supraventricular tachycardia
"Changed from atenolol 50mg to metropolol er succinate 25 mg not by choice.  Transition very smooth.  Was taking atenolol for SVTs.  I added magnesium to my daily dose after some research on SVTs.  Stomach bloating from atenolol reduced and my sleep improved. I'm a mid distance runner with HR in the upper 50s.  Feeling very good."