It would probably be worth it to try increasing the dose of
atenololAtenolol
Atenolol-chlorthalidone by another 12.5 mg. It might make you sleepy, but the only way to know would be to try it. If the tachycardia is not particularly fast, ignoring it and trying the atenolol are really the best thing. If the rate is very fast and causes unberable symptoms, then you could consider having an ablation procedure done by an electrophysiologist, though I would only suggest this as a last resort.
Chris S.
I am on such a small dose of atenolol for NCS and IST. It has dramatically improved my energy level, not to say it's great(because the fatigue was from my conditions, says my EP), but the dose was not enough for my IST . When they tried to up it I became fatigued and had other side effects. However, I am unmotivated, I have been trying to figure out why. I will have to remember to ask my dr. about switching. I am glad you posted.
Cybill, my dr. put me on verapamil additionally for the IST and it has helped.