? false negative nuclear isotope scan - angina symptoms

I wonder if anyone has had a negative isotope scan but been diagnosed at angiogram with ischaemic heart disease? I had a scan in April - when I was symptom-free, which didn't reveal anything significant. In the autumn I had been getting chest pain, hence the investigation. Once my blood pressure was stabilised - at the time it was 200/110, I had no problems until 10 days ago, but am now getting chest pain at least once a day, sometimes several times. Although I do also get indigestion, the pains are very different.

Symptoms:

[list=]Central chest pain/discomfort like someone pressing down
Often radiates into neck
Precipitated by exercise, work stress or intense concentration
Relieved by GTN spray[/list]


I'm in the UK so we don't have some of the more specialist investigations under the NHS.

I eat a healthy diet - low fat, plenty of fruit and veg and have started at the gym, but tend to push it a bit much there.

What does anyone else think? Could it be a false negative?

Risk factors:

A[list=]ge 61 - i.e. postmenopausal
Hypertension (although now controlled)
high cholesterol (now controlled - HDL good)
Slightly abnormal fasting glucose
Slightly raised triglycerides
Overweight (down from obese, though)
Store fat around my middle
Virtually every member of my father's family had ischaemic heart disease - dad at about 54[/list]