After 360 days, 98 percent of patients who were implanted with Boston Scientific’s subcutaneous implantable defibrillator (S-ICD) system were free from complications, according to a multi-national registry.

Lead researcher Lucas V.A. Boersma, MD, PhD, of St. Antonius Hospital in the Netherlands, presented the results on May 6 during a late-breaking clinical trial session at the Heart Rhythm Society’s scientific sessions in San Francisco.

In September 2012, the FDA approved the S-ICD system for patients at risk for sudden cardiac arrest. The system sits below the skin and does not need intracardiac leads.

This analysis examined the EFFORTLESS, the largest S-ICD registry in the world which enrolled 994 patients at 42 sites in nine European countries and New Zealand from August 2009 to December 2014.

The mean age was 48 years old, and 28 percent of patients were females. The mean left ventricular ejection fraction was 44 percent, and 65 percent of patients had a primary prevention indication.

After a mean follow-up period of 3.1 years, device extraction occurred for infection in 2.4 percent of patients. Further, 0.5 percent of S-ICDs were removed to implant patients with a defibrillator with anti-tachycardia pacing capabilities and 0.1 percent were removed to allow for a device with bradycardia pacing capabilities.

The freedom of complications causes by the S-ICD was 99.7 percent at 30 days and 98.0 percent at 360 days. At one year, inappropriate therapy for atrial fibrillation/supraventricular tachycardia was 1.5 percent. The total inappropriate shock rate was 8.1 percent at one year and 11.7 percent at three years, while the rate of appropriate shock was 5.8 percent at one year and 13.5 percent at one year.

Further, the researchers said there were no reports of lead failure, endocarditis or mortality through January 2016.

“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,” Boersma said in a news release. “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.”

Kenneth Stein, MD, Boston Scientific’s chief medical officer for rhythm management, noted in a news release that the company is developing the Empower modular pacing system, which includes its leadless pacemaker and the Emblem S-ICD system.

The FDA approved the Emblem S-ICD system in March 2015.