Reduction of inappropriate shock rate through signal filtering (smart-pass) in patients with implantable subcutaneous cardioverter-defibrillator: a systematic review and meta-analysis

Subcutaneous implantable cardioverter-defibrillators (S-ICD) are effective in protecting patients against sudden death but expose them to a higher risk of inappropriate shock (IAS). We performed a systematic search of studies published between January 2010 and December 2019 assessing IAS due to cardiac oversensing by the selection process (PRISMA) and identified 17 eligible articles. A total of 15 studies were observational, and 2 were retrospective. For the meta-analysis, the final population included 6111 patients: 3356 without the SMART-pass (SP) filter (group 1) and 2755 with the SP filter (group 2). A total of 1614 shocks (appropriate shocks plus IAS) were registered (1245 in group 1 and 369 in group 2). The random effects meta-analysis estimated an overall IAS rate of 7.78% (95% confidence interval: 4.93-10.64) with substantial variability between studies (I2=96.05%, p<0.001). The IAS rate was 10.75% (95% confidence interval: 8.49-13.02) for group 1 and 3.61% (95% confidence interval: 1.36-5.86) for group 2 (p<0.001). Third-generation S-ICD technology with SP filters reduced the risk of cardiac signal-related IAS.