CHICAGO — The high cardiac event rate in women with long QT syndrome drops dramatically post menopause, according to a registry analysis.
This finding suggests that estrogen is a major contributor to arrhythmic events in women with long QT syndrome (LQTS), Jehu S. Mathew reported at the annual meeting of the American College of Cardiology.
If this indeed proves to be the case, the clinical implications could be profound. Planned future observational studies will look at LQTS patients who are on antiestrogen therapy—tamoxifen or aromatase inhibitors—for prevention of breast cancer. If their cardiac event rate turns out to be substantially lower than expected, it could open the door to a whole new form of cardiovascular preventive therapy in the extremely high-risk population of women with heritable LQTS, added Mr. Mathew, a fourth-year medical student at the University of Rochester (N.Y.), in an interview.
“The potential impact of those therapies on women with long QT syndrome is astounding if estrogens are actually implicated in their cardiac event risk,” he observed.
Mr. Mathew reported on 1,624 women aged 20–70 years who were enrolled in the International Long QT Syndrome Registry, including 560 who were postmenopausal. The risk of the combined end point of syncope, LQTS-related sudden death, or aborted cardiac arrest was 94% lower in the postmenopausal group.
The impact of menopause was particularly striking in women with the LQT2 genotype. Their annual combined event rate was 11.86/year before menopause and 1.91/year after menopause.
Among women with a QTc interval of 500 msec or more, the event rate was 9.68/year before menopause and 2.35/year afterward. And among women with a history of syncope before age 20, the event rate was 8.21/year prior to menopause, compared with 2.26/year postmenopause.
The genesis for this study examining the influence of menopause on cardiac events in LQTS was prior work establishing that females have a substantially higher cardiac event rate than have males with LQTS and that women with LQTS have a higher event rate during the first 9 months post partum—a period of hormonal flux—than they do during pregnancy.