A Brazilian scientist reported similar findings in a 2004 issue of the institute's journal, he said, adding, "there are two main questions: Is this a true relationship, and if true, what are the underlying mechanisms?"
Madjid and colleagues have published a series of studies showing that influenza infection can cause inflammation in the cardiovascular system, which might cause acute effects such as heart attack.
On the other hand, this study suggests a long-term effect whose mechanism is not clear, he said.
"Potential mechanisms could include an uncontrolled immune response, inflammatory response, change in chronic risk factors, socio-economical effects, and most likely a combination of these," he said.
John Barry, author of The Great Influenza: The Epic Story of the Deadliest Plague in History, said the study is additional confirmation of the virulence of the 1918 flu.
"The 1918 virus was very nasty," he said. "And novel H1N1, though mild in the overwhelming majority of cases, seems to be creating similar problems, though fortunately only in very few instances."
In the study, Finch and colleagues found that men and women born in the first quarter of 1919 -- those whose mothers were pregnant with them during the peak of the pandemic -- reported a 10.9 percent excess in heart disease later in life.
Most of the increase was accounted for by a 25.4 percent excess of ischemic disease, also known as coronary artery disease.
There was no significant excess of hypertensive or rheumatic disease, the researchers found.
But the differences were driven almost entirely by disease among men, the researchers said.
This article was developed in collaboration with ABC news.