Failure to defibrillate or cardiovert due to premature truncation of biphasic shocks from implantable defibrillators.

BACKGROUND: In 2022 and 2023, Medtronic recalled implantable defibrillators because they may deliver less than full-energy shocks. The 2022 problem truncates the second phase of the waveform (SCP-T2), resulting in ∼32-J shocks, and is mitigated by downloadable software. The 2023 malfunction truncates the first phase of the waveform, resulting in 0- to 12-J shocks due to a glassed feedthrough problem (GFT-T1) that might be avoided by programming B>AX shock polarity. OBJECTIVE: The purpose of this study was to assess the consequences of GFT-T1 and SCP-T2 shocks in the Food and Drug Administration's Manufacturers and User Facility Device Experience (MAUDE) database and to estimate the incidences of GFT-T1 and SCP-T2. METHODS: We analyzed MAUDE reports supplemented by Medtronic data; lead failures were excluded. The incidences of SCP-T2 and GFT-T1 were estimated using USA volumes for devices with glassed feedthroughs. RESULTS: One hundred thirty-two devices delivered truncated shocks: 27 (20.5%) were GFT-T1; 103 (78.0%) were SCP-T2; and 2 (1.5%) truncated both phases (BOTH-T1&2). Of 54 ventricular fibrillation (VF) patients, 21 (38.9%) were not defibrillated by truncated shocks: 8 (38.1%) received GFT-T1 shocks, 12 (57.1%) received SCP-T2 shocks, and 1 received a BOTH-T1&2 shock; 2 patients suffered unrelated deaths; 1 was externally rescued; 1 outcome was unknown; the others were defibrillated by subsequent shocks or terminated spontaneously. The majority of patients (79.1%) shocked for ventricular tachycardia (VT) were converted, primarily (94.1%) by SCP-T2 shocks. Estimated incidences of GFT-T1 and SCP-T2 were 0.0078%-0.0088% and 0.1062%-0.1110%. CONCLUSION: GFT-T1 and SCP-T2 shocks can result in failure to terminate VF/VT, but they may be preventable. Although the incidences of these truncated shocks are very low, heightened surveillance is warranted.

Leadless pacemaker perforations: Clinical consequences and related device and user problems.

BACKGROUND: Cardiac perforation during leadless pacemaker implantation is more likely to require intervention than perforation by a transvenous lead. This study reports the consequences of Micra pacemaker perforations and related device and operator use problems based on information the manufacturer has submitted to the Food and Drug Administration (FDA). METHODS: FDA's Manufacturer and User Facility Device Experience (MAUDE) database was searched for Micra perforations. Data extracted included deaths, major adverse clinical events (MACEs), and device and/or operator use problems. RESULTS: Between 2016 and July 2021, 563 perforations were reported within 30 days of implant and resulted in 150 deaths (27%), 499 cardiac tamponades (89%), 64 pericardial effusions (11%), and 146 patients (26%) required emergency surgery. Half of perforations were associated with 139 (25%) device problems, 78 (14%) operator use problems, and 62 (11%) combined device and operator use problems. Inadequate electrical measurements or difficult positioning were the most frequent device problems (n = 129); non-septal implants and perforation of other structures were the most frequent operator use problems (n = 69); a combined operator use and device problem resulted in 62 delivery system perforations. No device or operator use problem was identified for 282 perforations (50%), but they were associated with 78 deaths, 245 tamponades, and 57 emergency surgeries. CONCLUSION: The Micra perforations reported in MAUDE are often associated with death and major complications requiring emergency intervention. Device and use problems account for at least half of perforations. Studies are needed to identify who is at risk for a perforation and how MACE can be avoided or mitigated.