Should a 15 year old take 650mg of acetyl l-carnitine with a heart problem? and is it safe?

It depends,safe if..: What type of heart problem? L-carnitine can be useful for angina & heart failure- i hope the 15 yo does not have either of those. Acetyl-l-carnitine is used more for brain health. Re: safety, here's a good analysis: http://www.Drsinatra.Com/l-carnitine-is-not-only-safe-its-essential so best avoided by those who eat much red meat! also see http://www.Umm.Edu/altmed/articles/carnitine-l-000291.Htm.