No implantable medical device is perfectly safe. It is the duty of manufacturers and regulators to minimise risks—and the purpose of evaluating and regulating devices is to ensure safety and effectiveness.

The product life cycle of many medical devices is short—often quoted as an average of two years or less—because of the rapid rate of technological change and because of frequent modifications (called iterative changes) to their design, manufacture, or programming. It would be desirable for all implantable devices to undergo long term clinical studies—but there is pressure from interventional specialists as well as from industry to base approval on shorter term studies with surrogate rather than clinical end points. This facilitates innovation but transfers responsibility for proof of safety and clinical efficacy to follow-up studies.

Regulatory approval in Europe hinges on the principle that as long as a device has been shown to perform its stated task, it can be approved if its potential benefits outweigh any expected risks. Approval on this basis can mean estimating benefit before clinical effectiveness has been confirmed, and it means accepting some risk as the trade-off for more rapid availability of devices. The system of approval by 74 notified bodies in the European Union (EU) …