Clinical and Electrophysiological Characteristics of Incessant Atrioventricular Nodal Re-Entrant Tachycardia.

Objectives: This study investigated clinical and electrophysiological findings in patients with incessant atrioventricular nodal reentrant tachycardia (AVNRT).

Background: AVNRT is the most frequent cause of paroxysmal supraventricular tachycardia (SVT) and, rarely, incessant SVT. There are a few case reports describing incessant AVNRT.

Methods: Among 342 patients treated using ablation for AVNRT, we identified 8 patients with incessant AVNRT (2.3%). We describe the clinical and electrophysiological features of patients with incessant AVNRT and compare them with those of patients with paroxysmal AVNRT (n = 334).

Results: This study population consisted of 5 men and 3 women with incessant AVNRT. Patients with incessant AVNRT presented more frequently with the fast-slow form than those with paroxysmal AVNRT (63% vs. 14%, respectively, p < 0.001). The ejection fraction in patients with incessant AVNRT was significantly lower than that in patients with paroxysmal AVNRT (49 ± 12% vs. 60 ± 8%, p = 0.03). The H-V interval in patients with incessant AVNRT was significantly longer than that in patients with paroxysmal AVNRT. A large circuit path length is inferred by spontaneous tachycardia induction in response to slight changes in sinus rate or random premature beats, suggesting that slight changes in rate produce changes in atrial or nodal refractoriness and provoke SVT. Catheter ablation in the conventional slow pathway region was successful in eliminating SVT.

Conclusions: AVNRT can rarely present as incessant SVT, mimicking permanent junctional reciprocating tachycardia, and can be associated with tachycardia-associated cardiomyopathy. Catheter ablation in the slow pathway region leads to long-term success.