INFLUENCE OF PREGNANCY ON THE RISK FOR CARDIAC EVENTS IN PATIENTS WITH HEREDITARY LONG QT SYNDROME

Background-The effects of pregnancy on women with the hereditary long QT syndrome are currently unknown. The appropriate medical management of pregnant patients with the long QT syndrome has not been establishe d. Methods and Results-The study was a retrospective analysis of the 4 22 women (111 probands affected with the long QT syndrome and 311 firs t-degree relatives) enrolled in the long QT syndrome registry who had one or more pregnancies. The first-degree relatives were classified as affected (QTc >0.47), borderline (QTc=0.45 to 0.47), and unaffected ( QTc <0.45). Cardiac events were defined as the combined incidence of l ong QT syndrome-related death, aborted cardiac arrest, and syncope. Th e incidence of cardiac events was compared during equal prepregnancy, pregnancy, and postpartum intervals (40 weeks each). Multivariate logi stic regression analysis was performed by use of a mixed-effects model to identify independent predictors of cardiac events among probands. The pregnancy and postpartum intervals were not associated with cardia c events among first-degree relatives. The postpartum interval was ind ependently associated with cardiac events among probands (odds ratio [ OR], 40.8; 95% confidence interval [Cl], 3.1 to 540; P=.01); the pregn ancy interval was not associated with cardiac events. Treatment with b eta-adrenergic blockers was independently associated with a decrease i n the risk for cardiac events among probands (OR, 0.023; 95% Cl, 0.001 to 0.44; P=.01). Conclusions-The postpartum interval is associated wi th a significant increase in risk for cardiac events among probands wi th the long QT syndrome but not among first-degree relatives. Prophyla ctic treatment with beta-adrenergic blockers should be continued durin g the pregnancy and postpartum intervals in probands with the long QT syndrome.