Possible side effects

My husband suffered a heart attack on 7/26. Quick EMS response to hospital saved his life. Had 99% blockage, but no damage with fervent prayer and excellent care! He is on Plavix, Metroprolol Succinate ER, Tricor, and Lipitor. Was doing great but gradually he has become more fatigued at moderate walking and has experienced lightheadedness. He is having to sleep a couple of times during the day because he feels tired. No other symptoms. Of course we are contacting our cardiologist in a.m. (Monday) for further advise, but I was wondering if the above symptoms are a side affect of the Metoprolol. My own internist had to take me off it some time ago. Thank you.