Why stress test after angioplasty? Side effects of Persantive?

[NC__0]

  My father is 83 yrs old and recently had angioplasty for one blockage.
  Symptom was chest pain whil mowing his lawn with a push mower. His GP asked him to
  resume lawn mowing to "see if we did you any good". He has done so
   for the past month with no pain. GP now want him to take thalium stress
  again, which he declined due to pains in his back (arthritus).
  Now the GP wants him to take a Persantine/Thalium test instead of treadmill
  My father does not ask questions or find out the purpose or reason
  for any of this, but does about anything they want him to do.
  I have read the material on this forum re Persantine side effects
  and have concerns about these possible side effects.
      My questions are these"
        Why is a stress test needed six weeks after angioplasty?
        He does not have any symptoms now, what will such a test determine?
        What are the potential side effects of persantine injection?
        What are the risk/rewards for this procedue in a 83 yr old man?
  Thank you for your response. Your forum is most informative and
   professional and objective.

[CCF CARDIO MD APS]

Dear NC,
There are a couple of reasons why cardiologists order stress tests following a
revascularization procedure (revascularization includes anything from angioplasty
to coronary artery bypass surgery) and here they are:
1)Since some angioplasties appear successful (pateint has no further pain) but actually
do re-stenose/recoil/or return to the significantly blocked state, it is best evaluated with
a functional test like a stress or persantine thallium that will assess for heart muscle wall
that is still at risk.  Of course, there can be some recoiling in the vessel that was angioplastied
and the thallium will still be normal-this is because the recoiling is not significant such that
it does not impede blood flow significantly.  
2)In doing a catheterization, aside from the culprit vessel-i.e. the one that had a severe blockage and was angioplastied,
the cardiologist sometimes notes that there are other blockages but of unclear significance.  For example
a 60% blockage seen in another vessel at the time of catheterization can be
evaluated for it's significance with a stress or persantine thallium also.  
3)It is well known that in the heart vessels there can be significant blockages
and yet the patient has no chest discomfort, so it is not unusual at all for
cardiologists to follow their patients intermittently with a thallium of some sort.
4)Persantine is a short acting substance that dilates all the vessels in the body
all at the same time (which is somewhat equivalent to what occurs when we exercise)
and this essentially makes the heart share the blood flow equally with all the other parts of the
body; the heart and brain are used to getting the lion's share of the blood flow so to speak.  This is how
persantine mimics stress.  Also in this manner, the patient can feel a flush or hot sensation, dizzi, sweaty, even
chest discomfort and shortness of breath(these from the heart being unhappy about the stress).  Another side effect from the
persantine is headache.  As I said before this is a short acting drug and the side effects go away when the drug
goes away (1/2 to one hour or so) and if needed there is a reversal drug that can be given called aminiophylline should the
patient not tolerate the medicine, or the blood pressure go too low from all the
dilating vessels.  These things are all watched very carefully during the test.  
Of course any drug carries with it the possibility of an allergic reaction,small but possible.  
5)Age should not preclude your father from being evaluated as all cardiology patients are, however
it is very much agreed upon that no patient should undergo unnecessary tests and procedures.
I hope that this will help you to better understand your father's condition as well as in the understanding of his test results.
You should seriously consider going to an appointment with your father and if this is not possible, send him with a few questions that
are written down by you.  Good Luck.  Information provided in the heart forum is intended for general medical informational purposes only,
actual diagnosis and treatment can only be made by your physician(s).