Fehmi Keçe

Chapter 3 86 5 mm and an improved signal-to-noise ratio (18). As the lesion size of ACE in our trial was between 3 and 6 mm and lesions tend to decrease in size during follow-up (14), lesions may have been missed on follow-up MRI. 3.4.2 Transcranial Doppler Across the entire procedure, the number and concentration of MES were much higher in the PVAC-Gold group. In the pre-ablation phase however, the Thermocool catheter showed a higher number of MES. Besides energy delivery, catheter manipulation contributes to the generation of MES (6) The additional mapping procedure before ablation may therefore explain this finding. During ablation, a higher number and concentration of MES were detected with PVAC-Gold. In our pilot with the first-generation PVAC and ACT >300 s, we detected a mean MES number of 2324±1406 (15), comparable to other reports with relatively high MES numbers with this catheter (8,19). In the current study with ACT >350s, we still detected a higher number of MES with PVAC-Gold compared to the Thermocool catheter. We therefore believe that several factors (energy mode, temperature overshoot, anticoagulation protocol and aspect of non-irrigation) may contribute to the incidence of ACE in the PVAC-Gold. 3.4.3 Parameters of Coagulation Activity There are no other studies comparing coagulation activity between cooled RF ablation and PVAC. During and after the procedure we observed a progressive increase in D-dimers levels which reflects fibrin formation and subsequent breakdown of fibrin, suggesting activation of coagulation during the procedure. In addition, we observed a progressive increase of Von Willebrand factor antigen reflecting endothelial damage and/or acute phase response. These observations may indicate that the ablation procedure in itself is pro-thrombotic. However, we did not observe significant differences between the two groups. Accordingly, the difference in ACE cannot solely be attributed to the observed in the pro-coagulant state. One study comparing PVAC to the Cryoballoon catheter also showed no significant differences in coagulation activity (7)(20), similar to our results. 3.4.4 Clinical Significance of ACE In our study, 42 (60%) patients had pre-existent white matter lesions and 14% exhibited a previous lacunar infarction. It is known that pre-existent white matter lesions can cause cognitive decline (21). However, the additive cognitive effect of new ACE in AF-ablation patients is still a matter of debate. In previous studies, both presence (9) and absence (8) of negative cognitive effects of ACE have been described. In our study, we did not detect