Fehmi Keçe

Optimizing Ablation Duration using Dormant Conduction 127 6 6.1 Introduction Cryoballoon ablation is an effective single-shot technique for the treatment of paroxysmal atrial fibrillation (AF) and is non-inferior to radiofrequency catheter ablation (1). Several ablation protocols for cryoballoon ablation have been proposed (2, 3). Optimizing the ablation duration to obtain durable ablation lesions without causing extra-cardiac complications is crucial. It has been shown that time to pulmonary vein (PV) isolation (time-to-isolation) is related to balloon-tissue contact, with a shorter time-to-isolation indicating a better contact (4). It can be expected that with a fixed ablation duration, a better balloon-tissue contact will lead to an earlier lesion transmurality and a potentially higher risk for extra- cardiac complications. It may be beneficial to adapt the application duration according to the time-to-isolation. The most common extra-cardiac complications related to cryoballoon ablation are right phrenic nerve palsy (7-8%) and esophageal ulceration (12%) (5, 6). Right phrenic nerve palsy can be permanent and may lead to significant dyspnea (7). A rare, but severe complication is the development of an atrio-esophageal fistula, which can be fatal (8). Optimizing the ablation duration may prevent these complications. After ablation, testing for dormant conduction (DC) with adenosine can be used to reveal incomplete pulmonary vein isolation (PVI) (9, 10). The absence of reconnection/ DC after 30 minutes waiting period may be considered as parameter for durable PVI and is therefore selected as a clinical outcome parameter. The primary objective of this randomized clinical trial was to determine the optimal additional ablation after time-to- isolation with absence of reconnection/DC as the primary endpoint.