The U.S. Food and Drug Administration today approved a heart defibrillator that helps to restore regular heart rhythms with leads that can be implanted just under the skin (subcutaneously) instead of connected directly into the heart.
An implantable defibrillator is a small battery-powered device that constantly monitors a person’s heart rhythm and can deliver a therapeutic dose of electricity to restore the rhythm when it senses the heart is beating dangerously fast (tachycardia) or chaotically (sudden cardiac arrest).
Other implantable defibrillators on the market require a physician to insert one or more electrical conductor wires, called “leads,” into a vein in the upper chest and guide them into the patient’s heart. X-ray fluoroscopy, a real-time imaging method, helps the physician to visualize the heart and blood vessels to guide the leads to the correct position.
The Subcutaneous Implantable Defibrillator (S-ICD) System uses a lead that is implanted just under the skin along the bottom of the rib cage and breast bone. Because the lead is placed under the skin rather than through a vein into the heart, a physician can implant the device without accessing a patient’s blood vessels or heart and without the need for fluoroscopy.
“The S-ICD System provides an alternative for treating patients with life-threatening heart arrhythmias for whom the routine ICD placement procedure is not ideal,” said Christy Foreman, director of the Office of Device Evaluation at FDA’s Center for Devices and Radiological Health. “Some patients with anatomy that makes it challenging to place one of the implantable defibrillators currently on the market may especially benefit from this device.”
The S-ICD System is approved to provide an electric shock to the heart (defibrillation) when the patient’s heart is beating at a dangerous level or abnormally fast (ventricular tachyarrhythmias). It is approved only for patients who do not require a pacemaker or pacing therapy.
FDA has reviewed data from a 321-patient study in which 304 patients were successfully implanted with the S-ICD System. At the time of implantation, the investigator tested the effectiveness of the device by inducing heart arrhythmias. The S-ICD System was successful at converting all abnormal heart rhythms that it detected back to normal rhythms. Investigators followed these patients for six months following implantation, during which time the device detected and recorded 78 spontaneous arrhythmias in 21 patients; all arrhythmias were either successfully converted back to normal by the defibrillator or resolved on their own. Because the S-ICD System memory stores data from only the 22 most recent arrhythmia episodes, there may have been other detected episodes that could not be analyzed by investigators.
FDA reviewed safety data based on the entire 321-patient study population to identify complications that can occur during and after implantation of the S-ICD System. The most common complications included inappropriate shocks, discomfort, system infection, and electrode movement, which required repositioning. Eight patients died during the study; however, experts (who were not involved with the study) could not definitively attribute the deaths to the S-ICD System. Eleven patients required the removal of the device, and 18 had discomfort that was resolved without repositioning the device or surgery. At the end of six months, more than 90 percent of patients had no complications.
As part of the approval, FDA is requiring the manufacturing company to conduct a postmarket study to assess the long-term safety and performance of the device and to assess differences in effectiveness across genders. The study will follow 1,616 patients for five years.
The S-ICD System is manufactured by Cameron Health Inc. of San Clemente, Calif.