Is It Safe To Take Metroprolol For Abnormal Heartbeat?

I had an incident of tachy of 146bpm at a health club. When I took a cardio gram at the urgent health center it recorded about the same bpms. Then I went to the emergency room, where after 45 minutes I was given a strip cardio gram and an extensive series of blood tests. Even though all the tests were normal they recommended that I see my internist, a cardiologist. He gave me a short cardio gram, which was normal. Then he put me on a heart monitor, which recorded no abnormal heartbeat after 2 days. The echo I took after returning the monitor was also normal. Then the doctor examined me one last time with a stethoscope and heard an irregular heartbeat. The was subsequently confirmed by a short cardiogram. He recommended that I take 50 mg of metroprolol 1x and 5mg eliquis 2x. This treatment was confirmed by an electrocardiologist on the same floor. How can I determine if they are over reacting?