RESUMO
AIMS: The natural history and outcome of pregnancy in patients with a pacemaker or those presenting with atrioventricular conduction block in pregnancy are unknown with only a limited number of case reports published. METHODS AND RESULTS: This study examines the progress and outcome of 25 pregnancies in 18 women who were either paced or presented with untreated atrioventricular conduction block during pregnancy. All patients were seen in a single referral centre between 1998 and 2008 and were evaluated at regular intervals with ECG, echocardiography, and 24 h Holter. Four women (4 pregnancies) had new-onset atrioventricular block, 3 women (5 pregnancies) had previously diagnosed atrioventricular block who had not undergone pacing, and 11 women (16 pregnancies) had known atrioventricular block with a pacemaker prior to pregnancy. Of the four patients presenting for the first time in pregnancy, the frequency or severity of atrioventricular conduction block increased during pregnancy. One required pacing during and one after pregnancy. In two patients the conduction disturbance resolved postpartum. In the three patients who had known but untreated atrioventricular block before pregnancy, this progressed during each pregnancy but did not require pacing. In patients paced before pregnancy, there were no complications as a result of the pacemaker, but maternal complications were seen in patients with underlying structural heart disease. CONCLUSIONS: Atrioventricular block in pregnancy is progressive; pacing is not always required but all patients should be closely monitored during and after pregnancy. In patients paced before pregnancy, pacing is well tolerated.