Atrial fibrillation (AFib) progressively leads to electrical remodeling (ER) and anatomical-mechanical remodeling (AMR) whose relationships remain poorly known.

ER and AMR were compared in patients undergoing percutaneous RF ablation for AFib. ER was defined by right and left appendage activation rate (RAAAR and LAAAR) as a surrogate for atrial refractory periods. AMR was approached by left atrium (LA) diameters and area and left atrial appendage (LAA) area and contractile function (mean emptying flow velocity) (LAAFV) as determined during transoesophageal and transthoracic echocardiography performed during AFib the day before or immediately before RF ablation. Mean duration between successive LAA contractions was considered as LAA mechanical rate.

40 pts with paroxysmal AFib (n=10), persistent AFib (n=25) or long-persistent AFib (n=5) were included (30 men, 64±9 yo, EF 39±14%). 63% were on amiodarone.

Parameters exploring AMR were highly correlated to each other: LA area 27±7cm²; LAA area 5.5±2cm²; LA transv 48±14 mm; LA ant-post 58±13 mm; LAA velocity 28±13cm/sec (p<0,05 for each comparison).

Parameters exploring ER were also highly correlated: RAAAR 180±39 msec; LAAAR 175±34 msec (p<0,0001). There was no significant correlation between any ER and AR parameter.

Only LAA mechanical rate (172±36 msec) was highly correlated the LAAAR (p<0,01).

ER and AMR are not mutually related, atrial activation rate being not correlated to LA or LAA size and mechanical function. Thus, the mechanisms leading to AFib induced atrial remodeling may differ for anatomical-mechanical and electrophysiological aspects.