I am post quadruple bypass surgery by about 6 weeks. Prior to surgery i was taking 100 mg cozaar and 360 mg tiazac diltiazem. Post surgery i am again on 100 mg cozaar but also 12.5 mg metoprolol taken twice daily. Recently at cardiac rehab they noticed my blood pressure is back up to 155/90 or so. I contacted my physician and he suggested starting back on the tiazac diltiazem. My concern is that reading online here there is some interaction potential between the diltiazem and metroprolol. Should i be concerned?