Automated template matching available in some
Automated template matching, available in some electrophysiology systems, has been used to improve pace matching in the ventricle . We found that using automated analysis improved the resolution of pace mapping, especially with bipolar EGMs. The matching algorithms are relatively simple and not computationally intensive, making it possible to implement this on a real-time basis. Our results suggest that using such automated matching on bipolar EGMs can provide very accurate pace matching. Automated matching would also provide the advantage of being instantaneously available compared to manual matching, which may take a couple of minutes to perform each time.
One limitation of this approach is the need to have catheters in the right atrium and coronary sinus in order to record bipolar EGMs. However, these would already be in place in most patients undergoing mapping and ablation of atrial arrhythmias. We simulated tachycardia focus only in the right atrium, although we tested locations both in the superior and inferior parts of the lateral wall. In a previous study , the spatial resolution was poorer in the coronary sinus compared to that in the right atrium. We only used a single Apremilast length of 400ms in all patients. However, there is no reason to believe that the results would be significantly different at faster cycle lengths. In fact, at faster cycle lengths, pace mapping using ECG leads would be worse due to merging with T waves, while that using bipolar EGM may be unaltered. Finally, manual matching was only performed by one observer. However, since the results were verified using an objective system of automated template matching, we did not find the need for a second observer to perform the manual matching. We used a pacing output of 1.5 times the diastolic threshold. The size of the virtual electrode is dependent on the stimulus strength. However, the increase in size is roughly related logarithmically to stimulus strength, and is not significant up to outputs of 7mA . Therefore, we do not expect bias due to large virtual electrode size at the stimulus strengths used in this study.
Conflict of interest
Introduction Radiofrequency (RF) catheter ablation is becoming an effective therapy for drug-resistant atrial fibrillation (AF) . However, the rate of AF recurrence after successful RF catheter ablation remains relatively high , and recurrences are common within 3d after the procedure [3,4]. Immediate AF recurrence interferes with postprocedural management, prolongs hospital stays, and increases healthcare costs. However, immediate pharmacological management after AF ablation is often difficult because of a lack of drugs with both good efficacy and dose adjustability. Therefore, a new treatment strategy is needed for preventing immediate AF recurrence after ablation. Although there is considerable evidence for a mechanistic link between cardiac sympathetic nervous dysfunction and the development of AF [5,6], it is not clear whether sympathetic nerve activity is related to immediate AF recurrence after catheter ablation. As left atrial (LA) ganglionated plexi is present in the vicinity of the pulmonary vein (PV), RF energy applications around the PV affect sympathetic nervous activation  and may be associated with immediate AF recurrence after catheter ablation. Several recent studies have described the efficacy of landiolol hydrochloride, an ultra-short-acting beta adrenoceptor antagonist, for the prevention of AF after open-heart surgery [8–11]. It has mainly been used to treat AF after cardiovascular surgery. Because of its extremely short half-life (4min) and high β1 selectivity, landiolol may also be useful for controlling AF after RF catheter ablation without major side effects. At low doses, landiolol exerts a clinically relevant negative chronotropic effect without negative inotropic effects [11–14]. Accordingly, the purpose of the present study was to investigate the prophylactic effect of continuous low-dose landiolol administration against immediate AF recurrence after catheter ablation.