According to researchers in the U.S. older couples who argue and row harm their hearts.
The researchers say the fighting results in artery disease both for wives and husbands.
It seems hardening of the coronary arteries is more likely in wives when they and their husbands express hostility during marital disagreements, and more common in husbands when either they or their wives act in a controlling manner.
The study by Professor Tim Smith and other psychologists from the University of Utah looked at 150 healthy, older, married couples, mostly in their 60s.
Professor Smith says they found that the levels of dominance or control in women or their husbands were not related to women's heart health, but women who are hostile are more likely to have atherosclerosis, especially if their husbands are hostile too.
He says in men, the hostility either their own or their wives hostility during the interaction also wasn't related to atherosclerosis, but their dominance or controlling behavior - or their wives dominance - was related to atherosclerosis in husbands.
Smith suggests that a poor or low-quality relationship, is a risk factor for cardiovascular disease.
The study began in 2002 and ended in 2005 and involved 150 married couples with at least one member between 60 and 70 years of age and the other one no more than five years older or younger.
The couples were recruited through newspaper advertisements and a polling firm and had no history of cardiovascular disease and were not taking medicine for it.
Each husband and wife was paid $150 to participate, and also received free of charge a $300 CT scan to look for calcification in their coronary arteries - the arteries that supply the heart muscle and that can cause a heart attack when clogged.
Smith says that in otherwise healthy people, calcification represents hardening and narrowing of the arteries that puts them at risk for later heart attack.
Each couple were instructed to pick a topic that was the subject of disagreements in their marriage, then, while sitting in comfortable chairs and facing each other across a table, they discussed the chosen topic for six minutes while they were videotaped.
Psychology graduate students coded the videotaped conversations so that "each comment that reflected a complete thought" was given a code indicating the extent to which it was friendly versus hostile, and submissive versus dominant or controlling.
According to Smith some of the marital discussions were calm and peaceful, but in some cases, the couples were so hostile, that the observers referred them to marriage counseling.
The researchers made the assumption that a couple's behavior during the discussion reflected their long-term pattern of behavior at home, if somewhat moderated.
Two days after their discussion, each couple underwent a CT scan of the chest at the University of Utah's Center for Advanced Medical Technologies to check each person's level of coronary artery calcification.