The study of 1,900 heart attack victims found that those who drank the most tea before their heart attacks - about 19 cups a week - were 44 percent less likely than nondrinkers to die in the three to four years afterward.
Moderate drinkers, or those who had fewer than 14 cups, had a 28 percent lower death rate. The study looked at deaths from all causes, not just heart disease.
"I have to say that the magnitude of the association we found between tea drinking and mortality and people who survive a heart attack was pretty dramatic, certainly more so than I think I would have expected," said Dr. Kenneth Mukamal, assistant professor of medicine at Harvard Medical School.
The study was published in Tuesday's issue of the American Heart Association journal Circulation.
Several studies have found that regular tea drinkers seem to have a lower risk of heart attacks, though it remains unclear why.
Researchers involved in the latest study suspect the findings are linked to flavonoids, antioxidants found naturally in various foods derived from plants. Tea is a major source of flavonoids in American diets.
"We found that tea drinkers generally had lower death rates regardless of age, gender, smoking status, obesity, hypertension, diabetes or previous heart attack," Mukamal said.
Alice H. Lichtenstein, a nutrition professor at Tufts University, said more research must be done before a firm relationship is established between tea and heart health. She said there might be other aspects of the participants' diets that could account for the results.
The researchers acknowledged that more study is needed.