DRAFT FDA Questions for the Circulatory System Devices Panel
March 6, 2003
CryoCath Technologies, Inc.
7F Freezor Cardiac Cryoablation Catheter and
CCT.2 Cryoablation Console System
Effectiveness - Ablation
1. The primary
effectiveness endpoint was defined for patients with AVNRT and AVRT as the
absence of recurrence and non-inducibility of sustained SVT at the end of the
procedure. For patients with AF, it was
defined as the absence of AV node conduction at the end of the procedure. Study r esults were compared to e ffectiveness
objective performance criteria (OPCs) established
for the study. Results
showed that the device did not meet the OPC
for the overall study population or for each patient subgroup.
Please discuss whether the results of the clinical study provide a reasonable assurance of effectiveness in (a) the overall patient population or (b) in any individual patient subgroup.
Safety 2. The primary safety endpoint was the occurrence
of major complications, as defined in the study protocol. Results were compared to the safety OPC
established for the study and showed that t he study complication rate
exceeded the safety OPC. Please comment
on the following a. The safety OPC for this study was based on clinical experience with
radiofrequency ablation for the treatment of supraventricular tachycardias
discuss the applicability of this safety OPC on the evaluation of safety of
cryoablation for the treatment of SVT . b. Please discuss whether the results of the clinical study provide a
reasonable assurance of device safety for the intended patient population.
Effectiveness - Cryomapping
3. The submission describes the use of cryomapping technology
results of the effectiveness of this
technology are described in the submission. Please comment on whether the
study results demonstrate that the cryomapping technology is reasonably effective
for use in the intended patient population.
The applicant suggests that the study result s an
institutional learning curve, with improvement after the fifth procedure per
investigational site. The total
number of participating physicians and site were 34 and 13 ,
respectively. Please comment on the
a. Please discuss the concept of site-based and physician-based learning curves.
b. Please discuss whether the concept of a learning curve, either per site or per physician, may be considered in the evaluation of device safety and effectiveness.
decide that a learning curve may be considered in device safety and
effectiveness, please discuss conclusions that may be made from the data
submitted in this PMA and its impact on safety and effectiveness of the device. d. Please discuss whether and/or
what type of physician training should be required for this device if approved.
User Skill 5. Success of ablation procedures depends both on device performance
and user skill. Please discuss clinical
trial designs that would help FDA assess and/or reduce this source of bias in the
6. Labeling for a new device should
indicate which patients are appropriate for treatment, should identify
potential device-related adverse events, and should explain how the device
should be used to optimize its risk/benefit profile. If you recommend device approval, please address the following:
a. Please discuss whether the proposed warnings, precautions, and contraindications are acceptable, based on the study results.
b. Please discuss whether the instructions for use adequately describe how the device should be used.
7. If you recommend approval, please
discuss whether a post-market study should be performed to address any issues
that are unresolved, but not essential to the premarket approval of the device.
prepared EMallis, 01/15/03