The ICD for Primary Prevention in Patients With Inherited Cardiac Diseases

Background—

Indications for prophylactic implantable cardioverter-defibrillator (ICD) therapy in patients with inherited cardiac diseases stem from observational studies and are uncertain. This study evaluates the efficacy and harm rate of ICD implantations for primary prevention compared with secondary prevention in inherited cardiac diseases.

Methods and Results—

Between January 1, 1993, and April 1, 2011, 354 patients with inherited cardiac diseases were treated with ICDs. Incidence rates of appropriate shocks in primary prevention patients with arrhythmogenic right ventricular cardiomyopathy and hypertrophic cardiomyopathy were 4.2 to 6.7/100 patient-years, whereas the risk for appropriate shocks in primary prevention patients with Brugada syndrome, long QT syndrome, or carrying the DPP6 haplotype approached zero. Conversely, in secondary prevention patients there was a considerably higher incidence rate of appropriate shocks. None of the indications for primary prevention were associated with appropriate shock therapy. One hundred twenty-three patients (35%) experienced ICD-related adverse events.

Conclusions—

For Brugada syndrome, long QT syndrome, and DPP6 the efficacy of an ICD for primary prevention contrasts with the amount of harm, and factors that formed the indication for ICD implantation do not relate to the occurrence of appropriate shocks. The higher appropriate discharge rates in arrhythmogenic right ventricular cardiomyopathy and hypertrophic cardiomyopathy compared with primary electric diseases might result from a more advanced risk stratification scheme in these inherited cardiomyopathies.

Troubleshooting in transatrial tricuspid valve-in-valve implantation

The established treatment for degenerated stenotic tricuspid bioprostheses is reoperation. Recently, transcatheter tricuspid valve implantation has been reported as an alternative option. This case report describes a complex transcatheter tricuspid valve implantation in a degenerated Medtronic intact 31 mm bioprosthesis. Implantation of a 26 mm Edwards Sapien valve failed, subsequent transcatheter implantation of a 29 mm Edwards Sapien valve was successful.

Unidentified candidates for cardiac resynchronization therapy: guideline adherence in a large academic outpatient clinic in the Netherlands

BACKGROUND

Cardiac resynchronization therapy (CRT) reduces mortality and morbidity in patients with heart failure, diminished left ventricular function, and prolonged QRS duration. We investigated adherence to the CRT guidelines and screened for unidentified CRT candidates.

METHODS

Every unique patient visiting the outpatient clinic during three months was analyzed. In patients with QRS duration ≥120 ms or a paced QRS duration ≥200 ms on the electrocardiogram (ECG), left ventricular ejection fraction (LVEF), and New York Heart Association functional class were retrieved from hospital records and compared with the institutional implantable cardioverter defibrillator/pacemaker implantation database. The appropriateness of CRT indication was studied in patients who previously received CRT.

RESULTS

QRS duration was <120 ms in 2,609 out of 3,053 patients screened. LVEF was ≤35% in 28 out of 282 patients with a QRS duration ≥120 ms or a paced QRS duration ≥200 ms. Of those, 11 patients were potential CRT candidates. During follow-up, three patients received a CRT device, two patients died, one patient improved, and one refused implantation, leaving four potential CRT candidates. Forty-six patients previously implanted with a CRT device visited the outpatient clinic, of whom 42 (91.3%) fulfilled the guideline criteria. Hence, 45 out of 49 patients (91.8%) qualifying for CRT had received CRT or were implanted during follow-up, and four (8.2%) CRT candidates were unidentified.

CONCLUSION

In a large, tertiary academic hospital, >91% of patients fulfilling guideline criteria received CRT, and 8.2% of patients were unidentified. Systematic ECG screening of every patient may prove a simple tool to detect CRT candidates who were otherwise unrecognized.

Sudden Cardiac Death in Adult Congenital Heart Disease

Background—

Sudden cardiac death (SCD) is a major cause of mortality in adults with congenital heart disease (CHD). The aim of this study was to determine the adult CHD population at risk of SCD and the clinical parameters associated with SCD.

Methods and Results—

We performed a multicenter case-control study. Patients who died suddenly as a result of proven or presumed arrhythmia were included (cases). For each case, 2 controls matched on diagnosis, type of surgical intervention, age, and gender were included. From 3 databases including 25 790 adults with CHD, 1189 deaths (5%) were identified, of whom 213 patients (19%) died suddenly. Arrhythmic death occurred in 171 of 1189 patients. The underlying cardiac lesions were mild, moderate, and severe CHD in 12%, 33%, and 55% of the SCD cases, respectively. Clinical variables associated with SCD were supraventricular tachycardia (odds ratio [OR], 3.5; 95% confidence interval [CI], 1.5–7.9; P= 0.004), moderate to severe systemic ventricular dysfunction (OR, 3.4; 95% CI, 1.1–10.4; P= 0.034), moderate to severe subpulmonary ventricular dysfunction (OR, 3.4; 95% CI, 1.1–10.2; P= 0.030), increased QRS duration (OR, 1.34 [per 10-ms increase]; 95% CI, 1.10–1.34; P =0.008), and QT dispersion (OR, 1.22 [per 10-ms increase]; 95% CI, 1.22–1.48; P =0.008).

Conclusions—

The clinical parameters found to be associated with SCD in adults with a broad spectrum of CHD, including systemic right ventricles, are similar to those in ischemic heart disease. Moreover, even those patients with mild cardiac lesions are potentially at risk for SCD. This highlights the need for further prospective studies as well as vigilant ongoing follow-up of the adult with CHD.

The entirely subcutaneous implantable cardioverter-defibrillator: initial clinical experience in a large Dutch cohort

OBJECTIVES

The purpose of the study was to evaluate the efficacy and safety of the entirely subcutaneous implantable cardioverter-defibrillator (S-ICD).

BACKGROUND

A new entirely S-ICD has been introduced, that does not require lead placement in or on the heart. The authors report the largest multicenter experience to date with the S-ICD with a minimum of 1-year follow-up in the first 118 Dutch patients who were implanted with this device.

METHODS

Patients were selected if they had a class I or IIa indication for primary or secondary prevention of sudden cardiac death. All consecutive patients from 4 high-volume centers in the Netherlands with an S-ICD implanted between December 2008 and April 2011 were included.

RESULTS

A total of 118 patients (75% males, mean age 50 years) received the S-ICD. After 18 months of follow-up, 8 patients experienced 45 successful appropriate shocks (98% first shock conversion efficacy). No sudden deaths occurred. Fifteen patients (13%) received inappropriate shocks, mainly due to T-wave oversensing, which was mostly solved by a software upgrade and changing the sensing vector of the S-ICD. Sixteen patients (14%) experienced complications. Adverse events were more frequent in the first 15 implantations per center compared with subsequent implantations (inappropriate shocks 19% vs. 6.7%, p = 0.03; complications 17% vs. 10%, p = 0.10).

CONCLUSIONS

This study demonstrates that the S-ICD is effective in terminating ventricular arrhythmias. There is, however, a considerable percentage of ICD related adverse events, which decreases as the therapy evolves and experience increases.

Implantable cardioverter-defibrillators have reduced the incidence of resuscitation for out-of-hospital cardiac arrest caused by lethal arrhythmias

BACKGROUND

Over the last decades, a gradual decrease in ventricular fibrillation (VF) as initial recorded rhythm during resuscitation for out-of-hospital cardiac arrest (OHCA) has been noted. We sought to establish the contribution of implantable cardioverter-defibrillator (ICD) therapy to this decline.

METHODS AND RESULTS

Using a prospective database of all OHCA resuscitation in the province North Holland in the Netherlands (Amsterdam Resuscitation Studies [ARREST]), we collected data on all patients in whom resuscitation for OHCA was attempted in 2005-2008. VF OHCA incidence (per 100 000 inhabitants per year) was compared with VF OHCA incidence data during 1995-1997, collected in a similar way. We also collected ICD interrogations of all ICD patients from North Holland and identified all appropriate ICD shocks in 2005-2008; we calculated the number of prevented VF OHCA episodes, considering that only part of the appropriate shocks would result in avoided resuscitation. VF OHCA incidence decreased from 21.1/100 000 in 1995-1997 to 17.4/100 000 in 2005-2008 (P<0.001). Non-VF OHCA increased from 12.2/100 000 to 19.4/100 000 (P<0.001). VF as presenting rhythm declined from 63% to 47%. In 2005-2008, 1972 ICD patients received 977 shocks. Of these shocks, 339 were caused by a life-threatening arrhythmia. We estimate that these 339 shocks have prevented 81 (minimum, 39; maximum, 152) cases of VF OHCA, corresponding with 33% (minimum, 16%; maximum, 63%) of the observed decline in VF OHCA incidence.

CONCLUSIONS

The incidence of VF OHCA decreased over the last 10 years in North Holland. ICD therapy explained a decrease of 1.2/100 000 inhabitants per year, corresponding with 33% of the observed decline in VF OHCA.

Rationale and design of the PRAETORIAN trial: a Prospective, RAndomizEd comparison of subcuTaneOus and tRansvenous ImplANtable cardioverter-defibrillator therapy

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) are widely used to prevent fatal outcomes associated with life-threatening arrhythmic episodes in a variety of cardiac diseases. These ICDs rely on transvenous leads for cardiac sensing and defibrillation. A new entirely subcutaneous ICD overcomes problems associated with transvenous leads. However, the role of the subcutaneous ICD as an adjunctive or primary therapy in patients at risk for sudden cardiac death is unclear.

STUDY DESIGN

The PRAETORIAN trial is an investigator-initiated, randomized, controlled, multicenter, prospective 2-arm trial that outlines the advantages and disadvantages of the subcutaneous ICD. Patients with a class I or IIa indication for ICD therapy without an indication for bradypacing or tachypacing are included. A total of 700 patients are randomized to either the subcutaneous or transvenous ICD (1:1). The study is powered to claim noninferiority of the subcutaneous ICD with respect to the composite primary endpoint of inappropriate shocks and ICD-related complications. After noninferiority is established, statistical analysis is done for potential superiority. Secondary endpoint comparisons of shock efficacy and patient mortality are also made.

CONCLUSION

The PRAETORIAN trial is a randomized trial that aims to gain scientific evidence for the use of the subcutaneous ICD compared with the transvenous ICD in a population of patients with conventional ICD with respect to major ICD-related adverse events. This trial is registered at ClinicalTrials.gov with trial ID NCT01296022.

Implantable Cardioverter Defibrillator Therapy in Adults With Congenital Heart Disease

Background—

The value of implantable cardioverter defibrillators (ICDs) in adults with congenital heart disease (CHD) is unknown. We investigated the long-term outcome after ICD implantation and developed a simple risk stratification score for ICD therapy.

Methods and Results—

A total of 136 adults with CHD and ICD (mean age±SD, 41±13 years; 67% male) were identified from 10 tertiary referral centers in the Netherlands and Belgium. The indication for ICD implantation was primary prevention in 50% of patients. Diagnoses included tetralogy of Fallot (51%), septal defects (20%), (congenitally corrected) transposition of the great arteries (13%), and other (16%). Thirty-nine patients (29%) received appropriate ICD shocks during a median follow-up of 4.6 years. Secondary prevention indication (hazard ratio [HR], 3.6; 95% CI, 1.3–9.5; P= 0.009), coronary artery disease (HR, 2.7; 95% CI, 1.0–7.2; P= 0.042), and symptomatic nonsustained ventricular tachycardia (NSVT; HR, 9.1; 95% CI, 2.8–29.2; P= 0.001) were associated with appropriate ICD shocks. A risk score was developed to evaluate the likelihood of appropriate ICD shocks. The 8-year survival curve to first appropriate shocks was 94%, 57%, and 26% for low-, intermediate-, and high-risk patients, respectively. In primary prevention, symptomatic NSVTs (HR, 8.0; 95% CI, 2.3–27.1; P= 0.001) and subpulmonary ventricular dysfunction (HR, 3.0; 95% CI, 1.2–12.6; P =0.02) were associated with appropriate shocks in univariable analysis. Inappropriate shocks occurred in 41 patients (30%). In addition, 40 patients (29%) experienced 45 implantation-related complications.

Conclusions—

Adults with CHD and ICDs receive high rates of appropriate and effective shocks. Patients with secondary prevention indication, coronary artery disease, and symptomatic NSVT are at highest risk of receiving appropriate ICD shocks. ICD implantation is accompanied by considerable morbidity, including inappropriate shocks and procedure- related complications.

[Thoracoscopic treatment of atrial fibrillation]

Atrial fibrillation (AF) is the most common arrhythmia in humans. The majority of patients with AF can function reasonably well on a daily basis with anti-arrhythmic drugs. A small proportion of patients with AF remain symptomatic despite anti-arrhythmic drugs. They might have an indication for invasive treatment for AF, such as endovascular catheter ablation (effective particularly in paroxysmal AF) or the Cox-Maze procedure (open heart surgery), in which the conductivity between the pulmonary veins and the left atrium is blocked. Hybrid thoracoscopic pulmonary vein isolation (VATS-PVI) is a new minimally invasive treatment for AF where the cardiothoracic surgeon and cardiologist work closely together. During this procedure the cardiologist performs electrophysiological measurements to verify whether the blockade of conductivity is successful. This approach has a success rate of 86% at a follow-up of 12 months.

Effect of remote ischemic conditioning on atrial fibrillation and outcome after coronary artery bypass grafting (RICO-trial)

Background

Pre- and postconditioning describe mechanisms whereby short ischemic periods protect an organ against a longer period of ischemia. Interestingly, short ischemic periods of a limb, in itself harmless, may increase the ischemia tolerance of remote organs, e.g. the heart (remote conditioning, RC). Although several studies have shown reduced biomarker release by RC, a reduction of complications and improvement of patient outcome still has to be demonstrated. Atrial fibrillation (AF) is one of the most common complications after coronary artery bypass graft surgery (CABG), affecting 27-46% of patients. It is associated with increased mortality, adverse cardiovascular events, and prolonged in-hospital stay. We hypothesize that remote ischemic pre- and/or post-conditioning reduce the incidence of AF following CABG, and improve patient outcome.

Methods/design

This study is a randomized, controlled, patient and investigator blinded multicenter trial. Elective CABG patients are randomized to one of the following four groups: 1) control, 2) remote ischemic preconditioning, 3) remote ischemic postconditioning, or 4) remote ischemic pre- and postconditioning. Remote conditioning is applied at the arm by 3 cycles of 5 minutes of ischemia and reperfusion. Primary endpoint is the incidence AF in the first 72 hours after surgery, detected using a Holter-monitor. Secondary endpoints include length-of-stay on the intensive care unit and in-hospital, and the occurrence of major adverse cardiovascular events at 30 days, 3 months and 1 year.

Based on an expected incidence in the control group of 27%, 195 patients per group are needed to detect with 80% power a reduction by 45% following either pre- or postconditioning, while allowing for a 10% dropout and at an alpha of 0.05. With the combined intervention expected to be stronger, we need 75 patients in this group to detect a reduction in incidence of AF of 60%.

Discussion

The RICO-trial (the effect of Remote Ischemic Conditioning on atrial fibrillation and Outcome) is a randomized controlled multicenter trial, designed to investigate whether remote ischemic pre- and/or post-conditioning of the arm reduce the incidence of AF following CABG surgery.

Trial registration

ClinicalTrials.gov under NCT01107184.

Shift in the pattern of autonomic atrial innervation in subjects with persistent atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is a multifactorial disease of the atria.

OBJECTIVE

We studied the differences in the atrial autonomic innervation pattern in subjects with AF compared with sinus rhythm (SR).

METHODS

Preparation of postmortem isolated hearts of subjects with documented persistent AF (group A) and SR (group B) included: (1) histological sectioning of predefined areas and quantification of nerve density, and (2) differentiation using immunohistochemistry in adrenergic (sympathetic, tyrosine-hydroxylase antibody), cholinergic (parasympathetic, choline-acetyltransferase antibody) and mixed (adrenergic and cholinergic staining) nerves.

RESULTS

Characteristics of subjects in group A (N = 15) and group B (N = 24) did not differ. The mean overall nerve density was similar between groups (A: 0.31 ± 0.25/mm(2); B: 0.35 ± 0.25/mm(2); P = .87). Nerve density appeared higher in the region of the pulmonary vein ostia and antrum (group A: 0.38 ± 0.21/mm(2); group B: 0.32 ± 0.19/mm(2),) compared with other locations of the right and left atrium. A total of 2,224 (group A: 685; group B: 1539) nerves were differentiated using immunohistochemistry. There was a high degree of colocalization of adrenergic and cholinergic nerves (group A: 80% mixed staining, group B: 69% mixed staining). In group A hearts there was a significantly lower density of predominantly cholinergic nerves (0.025 ± 0.052/mm(2) vs. 0.058 ± 0.099/mm(2); P = .008) and a higher density of nerves containing adrenergic components (0.24 ± 0.18/mm(2) vs. 0.18 ± 0.17/mm(2), P = .046).

CONCLUSION

Overall autonomic nerve density did not differ between atria with persistent AF compared with SR. On a morphological level, we detected a shift toward a lower density of cholinergic nerves and a higher density of nerves containing adrenergic components in AF subjects.

Treatment of congenital heart disease: risk-reducing measures in young adults

Adults with congenital heart disease form a new and relatively young population, since surgical treatment of heart defects became available three to four decades ago. Owing to improved survival this population is steadily growing in number and age. Little is known regarding long-term survival; however, late complications occur frequently. During adulthood, almost half of the patients have one or more complication, such as endocarditis, stroke, systemic or pulmonary hypertension, aortic aneurysm or dissection and arrhythmias. Heart failure and sudden cardiac death are the main causes of death. Treatment of adults with congenital heart disease is aimed at the reduction of symptoms, but also at minimizing the risk and severity of late complications. In this article the most recent advances in the treatment of congenital heart disease will be discussed. The main focus of the article will be on pharmacological, interventional and surgical interventions that reduce the risk of heart failure, arrhythmias, vascular complications, pulmonary hypertension and endocarditis.

Reentry in survived subepicardium coupled to depolarized and inexcitable midmyocardium: insights into arrhythmogenesis in ischemia phase 1B

BACKGROUND

Delayed ventricular arrhythmias during acute myocardial ischemia (1B arrhythmias) are associated with an increase in tissue impedance and are most likely sustained in a thin subepicardial layer.

OBJECTIVE

The goal of this study was to test the hypothesis that heterogeneous uncoupling between depolarized midmyocardium and surviving subepicardium results in heterogeneous refractoriness in the latter, providing the reentry substrate after a premature beat.

METHODS

A 3-dimensional bidomain slab was constructed comprising a normal subepicardial layer coupled to a slightly depolarized (-80 to -60 mV) but inexcitable midmyocardium. Experimentally measured tissue impedance served as input for the model. Four stages of heterogeneous uncoupling between the 2 layers were simulated, each corresponding to an experimental ischemic impedance value. Effective refractory periods (ERP), conduction velocities, and inducibility of reentry were examined.

RESULTS

Heterogeneous uncoupling resulted in subepicardial ERP dispersion, allowing reentry to occur. The minimum ERP dispersion needed to induce reentry was 28 ms. Reentry induction was only possible in this model at the 2 intermediate stages of uncoupling, and only when midmyocardial resting membrane potential was more negative than -60 mV. Complete uncoupling of the layers resulted in normal subepicardial conduction without arrhythmias. The minimum length of the reentrant pathway was 2.5 cm, comparable to 2.4 cm reported in previous experiments.

CONCLUSION

Heterogeneous uncoupling to a negative sink such as depressed inexcitable midmyocardium may be a substrate for ischemia 1B arrhythmias. Total uncoupling removes the arrhythmogenic substrate.