Product Education Brief: Boston Scientific Lead Advisory

Medtronic ICDs and CRT-Ds
Original Date of Communication: September 2025

View specific models that this applies to

Applicable Product:

Single coil (SC) and dual coil (DC) RELIANCE™ G/SG defibrillation leads manufactured by Boston Scientific Corporation (BSC) from 2002 to 2021 with GORE™ expanded polytetrafluoroethylene (ePTFE) coil treatment connected to Medtronic ICD/CRT-D systems.

Overview

This Product Education Brief leverages information in published literature, BSC’s July 2025 Field Correction Action (FCA) letter*, and Medtronic data analysis to date to review:

• Reason for the advisory on BSC GORE™ ePTFE RELIANCE™ defibrillation leads
• BSC risk-mitigation recommendations for BSC devices
• Comparison of Medtronic device behavior to BSC device behavior when attached to BSC leads on advisory
• Medtronic position on the BSC advisory and Medtronic devices

Reason for BSC Recall of ePTFE RELIANCE leads*

The association of calcified defibrillation lead coil(s) with a pattern of gradually rising Low Voltage Shock Impedance (LVSI) measurements has been reported to BSC and described in several publications (listed in the BSC advisory letter*). The chronic calcification process originates in the ePTFE membrane coating the defibrillation coils. This calcification phenomenon can biologically encapsulate and electrically insulate the defibrillation lead coil(s), thus potentially reducing the amount of energy delivered and increasing the chances of unsuccessful defibrillation of ventricular tachyarrhythmias. At the time of the advisory letter, FDA disclosed that BSC reported 16 patient deaths, and 386 serious patient injuries related to the lead.

BSC’s Risk Mitigation for BSC Devices

The July 2025 BSC advisory letter provides the following risk mitigation recommendations for BSC leads attached to BSC devices:

“If an ePTFE lead is experiencing a gradually rising LVSI that exceeds 90Ω for a SC or 70Ω for a DC lead [on a BSC device], the risk of compromised shock efficacy can be mitigated by programming all shocks to maximum energy and shock polarity to Initial (RV- ) in those patients whose [BSC] devices are not already programmed in this manner. For ePTFE leads with a gradually rising LVSI, there is a 4.5x higher likelihood of generating a EC-1005 in Reversed (RV+) polarity compared to Initial (RV-) polarity [on a BSC device]”*

These recommendations are specific to lowering the occurrence rate of triggering Code-1005 in a BSC device. Code-1005 indicates that high-voltage energy delivery in BSC devices was truncated in response to higher shock lead impedance. Important points regarding the BSC recommendations:

1. Code-1005 is unique to BSC devices. Medtronic devices are at ZERO risk of a Code-1005 equivalent fault and its associated constraints on high voltage therapy delivery, irrespective of shock polarity (see next section for details).
2. The BSC shock-polarity recommendation reduces, but does not eliminate, the potential for triggering a post-shock Code-1005 in leads with gradually rising impedances.
3. For BSC leads demonstrating LVSI > 150ohms, consider lead replacement.

BSC Code-1005 functionality is limited to BSC devices

BSC Code-1005 is unique to BSC devices and is designed to respond to conditions that could be related to an open-circuit condition in a BSC system.

With respect to the behavior described in the July 2025 BSC advisory, events that contribute to Code-1005 include the following:

• As impedance rises in a calcified lead, the pulse width of a high-voltage shock waveform will extend. This is true of all fixed-tilt waveform systems.†
• The BSC first-phase shock delivery in a biphasic waveform is limited to a 20.1ms pulse width. If the first phase of a BSC shock is not completed within 20.1ms, the “waveform is truncated and a monophasic shock is delivered, potentially reducing shock efficacy.”*

The shock-polarity recommendations in the BSC advisory letter provide a path to temporarily reduce the risk of triggering Code-1005 in the BSC system. The statement, “4.5x higher likelihood of generating a Code-1005 in Reversed (RV+) polarity compared to Initial (RV-) polarity”* is not applicable to Medtronic devices.

Medtronic High Voltage Delivery

Medtronic ICDs and CRT-Ds incorporate critical differences in high-voltage delivery that are highly relevant with respect to the BSC recalled leads when compared to BSC devices.

1. Medtronic devices use a 50% first-phase tilt (versus a 60% first phase tilt in BSC devices).
   • This means the first phase of energy delivery needs to unload a lower percentage of total energy in Medtronic devices before the timeout is reached than in the BSC system.
2. Medtronic devices allow a 25.25ms pulse width for the first phase of waveform delivery. Due to differences in tilt and capacitance in Medtronic devices, waveform timeout will not typically occur until high-voltage impedances exceed ~200-250ohms.
   • The BSC devices have a 20.1ms pulse width limitation, which will be reached at ~145-150ohms in a 60% first phase tilt.†
3. In Medtronic devices, if the entire first phase energy has not been delivered within 25.25ms, the system will proceed to the second phase of energy delivery at the current voltage and deliver in the opposite polarity.
   • The BSC devices will truncate energy delivery at 20.1ms in the first phase, resulting in a monophasic, limited-energy delivery.

These differences in Medtronic device design are not accounted for in the BSC shock-polarity recommendations. Therefore, the performance of a Medtronic device will not have the same limitations as a BSC device on a calcified lead. As such, specific polarity programming may not be relevant in Medtronic devices for this issue.

Medtronic position regarding BSC recalled leads

• Medtronic devices are at ZERO risk of a waveform timeout (ie: Code-1005 equivalent fault) and its associated constraints on high-voltage therapy delivery, irrespective of shock polarity.
  • This difference in risk is due to Medtronic waveform tilt, capacitance, leading edge voltage, and algorithms controlling high-voltage shock delivery.
• Reprogramming shock polarity on leads with abnormal impedances does not completely mitigate the risk of Code-1005 in Boston Scientific devices.
  • Normal HV coil impedances are below 70 ohms/dual coil or 90 ohms/single coil.
  • Figure 1* in the BSC advisory illustrates that the effectiveness of the BSC shock-polarity mitigation decreases as LVSI increases.
• Medtronic devices that include labeling recommendations for shock polarity of B>AX (ie: known as “Reverse RV+” in BSC devices), that are connected to BSC ePTFE calcified leads, should not be reprogrammed to AX>B in an attempt to match Medtronic system performance with BSC system performance.
  • While Medtronic AX>B shock polarity correlates to BSC Initial (RV-) shock polarity, currently available data shows the differences in system design (described earlier) result in very different outcomes when lead impedance increases.
  • The BSC Advisory letter states that for devices that cannot be reprogrammed to Initial (RV-) shock polarity, clinicians should weigh the continued and increasing risk of ineffective therapy against that of lead replacement.
• Medtronic does not have reason to deviate from the BSC recommendation to consider lead replacement if LVSI continues to rise from 70/90 ohms to 150 ohms per Table 1* irrespective of the manufacturer of the associated ICD/CRT-D device.