The subcutaneous implantable cardiac defibrillator (S-ICD) system is a viable alternative to conventional ICD systems for selected patients, results from a Dutch experience have shown.
Data from the largest cohort to date, with a median follow-up of nine months, were presented at Heart Rhythm 2011 in San Francisco, USA.
Lara Dabiri Abkenari, Erasmus Medical Center, Rotterdam, The Netherlands, presented the results of 98 patients who received the S-ICD system (Cameron Health) in three hospitals in the country (Erasmus, Academic Medical Center Amsterdam and St Antonius Hospital in Nieuwegein).
“Conventional ICDs reduce mortality in primary and secondary prevention, but are associated with substantial short and long-term morbidity,” she told delegates.
In the Dutch study, ICDs were implanted according to the ACC/AHA/ESC guidelines. The first 17 patients (18%) were part of the reported CE trial. The remaining 82% were part of the post CE mark study. Implantation was performed without fluoroscopy and the device was entirely subcutaneous, Dabiri said. Defibrillation efficacy was tested after implantation using 65J shocks.
Of the 98 patients, 78 were males and 20 were females. Mean age was 56 years. A primary prevention indication was present in 62 patients (63%). Ischaemic cardiomyopathy was diagnosed in 40 patients (41%). Other causes of cardiac disease included non-ischaemic dilated cardiomyopathy (14%), Brugada Syndrome (7%), and idiopathic ventricular fibrillation (28%). Three patients had a history of explanted intravenous systems.
Sensitivity for induced ventricular fibrillation and conversion efficacy were 100%. The median follow-up was nine months (1–21 months). Thirty four spontaneous ventricular arrhythmias (sustained and non-sustained) were accurately detected in six patients. A total of 23 arrhythmic episodes were effectively treated in three patients. Inappropriate therapy occurred in eight (early) patients due to oversensing. A software upgrade improving the detection algorithm prevented recurrences of inappropriate therapy to date in all cases, Dabiri stated.
She told delegates that lead migration was observed in three early patients, with no recurrence since the use of an additional suture sleeve at the xiphoid incision. The number of adverse events declined after adjusting implant technique and reprogramming the T-wave sensing algorithm. One patient died from an aggressive lung carcinoma.
In our experience, Dabiri said, all episodes of induced ventricular fibrillation were accurately detected, and successfully converted. No sudden deaths occurred, she added.
“This subcutaneous ICD system has proved to be a great option for many of our patients who do not require pacing,” said Abkenari. “Patients with the system have been very satisfied because it is easily implanted, easily removed if needed, and allows patients more arm movement and mobility than the conventional ICD. This S-ICD system is ideal for young adults and all those who are at risk of sudden cardiac arrest yet have no resynchronisation or pacing indications,” Dabiri concluded.
The S-ICD system is currently under review by FDA for use in the United States.