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This attachment accompanies Medtronic’s physician letter dated October 15, 2007 and provides background information on our vigilance process.
Medtronic’s vigilance process is multifaceted and comprehensive. All complaints with or without returned product and associated trends are analyzed, and qualifying events are reported to regulatory agencies. As part of Returned Product Analysis (RPA), Medtronic analyzes all explanted and returned leads to characterize the failure mode, if any. The Medtronic System Longevity Study (SLS) is leveraged to understand, monitor, and report lead survival. We developed a proprietary methodology to analyze data from the Medtronic CareLink® Network database to estimate lead integrity and lead performance. Using RPA, SLS, and CareLink™ Network data, we are able to implement the most comprehensive vigilance process for assessing the performance of Fidelis leads.
The Medtronic RPA Lab analyzes all leads or partial lead segments that are returned to us. The purpose of the analysis is to identify the failure mode, if any. If a failure mode is found, the data are categorized and stored in a database intended for trending and analysis. All the leading CRM device manufacturers use RPA as a tool to estimate device performance; however, the protocols for product analysis and reliability estimates differ among manufacturers.
RPA’s primary benefit is that it can help identify the nature of the failure in most cases and correlate the failure mode to the clinical presentation of the failure mode. In addition, it helps proportionally categorize all the failure modes associated with a given lead model. RPA’s primary limitation is under-reporting. Not all malfunctioning leads are explanted and returned to the manufacturer due to a number of factors including explant related clinical risks to the patient.
For over 24 years, Medtronic has conducted a System Longevity Study (SLS) which is a prospective multicenter study designed to monitor the performance of market-released cardiac therapy products. SLS data is updated every six months and published in our Product Performance Report. This ongoing measurement of lead performance provides prospective information that is not available through RPA.
SLS enrollments for Fidelis Model 6949 represent more than 50 physicians from 17 centers, 14 located in the United States and Canada. As of July 31, 2007, for Model 6949, SLS has 654 leads with a mean follow-up time of 15.1 months, a median follow-up of 12.4 months, and a cumulative follow-up of 9,894 months. The effective sample size between 27 and 30 months of implant time is 84 patients. The limitations of SLS include a smaller sample size, particularly at the leading edge of implant time.
Our CareLink data analysis was designed to overcome the limitations of RPA (under-reporting) and SLS (relatively small sample size). Using a proprietary algorithm, we analyzed data from over 25,000 devices enrolled on the CareLink Network remote monitoring system to determine lead integrity. The triggered files were reviewed by technical experts and compared with Medtronic Device Registration Services and RPA databases to confirm lead integrity. In the event we could not confirm the lead status, we contacted the physicians directly to verify the status of the lead. The addition of this data gives us increased confidence in our analysis of Fidelis’ performance (see Appendix B).
In addition to confirming lead fractures, our analysis of the CareLink Network also identified other causes for abnormal parameters, including findings related to the set screws in up to 20% of the confirmed lead integrity issues.
Medtronic is committed to ensuring the highest standards of product reliability. We will continue to provide performance updates every six months via our Product Performance Report.
If you have questions or concerns, please contact your Medtronic Representative or Medtronic Technical Services at 1-800-723-4636 (US).