The impact of atrial prevention and termination therapies on atrial tachyarrhythmia burden in patients receiving a dual-chamber defibrillator for ventricular arrhythmias

Pacing therapy for prevention of atrial fibrillation

The role of permanent pacing for the prevention of atrial fibrillation is reviewed. A moderate decrease in the incidence of acute and chronic atrial fibrillation has been seen with atrial pacing compared with ventricular pacing, especially in patients with sinus node dysfunction based on a meta-analysis of clinical trials. A variety of different pacing algorithms have been studied in small numbers of patients for only short durations of time and have shown an inconsistent effect on different measures of atrial fibrillation burden. The interatrial septum or Bachmann's bundle has been shown in some, but not all, studies to have a beneficial effect on reducing the incidence of atrial fibrillation. Less well studied is the combined benefit of alternate site atrial pacing combined with atrial fibrillation prevention pacing algorithms. Device measurement of the duration of atrial fibrillation appears to be an accurate measure of disease burden, and preliminary evidence suggests that atrial fibrillation burden is associated with an increased risk of stroke and death. Future studies are needed to demonstrate the long-term efficacy of device algorithms for the prevention or termination of atrial fibrillation.

Long-term reduction of atrial tachyarrhythmia recurrences in patients paced for bradycardia-tachycardia syndrome

BACKGROUND

Atrial tachyarrhythmias (AT) are considered progressive diseases. Several rhythm control therapies for treatment of AT have been proposed.

OBJECTIVES

The Italian AT500 Registry was designed to prospectively study long-term AT evolution in patients paced for the brady-tachy form of sinus node disease (BT-SND).

METHODS

Three hundred forty-six BT-SND patients received an antitachycardia dual-chamber pacemaker and were followed-up for a minimum of 12 months (median 19 months). Prevention and antitachycardia pacing (ATP) features were enabled in all patients.

RESULTS

During the observation period, 224 (65%) patients were treated by antiarrhythmic drugs and 45 (13%) patients were cardioverted. Five patients suffered a stroke, 4 transient ischemic attack, 22 permanent AT, and 98 AT recurrences longer than 7 days. AT mean cycle length changed from 246 to 270 ms, and the percentage of patients with AT-related hospitalizations significantly decreased with an annual 28% relative reduction. AT burden and the percentage of patients with AT recurrences longer than 2 days remained constant with time in the overall population but decreased significantly in the subgroup of patients who did not develop permanent AT. High ATP efficacy was associated with an increasingly higher prevention of AT recurrences longer than 2 days.

CONCLUSION

In a long-term observation of BT-SND patients, AT-related hospitalizations decreased significantly and mean AT cycle length increased significantly. The data suggest that rhythm control therapies induce inversion of AT progression.

Symptomatic burden as an endpoint to evaluate interventions in patients with atrial fibrillation

Management of patients with atrial fibrillation (AF) is clinically challenging and has led to the development of new pharmacologic and nonpharmacologic therapies. However, no clear consensus on optimal endpoints for defining responses to therapy exists. This paradox arises largely because symptoms, often used to gauge efficacy of interventions, have not been well correlated with long-term "hard" endpoints such as stroke and death. One widely used symptom-based metric is "time to first symptomatic AF episode," but this correlates poorly with frequency of symptomatic episodes. Similarly, although quality-of-life (QOL) measures have been used, the precise and unbiased assessment of QOL is difficult to define and measure. The availability of implantable devices capable of monitoring and recording all AF episodes has made the accurate determination of total time in AF ("burden") possible. However, QOL tools and formal measures of AF burden do not correlate well, suggesting that measures of subjective well-being are important adjunct measures to conventional measures of disease severity when evaluating the therapeutic efficacy of treatments for AF. Although measurement of total AF burden requires invasive monitoring, symptomatic AF burden (defined by frequency, duration and severity of symptoms) can be determined in all patients with symptomatic AF and may serve as a valid endpoint, as elimination of symptoms is a common and realistic therapeutic goal. Therefore, we propose an algorithm to quantify symptomatic AF burden as an endpoint in clinical trials.