 66 ± 9 years, and 1013 (83%) were men. A total of 37,861 months of follow-up data were available, with 258 HF hospitalizations (event rate 0.68% per month). There were 33 HF hospitalizations during low-risk months (0.21% per month), 123 during medium-risk months (0.66% per month), and 102 during high-risk months (2.61% per month). Compared with low-risk months, and 95% confidence intervals) of HF hospitalizations during medium-risk months was 2.9 (2.0-4.4) and during high-risk months was 10.7 (6.9-16.6). Multivariable analysis demonstrated that each ID variable had independent association with HF hospitalization.

CONCLUSION

The risk of HF as determined by the ID algorithm correlated with HF hospitalization and several HF signs and symptoms among patients in the Resynchronization-Defibrillation for Ambulatory Heart Failure Trial. This may present a useful adjunct to detect early signs of HF and adjust therapy to reduce morbidity and costs involved with hospital admission.

Newer algorithms in bradycardia management

Permanent cardiac pacemakers (PPM) are effective in the treatment of bradycardia in a growing number of clinical scenarios. An appreciation of the capacity of PPMs to result in negative hemodynamic and proarrhythmic effects has grown alongside clinical experience with permanent pacing. Such experience has necessitated the development of algorithms aimed at optimizing device functionality across a broad spectrum of physiologic and pathologic conditions. This review highlights recent device-based algorithms used in automated threshold testing, reduction of right ventricular pacing, prevention and treatment of pacemaker-mediated tachycardia, mode switching for atrial tachyarrhythmias, rate-modulated pacing, and advances in arrhythmia storage and remote monitoring.

Decreased delivery of inappropriate shocks achieved by remote monitoring of ICD: a substudy of the ECOST trial

INTRODUCTION

Inappropriate shocks remain a highly challenging complication of implantable cardioverter defibrillators (ICD). We examined whether automatic wireless remote monitoring (RM) of ICD, by providing early notifications of triggering events, lowers the incidence of inappropriate shocks.

METHODS AND RESULTS

We studied 433 patients randomly assigned to RM (n = 221; active group) versus ambulatory follow-up (n = 212; control group). Patients in the active group were seen in the ambulatory department once a year, unless RM reported an event requiring an earlier ambulatory visit. Patients in the control group were seen in the ambulatory department every 6 months. The occurrence of first and further inappropriate shocks, and their causes in each group were compared. The characteristics of the study groups, including pharmaceutical regimens, were similar. Over a follow-up of 27 months, 5.0% of patients in the active group received ≥1 inappropriate shocks versus 10.4% in the control group (P = 0.03). A total of 28 inappropriate shocks were delivered in the active versus 283 in the control group. Shocks were triggered by supraventricular tachyarrhythmias (SVTA) in 48.5%, noise oversensing in 21.2%, T wave oversensing in 15.2%, and lead dysfunction in 15.2% of patients. The numbers of inappropriate shocks delivered per patient, triggered by SVTA and by lead dysfunction, were 74% and 98% lower, respectively, in the active than in the control group.

CONCLUSION

RM was highly effective in the long-term prevention of inappropriate ICD shocks.

Effects of flecainide on exercise-induced ventricular arrhythmias and recurrences in genotype-negative patients with catecholaminergic polymorphic ventricular tachycardia

BACKGROUND

Conventional therapy with beta-blockers is incompletely effective in preventing arrhythmic events in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT). We have previously discovered that flecainide in addition to conventional drug therapy prevents ventricular arrhythmias in patients with genotype-positive CPVT.

OBJECTIVE

To study the efficacy of flecainide in patients with genotype-negative CPVT.

METHODS

We studied the efficacy of flecainide for reducing ventricular arrhythmias during exercise testing and preventing arrhythmia events during long-term follow-up.

RESULTS

Twelve patients with genotype-negative CPVT were treated with flecainide. Conventional therapy failed to control ventricular arrhythmias in all patients. Flecainide was initiated because of significant ventricular arrhythmias (n = 8), syncope (n = 3), or cardiac arrest (n = 1). At the baseline exercise test before flecainide, 6 patients had ventricular tachycardia and 5 patients had bigeminal or frequent ventricular premature beats. Flecainide reduced ventricular arrhythmias at the exercise test in 8 patients compared to conventional therapy, similar to that in patients with genotype-positive CPVT in our previous report. Notably, flecainide completely prevented ventricular arrhythmias in 7 patients. Flecainide was continued in all patients except for one who had ventricular tachycardia at the exercise test on flecainide. During a follow-up of 48±94 months, arrhythmia events (sudden cardiac death and aborted cardiac arrest) associated with noncompliance occurred in 2 patients. Flecainide was not discontinued owing to side effects in any of the patients.

CONCLUSIONS

Flecainide was effective in patients with genotype-negative CPVT, suggesting that spontaneous Ca(2+) release from ryanodine channels plays a role in arrhythmia susceptibility, similar to that in patients with genotype-positive CPVT.

A randomized study of remote follow-up of implantable cardioverter defibrillators: safety and efficacy report of the ECOST trial

AIMS

The ECOST trial examined prospectively the long-term safety and effectiveness of home monitoring (HM) of implantable cardioverter defibrillators (ICD).

METHODS AND RESULTS

The trial's primary objective was to randomly compare the proportions of patients experiencing ≥ 1 major adverse event (MAE), including deaths from all causes, and cardiovascular, procedure-related, and device-related MAE associated with HM (active group) vs. ambulatory follow-ups (control group) in a sample of 433 patients. The 221 patients assigned to the active group were seen once a year, unless HM reported an ICD dysfunction or a clinical event requiring an ambulatory visit, while the 212 patients in the control group underwent ambulatory visits every 6 months. The characteristics of the study groups were similar. Over a follow-up of 24.2 months, 38.5% of patients in the active and 41.5% in the control group experienced ≥ 1 MAE (P < 0.05 for non-inferiority). The overall number of shocks delivered was significantly lower in the active (n = 193) than in the control (n = 657) group (P < 0.05) and the proportion of patients who received inappropriate shocks was 52% lower in the active (n = 11) than in the control (n = 22) group (P < 0.05). At the end of the follow-up, the battery longevity was longer in the active group because of a lower number of capacitor charges (499 vs. 2081).

CONCLUSION

Our observations indicate that long-term HM of ICD is at least as safe as standard ambulatory follow-ups with respect to a broad spectrum of MAE. It also lowered significantly the number of appropriate and inappropriate shocks delivered, and spared the device battery. Clinical trials registration NCT00989417.

A presumably benign human ether-a-go-go-related gene mutation (R176W) with a malignant primary manifestation of long QT syndrome

A 12-year-old girl presented with a first prolonged syncope. She was successfully resuscitated by external defibrillation after recording torsade de pointes tachycardia. Repeated electrocardiograms and a 12-channel Holter monitoring showed an intermittent prolongation of the QT interval. Genetic analysis identified a heterozygous point mutation in the KCNH2 gene, which is thought to be associated with a rather mild clinical phenotype of the long QT syndrome.

Pacing for drug-refractory or drug-intolerant hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a genetic disease with an autosomal-dominant inheritance for which negative inotropes are the most widely used initial therapies. Observational studies and small randomised trials have suggested symptomatic and functional benefits using pacing and several theories have been put forward to explain why. Pacing, although not the primary treatment for HCM, could be beneficial to patients with relative or absolute contraindications to surgery or alcohol ablation. Several randomised controlled trials comparing pacing to other therapeutic modalities have been conducted but no Cochrane-style systematic review has been done.

OBJECTIVES

To assess the effects of pacing in drug-refractory or drug-intolerant hypertrophic cardiomyopathy patients.

SEARCH METHODS

We searched the following on the 14/4/2010: CENTRAL (The Cochrane Library 2010, Issue 1), MEDLINE OVID (from 1950 onwards ), EMBASE OVID (from 1980 onwards ), Web of Science with Conference Proceedings (from 1970 onwards). No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials of either parallel or crossover design that assess the beneficial and harmful effects of pacing for hypertrophic cardiomyopathy were included. When crossover studies were identified, we considered data only from the first phase.

DATA COLLECTION AND ANALYSIS

Data from included studies were extracted onto a pre-formed data extraction paper by two authors independently. Data was then entered into Review Manager 5.1 for analysis. Risk of bias was assessed using the guidance provided in the Cochrane Handbook. For dichotomous data, relative risk was calculated; and for continuous data, the mean differences were calculated. Where appropriate data were available, meta-analysis was performed. Where meta-analysis was not possible, a narrative synthesis was written. A QUROUM flow chart was provided to show the flow of papers.

MAIN RESULTS

Five studies (reported in 10 papers) were identified. However, three of the five studies provided un-usable data. Thus the data from only two studies (reported in seven papers) with 105 participants were included for this review. There was insufficient data to compare results on all-cause mortality, cost effectiveness, exercise capacity, Quality of life and Peak O2 consumption.When comparing active pacing versus placebo pacing on exercise capacity, one study showed that exercise time decreased from (13.1 ± 4.4) minutes to (12.6 ± 4.3) minutes in the placebo group and increased from (12.1 ± 5.6) minutes to (12.9 ± 4.2) minutes in the treatment group (MD 0.30; 95% CI -1.54 to 2.14). Statistically significant data from the same study showed that left ventricular outflow tract obstruction decreased from (71 ± 32) mm Hg to (52 ± 34) mm Hg in the placebo group and from (70 ± 24) mm Hg to (33 ± 27) mm Hg in the active pacing group (MD -19.00; 95% CI -32.29 to -5.71). This study was also able to show that New York Heart Association (NYHA) functional class decreased from (2.5 ± 0.5) to (2.2 ± 0.6) in the inactive pacing group and decreased from (2.6 ± 0.5) to (1.7 ± 0.7) in the placebo group (MD -0.50; 95% CI -0.78 to -0.22).When comparing active pacing versus trancoronary ablation of septal hypertrophy (TASH), data from one study showed that NYHA functional class decreased from (3.2 ± 0.7) to (1.5 ± 0.5) in the TASH group and decreased from (3.0 ± 0.1) to (1.9 ± 0.6) in the pacemaker group. This study also showed that LV wall thickness remained unchanged in the active pacing group compared to reduction from (22 ± 4) mm to (17 ± 3) mm in the TASH group (MD 0.60; 95% CI -5.65 to 6.85) and that LV outflow tract obstruction decreased from (80 ± 35.5) mm Hg in the TASH group to (49.3 ± 37.7) mm Hg in the pacemaker group.

AUTHORS' CONCLUSIONS

Trials published to date lack information on clinically relevant end-points. Existing data is derived from small trials at high risk of bias, which concentrate on physiological measures. Their results are inconclusive. Further large and high quality trials with more appropriate outcomes are warranted.