title: Atrial tachyarrhythmia recurrence temporal patterns in bradycardia patients implanted with antitachycardia pacemakers.
abstract: BACKGROUND
  New-generation pacemakers allow continuous atrial tachyarrhythmia (AT) monitoring that provides accurate information about AT type, frequency, burden, and temporary evolution.
  
  
  RESULTS
  We performed a prospective multicenter study to describe AT temporal patterns in patients with sinus bradycardia and AT. Two hundred forty patients (123 men; age 71 +/- 8 years) were implanted with a DDDRP pacemaker (model AT500, Medtronic Inc.). All patients were followed for 13 months. The first-month stabilization period of all patients was discarded from analysis. Seventy percent of patients had AT recurrences. Mean time to first AT recurrence (48.2 days, 95% confidence interval [CI] 37.0-59.5 days) was significantly longer than the time between first and second AT episode (10.3 days, 95% CI 6.7-13.9 days, P < 0.01). A minority of patients had a uniform time distribution of AT recurrences: <25% of patients had AT episodes in more than 6 of the 12 months considered in the study. The probability density function of consecutive sinus rhythm days between AT episodes was calculated for each of 40 patients who experienced >25 AT episodes and fitted by power law and exponential functions. The best fit was obtained by power law function in 60% of patients, by exponential function in 10%, and the two models gave comparable results in 30% of patients.
  
  
  CONCLUSIONS
  In our population of patients with a history of sinus bradycardia and AT who were implanted with a new device equipped with atrial pacing therapies, 30% did not experience AT recurrences in the 12-month study period. Analysis of interevent time showed that in 60% of patients AT recurrences do not follow a uniform or random distribution. These findings bring into question the use of cross-over design and time to first AT recurrence as a clinical outcome in trials for AT therapy in this patient population.
authors.affiliation: Institute of Cardiology, S. Filippo Neri Hospital, Rome, Italy. renatopieroricci@tin.it
authors.forename: Renato
authors.initials: R
authors.lastname: Ricci
authors.forename: Massimo
authors.initials: M
authors.lastname: Santini
authors.forename: Luigi
authors.initials: L
authors.lastname: Padeletti
authors.forename: Guiseppe
authors.initials: G
authors.lastname: Boriani
authors.forename: Alessandro
authors.initials: A
authors.lastname: Capucci
authors.forename: Gianluca
authors.initials: G
authors.lastname: Botto
authors.forename: Michele
authors.initials: M
authors.lastname: Gulizia
authors.forename: Guiseppe
authors.initials: G
authors.lastname: Inama
authors.forename: Antonio
authors.initials: A
authors.lastname: Galati
authors.forename: Francesco
authors.initials: F
authors.lastname: Solimene
authors.forename: Massimilano
authors.initials: M
authors.lastname: Pepe
authors.forename: Andrea
authors.initials: A
authors.lastname: Grammatico
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000517:prevention & control*; D001919:Bradycardia / Q000453:epidemiology* / Q000628:therapy*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000706:statistics & numerical data*; D055502:Secondary Prevention; D013612:Tachycardia, Ectopic Atrial / Q000453:epidemiology* / Q000517:prevention & control*; D014481:United States / Q000453:epidemiology