Thyrotoxicosis and heart failure that complicate pregnancy

Objective: When untreated, Graves' thyrotoxicosis has profound cardiovascular effects, although it rarely causes heart failure in otherwise healthy patients. Preliminary observations suggest that pregnant women are the exception. To further elucidate this association, we studied both immediate and long-term outcomes in women who had thyrotoxicosis and heart failure during pregnancy. Study design: We reviewed clinical outcomes of pregnant women with Graves' disease and heart failure at our institution from 1974 through 2001. Women with other underlying heart disease were excluded. A standardized antithyroid regimen and serial echocardiography and/or chest radiography were performed. Results: The 13 women with thyrotoxicosis and heart failure were either noncompliant with antithyroid therapy or had no medical care during pregnancy. Six women had heart failure before fetal viability; decompensation was precipitated by hemorrhage, sepsis, or both. The other 7 women were in the last trimester when heart failure developed; in 4 women, the heart failure was precipitated by severe preeclampsia-eclampsia and in 2 women was precipitated by sepsis. Overall, 11 of 13 women had an underlying obstetric event. In follow-up of 11 women from 2 to 25 years, resolution of cardiomyopathy was confirmed after successful treatment of thyrotoxicosis. Conclusion: Normal pregnancy mimics and amplifies some of the hyperdynamic cardiovascular changes that are caused by thyrotoxicosis. When they occur simultaneously, there is usually a compensated high-output state. In some women, however, common pregnancy complications that include hemorrhage with associated anemia, sepsis, and severe preeclampsia-eclampsia will precipitate heart failure. The immediate treatment of heart failure and the correction of precipitating pregnancy factors usually results in good outcome. Long-term follow-up confirmed that thyrotoxic cardiac dysfunction is reversible with successful antithyroid therapy.