Could Atrial Fibrillation Be The Side Effect Of Diltiazem?

can diltiazem CD - capsule 180mg (vasocardol) contribute to or cause Atrial Fibrillation - dose one calsule daily ? - currently taken at night with one 32mg Atacand - then morning one Atenolol 50mg . in morning. One week ago also took one Atenolol 50 mg. at night. Current blood pressure morning 146/84 pulse 66 - midday 126/81 pulse 56 - 8pm. 126/71 pulse70 - 11pm. 119/64 pulse 60. ultrasound Nov. was normal . ECG Dec. normal- ECG late Jan. showed irregular heartbeat . Age 71 . started taking Diltiazem some 3 -4 months ago Please advise Doug