Could dizziness be a sign of heart disease?

i've had blood tests for anaemia, thyroid function, kidney function, cholesterol level - the doctor said my platelet level was slightly high but nothing to worry about -is that true or should i insist on more tests? some days i'm not dizzy at all other days i feel as if i may fall over.

have you had an ecg done? you might have a fast heart beat which can make you dizzy as your blood carrys oxygen,if the heart is too fast not enough oxygen is carried

I would be more worried about a brain tumour to be honest.

Do you have blurred vision as well? Headaches?

If so definitely get a scan.

EDIT

For those of you down thumbing me please read the below link - it specifically says a symptom is unsteadiness which is exactly what they have described above "feel as though I may fall over". So don't be so quick to dismiss it. I am trying to help someone by warning them of all possible dangers and being honest instead of molly coddling it and then it goes for months unchecked.
Sorry to be so dramatic but it is better to catch these things as early as possible.

http://www.tbts.org/itemdetail.asp?categ...
i don't think it can it might be more of diabetic like you need sugar but I'm not one to say not a doctor XX hope everything OK
Firstly do you wear glasses - if not - maybe you need them or need a re-test if you do wear them maybe you need stronger lenses!
it could be a variety of reasons, I should think that your heart was one of the first things your doctor checked, Have you noticed irregular heart rythm, pain in left arm or shoulder, numbness in fingers. Blood pressure checked?
I would not rest until you get proper answers from your doc. Saying that a certain thing is not something to worry about is not an answer to your problem. Dizzy spells is caused by something so get it checked again.
Glasses could be the problem also so get your eyesight checked
Platelets

Platelets are very small cells in the blood that clump together at sites of injury to blood vessels. They form the basis of the blood clot that would form if you cut yourself.

Low numbers of platelets can make a person vulnerable to bleeding, sometimes even without injury occurring. Causes of low platelet counts include autoimmune diseases where you produce an antibody to your own platelets, chemotherapy, leukaemia, viral infections and some medicines.

High numbers of platelets make a person more vulnerable to blood clots. High platelet counts are found in conditions involving the bone marrow such as leukaemia and cancer.
more like diabetes. but heart disease could play a factor.