ATRIAL CONDUCTION CURVES IN PATIENTS WITH AND WITHOUT ATRIAL-FIBRILLATION

In order to quantify underlying atrial conduction properties in patien ts with atrial fibrillation (AF) using clinical electrophysiology tech niques, atrial conduction curves relating intra-atrial conduction time s to extrastimulus prematurities during programmed atrial stimulation were drawn. Based on the presence or absence of AF episodes, 95 subjec ts were divided into 2 groups: control (n=42); and AF (n=53). During p rogrammed stimulation introduced from the right atrial appendage, an a trial conduction curve was drawn for each patient, For most of the con trol subjects, when the extrastimulus prematurity was increased by 10- ms steps, the intra-atrial conduction times also increased gradually; the maximum stepwise prolongation in intraatrial conduction time was 1 1.0+/-3.4 msec. For patients with AF, a 10-msec increase in extrastimu lus prematurity often produced a sudden marked prolongation in the int ra-atrial conduction time; the maximum stepwise prolongation of intra- atrial conduction time was 21.4+/-5.9 msec. In contrast to the gradual atrial conduction curves recorded in control subjects, the sudden pro longation of intra-atrial conduction time was remarkable on the curves obtained in patients with AF. Statistical significance was clearly es tablished (p<0.0001). This difference could be related to differences in the underlying conduction properties in patients with and without A F.