Lightheadedness

36 Year Old, non-smoker, non-drinker with familiy history of MI (maternal grandfather died in 40's and father had MI at age 55).  I had a drug eluting stent put in 2/2004 due to a failed nuclear stress test which showed a LD blockage of over 90%.  Previous to that I had numerous EKGs, regular stress tests, holter tests and and passed them all with flying colors, the nuclear was only ordered as I went to one of those Heart Scan places and the test showed calcification.   Just before the nuclear test  I was having trouble walking long distances but could still ride a bike or go jogging no problem.   I've had hypertension and high cholesterol which are both under control with meds and losing weight (although I have more to lose) .  In 2/2007 I had another nuclear stress test which showed that everything was going well.

Recently I have had some episodes of lighheadedness, sometimes during the day it almost feels as if my head is in a cloud.  Three weeks ago while running and coming down stairs I felt like I was going to faint.  A week after that I got up real quick from a chair and once again became very lightheaded to the point where I had to sit down.  I saw my PCP who did an EKG and a full blood test and all came back great.  She reviewed the Nuclear and said she was pretty confident that it wasn't cardiac.  I have my normal 6 month coming up with my cardiologist.   There are really no other symptoms.

I know that for the past three years I have been very anxious about any type of symptom and recently have talked to somebody about that. Can lightheadeness be associated with CAD and how accurate is a nuclear stress test after stenting?