Researchers say the findings do not mean that constipation, per se, explains the extra risk.
In fact, when the researchers accounted for those and other factors, the link between constipation and heart disease largely disappeared.
"We cannot make definitive recommendations based on this study," lead researcher Dr Elena Salmoirago-Blotcher said. "We only suggest that constipation may be a helpful tool to identify women who may have several risk factors for cardiovascular disease and consequently be at increased cardiovascular risk," said Salmoirago-Blotcher, a cardiologist at the University of Massachusetts Medical School in Worcester.
However, she said, all postmenopausal women should be evaluated for heart disease and stroke risk factors, like high blood pressure and high cholesterol.
The findings, which appear in the American Journal of Medicine, are based on 73,000 postmenopausal US women, followed for six to 10 years.
At the outset, the women reported on their health and lifestyle habits, including whether they'd had constipation problems over the past month.
Overall, 35% had constipation. And over the following years, they were more likely than other women to develop clogged arteries, have a heart attack or stroke, or die of heart disease.
Among women with severe constipation - meaning it disrupted their normal daily routine - just under 2% suffered a cardiovascular event each year of the follow-up.
That compared with just under 1% of women who had regular bowel movements at the outset. Meanwhile, women with mild to moderate constipation problems fell somewhere in between.
Severe constipation only clear link
But the link largely disappeared once the researchers accounted for a range of other factors -- including age, weight, diet, exercise and traditional heart risk factors like high blood pressure, diabetes and high cholesterol.
In the end, only severe constipation remained linked to heart trouble.
But it's hard to draw conclusions from that, according to Salmoirago-Blotcher.
For one, it's not possible to account for all the factors that might explain a link between constipation and cardiovascular disease. And only a small number of women in the study - 1.6% of the total group - reported severe constipation.
More studies are needed to confirm the findings, Salmoirago-Blotcher said, and to see whether they hold true for men and younger adults too.
For now, she suggested that women be aware that constipation may act as a marker for heart risks. And they might want to consider lifestyle changes to manage the problem, rather than relying on laxatives, Salmoirago-Blotcher said. - (Amy Norton/Reuters Health, June 2011)