Limitations:
FROZEN AF is a large, multicenter, multicountry prospective trial to
assess the safety and effectiveness of POLARx for cryoablation of PAF in
drug-refractory patients. While all endpoints were met and the study
conclusions are clear, the trial design has limitations: 1) This study
enrolled drug refractory PAF patients, thus did not directly address use
in other patient populations, such as those with persistent AF or
patients with early AF that have not yet been on AADs, 2) Though the
study was conducted with a primary arm of 325 patients that received PVI
with POLARx and an extension arm of 50 pts treated with the variable
size POLARx FIT, it was essentially a single arm design and did not
directly compare cryoablation to alternative therapies, 3) The trial was
run across 55 centers with a wide range of patients treated per center
with a minimum of 1 and a maximum of 48. Thus, many operators were
relatively inexperienced with the device. While this precluded
examination of learning curves, as few operators treated enough patients
to make examination of procedure times or outcomes over time meaningful,
the high freedom from recurrence with so little device use speaks to the
ease of use of the device. 4) Additionally, the size of the extension
arm limits the conclusions that can be reached about the novel variable
size cryoballoon, which allows ablation at either 28mm or 31mm without
catheter change out. To better understand how this new option may
transform workflow and patient outcomes, future studies should examine
acute and chronic endpoints in larger patient cohorts.