Subcutaneous implantable cardioverter-defibrillator maintains efficacy over 5 years

The EFFORTLESS S-ICD Registry evaluated the 5-year safety and efficacy of the subcutaneous implantable cardioverter-defibrillator (S-ICD). The system was shown to maintain high shock efficacy over time. The burden of inappropriate shocks was relatively low and it could be shown that re-programming after early incidents could reduce inappropriate shocks in years 2-5 [1].

The objective of the EFFORTLESS S-ICD Registry (NCT01085435) was to evaluate the long-term outcomes of patients implanted with an S-ICD. Prof. Pier Lambiase (University College London, United Kingdom) presented on the spontaneous efficacy throughout the 5-year study and predictors of later outcomes. Enrolled were 984 patients with diverse underlying aetiologies, of which 703 patients completed the study. Mean study follow-up was 4.44 years. In only 2% of the patients, S-ICD was replaced with a transvenous device for pacing.

Prof. Lambiase presented the 5-year efficacy outcomes:

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  • No definite electrode failures occurred, and year-1 complications did not predict later complications.
  • Inappropriate shocks were registered in 16.9% of the patients, with the main cause being cardiac oversensing. Patients whose S-ICD was re-programmed for causes of inappropriate shocks in year 1 had fewer inappropriate shocks in years 2-5, but this reduction was not statistically significantly different from patients without re-programming after inappropriate shocks.
  • Evaluation of late appropriate shocks showed that 10% of participants had untreated episodes which self-terminated, 6% had monomorphic ventricular tachycardia, 3% a combination of monomorphic and polymorphic ventricular tachycardia/ventricular fibrillation, and 6% had ventricular fibrillation alone. The main predictor for appropriate shocks was appropriate shocks in the first year (P<0.0001).
  • High shock efficacy was maintained throughout the entire study period and shock efficacy was not significantly different between rhythm types.
  • Of the 91 (9.2%) deaths reported, none was associated with the S-ICD system or procedure.

In summary, the results of this 5-year follow-up of S-ICD in a large cohort showed that S-ICD maintained a high level of cardioversion efficacy over 5 years. Prof. Lambiase also emphasised: “Importantly, untreated inappropriate sensing episode did predict late inappropriate shocks, and this is an opportunity for re-programming and personalising therapy for these patients.”

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   1. Lambiase P. Long term efficacy and final outcomes of the subcutaneous implantable cardioverter-defibrillator registry. 2021 EHRA Congress, 23-25 April.

Posted on 25 April, 202116 June, 2021