76 years old woman has permanent atrial fibrillation caused by colon cancer. Her blood pressure is normal.Before colon resection she took cardizem 180 mg / day. Her initial heart rate before cardizem was 125/ min, after 80-90/ min( at rest).She had blood transfusions due to low hemoglobin. After surgery her rate became 100/ min. The left atrial and ejection fraction are normal. What is the best way to control the rate?can I answer your health question? Please type your question here...