FDA releases S-ICD study data prior to panel review
Subcutaneous implantable cardioverter defibrillator - 87.86 Kb
Locations of the components of a subcutaneous implantable cardioverter–defibrillator in situ Source: New England Journal of Medicine
To lay the groundwork for the April 26 Circulatory System Devices advisory panel meeting, the FDA has made trial results of Cameron Health’s subcutaneous implantable cardioverter-defibrillator system (S-ICD), the first not to require implantation of an electrode on or in the heart, available to the public.

From 8 a.m. to 6 p.m. in Gaithersburg, Md., panelists will debate and make recommendations about the S-ICD, which is seeking indication for defibrillator therapy for the treatment of ventricular tachyarrhythmias.

A premarket approval application (PMA) was submitted to the FDA on Dec. 23, 2011, requesting marketing approval of the S-ICD device. The S-ICD model SQ-RX Model 101 pulse generator weights nearly 145 grams with a volume of 69 cc. The device has been commercially distributed outside the U.S. since July 2009. In June 2011, Cameron Health issued a safety warning about the device's battery undergoing premature depletion in investigational SQ pulse generators.

The sponsor-launched clinical study was a prospective, non-randomized, single-arm, multicenter trial including 33 study sites (28 in the U.S., two in the Netherlands, two in New Zealand and one site in the U.K.).

Researchers used complication free-rates at 180 days post device implant as the study’s primary safety endpoint. Three-hundred and thirty patients were enrolled in the study and 314 were implanted with an S-ICD. Mean follow-up duration was 321 days with a range of 17 to 715 days.

FDA has reported that the primary safety endpoint was met during the study; however, there were a total of eight deaths reported. “None of the deaths were conclusively identified to be associated with the S-ICD system or procedure,” FDA noted.

During the study, 198 clinical events occurred in 135 patients. FDA also reported 51 complications in 44 patients. Data showed a total of 43 events that were caused by the S-ICD system during the study. Four events were caused by user’s manual or labeling and 106 events were not caused by the S-ICD system; however, they would not have occurred in the absence of the implanted S-ICD system.

Eighteen episodes of infection were reported; four required device explants. Additionally, FDA reported that 48 clinical events from 38 patients were reported for shocks that were delivered in the presence of a rhythm other than ventricular tachyarrhythmia or ventricular flutter. More than 30 percent of the shocks that occurred were considered to be inappropriate.

“The prespecified primary safety endpoint was met. However, the primary endpoint includes only type I complications,” FDA wrote. “Therefore, it does not include other complications that FDA believes merit mention as additional information to interpreting the S-ICD primary safety endpoint.”

During the meeting, FDA will ask the panel to comment on whether the safety data provide scientific evidence that shows appropriate device safety.

The FDA has recommended that if the S-ICD system is approved, a post-approval study should be conducted as a condition of approval for the device. The study should, the FDA said, follow at least 100 patients enrolled every six months for a period of three years to evaluate device performance.

“Specifically, regarding safety, FDA has noted the risks of the device include inappropriate shocks, and in comparison to transvenous ICDs, higher rates of infection, increased time to delivered therapy, and reduced device service life,” according to the documents.

Panel members will comment on device safety and efficacy during the April 26 meeting.