Brief Answer:
No one can predict the course of a disease
Detailed Answer:
Hi
No one can predict the course of a disease like Atherosclerosis.It is a condition where there will be deposit in the lumen of a blood vessel.As the age increases, Atherosclerosis can occur.At what age it occurs varies from individual to individual.The risk factors that are modifiable can be dealt with some medication.I have seen many old people with Atherosclerosis without any risk factor.CT angiogram is the best investigation to know the progress.One positive point in your leg is that Collaterals are good.
Mild Aortic stenosis can be like that.But, regular ECHO should be done to know the progress of the condition.It is a very slow process.There are no specific symptoms which tell the progress.Only investigations will confirm the progress.
In my experience of 23 years after Medical degree,I came to know that every patient is different.A person who smokes 10 cigarettes a day will not have any complaint till 60/70 years.But,an adult who smokes 5 cigarettes a day present with Gangrene of the foot.
I hope that PTA will give excellent result and you will be symptom free.
Hope I answered your question.
Regards