While this may increase the use of Repatha, it could also open Amgen to the risk of speculative litigation over other side effects, said product safety expert Manoj Vaghela of Pinsent Masons, the law firm behind Out-Law.com.
Amgen made the offer as it announced the results of a study showing that Repatha reduced low-density lipoprotein cholesterol and thereby reduced the risk of major cardiovascular events.
To show its confidence in these results, Amgen said, it "will offer additional contracting options in the US to payers willing to remove access barriers", including refunding the cost of Repatha for all eligible patients who have a stroke or a heart attack. This should provide "reasonable budget predictability to help address budget impact concerns", it said.
Joshua Ofman, senior vice president at Amgen said: "Now that Repatha has proven a meaningful reduction in cardiovascular events, we expect payers to remove onerous barriers and help appropriate patients get access to Repatha."
Repatha costs £14,000 a year, the Financial Times has reported.
Vaghela said: "This is an interesting approach to try to increase take-up of Repatha. The risk, of course, is that if patients do suffer any side-effects, plaintiff lawyers will argue that Amgen has made an admission of liability. In an ever-increasing litigious environment, this is a brave move on any analysis."
"Medicines can have many and varied side effects, some of which are linked and some not. For example, medical opinion might support an allegation that a medicine causes irregular heartbeats and breathlessness and that may lead to heart attacks. Other side effects, such as an alleged link between an allergic reaction and strokes may be more difficult to establish but any such allegation would have to be investigated and the guarantee may well have to respond even if causation is not always clear," he said.
"Although the guarantee by Amgen is in relation to heart attacks and strokes, some medical opinion may well link other side effects to the guarantee. By offering a guarantee, manufacturers are opening themselves up to speculative litigation, particularly in jurisdictions that have class actions, contingency fees and a no costs rule," Vaghela said.
"Will other pharmaceutical companies or medical device manufacturers follow this path by offering guarantees or refunds if their products fail? Difficult to say but we can confidently predict that the plaintiff bar in the US and Europe will closely monitor such marketing initiatives," he said.