Inappropriate shocks from subcutaneous and transvenous implantable cardioverter-defibrillators: Reports from the FDA...

The subcutaneous implantable cardioverter-defibrillator (S-ICD) has been shown to be safe and effective for preventing sudden cardiac death. Clinical trial and registry data suggest that the incidence of S-ICD inappropriate shocks (IAS) is similar to or slightly higher than IAS from transvenous implantable cardioverter-defibrillators. However, little data exist for S-ICD IAS in everyday practice.

This study aimed to assess IAS events reported by Boston Scientific (BSC) to the Food and Drug Administration (FDA) for its Emblem S-ICDs and transvenous single-chamber implantable cardioverter-defibrillators (TV-VR ICDs).

We searched for reports of Emblem S-ICD and TV-VR ICD adverse events (AEs) in the FDA's Manufacturer and User Facility Device Experience (MAUDE) database that were received by the FDA from BSC during 2020-2024.

In 2024, BSC estimated 153,000 Emblem S-ICDs and 353,000 of its TV-VR ICDs were distributed worldwide. During 2020-2024, BSC submitted 22,957 MAUDE AE reports for Emblem S-ICDs and 6791 MAUDE AE reports for TV-VR ICDs. Of these, 5363 (23.4%) involved IAS for S-ICDs and 813 IAS (11.7%) for TV-VR ICDs. The most common cause of S-ICD IAS was oversensing of physiological and nonphysiological signals (91.1%; 4885 of 5363), whereas rapid atrial fibrillation or supraventricular tachycardia caused 69.5% of TV-VR ICD IAS. Emblem S-ICD IAS induced ventricular fibrillation or ventricular tachycardia in 69 patients and failed to defibrillate/convert 4 of them.

These real-word data suggest that S-ICD IAS may be more common than previously reported. The incidence, root causes, and consequences of these IAS in the general population of S-ICD recipients should be investigated.