Hi, lily, and welcome to our happy family.
I've been taking metoprolol ever since my valve surgery 7 years ago. Whether you need the beta blocker long term or not probably depends upon why it has been prescribed for you. Many surgeons prescribe a certain "pack" of meds for the first few months post-op, then re-evaluate later on. Others only prescribe what they feel each patient needs.
In my case, after aortic valve replacement, I had all sorts of heart rhythm and rate issues. I had afib (atrial fibrillation), missed beats, extra beats, even looong pauses of up to 20-30 seconds. I ended up with a pacemaker to protect against those pauses and metoprolol to help protect against afib. Originally, I was prescribed a dose of 100 mg/day of metoprolol. That was rough. I told my cardio that it felt like I was dragging a sled full of boulders around all day. At about 4 to 6 months post-op, I convinced him to cut my dose to 50 mg/day. I noticed an immediate improvement, with no recurrence of afib. A few months later, I again discussed it with him, and we agreed to try reducing my dose to 25 mg/day. That was a huge improvement, and that is the dosage I still take.
I'm a confirmed gym rat, and watch my heart rate during exercise. Before the surgery, I could easily run my heart rate up to the mid-160's under peak load. After surgery and rehab, but with the 100 mg/day metoprolol dose, I could barely get over 100. Couldn't do much at that rate. These days, 67 years after valve surgery and with only 25 mg/day of metoprolol, I can get my heart rate up to the mid-140's. My cardio and I (reluctantly) agree that at my age (now 70), that is a realistic limit to set.
If the beta blocker is getting in the way of your life, I would discuss it with your cardio to see if it may be worthwhile to try a reduced dose for a bit to see if it helps you in activities without allowing anything unusual to happen to your heart rate or blood pressure. (You don't mention any lingering atrial fibrillation, so my suggestion presumes that they are just trying to limit your max heart rate.)