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 reentrant tachycardia and to determine the effect of radio-frequency ablation of the slow AV node pathway on the inducibility of atrial flutter.

BACKGROUND: Studies have shown that both AV node reentrant tachycardia and atrial flutter are reentrant arrhythmias having an area of slow conduction that is located in the low posterior right atrium near the ostium of the coronary sinus.

METHODS: Ninety-one patients were prospectively evaluated using a standardized atrial pacing protocol. Three groups of patients were analyzed: 42 patients with inducible AV node reentrant tachycardia, 13 with a history of spontaneous atrial flutter and 36 control patients. A subgroup of 34 patients with AV node reentrant tachycardia who underwent successful radiofrequency ablation of the slow AV node pathway underwent atrial pacing again after ablation.

RESULTS: Atrial flutter was more frequently inducible in patients with AV node reentrant tachycardia (88%) and in those with a history of atrial flutter (92%) than in control patients (36%) (p = 0.0001). There were no differences between the patient groups with respect to atrial effective refractory period, P wave duration or PA interval at the His position. Among the 34 patients with AV node reentrant tachycardia who underwent atrial pacing before and after radiofrequency ablation, there were 30 with atrial flutter and 4 with atrial fibrillation before ablation and 29 with atrial flutter and 5 with atrial fibrillation after ablation (p = NS). There was no difference in the duration of the induced atrial flutter before and after ablation. The mean atrial flutter cycle length before ablation (206 +/- 22 ms) was not different from that after ablation (196 +/- 20 ms) (p = NS).

CONCLUSIONS: There is a strong association between AV node reentrant tachycardia and inducible atrial flutter, suggesting that there may be a common area of perinodal atrium participating in the two tachycardia circuits. However, radiofrequency ablation of the slow pathway of the AV node reentrant tachycardia circuit does not influence the inducibility of atrial flutter.