Fehmi Keçe

Chapter 3 78 3.2.5 Laboratory Measurements 2x5 ml Citrated blood samples were collected the day before ablation (T1), during the procedure before the first RF application (T2), before sheath removal (T3) and the day after ablation (T4). Samples were centrifuged at 2700 g for 10 min at 18°C. Markers of intrinsic and extrinsic coagulation (APTT, PT/INR), fibrin-turnover (D-Dimer), acute phase markers and coagulant potential (fibrinogen) were measured directly. Other coagulation parameters were analyzed on frozen -70°C aliquots: Von Willebrand factor antigen as a marker of endothelial damage, Prothrombin fragment 1+2 as a marker of thrombin generation, tissue plasminogen activator as a marker of fibrinolysis and soluble P-selectin as a marker of platelet activation. Measurements are described in the Supplemental Methods A. 3.2.6 Neuropsychological Assessment Two weeks before and 3 months after the ablation patients underwent neuropsychological tests for global cognitive functioning and intelligence level, memory function, attention and concentration, executive functioning, psychomotor speed and mood. The education- matched (13) reference group underwent the same tests. The tests are described in the Supplemental Methods B. 3.2.7 Statistical Analysis Power analysis was based on the outcome of 3 prior studies (2,4,14) and the results of our pilot study (15). Taking the outcome of these studies together, 56 of the 142 patients (39.4%) showed ACE after PVAC-ablation and 8 of 82 (9.8%) patients showed ACE after cooled-tip ablation. The rate difference was therefore 29.6% ; with a required sample size of 64 to detect a difference in ACE with 80% power at a 0.05% probability level (SPSS Sample Power 2.0 (SPSS Inc. Chicago, Illinois, USA). Accordingly, the group size was set to 35. All continuous data was checked for normality with the Shapiro-Wilk or Kolmogorov- Smirnov test and expressed as mean±standard deviation or median and interquartile range (IQR), when appropriate and compared using an unpaired t-test or Mann-Whitney U test. For categorical data, numbers and frequencies were provided and compared using an chi-square test or Fisher’s exact test for low expected count. A mixed linear model with between subject (group) and within subject (time) factors was used for the laboratory values and neuropsychological measures. Kaplan Meier survival curves were constructed (log-rank test) to compare the AF-free survival between the 2 groups. A p-value of <0.05 (two-sided) was considered statistically significant. Data were analyzed using SPSS (version 23).