SunLife has announced changes to its critical illness cover in line with the ABI's updated best practice.
Cancer and stroke definitions will remain ABI standard, the definition for heart attack is now ABI+.
The new heart attack definition requires a "rise of biochemical cardiac specific markers" rather than requiring a troponin level of at least 0.2 which is the ABI definition.
Mark Jones, protection director at SunLife, said: "We have enhanced our heart attack definition to make it a little easier for customers to claim for Heart Attack."
Jones added: "Most critical illness products have great long lists of illnesses, making it difficult for customers to be confident that they understand what is and isn't covered; we wanted to do something different."
He said: "Cancer, Heart Attack and Stroke make up nearly 90% of critical illness claims, and our qualitative research found that the majority of customers were unable to name any additional illnesses that they would expect to see covered over and above cancer, heart attack and stroke.
"Using this information we decided to bring to the market a critical illness product that is straightforward and affordable; our cover is available from £5 a month and is easy to understand as it covers just the three critical illnesses - heart attack, stroke and cancer.
"Initially we had expected that the critical illness take-up rate would be around 20-30% however our simplified approach has seen over half of our customers choose to add CI since we launched in September 2014."