@Soulfox -- I'm not sure that it is terribly different, but the problem is that amyloidosis can turn very deadly if it is misdiagnosed as routine heart trouble. I'm no expert, but I do know that amyloidosis tends to reveal itself as heart trouble in its early stages -- misdiagnosing as something other than "stiff heart" and treating it by more conventional means could allow amyloidosis to spread and create other organs from functioning properly. When amyloidosis is spread through the body, that is when it must be treated with aggressive regimens such as chemotherapy.
The problem with amyloidosis, in general, is that it is extremely rare and hard to detect by more conventional means. If a doctor sees heart trouble, the chances the diagnose is correct will be correct the vast majority of the time. It seems the medical profession is still learning about amyloidosis and how to treat it effectively.
If the condition does advance to the stage where chemotherapy, a lot of the problem is that amyloidosis (whether stiff heart or otherwise) tends to show up in the elderly. Chemotherapy is tough on the body, and an elderly patient might not be strong enough to hold up under it for long. That is why it is critical to catch the condition early and take steps to treat it.