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First long-term results show S-ICD is safe for heart arrhythmia patients

The mid to long-term results from the EFFORTLESS study, the largest subcutaneous implantable cardioverter-defibrillator (S-ICD) registry in the world, show the device provides reliable treatment for ventricular tachyarrhythmias. This is the first report on the fully enrolled EFFORTLESS cohort and includes real-world outcomes of almost 1,000 patients implanted with an S-ICD. Positive results showing longevity during three- and up to five-year follow-ups were presented at Heart Rhythm 2016, the Heart Rhythm Society’s 37th Annual Scientific Sessions.

A conventional ICD includes leads, which can cause complications such as systemic infections, acute and chronic displacement, pneumothorax, cardiac perforation, tamponade and inappropriate shocks associated with insulation failure or lead fractures. The S-ICD was therefore developed to manage ventricular arrhythmias without the need for intracardiac leads. Until this study, there has been no mid to long-term, real-world data that shows how the S-ICD performs in a multi-center, heterogeneous ICD population.

The EFFORTLESS study enrolled 994 patients at 42 sites in nine European countries and New Zealand from August 2009 to December 2014. The average patient age was 48 years and 28 percent of patients were female. The average left ventricular ejection fraction was 43 percent, and 65 percent of patients had a primary prevention indication. The pre-defined endpoints were complications caused by the S-ICD at 30 and 360 days as well as inappropriate shocks for atrial fibrillation and supraventricular tachycardia.

The average follow-up time was three years, and five year follow up was completed in eight percent of patients. Freedom of complications caused by the S-ICD was 99.7 percent at 30 days and 98.0 percent at 360 days. Inappropriate therapy for atrial fibrillation/supraventricular tachycardia at one year was 1.5 percent, with a total inappropriate shock rate of 8.1 percent at one year, and 11.7 percent at three years. The one- and five-year rates of appropriate shock were 5.8 percent and 13.5 percent, respectively. Device extraction occurred due to infection in 24 patients (2.4 percent), failed conversion at implant in four (0.4 percent), and bradycardia pacing need in one (0.1 percent). There have been no reports of lead failure, endocarditis or mortality to date.

“For the first time, we’re reporting on the fully enrolled registry and seeing positive mid- and long-term results, which to date show that this device is safe and effective, even at the five-year mark,” said lead author Lucas V. A. Boersma, MD, PhD, St. Antonius Hospital, Nieuwegein, Netherlands. “Now we are truly able to see the unique advantages of the S-ICD as compared to the conventional ICD, which will help clinicians meet individual patient need and improve overall patient care.”

Since this study began, there have been new software updates to the device that will greatly enhance future device performance. In fact, Boston Scientific’s EMBLEM S-ICD received FDA and CE Mark approval in March 2016. Study authors stress the importance of continued research and innovation in this field as advancing technology improves patient care.

Session details: Performance and Outcomes in Patients with the Subcutaneous Implantable Defibrillator Through Mid Term Follow-Up: The EFFORTLESS Study, Heart Rhythm 2016.