Disclosures: Moloy Das has no relationships to declare,
FILMED AT THE CARDIOSTIM ANNUAL MEETING, JUNE 2016WHAT ARE THE CURRENT LIMITATIONS OF CATHETER ABLATION FOR AF?
00:11 – Well I think there are two main limitations currently. First of all, although the pulmonary veins have been well established as the main source of triggers in paroxysmal AF, it’s more unclear as to what other areas are important for ablation in more persistent forms of AF. I think the second major limitation is even when it is clear we are to target ablation, it’s often the case that the lesions that we deliver are not durable.
HOW WIDESPREAD IS THE OCCURRENCE OF PULMONARY VEIN RECONNECTION FOLLOWING PULMONARY VEIN ISOLATION IN AF ABLATION?
00:48 – Well, there have been a number of studies recently that have brought patients back for a protocol mandate repeat EP study after initially successful radiofrequency PVI procedure. And these have shown that up to two thirds of patients have evidence of PV reconnection. This includes the EFICAS-1 study in 2014 and the recently published GAP study in which the completed circles arm cohort had PV reconnection in 70% of the patients. And also the PRESSURE study that we recently reported also showed a similar proportion. That proportion was reduced in the EFICAS-2 study by the use of contact force in FTI targets. But, nevertheless, more than one in three patients still have PV reconnection.
CAN YOU TELL US ABOUT THE RELEVANCE OF THE BLANKING PERIOD FOLLOWING PULMONARY VEIN ISOLATION?
01:39 – Well the blanking periods are undoubtedly important because there are certainly a number of pro-arrhythmic factors following ablation that can lead to early arrhythmia recurrence that don’t necessarily mean longer term failure. These factors include things like inflammation related to ablation, transient autonomic dysfunction and also the time taken for lesions to develop and mature. But there has been some data suggesting that these factors resolve within about a month after the ablation. And other studies have shown a very strong association between recurrence beyond the first month after ablation and later occurrence. In keeping with that, we published a study last year that showed a strong relationship between early recurrence beyond the first month of the blanking period and reconnection of pulmonary veins, and particularly of two or more pulmonary veins. So I think all that together, I think the blanking period is important, and it should be there, but there’s a question as to whether the three-month duration is excessive.
CAN YOU GIVE US AN OVERVIEW OF THE PRESSURE TRIAL AND ITS FINDINGS?02:54 – Given the high rates of PV reconnection seen in the studies that I already mentioned and the disappointing success rates for ablation, even of paroxysmal AF, despite the use of modern technology, we hypothesise that bringing patients back for repeat procedure after two months, after their initial PVI, with assessment of the pulmonary vein for reconnection and re-isolation of those pulmonary veins, irrespective of symptoms in the intervening period, might improve outcomes. So we studied a group of 80 patients with paroxysmal AF who were randomised to undergoing the repeat procedure after two months or to standard care. And we followed them up very intensively with portable ECG monitors and we asked them to take an ECG recording every day, and whenever they experienced symptoms over the 12-month duration of the study. We found that 62.5% of the patients who were in the repeat study arm had PV reconnection, and all of that was of course re-ablated. And after 12 months the proportion of patients with freedom from atrial tachyarrhythmia was significantly higher in the repeats of the group at 82.5% compared to 57.5% in the standard care arm. There was a significant improvement in quality of life in atrial tachyarrhythmia burden and time to first atrial tachyarrhythmia recurrence, and there were no complications associated with those repeat studies. So, overall it would suggest that until we can achieve more durable pulmonary vein isolation first time around, a second procedure after two months may be a potentially reasonable strategy.