ORLANDO — Pregnancy and postpartum are not especially high-risk periods for cardiac events in women with long QT syndrome, G. Michael Vincent, M.D., reported at the annual meeting of the American College of Cardiology.
Indeed, cardiac event rates—sudden death, syncope, and aborted cardiac arrest—are highest in women with long QT syndrome (LQTS) in the periods prior to first pregnancy and during the nonpregnant portion of the childbearing years, according to Dr. Vincent of LDS Hospital and the University of Utah, Salt Lake City.
These findings from a unique database housed at LDS Hospital are at odds with an earlier report by other investigators, who reported that the postpartum period in women with LQTS was associated with a 41-fold increased rate of cardiac events (Circulation 1998;97:451–6).
That report was based on data from nongenotyped probands in the International LQTS Registry. Probands are almost always the most symptomatic members of LQTS families, and they are not representative of the LQTS population as a whole, he argued.
In contrast, the 32-year-old LDS Hospital database contains 367 LQTS families whose pedigrees have been expanded to include 6,268 members. Most have been systematically screened for LQTS, and since 1992, many have been genotyped. This database thus includes unaffected family members, as well as others encompassing the full spectrum of the LQTS phenotype, rendering the Utah data singularly applicable to the broad population of LQTS women.
For this analysis Dr. Vincent reported on 255 women with 747 term pregnancies. They came from 120 LQTS families. The combined cardiac event rate during pregnancy was 3.1%.
The event rate in the postpartum period—defined as the 9 months after delivery—was 3.5%. In contrast, 23.9% of the women experienced a cardiac event while not pregnant but in their childbearing years, as defined by the interval from their first pregnancy to last postpartum period.
Prior to their first pregnancy, 23.5% of subjects experienced a cardiac event, as did 2.4% after their final postpartum period.
No sudden cardiac deaths occurred during pregnancy. There were four post partum: three among 46 women with the LQT2 genotype, compared with just one of 101 LQT1 women. Most cardiac events in LQT1 women occurred prior to the childbearing years.