Metoprolol
"I was diagnosed with SVT following complications from a vaginal hysterectomy at age 58 (pulmonary embolism, pelvic hematoma and pneumonia).  ER diagnosed it as A-fib; cardiologist later said SVT following 48 hr. Holter monitor and echocardiogram.  Started me on 25 mg once a day which I take at night.  Have been taking about a month and it is working well.  Heart racing if I have it is not noticeable; pounding heart occasionally but tolerable and minor compared to what it was previously.  Recommended going up to 50 mg but I am going to keep trying at this dose longer.  No noticeable side effects, no weight gain or sleepiness."