It is the medical device manufacturer that is legally responsible for identifying when they need to undertake field action to address a safety risk with their devices. They should always issue a Field Safety Notice (FSN) when they do so to explain what they are doing and why. For cardiac implantable electronic devices (CIEDs) companies usually target their FSN to all customers or centres they can identify who received the devices or are managing affected patients. So some FSNs, affecting many patients, go to a large number of UK pacing centres, while others may be targeted to only a few.
As the regulatory authority MHRA is responsible for monitoring the action taken by the manufacturer. They will only issue a Medical Device Alert (MDA) if this will add value to the action already taken by the manufacturer. In rare circumstances MHRA will issue an MDA because there is no FSN, such as if the company no longer exists, does not recognised there is a problem, or if the concern is generic to a device type rather than to specific device models. MHRA reviews the FSN to help decide if they need to take any extra action. Criteria for when an MDA is issued following an FSN include: where additional advice or clarification would be helpful; where the message needs to reach a wider number of centres; if there is concern that the FSN may not have been appropriately received; or if an issue is sufficiently high profile or high risk that an MHRA opinion is expected.