Intra-cardiac and peripheral levels of biochemical markers of fibrosis in patients undergoing catheter ablation for atrial fibrillation

Abstract

Aims Measurement of circulating biomarkers of fibrosis may have a role in selecting patients and treatment strategy for catheter ablation. Pro-collagen type III N-terminal pro-peptide (PIIINP), C-telopeptide of type I collagen (ICTP), fibroblast growth factor 23 (FGF-23), and galectin 3 (gal-3) have all been suggested as possible biomarkers for this indication, but studies assessing whether peripheral levels reflect intra-cardiac levels are scarce. Methods We studied 93 patients undergoing ablation for paroxysmal atrial fibrillation (AF) (n ¼ 63) or non-paroxysmal AF and results (n ¼ 30). Femoral venous, left and right atrial, and coronary sinus blood were analysed using ELISA to determine biomarker levels. Levels were compared with control patients (n ¼ 36) and baseline characteristics, including left atrial voltage mapping data. C-telopeptide of type I collagen levels were higher in AF than in non-AF patients (P ¼ 0.007). Peripheral ICTP levels were higher than all intra-cardiac levels (P < 0.001). Peripheral gal-3 levels were higher than left atrial levels (P ¼ 0.001). Peripheral levels of FGF-23 and PIIINP were not significantly different from intra-cardiac levels. CS levels of ICTP were higher than right and left atrial levels (P < 0.001). gal-3 was higher in women vs. men (P 0.001) and with higher body mass index (P 0.001). ICTP levels increased with reducing ejection fraction (P 0.012). Conclusions Atrial fibrillation patients have higher levels of circulating ICTP than matched non-AF controls. In AF ablation patients, intra-cardiac sampling of FGF-23 or PIIINP gives no further information over peripheral sampling. For gal-3 and ICTP, intra-cardiac sampling may be necessary to assess their association with intra-cardiac processes. None of the biomarkers is related to fibrosis assessed by left atrial voltage.