Fehmi Keçe

Cerebral Embolism during Atrial Fibrillation Ablation 85 3 3.4 Discussion To the best of our knowledge, this is the first randomized controlled trial comparing cerebral embolism with the new non-irrigated PVAC-Gold catheter and with the irrigated Thermocool catheter. The main findings are: (1) ablation with the PVAC-Gold catheter is associated with higher incidence of cerebral lesions (23% vs. 6%) and in addition, in the PVAC-Gold group the majority of these lesions were cerebral infarcts compared to none in the Thermocool group, (2) there was a significantly higher number of MES on transcranial Doppler in the PVAC-Gold group, (3) coagulation activity and cognitive functioning did not differ between the groups. 3.4.1 Incidence of ACE In the first generation PVAC, a high incidence of ACE (up to 42%) was reported in several studies (2,3). Investigations revealed a suboptimal ACT, air entrapment during catheter introduction, peri-procedural cardioversion, temperature overshoot during intermittent catheter-tissue contact (6) and electrical interaction between electrodes 1 and 10 as possible causes (16). After implementation of procedural modifications (ACT >350 s, catheter submersion before introduction and deactivating of electrode 10), ACE incidence was reduced to 1.7% (17). Subsequently, the nine-polar PVAC-Gold was developed to prevent temperature overshoot and electrode interaction, which yielded an ACE incidence of 2.1% (7). However, discussions were raised about MRI timing and ACE definition in these studies (3). A positive FLAIR sequence was demanded for ACE diagnosis although scans were performed 16-72 hours post-ablation (7,17). As the FLAIR sequence usually becomes positive after 2-7 days, underestimation of the real ACE incidence may have occurred (3). In the current trial, ACE incidence with PVAC-Gold was 23%, more than 10-fold compared to the previous studies. In the PVAC-Gold group the majority of the patients (7 of 8) the lesions were cerebral infarctions compared to none in the Thermocool group. Although we performed the MRI 21 (IQR: 18-25) hours after ablation, FLAIR positivity was seen in 83% of all lesions. Therefore, MRI timing cannot fully explain the differences in ACE found. Additionally, the total duration of RF delivery was similar to other studies (7,17). However, in this study 99% of the applications were performed in the 2:1 mode. In prior studies, 57- 67% of the ablations were performed with the 2:1 mode, 7% in 1:1 mode and 36-26% in 4:1 mode (7,17). Accordingly, the mixture in energy mode may have influenced the results. At 3 months follow-up, we detected a lower incidence of cerebral lesions compared to directly post-ablation. In a study with 3 instead of 1,5 Tesla MRI, the incidence of ACE was doubled to tripled due to the higher spatial resolution, a slice thickness of 2.5 instead of