Early markers of atrial fibrillation recurrence after pulmonary vein isolation.

BACKGROUND: Postprocedural atrial extrasystole (AES) frequency predicts atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) in patients with paroxysmal AF. However, the predictive value of preprocedural AES frequency is unknown. We investigate whether preprocedural AES frequency is a feasible marker to predict (timing of) AF recurrence after PVI. METHODS: Patients (N = 684) with paroxysmal or persistent AF undergoing first-time PVI were evaluated for (a) the frequency of AES/day on Holter recordings without AF prior to PVI, (b) AF episodes during the 90 days blanking period, and (c) AF recurrences afterward. The correlation between AES/day and both development and timing of AF recurrences was tested. RESULTS: Preprocedural AES/day was similar in patients with paroxysmal (66 [20-295] AES/day) and persistent AF (115 [12-248] AES/day, P = .915). During the blanking period, 302 (44.2%) patients showed AF episodes. AF recurred in 379 (55.4%) patients at 203 (105-400) days after PVI. AF recurred more frequently in patients with persistent (N = 104 [69.3%]) than in patients with paroxysmal AF (N = 275 [51.5%], P < .001). Frequency of AES prior to PVI was not correlated with development (P = .203) or timing (P = .478) of AF recurrences. AF recurrences occurred both more frequently (P < .001) and earlier (P < .000) in patients with AF during the blanking period. CONCLUSION: AES/day prior to PVI is not correlated with (timing of) AF during the blanking period or AF recurrences, and is therefore not a feasible marker for AF recurrences in patients with PAF. AF during the blanking period is correlated with AF recurrence.

Early mortality in prophylactic implantable cardioverter-defibrillator recipients: development and validation of a clinical risk score.

AIMS: To reduce sudden cardiac death, implantable cardioverter-defibrillators (ICDs) are indicated in patients with ischaemic and non-ischaemic dilated cardiomyopathy and a left ventricular ejection fraction (LVEF) ≤35%. Current guidelines do not recommend device therapy in patients with a life expectancy <1 year since benefit in these patients is low. In this study, we evaluated the incidence and predictors of early mortality (<1 year after implantation) in a consecutive primary prevention population. METHODS AND RESULTS: Analysis was performed on a prediction and validation cohort. The primary endpoint was all-cause mortality at 1 year. The prediction cohort comprised 861 prophylactic ICD recipients with ischaemic cardiomyopathy or dilated cardiomyopathy from the Academic Medical Center (Amsterdam) and Thorax Center Twente (Enschede). Detailed clinical data were collected. After multivariate analysis, a risk score was developed based on age ≥75 years, LVEF ≤ 20%, history of atrial fibrillation, and estimated glomerular filtration rate (eGFR) ≤30 mL/min/1.73 m(2). Using these predictors, a low (≤1 factor), intermediate (2 factors), and high (≥3 factors) risk group could be identified with 1-year mortality of, respectively, 3.4, 10.9, and 38.9% (P< 0.01). Afterwards, the risk score was validated in 706 primary prevention patients from the Erasmus Medical Center (Rotterdam). One-year mortality was, respectively, 2.5, 13.2, and 46.3% (all P< 0.01). CONCLUSION: A simple risk score based on age, LVEF, eGFR, and atrial fibrillation can identify patients at low, intermediate, and high risk for early mortality after ICD implantation. This may be helpful in the risk assessment of ICD candidates.

Implantable cardioverter-defibrillators in hypertrophic cardiomyopathy: patient outcomes, rate of appropriate and inappropriate interventions, and complications.

BACKGROUND: Sudden cardiac death (SCD) is the most devastating complication of hypertrophic cardiomyopathy (HCM), but this can be prevented by an implantable cardioverter-defibrillator (ICD). The aim of this study is to evaluate HCM patients with ICDs for primary or secondary prevention of SCD. METHODS: The study population consisted of all HCM patients with an ICD in 2 tertiary referral clinics. End points during follow-up were total and cardiac mortality, appropriate and inappropriate ICD intervention, and device-related complications. Cox-regression analysis was performed to identify predictors of outcome. RESULTS: ICDs were implanted in 134 patients with HCM (mean age 44 ± 17 years, 34% women, 4.2 ± 4.8 years follow-up). Annualized cardiac mortality rate was 3.4% per year and associated with New York Heart Association class III or IV (HR 5.2 [2.0-14, P = .002]) and cardiac resynchronization therapy (HR 6.3 [2.1-20, P = .02]). Appropriate ICD interventions occurred in 38 patients (6.8%/year) and was associated with implantation for secondary prevention of SCD (HR 4.0 [1.8-9.1], P = .001) and male gender (HR 3.3 [1.2-9.0], P = .02). Inappropriate ICD intervention occurred in 21 patients (3.7%/year) and in 20 patients device related complications were documented (3.6%/year). CONCLUSION: ICDs successfully abort life-threatening arrhythmias in HCM patients at increased risk of SCD with an annualized intervention rate of 6.8% per year. End-stage heart failure is the main cause of mortality in these patients. The annualized rate of inappropriate ICD intervention was 3.7% per year, whereas device-related complications occurred 3.6% per year.

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.

Outcome and complications after implantable cardioverter defibrillator therapy in hypertrophic cardiomyopathy: systematic review and meta-analysis.

BACKGROUND: Previous observational studies demonstrated that patients with hypertrophic cardiomyopathy at risk for sudden cardiac death (SCD) may benefit from implantable cardioverter defibrillator (ICD) therapy. A complete overview of outcome and complications after ICD therapy is currently not available. This study pools data from published studies on outcome and complications after ICD therapy in patients with hypertrophic cardiomyopathy. METHODS AND RESULTS: A PubMed database search returned 27 studies on 16 cohorts reporting outcome and complications after ICD therapy in patients with hypertrophic cardiomyopathy. In case of >1 publications on a particular cohort, the publication with the largest number of patients was included in the meta-analysis. ICD interventions, complications, and mortality rates were extracted, pooled, and analyzed. There were 2190 patients (mean age, 42 years; 38% women), most of whom (83%) received an ICD for primary prevention of SCD. Risk factors for SCD were left ventricular wall thickness ≥30 mm (20%), family history of SCD (43%), nonsustained ventricular tachycardia (46%), syncope (41%), and abnormal blood pressure response (25%). During the 3.7-year follow-up, the annualized cardiac mortality rate was 0.6%, the noncardiac mortality rate was 0.4%, and the appropriate ICD intervention rate was 3.3%. The annualized inappropriate ICD intervention rate was 4.8% and the annualized ICD-related complication rate was 3.4%. CONCLUSIONS: This meta-analysis demonstrates a low cardiac and noncardiac mortality rate after ICD therapy in patients with hypertrophic cardiomyopathy. Appropriate ICD intervention occurred at a rate of 3.3%/year, thereby, most probably, preventing SCD. Inappropriate ICD intervention and complications are not uncommon.

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 defibrillator early after primary percutaneous intervention for ST-elevation myocardial infarction: rationale and design of the Defibrillator After Primary Angioplasty (DAPA) trial.

BACKGROUND: It has been shown that an implantable cardioverter defibrillator (ICD) may be beneficial when added to optimal drug treatment in patients with reduced left ventricular function who survive a myocardial infarction (MI). However, it is not known whether patients with increased risk of death after primary percutaneous coronary intervention (PCI) for ST-elevation MI also have benefit of prophylactic ICD therapy to reduce sudden cardiac death. METHODS AND STUDY DESIGN: The DAPA trial is designed to evaluate the efficacy and safety of ICD in high-risk patients after primary PCI for ST-elevation MI. In this randomized multicenter controlled study, a total of 700 patients will be included. Enrolment started in October 2004. Inclusion criteria are thrombolysis in myocardial infarction flow less than 3 after primary PCI or left ventricular ejection fraction lower than 30% as measured short after admission for the index MI. Patients will be randomized between 30 and 60 days after their MI. The primary end point will be total death during the follow-up period of at least 3 years for each patient. CONCLUSIONS: This multicenter trial of patients at high risk of death after primary angioplasty for ST-elevation MI will evaluate prophylactic ICD therapy in addition to the current standard of care.

Prevention of inappropriate therapy in implantable cardioverter-defibrillators: results of a prospective, randomized study of tachyarrhythmia detection algorithms.

OBJECTIVES: The purpose of this randomized study was to investigate the performance of single- and dual-chamber tachyarrhythmia detection algorithms. BACKGROUND: A proposed benefit of dual-chamber implantable cardioverter-defibrillators (ICDs) is improved specificity of tachyarrhythmia detection. METHODS: All ICD candidates received a dual-chamber ICD and were randomized to programmed single- or dual-chamber detection. Of 60 patients (47 male, age 58 +/- 14 years, left ventricular ejection fraction 30%), 29 had single-chamber and 31 had dual-chamber settings. The detection results were corrected for multiple episodes within a patient with the generalized estimating equations method. RESULTS: A total of 653 spontaneous arrhythmia episodes (39 patients) were classified by the investigators; 391 episodes were ventricular tachyarrhythmia (32 patients). All episodes of ventricular tachyarrhythmias were appropriately detected in both settings. In 25 patients, 262 episodes of atrial tachyarrhythmias were recorded. Detection was inappropriate for 109 atrial tachyarrhythmia episodes (42%, 18 patients). Rejection of atrial tachyarrhythmias was not significantly different between both groups (p = 0.55). Episodes of atrial flutter/tachycardia were significantly more misclassified (p = 0.001). Overall, no significant difference in tachyarrhythmia detection (atrial and ventricular) between both settings was demonstrated (p = 0.77). CONCLUSIONS: The applied detection criteria in dual-chamber devices do not offer benefits in the rejection of atrial tachyarrhythmias. Discrimination of atrial tachyarrhythmias with a stable atrioventricular relationship remains a challenge.