So, is that simple?
P wave duration is often considered an expression of longer atrial conduction time (6,7) and one could raise the question if this “easy-taken” parameter might simply used for the same purpose:identifying those patients at risk to develop AFL. P wave duration is an expression of the entire atrial conduction time between the two atria and, thus it is not comparable to RACT which marks the conduction time only within the right atrium.(8). P wave is the phenotypic expression of the more complex atrial conduction process and it is specifically influenced by the local conduction time in the left atrium. Therefore, we may observe longer P wave duration which is not always associated to longer RACT. Actually, it would have been useful to explore in this study population, if patients who exhibited AF over the follow up also had longer P wave at the time of index electrophysiologic procedure.
More unexpected is the finding that larger right/left atrial volumes were not associated to the development of AFL on multivariate analysis; I suspect that the limited number of patients included in the study prevents from a more detailed analysis that could yield a picture more adherent to the clinical reality. Assigning a precise cut-off value of RACT for the future development of typical AFL is a “debatable” action, just in terms of “let’s do cavo-tricuspid ablation” as empirical and prophylactic maneuver (9). In this regard, I’d be cautious, awaiting more robust and consistent data from larger population studies. On the contrary, I give credit to the authors that longer RACT can be found in patients undergoing AF ablation and without clinical history of typical AFL. Under these circumstances, I’d be in favor to add a “prophylactic” AFL ablation to left atrial ablation for AF, since the chance to have typical AFL afterwards is not negligible (2,10).
Therefore, despite the actual limitations of the role played by RACT, I support the estimation of this parameter in patients candidate to AF ablation as to reduce the likelihood of AFL occurrence over the follow up, even though, up to now there is no universal consensus of a preventive AFL ablation. What is lacking is the information about the potential influence on RACT of drugs used in patients with AFL. Did any antiarrhythmic medications affect the calculation of the conduction time across the right atrium? Do the antiarrhythmic drugs influence RACT at the same degree in patients with and without AFL? These questions deserve to be fulfilled in the near future including a higher number of patients as to corroborate the true value of RACT as predictive parameter of future risk of AFL occurrence