Atrial tachyarrhythmias are relatively common but mostly self-limiting complications after cardiac procedures. We report a case of atypical atrial flutter which developed early after surgery for severe mitral regurgitation and patent foramen ovale. The arrhythmia could not be managed by conservative measures and compromised the patient's recovery. The atypical atrial flutter was safely terminated by radiofrequency ablation despite the early post-operative period.