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  5. Catheter Correction: Boston Scientific Updates Use Instructions for POLARx and POLARx FIT Cryoablation Balloon Catheters due to Higher than Anticipated Number of Reports of Atrio-Esophageal Fistula
  1. Medical Device Recalls

Catheter Correction: Boston Scientific Updates Use Instructions for POLARx and POLARx FIT Cryoablation Balloon Catheters due to Higher than Anticipated Number of Reports of Atrio-Esophageal Fistula

This recall involves updating instructions for using devices, and does not involve removing them from where they are used or sold. The FDA has identified this recall as the most serious type. This device may cause serious injury or death if you continue to use it without following the updated instructions.

Affected Product

  • Product Names: POLARx Cryoablation System; POLARx and POLARx FIT Cryoablation Catheters and SMARTFREEZE Cryo-Console
  • Model, Material Number, UDI: 
    • CRBS POLARX FIT BALLOON CATHETER ST US, M004CRBS2060, 08714729992622
    • CRBS POLARX FIT BALLOON CATHETER LT US, M004CRBS2160, 00191506016463
    • CRBS POLARX BALLOON CATHETER ST 28MM OUS, M004CRBS2000, 08714729992561
    • CRBS POLARX BALLOON CATHETER LT 28MM OUS, M004CRBS2100, 08714729992660
    • CRBS POLARX FIT BALLOON CATHETER ST OUS, M004CRBS2010, 08714729992578
    • CRBS POLARX FIT BALLOON CATHETER LT OUS, M004CRBS2110, 00191506016456

What to Do

  • Be aware of the known and inherent risk of esophageal injury, including atrio-esophageal fistula, that may occur during catheter-based ablation procedures for rapid, irregular heartbeats (atrial fibrillation).
  • Be aware of updates to instructions for use for POLARx cryoablation catheters. These updates are outlined in the Urgent Medical Device Advisory.
  • Review the summary of cryoablation application temperatures and frequency parameters used in the device clinical trial and provided in the Urgent Medical Device Advisory.

On October 10, 2024, Boston Scientific sent all affected customers an Urgent Medical Device Advisory recommending the following actions:

  • Review instructions for use updates related to atrial esophageal fistulas, which include:
    • Section: Warnings Cryoablations may cause collateral thermal injury to the esophagus and in rare instances atrio-esophageal (AE) fistulas. Additions: To minimize potential esophageal injury, the following is recommended: 
      • Monitor the location of the cryoballoon relative to the esophagus prior to delivering cryotherapy.
      • Avoid performing cryoablation directly over the esophagus.
      • DO NOT perform cryoablation directly on the posterior wall of the left atrium, as this may place the cryoballoon over the esophagus and increase the risk of freezing injury to the esophagus.
      • Avoid catheter manipulation that may deform the cryoballoon or displace the atrium towards the esophagus.
      • Ablate cautiously if the balloon is within close proximity to the esophagus, especially when isolating the left inferior pulmonary vein, which was most implicated in the AE fistulas Stop the ablation if the balloon temperature decreases to -65 °C and avoid repeating ablations immediately in the same location to minimize potential for thermal accumulation.
      • Utilize temperature monitoring with a probe placed in the esophagus. Stop the ablation if the esophagus probe measurement decreases to 20 °C and allow the esophagus probe temperature to return to baseline levels before initiating another cryoablation application.
    • Section: Procedure Perform the cryoablation. (Refer to the SMARTFREEZE Console User’s Manual for setup, setting and use). Additions: To minimize the potential for unintended thermal injury, the following is recommended:
      • Utilize standard-of-care practices for verifying balloon position, esophageal monitoring, and phrenic nerve monitoring.
      • Ensure the balloon is appropriately positioned prior to starting cryoablation.
      • Utilize the minimum number of cryoablation applications necessary to achieve PV [pulmonary vein] isolation and avoid immediately repeating ablations in the same location. Note the POLARx FIT cryoablation catheter demonstrated effectiveness in the FROzEN AF clinical trial without use of additional applications following PV isolation.
      • Stop the ablation if the balloon temperature decreases to -65 °C.
  • Review Table 1 for a summary of cryoablation application parameters from the FROzEN AF clinical trial, which demonstrated safety and effectiveness of the POLARx Cryoablation System.
Table 1: Cryoablation Parameters from the FROzEN AF Clinical Trial
ParametersLeft Inferior (LIPV)Left Superior (LSPV)Right Inferior (RIPV)Right Superior (RSPV)
# of cryo applications1.67 ± 1.181.77 ± 1.231.8 ± 1.421.96 ± 1.24
# of cryo applications1.54 ± 0.971.61 ± 0.961.63 ± 1.121.63 ± 0.95
Lowest Measured Balloon Temperature (°C)-53.95 ± 7.45-58.29 ± 5.96-55.63 ± 6.43-58.36 ± 6.33
Total Duration (min)4.34 ± 2.364.41 ± 2.354.49 ± 2.824.3 ± 2.22
  • Share the communications with clinicians using Boston Scientific POLARx Cryoablation System and any other organization that may have received these devices.
  • Keep a copy of the notice in facility records.
  • Report all adverse events or quality concerns with use of these devices to Boston Scientific.
  • Complete the mandatory acknowledgement form and return it promptly, even if there are no consoles at the facility.

Reason for Updates to Use Instructions

Boston Scientific is updating use instructions for POLARx Cryoablation Balloon Catheters due to a higher than anticipated number of reports of esophageal injury, specifically atrio-esophageal fistula, after catheter ablation procedures for atrial fibrillation. The updates emphasize the risk of atrio-esophageal fistula and practices that may minimize risk, based on the observation that location, frequency, and intensity of cryoablation applications may be contributing factors to this complication.

The use of affected product may cause serious adverse health consequences, including atrio-esophageal fistula leading to air bubbles blocking blood vessels in the brain (cerebral air embolism), stomach and intestinal (gastrointestinal) bleeding, a system-wide infection (septic shock), and death.

There have been seven reported injuries. There have been four reports of death. 

Device Use 

The Boston Scientific Cardiac Cryoablation System using POLARx Cryoablation Balloon Catheters is indicated for the treatment of recurrent, symptomatic atrial fibrillation, which leads to irregular, fast heartbeats that resolve within seven days (paroxysmal) that do not respond to medication (drug-refractory).

Contact Information

Customers in the U.S. with questions about this recall should contact Boston Scientific at 1-888-272-1001 or by email.

Additional FDA Resources

Additional Resources

Unique Device Identifier (UDI)

The unique device identifier (UDI) helps identify individual medical devices sold in the United States from manufacturing through distribution to patient use. The UDI allows for more accurate reporting, reviewing, and analyzing of adverse event reports so that devices can be identified, and problems potentially corrected more quickly.

How do I report a problem?

Health care professionals and consumers may report adverse reactions or quality problems they experienced using these devices to MedWatch: The FDA Safety Information and Adverse Event Reporting Program.

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