In case atrial fibrillation occurs, therapeutic-dose anticoagulation should be given and an attempt should be made to restore sinus rhythm. Treatment with low molecular weight heparins is safe during pregnancy. Despite optimal therapy, if symptoms persist then invasive treatment should be considered, when anatomically suitable valves are present percutaneous mitral valvulotomy (PMV) has been shown to be a safe and effective treatment during pregnancy. Balloon valvuloplasty can be performed (with appropriate radiation shielding of the fetus). Mitral valve surgical commissurotomy or valve replacement has been performed, but fetal loss exceeds 30%. Percutaneous mitral balloon commissurotomy should preferably be performed after 20 weeks of gestation, the period safest for the fetus. During pregnancy atrial fibrillation is a great concern. Immediate treatment of a rapid ventricular response should include IVverapamil or cardioversion.