INTRODUCTION
Although pulmonary vein (PV) isolation (I) remains a cornerstone of any
AF ablation (1,2,3 ), other anatomical regions of the left
atrium (LA), i.e. non-PV substrates, are involved in AF, especially in
persistent (Ps) AF (4,5 ). High density (HD) endocardial voltage
mapping by means of multipolar catheters and 3d electro-anatomical
systems (3d-S) has been increasingly used in clinical practice to
identify both left ventricular (6) and LA anatomical areas of
low-voltage (LV) electrical activity (7,8) , which is commonly
considered a marker of atrial fibrosis (9 ). LA
substrate modification by targeting LV zones is an ablation strategy
that, in addition to PVI, tries to erase arrhythmogenic mechanisms
harbored in such tissue (7 ,10 ). However, bipolar
recordings have a limited ability to identify LV electrical activity, as
they are subject to various influences, such as the bipole orientation
expressed by the angle of attack and the activation wavefront; this can
mean that electrical signals may not be recorded even when they are
present (11 ). Recent reports have described experiences of the
use of new catheters with omnipolar recording capacity which do not seem
to be affected by the negative influences described above with regard to
bipolar HD maps (12,13). The aim of the present study was to
perform a post-hoc analysis in patients undergoing PVI, in order to
evaluate the incidence of non-PV substrates detected by different
diagnostic catheter technologies, including multipolar (MC), omnipolar
(OC), and circular mapping catheters (CMC), and by means of qualitative
and quantitative analysis of LV on applying various voltage ranges.