MCL1 and atrial fibrillation: The major findings in this study are as follows: 1) SVC-EAT volume in the SVC-AF group was significantly higher than that observed in the non-LVA-AF and PE group; 2) the SVC-AF group had the highest SVC/LA-EAT ratio among the four groups; 3) empirical SVC isolation may be considered if the SVC/LA-EAT ratio was over 6.8%.