PERMANENT ATRIAL RESYNCHRONISATION BY SYN CHRONOUS BI-ATRIAL PACING IN THE PREVENTION OF ATRIAL-FLUTTER ASSOCIATED WITH HIGH-DEGREE INTERNATIONAL CONDUCTION BLOCK

Interatrial conduction block results in a very delayed and retrograde activation of the left atrium and is associated with a high incidence of atrial tachyarrhythmias, especially a particular (and specific) for m of atypical atrial flutter. Electrophysiologic studies have suggeste d that these arrhythmias were usually due to reentry and could be dire ctly related to the conduction disturbances in the atrium. If so, we c an expect reasonably that permanent atrial resynchronization resulting from simultaneous pacing in different target sites in the atria, may not only correct for interatrial dysynchrony, but also may significant ly contribute to prevent arrhythmia recurrences. Twenty-eight patients , mean age 68 years, were included. The mean P wave duration in sponta neous sinus rhythm was 181 +/- 28 ms. In all patients, many recurrence s of atrial tachyarrhythmia were documented, especially a specific for m of atypical atrial flutter. Medical therapy was constantly ineffecti ve. Three different pacing modes were used: 6 patients, with normal A- V conduction were implanted with a SSI device, programmed in AAT mode and connected, using a Y bifurcated connector, to two atrial leads, on e positionned in the right atrium, the second one into the coronary si nus-in 14 patients, with A-V conduction defects, a conventional DDDR u nit was implanted and connected to a composite biatrial electrode and a ventricular lead. In that configuration atrial resynchronization was only effective on paced atrial cycles -a specific DDD Chorus ELA Medi cal device with a special algorithm loaded into the RAM memory was imp lanted in 14 patients (8 new indications, and 6 patients first implant ed with a DDDR unit). Results: during sinus rhythm atrial resynchroniz ation induced a reduction of the P wave duration from 181 +/- 28 ms to 116 +/- 12 ms. During permanent pacing the mean value decreased from 209 +/- 38 ms to 108 +/- 13 ms. During follow-up (34 +/- 15 months) ar rhythmia prevention was assessed by history, by monthly surface ECG's and by bimonthly 24 hours Holters recordings and telemetric interrogat ion of the pacemaker statistics. Twenty-one patients did not experienc ed any recurrence of arrhythmia. One to three recurrences occurred in the other seven patients, including six patients implanted with a conv entional DDDR unit. These preliminary results seem validate the new co ncept of atrial resynchronization for prevention of atrial arrhythmia associated with interatrial conduction block.