Danish researchers report that news in The Lancet.
Artery, Vein Clots
Heart attacks and most strokes are tied to blood clots -- but in arteries, not veins.
But the new Danish study suggests that when clots crop up in deep veins, they can follow years later in arteries, causing heart attacks and strokes.
The study included more than 205,000 Danish adults age 40 and older.
The group included almost 26,200 DVT patients, nearly 17,000 pulmonary embolism patients, and more than 163,000 people with no history of DVT or pulmonary embolism.
Participants were followed for up to 20 years. For DVT and pulmonary embolism patients, that period began when they left the hospital after DVT or pulmonary embolism treatment.
DVT and Heart Attack, Stroke
During the study, heart attacks and strokes were most common among the DVT and pulmonary embolism patients, particularly in the first year after having a DVT or pulmonary embolism.
Compared to people who had never had a DVT or pulmonary embolism, heart attack risk rose by 60% and stroke risk more than doubled in DVT patients in their first year after having a DVT.
By the same comparison, heart attacks were more than twice as common and strokes were almost three times as common in the year after pulmonary embolism.
Those risks eased over the years but remained about 20% to 40% higher than normal, report the researchers. They included Henrik Sorensen, DMSc, of Aarhus University Hospital.
The findings are "surprising," writes Gordon Lowe, MD, of Scotland's University of Glasgow, in a Lancet editorial.
Lowe notes that blood-thinning drugs are standard treatment after having a DVT, and those drugs should make heart attacks and clot-related strokes (the most common type of stroke) less likely.
Sorensen's team doesn't know how to connect the dots between DVT, pulmonary embolism, stroke, and heart attack.