Enlarged hearts regress faster in elderly women than in men after aortic valve replacement

June 04, 2017

Women had a higher frequency of increased left ventricular mass before surgery than men. After treatment the prevalence of left ventricular hypertrophy fell more in women (86 percent to 45 percent) than in men (56 percent to 36 percent). Shortly after surgery, the left ventricle decreased in size at the end of heart relaxation in both genders but more in women. Women, but not men, had a decrease in the ventricle's size at the end of contraction. Biopsies revealed higher expression of the collagen I and III and metalloproteinase-2 and -3 genes, well in agreement with higher levels of fibrous tissues in the hearts of men compared to women. Women did not show increased fibrous tissue gene expression. In a separate experiment in rats, cardiac fibroblasts (the cells that form fibrous tissue) from male and female animals were treated with E2, a female sex hormone.  Male cells showed increased collagen I and III expression while collagen expression decreased in female cells. More women than men had thyroid disorders, 34 percent to 8 percent. The researchers cannot exclude that low thyroid levels may have contributed to impaired heart growth in women because the thyroid hormone is known to stimulate heart growth. The number of patients in the study is still small. However, the German team plans to increase numbers in a follow-up study and is collaborating with researchers conducting two larger trials to further investigate genetic mechanisms to explain their findings.

If confirmed, these results may lead to the development of strategies to slow the increase of cardiac fibrous tissue in both men and women with aortic stenosis. The findings might also provide at least one prognostic tool. Failure of a woman's enlarged heart to regress quickly after surgery could be an ominous sign.

"It is important to study gender differences in elderly patients," Regitz-Zagrosek said. "Many think that when people don't have sex hormones or have low levels, women and men are the same. This is untrue. To develop optimal treatment for both, we need studies that pre-specify gender differences as an endpoint and that have enough statistical power to look at the differences between women and men."

SOURCE American Heart Association