Pleural Effusion following bypass surgery

My father, age 62, under went CABG surgery in August after being diagnosed with a 95% blockage and 5 smaller blockages.  Prior to the surgery he had no symptoms of heart disease, was active and exercised regularly.  Post surgery (7weeks following surgery) he had a thorencentisis performed due to a pleural effusion in the left lung and experienced severe pain in the chest area associated with the pleural effusion.  Following the procedure he has said that this has been the first time since the surgery he has been able to take a satisfying deep breath.  Now he is experiencing pain in his left arm, reduced stamina and symptoms of angina when excersizing (walking approximately 1-1/2 miles).  These symptoms were not present prior to his stay in the hopsital due to the pleural effusion.  My questions are:  Is angina normal after bypass surgery, when he had never experienced angina prior to having the surgery? Should a followup thallium stress test be performed to determine if a graph(s) has closed up since his operation?  What is the likely hood of a second pleural effusion developing?  He is now 12 weeks post surgery and has become frustated with his progress. Thank you.