FIRE and ICE randomised trial of RFA vs Cryoballoon for paroxysmal AF

Just released online on NEJM. Principal investigator was Karl Kuck of Hamburg.

[www.nejm.org]

More details on the trial in the appendix
[www.nejm.org]



Edited 1 time(s). Last edit at 04/05/2016 11:43AM by researcher.

I finally had to a chance to go through the article and appendix containing the trial details. When Kuck wrote about 8 countries and 16 centers, I assumed some US centers were involved. However, only high volume EU centers were involved. That explains the lower phrenic nerve palsy complications (2.7%) experienced in the trial compared to Doug Packer's review of STOP-AF trial which showed 13.5% phrenic nerve palsy. Not including low volume centers is the biggest issue in my opinion. RFA major complications at low volume centers is around 9% according Winkle's review of medicare data or 3-4X that of high volume centers so it would be interesting to see a comparison between RFA and cryo at low volume centers as cryo is being marketed as a simpler approach that low volume centers can use to get results just as good as RFA. Too bad there isn't a cheap magnetic system that even low volume centers can afford as that would drive RFA complication risks down to the same level as high volume centers.

The big discrepancy in phrenic nerve palsy complication results between "FIRE and ICE" and "STOP-AF" stoked my curiosity as both trials were sponsored by Medtronic. The former were all high volume EU centers with big representation by German referral centers and the latter is around a 60-40 mix (USA and Canada) of referral centers and community hospitals. Still the spread is wider than I would expect since the procedure mix in the STOP-AF trial would be skewed higher than 60-40 just based on procedure volume of the referral centers vs community centers.

Looking deeper, I found a trial concluded last year by a German referral center (Heidelberg) that was not sponsored by Medtronic and that was sufficiently powered. "FreezeAF"
It is also a randomized non-inferiority study and phrenic nerve palsy was 6%. Total major complications was about doubled between cryoballoon and RFA. Efficacy is the same as is repeat procedures so that part is consistent with "FIRE and ICE".

The devastation of PN palsy and the risk based on these trial results would not be acceptable to me if I was to undergo AF ablation. Medtronic and EPs that want to use cryoballoon need to do better in reducing this risk.

[clinicaltrials.gov]
[circ.ahajournals.org]



Edited 1 time(s). Last edit at 04/06/2016 01:38PM by researcher.

Hi Researcher,

The current view on phrenic nerve palsy from the newer second generation Artic Front cryo system , as noted repeatedly by various speakers from both the EU and US at both AF Symposium 2016 and EP Live 2016 this past January and early March, was 6.4% on average.

Surely there are higher incidence with lower volume centers although the mechanisms for most balloon-based (cryo or Laser) catheter phrenic nerve injury which does improve with greater experience, is still more likely to occur even with more experienced operators than by rough comparison the big drop in PV stenosis from RF ablation in the hands of highly experienced operators compared to greenhorns doing RF PVI ablations. There are some inherent anatomical challenges with the fully circumferential freeze or laser energy application around the complete PVs and when the ballon is either seated a little too deeply in the PV Ostium in which the freezing or laser lesions are being laid down, Or are too close to the phrenic nerve in a good number of folks due to their own anatomical close proximity of their phrenic nerve to the balloon lesion.

Fortunately, the vast majority of phrenic nerve injury is temporary in nature and complications tend to fade away in 6 to 9 months in the vast majority of such case and this is especially the case with RF ablation.

Nevertheless, regardless of the energy source used, the ablation patient is strongly advised to seek out the most experienced operator they possibly can arrange for themselves who specializes mostly in addressing the degree of AFIB one has as the large majority of the EPs caseload every day as you noted.

Shannon



Edited 1 time(s). Last edit at 04/11/2016 03:19PM by Shannon.