Document Detail

Temporal variability of atrial fibrillation in pacemaker recipients for bradycardia: implications for crossover designed trials, study sample size, and identification of responder patients by means of arrhythmia burden.
MedLine Citation:
PMID:  17284291     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Most clinical trials that have tested pacing therapies to prevent and treat atrial tachyarrhythmias (AT) have chosen endpoints such as AT frequency or burden (defined as percentage of time a patient is in AT), but failed to show unequivocal evidence of a clinical impact. AIM: The aim of our multicenter prospective observational study was to measure the variability of AT burden and estimate its impact on study outcomes. METHODS AND RESULTS: Two hundred and fifty patients indicated for permanent pacing and suffering from AT (age 71 +/- 9 years; 47.2% male) received a dual-chamber pacemaker. AT burden was measured in two consecutive, 2-month observation periods; the Monte Carlo method was then applied to simulate findings of a crossover design study. We simulated several models of therapy impact, each model being characterized by the percentage of responder patients and the percentage reduction in AT burden. To show a significant impact of AT therapies in a sample of 250 patients in whom 100, 75, or 50% would be theoretical responders to therapies, AT burden reduction should be at least 27, 32, or 57%, respectively. Temporal fluctuations in AT burden were so high that about 60% of patients would falsely appear as responders or nonresponders in a crossover study, regardless of AT burden reduction. CONCLUSIONS: In patients paced for bradycardia and suffering from AT, high intrapatient variability in AT burden was measured. Various models of therapy impact showed that, in crossover trials of AT therapies, time-related fluctuations in AT burden negatively impact on sample sizes and impair the ability to identify patients as responders or nonresponders.
Giovanni Luca Botto; Massimo Santini; Luigi Padeletti; Giuseppe Boriani; Gianni Luzzi; Francesco Zolezzi; Serafino Orazi; Alessandro Proclemer; Giacomo Chiarandà; Stefano Favale; Francesco Solimene; Mario Luzi; Marco Vimercati; Tiziana DeSanto; Andrea Grammatico
Publication Detail:
Type:  Journal Article; Multicenter Study     Date:  2007-01-30
Journal Detail:
Title:  Journal of cardiovascular electrophysiology     Volume:  18     ISSN:  1540-8167     ISO Abbreviation:  J. Cardiovasc. Electrophysiol.     Publication Date:  2007 Mar 
Date Detail:
Created Date:  2007-02-22     Completed Date:  2007-04-10     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  9010756     Medline TA:  J Cardiovasc Electrophysiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  250-7     Citation Subset:  IM    
Cardiology Department, S. Anna Hospital, Como, Italy.
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MeSH Terms
Atrial Fibrillation / complications*
Bradycardia / complications*,  therapy*
Cardiac Pacing, Artificial / statistics & numerical data*
Clinical Trials as Topic / methods*
Cost of Illness
Cross-Over Studies
Monte Carlo Method
Prospective Studies
Research Design
Sample Size
Time Factors

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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