I had a stent put in the right decending artery in 2003 and have been on metoprolol succinate to keep my pulse down ever since. Pulse usually stays 58-63, unless excercising. Over the years, the dosage was increased to 100mg as I was having some angina when excercising, walking, etc. I had a angiogram done in 2009 and the stent is still open and that was when the cardiologist increased the dosage to 100mg. Lately I have been suffering from fatique and extreme tiredness. My primary doctor reduced the dosage to 50mg a day. Now I am experiencing pounding heart, shortness of breath,dizziness when I lift something oveer 15-20 pounds with my left arm, or when I get in a hot bath. Any idean whats going on?