I Have Been Taking Metoprolol Since 2012. Before I Was

I have been taking metoprolol since 2012. Before I was having rapid heart rates and palpitations. I am now experiencing episodes of skipped heart beats and gasping/coughing for breath/air. Could the metoprolol be the cause of this? Should I request that the doctor change my medication to something other than a beta blocker. Do beta blockers change, alter or affect the electrical system of the heart?