Metoprolol
"I am taking Metoprolol 50mg 3 times per day since the beginning of January and my heart rate is still very high137 bpm on average for a seventy one year old male previously active and in good health.  When I climb stairs I am short of breath feel weaker than normal. Previous taking Digoxin 62.5mg x3/day. This controlled/capped my HR at 115bpm without side effects. So my HR has increased by comparison since starting Metoprolol. I would welcome all your comment."