Posted 12 June 2012
By Alexander Gaffney
Review staff from the US Food and Drug Administration (FDA) said Edwards Lifesciences' Sapien Transcatheter Heart Valve (THV) met trial endpoints for safety and effectiveness for the treatment of high-risk severe aortic stenosis, but expressed concern about trial biases, long-term risks to patients and the statistical validity of some of Edwards' findings.
Edwards' device is set to go before a meeting of the Circulatory Systems Advisory Committee on 13 June, where Edwards will argue to expand the population indicated to receive the device, which is already approved for inoperable patients with an aortic valve narrowed by disease. The expanded pool of patient candidates would include those with a 15% or greater risk of mortality during surgery to replace the aortic valve.
In its materials, FDA said Edwards' valve-in-valve implantation study data failed to answer all outstanding questions regarding the safety and effectiveness of the procedure, and recommended Phase IV post-approval clinical trials be conducted to obtain more information on Sapien THV if the device is approved. In particular, FDA was concerned about surface damage and corrosion resulting from linking two THVs together, saying as the technologies became more developed, "widespread use of the valve-in-valve technique might occur."
FDA did explain it found Edward's preclinical trial data to be acceptable, and said it had "no concerns" about minor device modifications made to delivery components during the course of testing. However, FDA said it was concerned about inconsistent selection and enrolment criteria across clinical trial sites, which may have influenced trial results. "The large variation between the ratios of those screen to those enrolled may represent different selection criteria among sites," concluded FDA. Similarly, the determination of which patients were inoperable and high-risk was inconsistent across clinical trial sites, which could have biased trial results.
"Although the primary endpoint was met, issues related to potential selection bias confound the interpretation of these results," said FDA, who also expressed concern about the statistical validity of Edward's data on instances of stroke complications.
FDA Executive Summary: Edwards SAPIEN THV
2012 Meeting Materials of the Circulatory System Devices Panel