A 31-year-old primiparous woman with a history of bigeminy as a teenager developed atrial fibrillation with rapid ventricular response during elective caesarean section. Initial postoperative medical management was undertaken on the maternal high dependency unit and involved the administration of beta-blockers and digoxin. On postoperative day 1 the patient was transferred to the coronary care unit where she subsequently required synchronised direct current cardioversion to restore sinus rhythm. The patient remained on the coronary care unit for 5 days before discharge. Magnetic resonance imaging undertaken 6 weeks postpartum showed non-ischaemic cardiomyopathy. In this report, we discuss tachycardia-induced and peripartum cardiomyopathies, along with their potential underlying pathologies, incidence and associated morbidity. We describe potential pharmacological therapies including beta-blockers and angiotensin-converting enzyme inhibitors, as well as the implications of such medications for breastfeeding mothers. Patients presenting with palpitations in the antenatal period should receive prompt investigation including electrocardiography with ambulatory monitoring considered for those with persistent symptoms. Anyone with a proven cardiac arrhythmia should undergo echocardiography. This report illustrates the importance of the investigation of the symptoms of arrhythmia during pregnancy and emphasises the role of multidisciplinary working in the management of obstetric patients with complex medical comorbidity.