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.