EFFORTLESS: Subcutaneous ICD effective in treating ventricular tachyarrhythmias
SAN FRANCISCO —The subcutaneous implantable cardioverter defibrillator successfully treats ventricular tachyarrhythmias without lead failure or endocarditis, according to EFFORTLESS registry data presented at the Heart Rhythm Society Annual Scientific Sessions.
The device had an inappropriate shock rate for AF/supraventricular tachycardia comparable to conventional ICDs, researchers reported.
“With the subcutaneous ICD, there is no transvenous lead. By being implanted under the skin, it is designed to have less complications than the transvenous lead,” said Lucas V.A. Boersma, MD, PhD, from St. Antonius Hospital, Nieuwegein, Netherlands during a press conference.
The researchers enrolled 985 patients (mean age, 48 years; 28% women) who were implanted with the device (Emblem S-ICD System, Boston Scientific) from August 2009 to December 2014 at 42 sites in nine European countries and New Zealand. According to Boersma, the EFFORTLESS registry was 50% retrospective and 50% prospective.
Lucas V.A. Boersma
Primary endpoints included 30- and 360-day complication rates and inappropriate shocks for atrial fibrillation/supraventricular tachycardia. Average follow-up was 3.1 years, with 8% of patients completing 5 years of follow-up.
According to the results, infection prompted device extraction in 24 (2.4%) patients, failed conversion at implant occurred in four (0.4%) and bradycardia pacing was needed in one (0.1%). Only 11 patients needed a change of device, Boersma said during a press conference. “Most importantly there were no lead fractures.”
The rate of freedom from complications was 99.7% at 30 days and 98% at 360 days. The total inappropriate shock rate was 8.1% at 1 year and 11.7% at 3 years. Last month Boston Scientific launched a new algorithm with the subcutaneous ICD system, which would have reduced the rate of inappropriate shocks from 8.1% to 3.8% had it been available for this patient cohort, Boersma said.
There was a 97.4% conversion rate of discrete arrhythmias, with 100% clinical efficacy. In addition, Boersma said, 99.5% of patients with testing at implant had successful acute conversion testing.
Boersma told Cardiology Today that the biggest takeaways from this study for physicians were that it was the largest study done to date and that the data are getting more robust.
“Infections were the most important complication and physicians are taking measures to prevent them,” he said. – by Tracey Romero
Boersma L, et al. LBCT 02. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 4-7, 2016; San Francisco.
Disclosure: Boersma reports receiving compensation from Boston Scientific and Medtronic and a research grant from Medtronic.