Effectiveness of Rapid Atrial Pacing for Termination of Drug Refractory Atrial Fibrillation: Results of a Dual Chamber Implantable Cardioverter Defibrillator Trial
AbstractThere is increasing interest in the use of an implantable cardioverter defibrillator (ICD) to manage atrial tachyarrhythmias. Although device-based shock therapy is highly effective in terminating persistent atrial tachyarrhythmias, atrial overdrive pacing may also be useful, particularly when this therapy is applied early after the onset of an arrhythmia. A dual-chamber ICD (Medtronic 7250 Jewel AF ®) has been studied in 267 patients with drug-refractory symptomatic AF. The patients were enrolled as part of multicenter clinical trial to evaluate the safety and efficacy of the device to manage atrial tachyarrhythm...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
AFFIRM and RACE Trials: Implications for the Management of Atrial Fibrillation
AbstractThe Atrial Fibrillation (AF) Follow-up Investigation of Rhythm Management (AFFIRM) and Rate Control versus Electrical Cardioversion for Persistent Atrial Fibrillation Study (RACE) Trials evaluated strategies of rate control or rhythm control in atrial fibrillation. AFFIRM enrolled patients with recent onset AF, and at entry over half of all patients were in sinus rhythm. At any point in the trial, the achieved difference in cardiac rhythm was likely only about 30%. In RACE all patients were entered in AF, and at the end of the study, sinus rhythm was present in 10% vs 39%. The strategy of rate control was non-infer...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Selecting the Appropriate Pacing Mode for Patients with Sick Sinus Syndrome: Evidence from Randomized Clinical Trials
AbstractSeveral observational studies have indicated that selection of pacing mode may be important for the clinical outcome in patients with symptomatic bradycardia, affecting the development of atrial fibrillation (AF), thromboembolism, congestive heart failure, mortality and quality of life. In this paper we present and discuss the most recent data from six randomized trials on mode selection in patients with sick sinus syndrome (SSS). In pacing mode selection, VVI(R) pacing is the least attractive solution, increasing the incidence of AF and —as compared with AAI(R) pacing, also the incidence of heart failure, thromb...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Detection of Atrial Fibrillation by Permanent Pacemakers: Observations from the STOP AF Trial
AbstractPacemaker telemetry is increasingly being used to infer the presence or absence of arrhythmias in clinical practice. To evaluate the reliability of these data in patients with sick-sinus syndrome, a sub-study of eighteen consecutive patients in the Systematic Trial of Pacing to prevent Atrial Fibrillation (STOP AF) implanted with dual-chamber pacemakers had simultaneous 24-hour Holter recordings and pacemaker telemetry down-loaded. Whilst heart rate data were very similar, telemetry data achieved only 57% sensitivity with 64% specificity for the presence of atrial fibrillation on Holter recording over 24 hours. Fal...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Atrial Arrhythmia Burden as an Endpoint in Clinical Trials: Is it the Best Surrogate? Lessons from a Multicenter Defibrillator Trial
AbstractTherapies to treat atrial tachyarrhythmias need to be evaluated in controlled, randomized clinical trials in order to optimize patient outcomes. If the maintenance of sinus rhythm is the ultimate goal, then atrial tachyarrhythmia burden may serve as a useful endpoint. Atrial tachyarrhythmia burden is defined as the total duration of all atrial tachyarrhythmias divided by the follow-up time and includes asymptomatic as well as symptomatic episodes. The measurement of atrial tachyarrhythmia burden is more practical now than in the past because of the availability of implantable devices capable of monitoring atrial ta...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
DEFibrillators In Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE)
AbstractThe DEFibrillators In Non-Ischemic Cardiomyopathy Treatment Evaluation (DEFINITE) was a multi-center, randomized, investigator-initiated trial. Patients enrolled in the trial had non-ischemic cardiomyopathy (LVEF ≤35%), a history of symptomatic heart failure and spontaneous arrhythmia (>10 PVCs/hr or non-sustained ventricular tachycardia defined as 3 to 15 beats at a rate of>120 bpm) on Holter monitor or telemetry within the past 6 months. All patients received standard oral medical therapy for heart failure including angiotensin converting enzyme inhibitors and beta-blockers. Patients were randomized to im...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Cardioversion Related Thromboembolism: Value of Transesophageal Echocardiography to Guide Cardioversion in Patients with Atrial Fibrillation
AbstractThe aim of this article is to review two recent investigations of the value of transesophageal echocardiography to guide direct current cardioversion in different patient populations. In the Ludwigshafener Observational Cardioversion Study (LOCS) a TEE was performed prior to electrical cardioversion in patients with atrial fibrillation who had been receiving oral anticoagulation adjusted to an international normalized ratio of 2 to 3 for at least three weeks. In contrast, the ACUTE study investigated the value of transesophageal echocardiography in patients with atrial fibrillation in whom long-term oral anticoagul...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Multisite Atrial Pacing for Atrial Fibrillation Prevention: Where to Go from Here?
AbstractAtrial fibrillation (AF) is a common arrhythmia associated with stroke, increased mortality and with a negative impact on quality of life. Pharmacologic treatments for AF have not provided long-term relief from arrhythmia recurrence. Multi-site atrial pacing was introduced by Daubert and colleagues about 10 years ago for the treatment of severe atrial conduction delays in patients with sick sinus syndrome. They found that this type of atrial stimulation reduced or prevented AF. Multi-site atrial pacing results in reduction of intra-atrial and interatrial conduction differences and diminishes heterogeneity of refrac...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Comparison of Permanent Left Ventricular and Biventricular Pacing in Patients with Heart Failure and Chronic Atrial Fibrillation: A Prospective Hemodynamic Study
Conclusions: In this small series of patients with atrial fibrillation, congestive heart failure and a prolonged QRS duration, LVP and BVP provided similar hemodynamic effects at rest whereas BVP was associated with better hemodyamic effects during exercise and fewer premature ventricular complexes. Although the mechanisms for the observed differences are uncertain, it is possible that there is worsening of right ventricular function due to a rise in left-to-right electromechanical delay during exercise. Increased catecholamines release might contribute to the lower exercise tolerance and greater number of premature ventri...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Enhancing Specificity Without Sacrificing Sensitivity: Potential Benefits of Using Microvolt T-Wave Alternans Testing to Risk Stratify the MADIT-II Population
AbstractThe MADIT-II study (Moss et al.,N Engl J Med 2002;346:877 –883) demonstrated that implantation of a cardioverter/defibrillator (ICD) reduced mortality from 19.8% to 14.2% during 20 months of follow-up in patients with prior myocardial infarction and left ventricular ejection fraction ≤0.30. Concerns have been raised both about the cost and potential mo rbidity of implanting ICDs in a large group of patients when only a small fraction of the patients would be expected to benefit from the treatment. This concern has given rise to the hope that an effective means of risk stratifying the MADIT-II population might b...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Oral Anticoagulants vs. Aspirin for Stroke Prevention in Patients with Non-Valvular Atrial Fibrillation: The Verdict is in
This article summarizes a recently published individual patient meta-analysis of all published RCTs comparing OAC and ASA in AF. In total, 4052 patients randomized to OAC or ASA were similar regarding important prognostic factors. Patients receiving OAC had a significantly lower risk of any stroke (hazard ratio [HR] 0.54 [95% CI 0.43 –0.71]), ischemic stroke (HR 0.48 [0.37–0.63]), or cardiovascular events (HR 0.71 [0.59–0.85]). Patients receiving OAC were more likely to experience major bleeding (HR 1.71 [1.21–2.41]). The benefit of OAC was most prominent in patients at a high risk of stroke and other cardiovascula...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Relationships between Pacing Mode and Quality of Life: Evidence from Randomized Clinical Trials
AbstractAlthough mode-dependent differences in mortality are for the moment unproven, establishing a health-related quality of life difference between assigned pacing modes would be useful. Such a difference, if one exists, should be ≥0.5 standard deviation units among scales using validated instruments to have significant clinical meaning. Two large data sets, the Canadian Trial of Physiological Pacing (CTOPP) and the Mode Selection Trial (MOST) both similar in design, largely failed to clearly establish such a significant di fference. Another trial the Pacemaker Selection in the Elderly (PASE) did suggest that for sinu...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Is Bachmann's Bundle the Only Right Site for Single-Site Pacing to Prevent Atrial Fibrillation? Results of a Multicenter Randomized Trial
AbstractThe site of atrial pacing influences atrial activation patterns. It is believed that disparities in atrial activation and repolarization are contributors to the development and recurrence of atrial arrhythmias. We hypothesized that pacing from Bachmann's Bundle would improve clinical outcomes in patients with paroxysmal atrial fibrillation compared to right atrial appendage pacing. Pacing from Bachmann's Bundle results in a significant reduction in P wave duration and improvement in biatrial activation symmetry compared to right atrial appendage pacing. Compared to right atrial appendage pacing, Bachmann's bundle p...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
Selection of Pacing Mode after Interruption of Atrioventricular Conduction for Atrial Fibrillation: Observations from the PA 3 Clinical Trial
AbstractThe optimal pacing mode for patients with paroxysmal atrial fibrillation (AF) following AV junction ablation remains the subject of some debate. Recent clinical trials have not demonstrated a superior advantage of maintenance of sinus rhythm over the rate control approach. However, clinical trials in pacemaker populations have demonstrated that physiologic pacing reduces the probability of paroxysmal and persistent AF compared to ventricular pacing. In the second phase of the PA3 study, patients were randomized to DDDR versus VDD pacing in a cross over study design. Of the 67 patients randomized, 42% developed perm...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
MADIT-II: Substudies and Their Implications
AbstractIn MADIT-II, prophylactic ICD therapy was effective in improving survival in patients with prior myocardial infarction and an ejection fraction ≤0.30, and a host of prespecified secondary analyses indicate that life-saving effect of ICD therapy is consistent across all studied subgroups. We have not been able to identify any traditional risk factors that will permit selection of patients who will receive a significantly better effect from the ICD within any subgroup. The ICD provides appropriate therapy for life-threatening ventricular arrhythmias on at least one occasion in over a third of the patients during th...
Source: Cardiac Electrophysiology Review - December 1, 2003 Category: Cardiology Source Type: research
