Insertable Cardiac Monitor (ICM) Performance Analysis

The Reveal LINQ™ and LINQ II™ ICMs are small, leadless devices that are inserted under the skin, in the chest that records subcutaneous ECG. These ICMs can be subject to malfunctions, similar to other implanted devices.

The performance report information is determined from the analysis of available complaint and available CareLink™ network data. An ICM model will be included in this report when it has accumulated at least 10,000 implant months and will remain in the report as long as at least 500 devices remain active in the CareLink™ population.

Using returned product data and CareLink™ to Estimate Insertable Cardiac Monitor Performance

ICMs returned to Medtronic are analyzed to determine whether or not they meet performance limits established by Medtronic. Although returned product analyses are valuable for gaining insight into failure mechanisms, this data can be limited in determining the survival probability as not all ICMs are returned to Medtronic for analysis. As ICMs are diagnostic devices, it is possible for a device not to be returned after meeting the device designated longevity or the patient receiving a diagnosis of their condition.

For certain malfunctions relating to oversensing for LINQ II™, CareLink™ Network data is leveraged. This data is related to FA1368: LINQ II™ Insertable Cardiac Monitoring Systems (LNQ22) with Potential for Amplified Noise.

Qualifying Complication or Malfunctions

All reported ICM complaints are adjudicated by subject matter experts for inclusion as a product performance event given available information. These product performance events are then cross-referenced with the CareLink™ population for inclusion in the survival analysis.

Product Performance events include, but are not limited to:

• Amplified Noise due to moisture (FA1368) – this only affects LINQ II™
• Premature Battery Depletion
• Electrical Component
• Software/Firmware
• Other

The CareLink™ Network

As noted previously, the CareLink™ Network is leveraged for data related to FA1368, in addition to determining the inclusion of product performance events in the survival analysis.

Statistical and Data Analysis Methods

The performance is expressed in terms of device survival estimates, where "survival" refers to the function of the device, not the survival of the patient. These survival estimates are intended to illustrate the probability that a device will survive for a given number of years without a chronic device-related complication.

Active surveillance normally begins at the time of implant and continues until a product performance or censoring event occurs. Of the several different statistical methods available for survival analysis, PPR survival analysis is estimated using the Standard Actuarial Method, with suspensions assumed distributed evenly within the intervals (Cutler-Ederer Method), and incorporated data from these retrospectively enrolled devices. Thus, in some cases sample sizes may fluctuate from one time interval to the next interval.

The survival estimate is the probability that a device is free of a product performance event at a given time point. For example, if a survival probability is 95% after 5 years of service, then the device has a 5% chance of experiencing a related complication in the first 5 years following implant.

Since the survival estimate can become very imprecise with small effective sample sizes, Medtronic truncates the survival curve when the effective sample size is less than 100 devices. The survival charts in the Product Performance Report show the effective sample size for each year interval where we have experience. When the effective sample size reaches 100, the next data point is added to the survival curve.

Because the information pulled from the CareLink™ network allows for assessment of all devices that were taken out of service there are no adjustments done for underreporting of malfunctions.

Definition of Analysis Dataset

To be included in the survival analysis dataset, the product must have been successfully implanted and on the CareLink™ network for at least 30 days.