Stretch and Inflammation- Their Relation to Fractionation of Electrograms in Atrial Fibrillation

Inflammatory markers (IM) are elevated in atrial fibrillation (AF). However the relation of IM to substrate modificationinAF remains unclear.We sought to assess the relationship of IM to fractio ated atrial electrogram (FAE) in patients undergoing AF ablation.

At baseline, left atrial (LA) pressure was recorded and peripheral blood was tested for IM. FAE mapping wasperformed before and after circumferential pulmonary vein and linear ablation (CPVA-L) and followed by FAEablation. Image processing was used to define the FAE areas. AF cycle-length (AFCL) was compared between baseline and after ablations from left atrial electrode.

Older patients had higher cytokine levels. FAE area at baseline (secondary FAE) negatively correlated with the levels of interleukin-6 (IL-6, R2= -0.97 and p=0.03) and interleukin-12p70 (IL-12p70, R2= -0.97 and p=0.03). In addition, a significant reduction in FAE area and index occurred after CPVA-L (p=0.0001). FAE after CPVA-L (primary FAE) correlated with left atrial pressure (LAP), [R2 0.5, (p=0.02)]. The AFCL (in msec) increased from 135 ± 41 to 149.5+30 (p=ns) after CPVA-L and further increased to 191.5 ± 60 (p=0.007) after FAE ablation.

There is a negative correlation of IL-6 and IL-12p70 to baseline FAE, suggesting a possibility of sequestration of these cytokines in left atrium. CPVA-L ablation reduces FAE area which when ablated increases AFCL, suggesting that these areas likely represent primary fragmentation due to rotors, triggered by atrial stretch as seen by the relation of left atrial pressure and post CPVA-L FAE.