Evaluation of atrial vulnerability with transoesophageal stimulation in patients with atrioventricular junctional: Comparison with patients with ventricular pre-excitation and with normal subjects

The aim of our work was to evaluate the inducibility of atrialfibrillation in a group of patients with atrioventricular junctionalreentrant tachycardia and to compare it with that of patientswith a Kent-type ventricular pre-excitation (Wolff-Parkinson-Whitesyndrome) and a control group. One hundred and twenty-five subjects were separated into groups.Group 1 comprised 49 Wolff-Parkinson-White patients, with amean age of 26.4, range 10.66 years; group 2, 51 patients withatrioventricular junctional reentrant tachycardia inducibleby transoesophageal atrial stimulation andlor clinically documented,with a mean age of 43.4, range 16–78 years; group 3, 25control subjects with a mean age of2.64, range 13–76 years. Each subject underwent atrial transoesophageal stimulation withthe following protocol: programmed atrial stimulation with 1and 2 stimuli during atrial pacing of 100. min^–1 and 150.min^–1; atrial stimulation for 10 s at a rate of 200–300–400–500–600.min^–1 with intervals of 10 s between stimulations, fivesuccessive ‘ramp-up’ atrial stimulations for 9 swith the rate increasing from 100 to 800. min^–1 with intervalsof 10 s between stimulations. The end point was the completionof the protocol or induction of sustained atrial fibrillation(>1 min). The chi-square test was used for statistical analysis. Our resultsshowed that in group 1 atrial fibrillation was induced in 27149patients (55.1%); this was sustained in 13149 (26.5%) and non-sustainedin 14149 (28.5%); in group 2, atrial fibrillation was inducedin 22151 patients (43.0%); it was sustained in 7151 (13.7%)and non-sustained in 15151 (29.4%); in group 3, sustained atrialfibrillation was not induced in any subject and in only onesubject was a non-sustained atrial fibrillation (4 s) induced. The chi-square test showed that group 2 vs group 1 were non-significant,while group 2 vs group 3 and group 1 vs group 3 were significant(P<0.003 and P<0.0007, respectively). Therefore group 2 patients showed a greater atrial vulnerabilityin comparison to the control subjects and a similar vulnerabilityto group 1 patients. It is possible that the greater atrialvulnerability in the patients of group 2 was due to the doublenodal pathway.