If atorvastatin 20mg is affecting all the muscles in a old person with a heart desease,can we replace it with rosuvastatin 10mg ? thanks in advance.

Doubtful: Both of these "statins" can cause muscle pain as a side effect but it is worth a try. In my experience, pitavastatin (livalo) may cause less muscle irritation but is not as potent of a cholesterol lowering effect as the two above. Whatever you do, you need to discuss this with your treating doctor.

Statin: Sometimes substituting one Statin for another can help. As rosuvastatin is more potent than atorvastatin we would usually try a less potent stain