BOSTON — US data and initial results from an international registry indicate that the subcutaneous implantable cardioverter defibrillator system may be a safe and effective treatment option for patients with ventricular arrhythmia.
To evaluate the safety and efficacy of Cameron Health’ subcutaneous ICD (S-ICD) system, Martin Burke, DO, of the University of Chicago, and colleagues conducted the S-ICD IDE trial. The prospective, nonrandomized, multicenter clinical study included 321 patients who underwent implantation (mean age, 52 years; 74% men). The primary efficacy endpoint was acute ventricular fibrillation conversion rate, defined as two consecutive successes of four attempts at 65 J, with a performance goal of 88%. The primary safety endpoint was 180-day system complication-free rate, with a performance goal of 79%.
All of the 304 patients included in the efficacy cohort underwent successful acute ventricular fibrillation conversion testing. A sensitivity analysis involving 315 patients also showed that the researchers met their performance goal at 96.5%.
The primary safety endpoint was also met, with a 99% 180-day system complication-free rate, Burke said. Further, the rate of freedom from all device- and procedure-related complications was 92.1%.
Additionally, Burke said, “The algorithm prevents therapy of ventricular tachycardia or ventricular fibrillation rhythms that are likely to spontaneously terminate, and unnecessary therapy was avoided in 63% of patients with ventricular tachycardia or ventricular fibrillation rhythm [with use of the subcutaneous ICD].
“Effectiveness endpoints were met, and acute ventricular fibrillation conversion testing has been exceptional. Chronic conversion testing is consistent with the acute endpoint and spontaneous episode results further support continued effectiveness [of the subcutaneous ICD],” he said.
The device also continues to perform well in real-world situations and continues to show positive results in patients, according to initial results from the international, observational, nonrandomized EFFORTLESS S-ICD Registry. Currently, the registry includes 230 patients (mean age, 49 years) from clinical centers in nine countries, including the United Kingdom, the Netherlands, the Czech Republic, Slovakia, Denmark, Italy, Germany, Portugal and New Zealand.
Data show the following:
- Sixty-four percent of devices were for primary prevention, of which 49% were ischemic.
- Ischemic indications accounted for 38% of all patients implanted.
- Channelopathies, including Brugada syndrome, long QT syndrome and catecholaminergic polymorphic ventricular tachycardia, accounted for 13% of all patients implanted.
- Thirteen percent of patients received ambulatory shock therapy, of which 6% received appropriate shocks and 7% received inappropriate shocks.
- Induced shock conversion efficacy is 98.5%, with an average time to therapy for first shock of 16 seconds.
- No patient received therapy for any supraventricular arrhythmias with rates above the shock zone cutoff.
"[These] data show us that the subcutaneous ICD System is proving to be safe and effective, and possibly even a slightly better option than a regular ICD for certain patients,” Pier D. Lambiase, MD, PhD, FRCP, senior lecturer and honorary consultant cardiologist at Heart Hospital, University College of London, said in a press release. “Our goal is to provide patients with heart devices that are less invasive, yet perform the same or better than other options. Real-world data is critical for us to understand therapy outcomes, and so far we are impressed with the performance of the S-ICD System in a wide range of patients.”
On April 26, the FDA Circulatory System Devices Advisory Committee recommended approval of Cameron Health’s subcutaneous ICD system, with the panel voting 7-1 that the device’s benefits outweigh the risks.
Data from both studies were presented at the Heart Rhythm Society’s 33rd Annual Scientific Sessions. – by Melissa Foster
Disclosure: The S-ICD IDE study was sponsored by Cameron Health. Dr. Lambiase has received consulting fees/honoraria from Cameron Health, is on the speakers’ bureau for Boston Scientific, and has received fellowship support from Boston Scientific, Medtronic and St. Jude Medical.