The Use of Ranolazine for Atrial Fibrillation and Diastolic Heart Failure

Inclusion Criteria: * Male or non-pregnant female \> 18 years of age; * Documentation of heart failure and who are in NYHA class II or III; * Documented history of symptomatic AF \< 6 months in duration at the time of presentation, currently in AF at the time of the external electrical cardioversion, and successfully restored to normal sinus rhythm; * Percutaneous coronary intervention (PCI) patients who can be placed on anticoagulation with warfarin post-cardioversion (and not on rivaroxaban or dabigatran); * Demonstration of preserved ejection fraction (EF) by echocardiography; * Echocardiographic evidence of impaired diastolic filling. Exclusion Criteria: * Known history of permanent or long-standing AF (\> 6 months); * Other acutely reversible causes of AF, including but not limited to: hyperthyroidism, pericarditis, myocarditis or pulmonary embolism; * Known history of cirrhosis; * NYHA Class IV; * Myocardial Infarction, unstable angina, or coronary artery bypass graft surgery within three months prior to screening; * Percutaneous coronary intervention (PCI) within 4 weeks prior to screening, if these patients need to be placed on rivaroxaban or dabigatran post-cardioversion; * Clinically significant valvular disease; * Clinically significant pulmonary disease; * Stroke within 3 months prior to screening; * Creatinine clearance \< 30 mL/min as calculated by Cockcroft-Gault formula; * Use of anti-arrhythmic drugs (Class Ia or IIIc) within 3 months prior to screening; * Concurrent use of drugs considered strong inhibitors of CYP3A; * Concurrent use of drugs considered as CYP3A inducers; * Prior treatment with ranolazine.