As a senior nurse in a Coronary Care Unit, I will chuck in my 2 cents worth.
Our cardiologists like the cholesterol level to be below 4.5, so patients with heart disease and high cholesterol are treated quite aggressively with high doses of good old Lipitor. As David says, Lipitor also has other heart friendly effects.
Cholesterol is one of the risk factors for heart disease, so if you can decrease it either by diet and/or medication, then thats great. Our docs dont reccommend the low carb/high protein diet, though I reckon its good.
I lost weight 10 years ago, and dropped my cholesterol from 7ish to 4 ish by doing this. You need carbs to absorb fat.
Not everyone with a high cholesterol will get heart disease, but combined with other risk factors of blood pressure/smoking/family history/stress/weight etc., it can be a worry.
As others have said, a combination of diet and exercise normally brings it down Ok, others need different approaches per their GP.
Take care all, otherwise I will see you in CCU.