REPRODUCIBILITY OF TRANSESOPHAGEAL PACING IN PATIENTS WITH WOLFF-PARKINSON-WHITE SYNDROME

The purpose of this study was to assess, in patients with ventricular preexcitation, the time dependent physiological variation of antegrade conduction properties in the AV node and in accessory pathways (Aps) as a function of autonomic tone variation induced by posture and physi cal effort, using noninvasive transesophageal atrial pacing. In 74 WPW patients (mean age 21.31 +/- 9.46 yrs), AV node and Kent antegrade ef fective refractory periods fort pacing cycle lengths 600, 400, and 320 ms), Wenckebach point, shortest preexcited RR intervals during sustai ned atrial fibrillation (AF) or atrial pacing, as well as the inducibi lity of AV reentry tachycardia (AVRT) and AF/flutter (AFL) were assess ed. All measurements were carried out at rest, in supine and upright p ositions, and during effort. A second study was carried out approximat ely 3 months after the first study. The coefficients of variation (CVs ) and reproducibility (CRs) were calculated. For each parameter, the d ifferences between the mean of the two studies were not statistically significant. The CVs and CRs ranged between 0.4% and 4% and between 2 and 28 ms, respectively. AF was induced in 40 (54%) of 74 patients at the first study and in 30 (40.5%) of 74 patients at the second study. AVRT was induced in 33 (45%) of 74 patients at the first study and in 38 (51.3%) of 74 patients at the second study. The reproducibility was 45% for AF/AFL and 65% for reentry tachycardia. Transesophageal atria l pacing is a reliable method for noninvasive reproducible evaluation of antegrade electrophysiological properties of both the AV node and A Ps in WPW patients. However, the effect of autonomic balance variation has to be taken into account and precisely defined because it may sig nificantly affect the inducibility of supraventricular arrhythmias and the estimation of the absolute values of the vulnerable parameters.