Commonwealth Bank has admitted it failed some life insurance customers after an investigation found the bank was using an outdated definition to determine heart attack claims.

The bank has vowed to update its heart attack policy as soon as possible, as chief executive Ian Narev conceded his organisation failed to meet its responsibility to deal with some claims as sensitively and fairly as possible.

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“I am saddened and disappointed by the handling of these cases,” Mr Narev said in a statement on Saturday.

“I will personally write to the customers concerned to apologise and offer to meet with them face to face.”

Mr Narev conceded the bank had focused “too much on process rather than people”.

Thoroughness in dealing with complex claims processes was important for the system’s integrity, he said, but must be balanced by customer need and dignity.

“Here, we got that balance wrong,” Mr Narev said.

“We focused on details which caused delays at critical times for customers that needed help.”

The statement follows a joint Four Corners-Fairfax investigation into the bank’s insurance arm, CommInsure.

Four Corners interviewed a heart attack survivor who said CommInsure rejected his $1.1 million life insurance claim because the level of the protein Troponin in his blood was too low.

CommInsure requires a certain blood level of Troponin to prove a severe heart attack, but cardiologists say its impossible to measure the severity using that indicator in isolation, the investigation found.

Four Corners and Fairfax claimed to have obtained an email showing CommInsure was aware Mr Kessel had suffered a severe heart attack before it rejected his claim.

Commonwealth Bank has pledged to accelerate and complete a planned update to its current heart attack definition as soon as possible.