ASSOCIATION BETWEEN ATRIOVENTRICULAR NODE REENTRANT TACHYCARDIA AND INDUCIBLE ATRIAL-FLUTTER

Objectives. The purpose of this study was to evaluate the inducibility of atrial flutter in patients with atrioventricular (AV) node reentra nt tachycardia and to determine the effect of radiofrequency ablation of the slow AV node pathway on the inducibility of atrial flutter. Bac kground. Studies have shown that both AV node reentrant tachycardia an d atrial flutter are reentrant arrhythmias having an area of slow cond uction that is located in the low posterior right atrium near the osti um of the coronary sinus. Methods. Ninety-one patients were prospectiv ely evaluated using a standardized atrial pacing protocol. Three group s of patients were analyzed: 42 patients with inducible AV node reentr ant tachycardia, 13 with a history of spontaneous atrial flutter and 3 6 control patients. A subgroup of 34 patients with AV node reentrant t achycardia who underwent successful radiofrequency ablation of the slo w AV node pathway underwent atrial pacing again after ablation. Result s. Atrial flutter was more frequently inducible in patients with AV no de reentrant tachycardia (88%) and in those with a history of atrial f lutter (92%) than in control patients (36%) (p = 0.0001). There were n o differences between the patient groups with respect to atrial effect ive refractory period, P wave duration or PA interval at the His posit ion. Among the 34 patients with AV node reentrant tachycardia who unde rwent atrial pacing before and after radiofrequency ablation, there we re 30 with atrial flutter and 4 with atrial fibrillation before ablati on and 29 with atrial flutter and 5 with atrial fibrillation after abl ation (p = NS). There was no difference in the duration of the induced atrial flutter before and after ablation. The mean atrial flutter cyc le length before ablation (206 +/- 22 ms) was not different from that after ablation (196 +/- 20 ms) (p = NS). Conclusions. There is a stron g association between AV node reentrant tachycardia and inducible atri al flutter, suggesting that there may be a common area of perinodal at rium participating in the two tachycardia circuits. However, radiofreq uency ablation of the slow pathway of the AV node reentrant tachycardi a circuit does not influence the inducibility of atrial flutter.