Lucas V.A. Boersma
Confirming data previously presented, at 1 year a subcutaneous implantable cardioverter defibrillator remained safe and effective in the treatment of patients with lethal ventricular arrhythmias and had low implant complication rates.
The data, published in the Journal of the American College of Cardiology, are the midterm outcomes of the full EFFORTLESS S-ICD registry, a nonrandomized, standard-of-care registry that enrolled 1,000 patients across 42 clinical centers in 10 countries, the preliminary results of which were presented at the Heart Rhythm Society Annual Scientific Sessions in May 2016.
“The present data provide important insights into the midterm performance of the S-ICD in the most comprehensively evaluated S-ICD cohort reported to date,” Lucas V.A. Boersma, MD, PhD, from St. Antonius Hospital Nieuwegein, the Netherlands, and colleagues wrote. “The larger database demonstrates consistent outcomes for efficacy and safety, in terms of successful conversion of both induced and spontaneous clinical ventricular arrhythmias and the nature of inappropriate therapies.”
To determine the safety of the subcutaneous ICD (S-ICD, Boston Scientific), Boersma and colleagues evaluated complications and inappropriate shock rates among 985 patients (mean age, 48 years; 28% women; 65% with primary prevention indication) who were followed for 3.1 ± 1.5 years.
Complication rate low
According to the study, the S-ICD system and procedure complication rate was 4.1% at 30 days and 8.4% at 360 days.
At 1 year, the complication rate trended toward improvement from the first to last quartile of enrollment (11.3% in quartile 1, 7.8% in quartile 2, 6.6% in quartile 3 and 7.4% in quartile 4; P = .06 for quartile 1 vs. quartiles 2 to 4).
According to Boersma and colleagues, only 10 patients required extraction due to antitachycardia, biventricular or bradycardia pacing.
The rate of inappropriate shocks was 8.1% at 1 year and 11.7% at 3.1 years.
Nearly all patients (99.5%) had a successful conversion of induced ventricular tachycardia or ventricular fibrillation, according to the researchers.
At 1 and 5 years, appropriate shock rates were 5.8% and 13.5%, respectively.
Researchers found that the overall conversion success rate for discrete spontaneous episodes was 97.4%.
In a related editorial, Jeanne E. Poole, MD, and Jordan M. Prutkin, MD, MHS, from the division of cardiology and department of medicine at the University of Seattle, Washington, wrote: “This cohort forms a key dataset in evaluating clinical outcomes with this new technology.
“Based on this and other studies, complication and efficacy rates with the S-ICD support the consideration of this device in any patient who only requires a single-chamber device and does not need bradycardia pacing at the time of implantation, [cardiac resynchronization therapy] or [antitachycardia pacing],” they wrote. “Perhaps we should no longer consider S-ICD as a novel or emerging technology, but as a viable alternative for many patients.” – by Dave Quaile
Disclosures: The registry is sponsored by Boston Scientific. Boersma reports consulting and speaking for Boston Scientific and Medtronic. Please see the study for all other authors’ relevant financial disclosures. Poole reports speaking or serving on advisory boards for Abbott, Biotronik, Boston Scientific, Kestra Inc. and Medtronic. Prutkin reports no relevant financial disclosures.