Search PubMed⌕ Search

Biomedical subjects

Carsten W Israel

Publications and source records attributed to Carsten W Israel.

At least 19 recordsLinked to original sources
PubMed2006

Effect of amiodarone and sotalol on ventricular defibrillation threshold: the optimal pharmacological therapy in cardioverter defibrillator patients (OPTIC) trial.

BACKGROUND: Many patients with implanted cardioverter defibrillators (ICDs) receive adjunctive antiarrhythmic drug therapy, most commonly amiodarone or sotalol. The effects of these drugs on defibrillation energy requirements have not been previously assessed in a randomized controlled trial. METHODS AND RESULTS: The Optimal Pharmacological Therapy in Cardioverter Defibrillator Patients (OPTIC) trial was a randomized clinical trial evaluating the efficacy of amiodarone plus beta-blocker and sotalol versus beta-blocker alone for reduction of ICD shocks. Within OPTIC, a prospectively designed substudy evaluated the effects of the 3 treatment arms on defibrillation energy requirements. Defibrillation thresholds (DFTs) were measured (binary step-down protocol) at baseline and again after 8 to 12 weeks of therapy in 94 patients, of whom 29 were randomized to receive beta-blocker therapy (control group), 35 to amiodarone plus beta-blocker, and 30 to sotalol. In the control group, the mean DFT decreased from 8.77+/-5.15 J at baseline to 7.13+/-3.43 J (P=0.027); in the amiodarone group, DFT increased from 8.53+/-4.29 to 9.82+/-5.84 J (P=0.091). In the sotalol group, DFT decreased from 8.09+/-4.81 to 7.20+/-5.30 J (P=0.21). DFT changes in the beta-blocker and the amiodarone group were significantly different (P=0.006). In all patients, adequate safety margins for defibrillation were maintained. No clinical variable predicted baseline DFT or changes in DFT on therapy. CONCLUSIONS: Although amiodarone increased DFT, the effect size with modern ICD systems is very small. Therefore, DFT reassessment after the institution of antiarrhythmic drug therapy with amiodarone or sotalol is not routinely required.

Adrenergic beta-Antagonists↗
PubMed2006

Efficacy and safety of ICD therapy in a population of elderly patients treated with optimal background medication.

INTRODUCTION: Implantable cardioverter-defibrillator (ICD) therapy has been shown to improve survival in patients with structural heart disease and at high risk for life threatening ventricular arrhythmias. Whether elderly patients benefit from device therapy in a similar way as younger patients is largely unknown. METHODS: We retrospectively analyzed data from 375 consecutive ICD recipients with structural heart disease. Patients were divided into two groups, younger than 70 years at time of ICD implantation (group 1) or 70 years or older (group 2). Main outcome measures were time to death from any cause and time from first appropriate ICD therapy to death. RESULTS: Group 1 and 2 patients were comparable with respect to clinical presentation and average follow-up duration. In the elderly patient group, 78% received an ICD for secondary prevention versus 63% in group 1 (p = 0.007). During a mean follow-up period of 26.5 +/- 18.1 months, there was no significant difference in overall mortality among the two groups: 47 patients died, 34 (12.5%) of group 1 versus 13 (12.7%) of group 2. The average time to death was 28.4 +/- 16.7 vs 30.4 +/- 22.1 months after device implantation, respectively (p = ns). There was no difference in time from device implantation to first adequate ICD therapy and time from first appropriate ICD therapy to death among the two groups (p = ns). Device associated complications were comparable in both groups. CONCLUSIONS: Elderly ICD recipients had comparable survival rates and appropriate use of the ICD compared to younger individuals.

Age Factors↗
PubMed2006

The role of pacing mode in the development of atrial fibrillation.

Asynchronous ventricular pacing has been shown to increase the risk of development of atrial fibrillation (AF) because of various mechanisms: retrograde atrioventricular (AV) conduction with increase in atrial pressure causing acute atrial stretch and reverse flow in the pulmonary veins, mitral regurgitation, reduced coronary blood flow, adverse neuroendocrine reactions, etc. Dual-chamber pacing preserves atrioventricular synchrony. However, in randomized multicentre trials comparing VVI(R) with DDD(R) pacing, AF is only slightly less frequent in the dual-chamber mode. This is most likely due to unnecessary ventricular pacing, which is frequent in dual-chamber pacing. At nominal values, dual-chamber devices usually do not permit intrinsic AV conduction but promote delivery of the ventricular stimulus at an inappropriate time in an inappropriate place. Programming of long AV delays facilitates spontaneous AV conduction but usually cannot completely avoid unnecessary ventricular pacing and causes other problems in the dual-chamber mode. Atrial septal lead placement can improve left-sided AV synchrony and promote spontaneous AV conduction. Programming of the AAI(R) mode is superior to the dual-chamber mode but cannot be used if AV conduction is impaired intermittently or permanently. Therefore, dedicated algorithms enhancing spontaneous AV conduction in the dual-chamber mode are desirable for a large proportion of pacemaker patients.

Atrial Fibrillation↗
PubMed2006

ASymptomatic atrial fibrillation and Stroke Evaluation in pacemaker patients and the atrial fibrillation Reduction atrial pacing Trial (ASSERT).

Asymptomatic atrial fibrillation (AF) is common and may have the same prognostic implications as symptomatic AF. Among patients receiving dual-chamber pacemakers, it is now possible to quantify asymptomatic AF accurately. Most of these episodes are of short duration, often lasting only seconds to minutes and are called atrial high-rate episodes (AHRE) to distinguish them from the longer episodes of overt AF. To understand properly the clinical importance of asymptomatic AF, a large study of pacemaker patients without clinically overt AF is required. ASSERT is a multicenter, cohort follow-up, and single-blinded randomized trial in elderly hypertensive patients with a pacemaker recently implanted for sinus or atrioventricular node disease. The goals of this trial are to evaluate whether the detection of AHRE with pacemaker telemetry predicts an increased risk of stroke and other vascular events and to evaluate if atrial overdrive pacing reduces symptomatic AF. ASSERT is evaluating the hypothesis that among pacemaker patients without a previous history of AF, detection of AHRE predicts an increased risk of stroke and systemic embolism. The second hypothesis to be tested is that overdrive atrial pacing will reduce the risk of symptomatic AF in pacemaker patients without a previous history of AF. Finally, a 400-patient substudy will use the noninvasive testing capabilities of the patients' pacemaker to evaluate changes in atrial electrophysiology over 2 years. This substudy will determine if atrial electrical remodeling is detectable in pacemaker patients and if it is associated with the development of AF.

Aged↗
PubMed2006

Recent primary prevention implantable cardioverter defibrillator trials.

PURPOSE OF THE REVIEW: The aim of this article is to summarize the most relevant findings of recently published trials on prophylactic implantable cardioverter defibrillator therapy. RECENT FINDINGS: A number of important randomized clinical trials on the efficacy of prophylactic implantable cardioverter defibrillator therapy in patients deemed to be at high risk for ventricular tachyarrhythmias have recently reported their results. Patients with chronic ischemic cardiomyopathy, a long history of heart failure, and an ejection fraction of 0.30 or below benefit from preventive device therapy and are thus candidates for prophylactic defibrillator implantation. For this purpose, a single chamber device appears to be appropriate since there have been no prospective studies showing convincing clinical benefit by adding an atrial lead. Prophylactic implantable cardioverter defibrillator therapy should not be used in patients with recent myocardial infarction. There is convincing evidence from one trial that benefit from the defibrillator in coronary patients accrue after a considerable time has elapsed from the most recent infarct, presumably at least 6 months or perhaps longer. Finally, in patients with chronic dilated non-ischemic cardiomyopathy and a left ventricular ejection fraction of 0.35 or below, there is also benefit from prophylactic implantable cardioverter defibrillator therapy. SUMMARY: Taken together, these trials allow an evidence-based approach to primary prevention of sudden cardiac death in patients with both ischemic and non-ischemic cardiomyopathy.

Cardiomyopathy, Dilated↗
PubMed2006

Incidence of atrial tachyarrhythmias in pacemaker patients: results from the Balanced Evaluation of Atrial Tachyarrhythmias in Stimulated patients (BEATS) study.

OBJECTIVES: The prospective Balanced Evaluation of Atrial Tachyarrhythmias in Stimulated patients (BEATS) study compared atrial tachyarrhythmia (AT) detection by means of serial ECG recordings versus device detection. BACKGROUND: The annual incidence of AT in patients with dual-chamber pacemakers may be significantly underestimated based on ECG and Holter recordings. METHODS: A DDD(R) device capable of AT-triggered dual-channel electrogram (EGM) storage was implanted in 254 patients (70 +/- 11 years, 159 men) with a class I pacing indication. Patients were seen at 6, 26, and 52 weeks after pacemaker implantation. At all visits, symptoms were checked, surface ECGs were recorded including a 24-hour Holter recording at 6 weeks, and the pacemakers were interrogated. Primary study endpoint was AT documentation by surface ECG/Holter versus stored EGMs. Secondary endpoints consisted of the association between patients' symptoms and AT documentation, and of the AT incidence depending on pacing indication and a history of AT. RESULTS: ATs were documented by ECG/Holter recordings in 37 patients (15%) and by stored EGMs in 137 patients (54%) (P < 0.0001). Symptoms were absent in 108 of 137 patients (79%) with device-documented AT but present in 70 of 117 patients (60%) without AT documentation. AT documentation was more frequent in patients with a history of AT but not in patients with sinus node compared to AV node disease. CONCLUSION: ATs occur in pacemaker patients significantly more frequently than estimated by ECG/Holter recordings. Only the analysis of device-stored EGMs allows reliable assessment of the AT burden.

Aged↗
PubMed2006

Reducing unnecessary right ventricular pacing with the managed ventricular pacing mode in patients with sinus node disease and AV block.

BACKGROUND: Frequent and unnecessary right ventricular apical pacing increases the risk of atrial fibrillation or congestive heart failure. We evaluated a new pacing algorithm, managed ventricular pacing (MVP) which automatically changes modes between AAI/R and DDD/R in patients receiving pacemakers for symptomatic bradycardia. METHODS: Patients were randomized to the MVP mode or DDD/R mode for 1 month and then crossed over to the alternate pacing modality for an additional month. On completion of the crossover phase, the pacing mode selected was individualized and patients were followed for an additional 4 months. RESULTS: Of the 129 patients who successfully completed the crossover study, the cumulative percent ventricular pacing was significantly reduced in the MVP mode (median 1.4%) compared to the DDD/R mode (median 89.6%, 94.0% relative reduction; 95% CI 89.3-98.8%, P < 0.001). Patients with sinus node disease (SND, n = 51) when compared to patients with AV block (AVB) (n = 68) experienced a greater reduction in ventricular pacing with the MVP mode compared to the DDD/R mode (median relative reduction 99.1%; 95% CI 97.5-99.9% vs median relative reduction 60.1%; 95% CI 16.7-93.9% P < 0.001). The reduced percent ventricular pacing during MVP was sustained over longer term follow-up. CONCLUSIONS: The majority of patients with a bradycardia indication for cardiac pacing do not require ventricular pacing most of the time. The MVP mode significantly reduces unnecessary right ventricular pacing. This mode benefits even patients with intermittent AVB and is sustained over longer term follow-up.

Aged↗
PubMed2005

ICD therapy in coronary artery disease. A reappraisal in 2005.

25 years after the first coronary artery patient received an implantable cardioverter defibrillator (ICD), many randomized controlled trials on prophylactic ICD therapy have been conducted. Taken together, these trials allow an evidence-based approach to primary prevention of sudden cardiac death in patients after a myocardial infarction. Patients with chronic ischemic cardiomyopathy, a long history of heart failure, and an ejection fraction of < or = 0.30 benefit from preventive device therapy and are thus candidates for prophylactic defibrillator implantation. For this purpose, a single-chamber device appears to be appropriate, since there have been no prospective studies showing convincing clinical benefit by adding an atrial lead. For similar patients who have additional intraventricular conduction delays, a biventricular ICD must be considered. However, this decision must be based on individual considerations until more data from prospective trials become available. Prophylactic ICD therapy should not be used in patients with recent myocardial infarction. There is convincing evidence that ICD benefit in coronary patients accrues after a considerable time having elapsed from the most recent infarct, presumably at least 6 months or perhaps longer.

Comorbidity↗
PubMed2005

Mode switching of dual chamber pacemakers from activation of a blanked flutter search algorithm by a single atrial event.

The Medtronic Kappa 700 and 900 pacemaker family offers a dedicated Blanked Flutter Search algorithm specifically designed for the detection of atrial flutter. This report describes 5 cases that demonstrate how the Blanked Flutter Search algorithm can be activated in the absence of atrial tachycardia, atrial flutter, or sinus tachycardia by a single atrial event (AR) detected in the atrial refractory period of the pacemaker provided it is either preceded or followed by a sensed atrial event (AS).

Algorithms↗