Electrophysiological abnormalities in subjects with lone atrial fibrillation – Too little, too late?

Arroja and colleagues present an interesting observational study providing insights into the electrophysiological characteristics of subjects with atrial fibrillation (AF) and no evidence of overt structural heart disease in this issue of the journal [1]. The authors utilized signal-averaged P-wave duration and intracardiac electrophysiological parameters (intra and inter-atrial conduction times and refractory periods) to qualify the presence of subclinical atrial structural damage (atrial remodeling) in subjects with AF. They compared the prevalence of electrophysiological parameters of atrial remodeling in subjects with AF undergoing catheter ablation to that in a control cohort of subjects without AF. The study also compared parameters of subclinical atrial remodeling in subjects with and without recurrence of AF after catheter ablation. The rationale, presumably was to test the hypothesis that subclinical atrial remodeling in subjects undergoing catheter ablation for AF may be associated with a higher incidence of AF recurrence. As expected the surrogate parameters of subclinical atrial remodeling (P-wave duration and intracardiac electrophysiological measurements) were abnormal in subjects with AF compared to subjects without AF. This finding is not novel or unique to the current study and the fact that subjects with AF and no evidence of overt structural heart disease can have subclinical atrial remodeling has been demonstrated previously by multiple investigators [2e7]. In the current study, no differences were noted in the prevalence of surrogate parameters of atrial remodeling in subjects with and without AF recurrence after catheter ablation. Even though the study is methodologically sound and well executed, it was not designed to detect a clinically meaningful difference in surrogate parameters of subclinical atrial remodeling between subjects with and without AF recurrence. The reason for this is that the study included a homogenous group of subjects with paroxysmal AF, who in general tend to have less atrial remodeling as shown in previous mechanistic studies evaluating the prevalence of electrophysiological markers of atrial remodeling (in paroxysmal and persistent AF phenotypes) [8]. The low prevalence of electrophysiological parameters and minimal severity of atrial remodeling in subjects included in the study predicated that a relatively large