5-Year efficacy of subcutaneous implantable cardioverter defibrillator

The EFFORTLESS S-ICD Registry showed that a subcutaneous implantable cardioverter defibrillator (S-ICD) is safe and maintains its high-shock efficacy over 5 years. The burden of inappropriate shocks was low, and re-programming of the device after early inappropriate shocks markedly reduced the incidence of inappropriate shocks in years 2-5 [1].

The objective of the EFFORTLESS S-ICD Registry (NCT01085435) was to report the long-term outcomes of patients implanted with the Boston Scientific S-ICD. In his presentation, Prof. Pier Lambiase (University College London, United Kingdom) focused on spontaneous efficacy throughout the 5-year study and predictors of later outcomes.

Enrolled in the study were 984 patients with diverse underlying aetiologies, of whom 703 completed the study. Mean study follow-up was 4.4 years. In only 20 out of 703 patients (2%), S-ICD was replaced for a transvenous device for pacing.

No definite electrode failures occurred. Evaluation of late complications and inappropriate shocks showed that 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 who were re-programmed for causes of inappropriate shocks in year 1 had fewer IAS in years 2-5, but this was not statistically significantly different from patients without re-programming after inappropriate shocks. Cardiac inappropriate shocks were more likely to occur in years 2-5, due to low amplitude signal and oversensing of ventricular tachycardia (VT)/ventricular fibrillation (VF) (P≤0.033) [1].

An evaluation of late appropriate shocks showed that 10% of patients had untreated episodes that self-terminated, 6% had monomorphic VT, 3% a combination of monomorphic and polymorphic VT/VF, and 6% had VF alone. The main predictor for appropriate shocks was an appropriate shock in the first year (P<0.0001). Other significant predictors were prior cardiac arrest, heart failure, NYHA class I/II, and arrhythmogenic right ventricular dysplasia (ARVD) (P≤0.028). Importantly, ARVD and ischaemic heart diseases were predictors for appropriate shocks for monomorphic VT, potentially identifying a special sub-population.

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, these long-term results on the efficacy of S-ICD in a large cohort showed that S-ICD maintains a high level of cardioversion efficacy over 5 years. Prof. Lambiase added that, “importantly, untreated inappropriate sensing episodes did predict late inappropriate shocks, and this is an opportunity for re-programming and personalising therapy for these patients.”

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

 



Posted on 16 June, 202125 June, 2021