Cardiovascular diseases often occur suddenly and unexpectedly and are a significant public health issue.

This systematic review aimed to re-evaluate the evidence about the effectiveness and safety of the subcutaneous implantable cardioverter-defibrillator (S-ICD) compared to the transvenous implantable cardioverter-defibrillator (TV-ICD).

In total, one randomised controlled trial (RCT), one post-hoc analysis of the RCT and four observational studies with a control group were included for the evidence synthesis. The quality of the evidence for the effectiveness and safety outcomes were rated as "very low" to "moderate".

The current evidence was insufficient to draw a definite conclusion about the effectiveness of S-ICDs compared to TV-ICDs. While the superiority of the S-ICD in terms of safety has not been demonstrated, there is moderate-quality evidence (1 RCT) that suggests non-inferiority of the S-ICDs versus the TV-ICDs. Furthermore, included studies indicate a statistically significantly lower risk for lead-related complications in patients with S-ICDs.

Against this background, the recommendation of the first assessment in 2018 that S-ICDs are to be refunded with restrictions should be maintained. A re-evaluation is recommended not before 2024 after an ongoing RCT has been completed.