Locate results before coding extra ECGs or other tests. Reporting an atrial fibrillation diagnosis will be simple under ICD-10, thanks to a one-to-one code shift. The current diagnosis under ICD-9-CM, 427.31 (Atrial fibrillation) will become I48.0 in October 2013. ICD-10 tip: Physicians might use electrocardiograms (ECGs), lab tests, chest X-rays, echocardiogram or transesophagealechocardiogram (TEE), or ambulatory ECGs to help evaluate the extent of the patient's condition. If so, be sure you have the physician orders and test results in the patient's chart before coding the services in conjunction with I48.0.