The Maestro Rechargeable System (Enteromedics, Inc) is a pacemaker-like device that is surgical implanted into the abdomen. It sends intermittent electric pulses along the nerve pathways between the stomach and the brain that signal feelings of hunger and fullness.
This device uses “VBLOC® vagal blocking therapy”—the process by which it blocks the body’s normal messaging system along the nerve pathway to the vagus nerve, which originates in the brain stem. The vagus nerve (in fact a pair of nerves) is responsible for a number of involuntary body functions, including digestion and the regulation of the heartbeat. Vagus nerve stimulation is also used to treat epilepsy.
The Maestro Rechargeable System is approved for adults with a BMI of 40 to 45, or a BMI of 35 to 39.9 and one or more obesity-related condition, who have been unable lose with a weight loss program. This is the first “non-anatomy altering or restricting, reversible therapy that allows patients to safely lose weight by helping patients feel less hungry, reduce the amount of food eaten at a meal, and feel full longer in between meals,” according to the device maker.
The FDA approved the device despite it not meeting its primary goal in a clinical trial. In a controlled trial of an activated Maestro device versus an inactivated device (the placebo arm of the study), active participants lost 8.5% more weight (or, an average of 24.5% of their excess weight) than those in the control group over 12 months. The original goal was for the experimental group to lose 10% more than the control group.
So why was the device approved anyway? For the first time, the FDA actively sought patient preference on acceptable levels of risk versus benefits for medical devices in making the approval decision. In an FDA-administered Patient Risk Tolerance Survey, participants with self-reported BMIs over 30 were asked an number of questions, including what was the maximum acceptable risk (MAR) that they would take in return for the benefit of a generic medical device for weight loss. This type of survey will be used in the future for other medical devices as well.
The SAE (severe adverse event) rate in the clinical trial (known as the ReCharge study) was 3.7%. Serious adverse events included nausea, pain at the neuroregulator site, vomiting, and surgical complications. The maker of the device, Enteromedics Inc, is required to conduct a five-year year post-approval study to collect more safety and effectiveness data.
For more information, see the FDA website.