Marfan Syndrome
MFS is a heritable mutation in fibrillin-1 (FBN-1) affecting a number of organ systems including the predisposition to thoracic aortic aneurysms (TAA) and AAD. MFS affects approximately 1 in 5,000 people in the United States, and the highest association of AAD in pregnancy23,24. The increased risk of complications have been reported in numerous studies over the years with drastic consequences of AAD, but this information is debated to be skewed towards the complicated pregnancies24. In fact, the actual percentage risk of AAD in pregnancy with MFS is reported to be approximately 3—4.4%5,21,24.
If counselling is necessary for these patients, debate still exists on the nature of risk in MFS, with some suggestion that an aortic root below 40mm has a relatively low risk of 1%5. The first study to show this was Pyeritz et al. in 1981, showing a low risk of complications and death when analysing 26 women with MFS across 105 pregnancies; their one maternal death had previous severe cardiac comorbidities, and they reported pregnancy in MFS as relatively safe for women without comorbidities25. A study by Rossiter et al . of 45 pregnancies in MFS noted that aortic diameters <40mm in MFS tolerated pregnancy well, and AD occurred in 2 patients with preceeding aortic risk26. Conversely, guidelines have recommended that MFS patients should not become pregnant if their ascending aorta diameter is greater than 45mm, or with severe comorbidities or family history of sudden death5. Aortic root diameter is influenced by sex, age and body surface area; assigning an arbitrary value of 40mm and 45mm may not be representative of every patient27.
For MFS patients with an aortic root >40mm but <45mm, it is unclear how to accurately assess risk of AAD in pregnancy; a suggestion of risk estimates at 10% once >40mm22. Immer et al. recommended pre-pregnancy surgery with elective aortic root replacement in their study for those with aortic root dilatation >40mm28. Other studies have suggested intensive echocardiography monitoring every 4 to 8 weeks, with surgery considered in the event of rapid diameter growth. In one study, aortic diameter increased, on average, by 3mm during pregnancy and did not fully recover at 5-year follow up24. By this notion, multiple pregnancies become higher risk for women with MFS, and they remain at higher risk postpartum; it is not known how long for29. However, the growth rate was contested by two smaller studies, who found no difference in aortic root before and after pregnancy29. The jury on whether aortic root diameter changes during pregnancy is, as yet, undecided15.