Clinical and electrophysiological characteristics of patients having atrial flutter with 1:1 atrioventricular conduction

Aims The purpose of this retrospective study was to assess characteristics of patients who had suffered atrial flutter (AFL) with 1:1 atrioventricular (AV) conduction (1:1 AFL). Methods and results Subjects were 8 patients (61 ± 14 years) with documented 1:1 AFL, and 101 AFL patients without a history of 1:1 AFL (control patients). 1:1 AFL occurred during physical activity with a ventricular rate of 218 ± 18 bpm. Antiarrhythmic agents were administered to all eight 1:1 AFL patients, whereas AV nodal conduction-suppressing agents were administered to four. The maximum ventricular rate at which 1:1 AV conduction occurred was significantly lower than when spontaneous 1:1 AFL occurred (164 vs. 218 bpm, P < 0.05). The 1:1 AFL patients had a significantly longer AFL cycle length (CL) (292 vs. 258 ms, P < 0.05) and more rapid AV nodal conduction time (maximum 1:1 AV conduction: 375 vs. 464 ms, P < 0.05) than did control. Arrhythmia had occurred in patients with an AFL CL ≥ 250 ms and a CL of maximum 1:1 AV conduction ≤400 ms. Conclusion Clinicians should be aware of the potential for 1:1 AV conduction in AFL patients, especially in those with remarkable prolongation of the CL in addition to enhanced AV conduction.