Ricci Renato, Santini Massimo, Padeletti Luigi, Boriani Guiseppe, Capucci Alessandro, Botto Gianluca, Gulizia Michele, Inama Guiseppe, Galati Antonio, Solimene Francesco, Pepe Massimilano, Grammatico Andrea
Institute of Cardiology, S. Filippo Neri Hospital, Rome, Italy.
J Cardiovasc Electrophysiol. 2004 Jan;15(1):44-51. doi: 10.1046/j.1540-8167.2004.03317.x.
New-generation pacemakers allow continuous atrial tachyarrhythmia (AT) monitoring that provides accurate information about AT type, frequency, burden, and temporary evolution.
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.
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.
