Timing Chain tension failure??

What is your question?

When I start my car in the mornings (or after spending 8hrs at work), there is a very loud rattle and then it subsides after about 10 seconds. I have been told this is because of the timing chain needs to be replaced. I have seen other complaints on other models where the timing chain tensioner has failed and I wonder if this is what's going on with my car. I don't feel safe anymore and I have scheduled an appointment to have this looked into asap!!