ICD and CRT-D Charge Time Performance
Medtronic continues its commitment to providing updated information on charge time performance.
Introduction
Information on charge time performance of Medtronic is presented in this section of the CRDM Product Performance Report. Medtronic implemented the collection of charge time data on July 1, 1999. The data are collected via our ongoing active clinical study of long-term system performance called the System Longevity Study. The study protocol requests device data be routinely taken and sent to Medtronic at no more than six-month intervals.
In our analysis performed for this report, only charge times resulting from full energy charges are considered. To ensure consistent reporting across devices, the charge time reported at implant represents the last charge time available from date of implant. When more than one charge time is available in a six-month interval, a conservative approach has been adopted whereby only the maximum charge in each 6-month interval is reported. As charge time is directly proportional to the time elapsed since the last capacitor reformation, charges occurring within 15 days of a previous charge are excluded. This precludes the reporting of overly optimistic results.
Data from over 20,000 devices contribute to the charge time data in this report. By tracking and reporting this charge time data, Medtronic is able to ascertain the actual performance of its charging circuitry. The insight gained through this information is applied to Medtronic’s ongoing efforts to provide charge times that are short and consistent over the life of the product.
Data Presentation
Charge time data for ICD and CRT-D models are presented using boxplots at 6-month intervals. The shaded box on the plots represents the middle half of the data – the Interquartile Range (IQR). The white line in the middle of each box is the median charge time. The top of the box representing the IQR is the 75th percentile (i.e., 75% of all charge times fall below this line), whereas the bottom of the box represents the 25th percentile. The brackets around the box represent the variance in charge times (analogous to a confidence interval), and are calculated as a function of the median and IQR. Individual values falling outside the brackets are labeled as outliers.
Results
As shown in the graph below, the performance of Medtronic ICD and CRT-D devices has improved. This graph shows the overall maximums, minimums, and medians for Medtronic ICD and CRT-D products, beginning with the 7221 Micro Jewel. A progression toward shorter mean charge times and less variation has occurred between 1996 and 2002. Models released after 2002 have limited experience, but appear to be continuing this performance.
GEMInSyncJewel & Micro Jewel |
MarquisEnTrustConcertoVirtuoso |