My father had an arrhythmia, which eventually led the doctor to realize he needed heart surgery. Unfortunately, my dad left it too late and ended up passing away from not getting the surgery done in time.
He actually told me, before going in that he had noticed that there was a problem, but he had ignored it. He knew his heart was acting up and he had been having trouble breathing and other signs, but he was afraid of going to the doctor, so he didn't do anything about it.
Getting checked if there is something strange with your heart, like a weird flutter or whatever, is so important.