Heavy drinking causes high blood pressure, stiff arteries and rigid heart muscles in men and enlarged hearts in women, boosting their risk of having heart attacks and strokes, researchers said.
They defined heavy drinking as more than 21 drinks a week for men and more than 14 per week for women.
"We definitely see quite a deleterious effect," said Dr. Azra Mahmud of St. James Hospital in Dublin, who presented her findings Wednesday at a meeting of the American Society of Hypertension in New Orleans.
"The most worrisome aspect is in women. It has a direct toxic effect," Mahmud said in a telephone interview. "Basically, women are not able to cope with high alcohol consumption. It is going directly to the heart and damaging it."
Once a heart becomes enlarged — a sign it has been overtaxed — it is difficult to reverse. Mahmud said prior studies have suggested that people with enlarged hearts are five to six times more likely to have heart attacks.
Moderate drinking has been shown in many studies to have heart benefits. But heavy drinking counteracts these benefits and can cause serious harm, she said.
In her study, Mahmud and colleagues looked at whether high alcohol consumption resulted in structural changes in the heart and arteries of people already at risk for high blood pressure.
Mahmud studied 200 men and women with an average age of 46 who were referred to her hypertension clinic but were not being treated for high blood pressure.
People in the study were put into three categories: nondrinkers, moderate drinkers (fewer than 21 drinks a week for men and fewer than 14 a week for women), and heavy drinkers (more than 21 drinks a week for men and more than 14 weekly for women).
About 20 percent of the women fell into the heavy drinker category and nearly 40 percent of the men were heavy drinkers, she said.
The researchers measured the heart muscle and assessed stiffness of arteries and blood pressure inside the aorta.
They found men who were the heaviest drinkers were the most likely to have high blood pressure and stiffening of the arteries and heart muscle. Women who were the heaviest drinkers were most likely to have enlarged hearts.
Mahmud said heavy drinking seemed to accelerate the effects of high blood pressure in men, and cause a direct toxic effect to heart tissue in women. The findings were above what would be expected for people of the same age with high blood pressure.
Heart disease is the No. 1 killer globally. According to the World Health Organization, heart disease killed 17.5 million people in 2005, and that number is expected to rise to nearly 20 million by 2015.