You successfully diagnosed the patient and identified the initial management, but to proceed further, it helps to risk stratify the patient correctly. The CHA2DS2-VASc score is to calculate the risk of developing a stroke in patients with atrial fibrillation, and so is of little use in this scenario.
It seems the ECG was crucial to the diagnosis, so perhaps that should take priority over imaging. You may not be so lucky next time if you forget.
Final score (out of 10): 7