Worldwide experience with a totally subcutaneous implantable defibrillator: early results from the EFFORTLESS S-ICD Registry

Abstract

AimsThe totally subcutaneous implantable-defibrillator (S-ICD) is a new alternative to the conventional transvenous ICD system to minimize intravascular lead complications. There are limited data describing the long-term performance of the S-ICD. This paper presents the first large international patient population collected as part of the EFFORTLESS S-ICD Registry.Methods and resultsThe EFFORTLESS S-ICD Registry is a non-randomized, standard of care, multicentre Registry designed to collect long-term, system-related, clinical, and patient reported outcome data from S-ICD implanted patients since June 2009. Follow-up data are systematically collected over 60-month post-implant including Quality of Life. The study population of 472 patients of which 241 (51%) were enrolled prospectively has a mean follow-up duration of 558 days (range 13–1342 days, median 498 days), 72% male, mean age of 49 ± 18 years (range 9–88 years), 42% mean left ventricular ejection fraction. Complication-free rates were 97 and 94%, at 30 and 360 days, respectively. Three hundred and seventeen spontaneous episodes were recorded in 85 patients during the follow-up period. Of these episodes, 169 (53%) received therapy, 93 being for Ventricular Tachycardia/Fibrillation (VT/VF). One patient died of recurrent VF and severe bradycardia. Regarding discrete VT/VF episodes, first shock conversion efficacy was 88% with 100% overall successful clinical conversion after a maximum of five shocks. The 360-day inappropriate shock rate was 7% with the vast majority occurring for oversensing (62/73 episodes), primarily of cardiac signals (94% of oversensed episodes).ConclusionThe first large cohort of real-world data from an International patient S-ICD population demonstrates appropriate system performance with clinical event rates and inappropriate shock rates comparable with those reported for conventional ICDs. Clinical trial registration URL: . Unique identifier NCT01085435.

Subcutaneous Implantable Cardioverter Defibrillator in Patients With Hypertrophic Cardiomyopathy: An Initial Experience

“…In contrast to the development of transvenous ICDs 20 to 30 years ago, step‐down defibrillation threshold (DFT) testing was rarely performed. In the largest S‐ICD registry to date, only 10 of 450 patients had any testing done at <65 J 6, 7…”

Routine exercise testing could not predict T‐wave oversensing in a patient after a subcutaneous implantable cardioverter‐defibrillator implant

“…On the other hand, as the leads are extracardiac, the sensing and programing differ from that of the TV‐ICD, posing new challenges. The 360‐day rate of IASs observed in the EFFORTLESS S‐ICD Registry was 7% 5. Supraventricular tachycardias account for the majority of IASs associated with TV‐ICDs, whereas oversensing, especially TWOS, is the primary cause of IASs associated with S‐ICDs 2, 4, 5, 6, 7.…”

“…The majority of IASs are due to T‐wave oversensing (TWOS), which has been reduced by exercise testing 4, 5. Here, we report the case of a patient who experienced an IAS due to TWOS, which a prior exercise test could not predict.…”

Longevity of the Subcutaneous Implantable Defibrillator

“…In subsequent S-ICD studies, premature battery depletion was observed in 2 cases (0.6%) in the IDE trial and in 1 case (0.2%) in the EFFORTLESS registry. 14,15 When considering transvenous ICD systems, premature ERI has been reported in 9% of transvenous devices. 21 Battery malfunctions were the most common cause of device failure in a meta-analysis of device registries.…”

“…The interim analysis of the EFFORTLESS registry reported a low explant rate of the S-ICD, occurring in 3.7% of patients mainly because of infection. 15 In 1% of patients, the S-ICD was replaced for a transvenous ICD system because of recurrent ventricular arrhythmias or patient decision.…”