Primary Results From the Understanding Outcomes With the S-ICD in Primary Prevention Patients With Low Ejection Fraction (UNTOUCHED) Trial

Abstract

Background: The Subcutaneous ICD (S-ICD) is safe and effective for sudden cardiac death prevention. However, patients in previous S-ICD studies had fewer comorbidities, less left ventricular dysfunction and received more inappropriate shocks (IAS) than in typical transvenous (TV)-ICD trials. The UNTOUCHED trial was designed to evaluate the IAS rate in a more typical, contemporary ICD patient population implanted with the S-ICD using standardized programming and enhanced discrimination algorithms. Methods: Primary prevention patients with left ventricular ejection fraction (LVEF) ≤ 35% and no pacing indications were included. Generation 2 or 3 S-ICD devices were implanted and programmed with rate-based therapy delivery for rates ≥ 250 beats per minute (bpm) and morphology discrimination for rates ≥200 and < 250 bpm. Patients were followed for 18 months. The primary endpoint was the IAS free rate compared to a 91.6% performance goal, derived from the results for the ICD-only patients in the MADIT-RIT study. Kaplan-Meier analyses were performed to evaluate event-free rates for IAS, all cause shock, and complications. Multivariable proportional hazard analysis was performed to determine predictors of endpoints. Results: S-ICD implant was attempted in 1116 patients and 1111 patients were included in post-implant follow-up analysis. The cohort had a mean age of 55.8±12.4 years, 25.6% women, 23.4% black race, 53.5% with ischemic heart disease, 87.7% with symptomatic heart failure and a mean LVEF of 26.4±5.8%. Eighteen-month freedom from IAS was 95.9% (Lower confidence limit LCL 94.8%). Predictors of reduced incidence of IAS were implanting the most recent generation of device, using the three-incision technique, no history of atrial fibrillation, and ischemic etiology. The 18-month all cause shock free rate was 90.6% (LCL 89.0%), meeting the prespecified performance goal of 85.8%. Conversion success rate for appropriate, discrete episodes was 98.4%. Complication free rate at 18 months was 92.7%. Conclusions: This study demonstrates high efficacy and safety with contemporary S-ICD devices and programming despite the relatively high incidence of co-morbidities in comparison to earlier S-ICD trials. The inappropriate shock rate (3.1% at one year) is the lowest reported for the S-ICD and lower than many TV ICD studies using contemporary programming to reduce IAS. Clinical Trial Registration: URL https://clinicaltrials.gov Unique Identifier NCT02433379

Outcomes of two versus three incision techniques: Results from the subcutaneous ICD post‐approval study

“…Overall complications rates over 1 year and 18 months follow‐up were not found to be impacted by the incision technique in predictor models for the PAS study 9 nor the UNTOUCHED study, 10 respectively. In this study, no difference in the rate of infection or pocket complications was noted between the 2IT and 3IT group.…”

“…IAS rates were not found to be significantly different between the two‐ and three‐incision groups in the Brouwer study, 7 and a low IAS rate of 2.8% was found over the 21‐month follow‐up in the Migliore study 12 . In contrast, IAS in the UNTOUCHED trial 10 recently demonstrated an association to 2IT, with 18 month rate of 4.9% versus the 2.5% in those patients implanted with 3IT. Prescribed high rate programming and use of the most recent device iterations in this study may be important differences leading to this finding of a small but statistically significant difference, although technique is likely a major factor for IAS occurrence and may also explain differences between studies.…”

Cardiac Implantable Electronic Devices in Hemodialysis and Chronic Kidney Disease Patients—An Experience-Based Narrative Review

“…Besides challenging vascular access (central veins stenosis, occlusion, AVF, or CVC for HD) and complications avoidance, the following indications for S-ICD placement should be considered: prior complications with transvenous ICDs, infection (bacteremia), and the young age of the ICD patient. Results published for randomized clinical trials support S-ICD use [61,62]. Koman et al reported data from the follow-up of 18 HD patients and 78 non-HD patients with implanted S-ICD.…”

The year in cardiovascular medicine 2020: arrhythmias

“…Concerning the latter, the UNTOUCHED study of primary prevention ICD therapy supports the PRAE-TORIAN data by showing an inappropriate shock-free rate of 95.9%, suggesting that the new SMART PASS filter technology and appropriate high rate S-ICD programming may minimize inappropriate shocks in S-ICD recipients. 55 jom klase I. ili IIa. za ICD terapiju za primarnu ili sekundarnu prevenciju, uz razdoblje praćenja od 49,1 mjesec.…”