HRS: Subcutaneous ICDs prove 100% effective in converting VF

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Locations of the components of a subcutaneous implantable cardioverter–defibrillator in situ. Image source: New England Journal of Medicine

SAN FRANCISCO--A subcutaneous implantable cardioverter-defibrillator (S-ICD) system was 100 percent effective in converting and detecting induced ventricular fibrillation (VF) through shock, according to a study presented May 4 at the annual Heart Rhythm Society scientific sessions. The S-ICD system can therefore be comparable to conventional ICD therapy.

The S-ICD is minimally invasive and does not require direct vascular access, which can result in fewer complications during procedure. However, the device cannot be used in patients who require pacing. Previous studies have shown improvements when the S-ICD was used.

To further study S-ICD efficacy, Lara Dabiri Abkenari, MD, of Erasmus Medical Center in Rotterdam, the Netherlands, and colleagues enrolled 98 patients who were implanted with S-ICDs in three sites across the Netherlands. The devices were implanted according to international guidelines and were tested using 65 shocks.

The researchers noted that there was a primary prevention indication in 63 percent of patients and 41 percent of patients was diagnosed with ischemic cardiomyopathy. The patients had a mean age of 56 and 78 patients were male and 20 were female.

After a nine-month follow-up, the researchers reported that there were no hospitalizations due to heart failure and no patients experienced episodes of sudden cardiac death. Additionally, the systems acutely detected and converted episodes of induced VF 100 percent of the time.

The researchers also reported that 34 sustained or non-sustained spontaneous ventricular arrhythmias were detected in six patients and 23 arrhythmic episodes were treated in three patients.

Dabiri Abkenari reported that inappropriate therapy occurred in eight cases because of over-sensing; however, a software algorithm integrated into the system prevented inappropriate therapy to recur in all cases. Adverse events were also reduced after the T-wave sensing algorithm was used.

“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,” Dabiri Abkenari said.

Additionally, she noted that the S-ICD is ideal for younger patients and those who have a heightened risk for sudden cardiac arrest.

The system is currently under review by the FDA in the U.S., but is available for use in Europe.