Fehmi Keçe

Chapter 9 188 applications, while the advised protocol for the second generation was two 240 second applications. Subsequent studies showed that a single applicationwas sufficient. In addition, shortening the ablation duration from 240 seconds to 180 seconds did not increase AF recurrence. Apart from ablation duration, adequate balloon-tissue contact is required to achieve durable pulmonary vein isolation. With a more adequate balloon-tissue contact, pulmonary vein isolation will be achieved more early causing a shorter time-to-isolation. Indeed, it has been shown that time-to-isolation in pulmonary vein ablation predicts durable PVI. The aim of this chapter was therefore to make ablation duration dependent on time-to-isolation and to determine the optimal ablation duration after time-to-isolation. To this end, patients were randomized to three groups with an additional ablation duration of 90, 120 or 150 seconds after PVI was achieved. Spontaneous or adenosine induced PV reconnection (early reconnection) was selected as primary outcome parameter. We showed that increasing the additional ablation duration caused a stepwise decrease in early reconnection and a decrease in additional cryoballoon applications, while recurrences and complication rates at one year were not significantly different. In addition, the rate of repeat procedures during follow-up decreased with increasing additional ablation duration. In conclusion based on these data, an additional ablation of 150s after PVI is the most appropriate approach in time-to-isolation based ablation. In chapter 7 we focused on the procedural and biophysical predictors of early reconnection. Predicting the absence of early reconnectionmay shorten the procedure and abolish the need for adenosine testing. For this chapter biophysical data of the cryoballoon ablation was analyzed in 151 patients with a 240 seconds fixed ablation duration. We found that three easily available parameters were associated with early reconnection. A higher number of unsuccessful freezes, longer time-to-isolation and higher nadir balloon temperature predicted early reconnection. We constructed a simple formula with cut-off values for these parameters. Using this formula during ablation may help to avoid a 30- min waiting period and adenosine testing in selected patients. While for the purpose of this chapter offline calculations were necessary, with the upcoming improvements of the cryo-console these biophysical parameters will be easily available and the implementation of this formula in the form of a cryoballoon ablation score, similar to ablation index, will be possible. With a cryoballoon ablation score the ablation procedure may be further optimized to improve AF-free survival. Finally, in chapter 8 we focused on isolation of the left atrial posterior wall in patients with persistent atrial fibrillation. The posterior wall is a well-known substrate for atrial fibrillation maintenance as it shares a common embryological origin with the pulmonary veins. Isolation of the posterior wall between the pulmonary veins, a so-called box lesion,