I have had SVTs since I was a child, they disappeared
for 20 years, when they came back they came back good, even with 240mg verapamil, magnesium, and potassium, all prescribed by my Dr. I had an ablation on Nov 6, 2007. They are still now a once a week ocurrence like clock work, usually in the early am at 175-190 bpm. Vagal sometimes works as does dunking my head in a bucket of ice water, this does not always work and then it's a shot of adenosene.