Background: The influence of the physiological circulatory changes during pregnancy on hypertrophic cardiomyopathy (HCM) is unclear. There have been no comprehensive studies of pregnant women with HCM in the Japanese population.
Methods and results: A total of 27 pregnancies (23 women with HCM) were retrospectively reviewed. A total of 18 cardiovascular events occurred in 13 of the 27 pregnancies (48%), and 13 of these events (76%) were related to arrhythmia. The cardiovascular events tended to occur in the early stage of pregnancy (≈30 gestational weeks) or postpartum. The events related to arrhythmia mainly occurred in the early stage of pregnancy or at approximately 30 gestational weeks. Four pregnancies were terminated because of cardiovascular events. Cardiovascular events occurred in 8 of 9 pregnancies in women on medication before pregnancy (88%), 7 of 10 pregnancies with high CARPREG score (70%), and in 9 of 12 pregnancies with high ZAHARA score (75%).
Conclusions: Cardiovascular events occurred in more than half of the pregnant women complicated with HCM, and the arrhythmia is the most common cardiovascular event. Medication in the pre-pregnancy period, and CARPREG or ZAHARA score ≥1 were identified as risk factors of cardiac events during pregnancy or postpartum.