Supraventricular tachycardia

I am 46 years old. I am a SVT (supraventricular tachycardia) patient since last 13 years.Before last four months,
I never had more than two SVT attacks in a year. Then four months earlier, I got pulse missing problems. The doctor
told me it's PVC. And there is nothing to worry. But then I have to face an increase in SVT attacks and now I get
5-25 SVT attacks per day which lasts from 2-3 minutes to long duration. And after every 3-4 days, they won't stop
without the injection (isoptin). I have been using Calan 40-mg and now I am using Calan SR 120-mg, Ascard 75-mg and
Vitamin-E daily for last three months.
Report result:
echo-normal
ETT:
Conclusion-Stress test is Positive for exercise induced ECG changes. No clinical angina provoked during exercise.
Adequate hemodynamic response. Average effort tolerance.
thallium test:
Conclusion- Exercise myocardial SPECT stury at 47% predicted HR and 7.2 METS is positive for medium sized inducible
ischemia of mild severity involvin inferior wall.
Now I want to know what is my best option considering my situation.
If you think my reports will help, I can scan them too.