Prediction of Sinus Node Dysfunction in Patients with Paroxysmal Atrial Fibrillation and Sinus Pause

Abstract

Background and Objectives: Sinus pause association of paroxysmal atrial fibrillation (PAP) is generally considered a sinus node dysfunction (SND) known as tachycardia-bradycardia syndrome (TBS). Cure of tachyarrhythmias in some patients with prolonged pauses on termination of tachyarrhythmia resulted in an improvement in sinus node function and/or a return to normal ranges thus avoiding the need for permanent pacing. The purpose of this study was to investigate the electrophysiological and clinical characteristics as well as their sinus node function in patients with prolonged pauses and PAP. Methods and Results: Of 1266 PAP patients undergoing radiofrequency catheter ablation (RFCA), 122 patients with pauses (>2 s) were studied. The mean maximum symptomatic prolonged pause on termination of tachycardias was 2.67 ± 1.4 s (2.0–12.6 s). SND developed in 32 patients. There was no difference between the patients with and without SND in terms of the age and sex. Patients were divided into two groups based on the intracardiac electrophysiology study after the RFCA procedure. Eleven patients (8 men, 3 women; age 30–72 years, mean 48.2 ± 9.3 years) were placed in a normal sinus node function (NSF) group, and 17 patients (12 men, 5 women; age 37–75 years, mean 62.2 ± 7.5 years) were in an SND group. There was no significant difference in gender, left atrial dimension, left ventricular ejection fraction, blood pressure, or the longest pause between the two groups. RFCA was successful in 28 patients. Electrophysiological data show that corrected sinus node recovery time (CSNRT) was 409 ± 152 ms in NSF group patients and 558 ± 178 ms in SND group before the ablation procedure (P 2 cycle lengths in 12 patients. In the multivariate analysis, prolonged pauses on termination of tachyarrhythmia, frequency of pauses, and mean heart rate after ablation were independent predictors of SND. Conclusions: (1) Catheter ablation of atrial fibrillation (AF) is effective in treating paroxysmal AF-related TBS; (2) in some patients, there is progressive improvement of sinus node function after elimination of AF, an indication that these sinus pauses may be a manifestation of tachycardia-mediated remodeling of the sinus node, and that permanent pacemaker implantation is unnecessary; (3) among the extrinsic and intrinsic causes of SND, intrinsic causes are seldom reversible and some causes of extrinsic SND may be reversible; and (4) prolonged pauses on termination of PAF, frequency of pauses (>2.0 s), and mean heart rate after ablation were independent predictive factors of SND.