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WASHINGTON -- The FDA has approved the first subcutaneous implantable cardioverter-defibrillator (S-ICD).

Unlike conventional ICDs, which require that leads be threaded through a vein to the heart under the guidance of fluoroscopy, the leads on this new-generation device are implanted just under the skin, along the bottom of the rib cage and breast bone, needing no x-ray guidance.

The S-ICD System, made by Cameron Health, is approved for patients at risk of ventricular tachyarrhythmias who do not require a pacemaker or pacing therapy.

In April, the FDA's Circulatory System Devices Advisory Committee voted 7-1 in favor of device approval.

Both the FDA and the committee reviewed data from a 321-patient nonrandomized study in which 304 patients were successfully implanted with the device. Only those needing a replacement or revision of an existing transvenous ICD were included.

In the 6 months of follow-up, researchers found that all 78 spontaneous arrhythmias in 21 patients were successfully converted to normal rhythm. There could have been other arrhythmias, however, as the device only stores the most recent 22 episodes.

The most common complications with the device included inappropriate shocks, discomfort, system infection, and electrode movement that required repositioning.

When the advisory committee made its recommendation for approval, it noted concern for the 28 inappropriate shocks caused by the device oversensing and another 20 that occurred because the ventricular rates were above the programmed threshold.

A total of eight patients died during the study, but their deaths could not be definitively attributed to the device, according to a statement from the FDA. Another 11 patients had the new device removed, and 18 required repositioning or surgery because of discomfort.

Cameron Health now intends to follow 1,616 patients for a long-term postmarket study examining safety and performance, as well as any differences between men and women.

From the American Heart Association:

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