The CoQ-10 from epic4health is one of the best forms.

I don't know what GNC is selling. Read your label, and call them up and see if Tischon is their supplier. Tischcon has a patent for this.

from http://www.epic4health.com/noname.html

The research into mitochondria damage as a cause of chronic illness is rather new and ongoing. I think trying to predict how long you would "need" CoQ-10 is very difficult.
When looking at synthesis in the liver, logic would suggest that perhaps 6mos to a year might reverse the loss of endogenous
synthesis that was suppressed by the statin drug.

But what about the mitochondria at the nerve level? We don't have any way to measure that damage yet. There are tissue biopsies used to diagnose genetic mitochondrial failure, and I think they count the mitochondria seen in microscope slides of the muscle tissue. From what I understand, these biopsies have to be done a special way, preserved carefully, etc so no false positives result.

CoQ-10 is not a toxic substance to the body, as we make it ourselves under ideal conditions.

The really only obivous way to know is by how you feel. If you get much better, then try going off and see if you fall back. Try to only change one thing at a time, so you can more clearly gauge if it is the reason.

There are medical studies on the heart at PubMed.
Like this one:
http://www.ncbi.nlm.nih.gov/pubmed/20586147

Use keyword search "CoQ-10 heart" and there are 571 entries there.