Inclusion Criteria:  Men and women ≥ 21 years of age Sustained AF Planned/scheduled direct current electrical cardioversion Consumption greater than or equal to one cup of coffee per day sometime in the past 5 years Willing and able to comply with coffee abstinence or continuation Life expectancy of at least 1 year Willing and able to return and comply with scheduled phone follow up visits Willing and able to provide written informed consent  Exclusion Criteria:  Established allergy or adverse reaction to coffee Stated inability to comply with coffee abstinence or continuation AF ablation in preceding 6 months or planned in next 12 months Recent cardiothoracic surgery in preceding 3 months Cardioversion for atrial flutter rather than AF Pregnancy or desire to get pregnant within next 6 months. Current enrollment in an investigation or study of a cardiovascular device or investigational drug that would interfere with this study Any other criteria, which would make the patient unsuitable to participate in this study as determined by the Principal Investigator (e.g., an uncontrolled drug and/or alcohol addiction)