Doctors have already known that oral contraceptives increased blood pressure and the risk of blood clots in women who took them -- a risk that is even higher in women who smoke.
But researchers involved with the new study say the findings concerning the formation of cholesterol plaques within arteries is a new one.
"The implications could be that you have higher stroke or heart attack rate," said lead study investigator Dr. Ernst Rietzschel of Ghent University, who noted that he was "surprised" at the findings.
"What we knew was that there was a risk of forming clots from taking pill, but once you stopped you had no residual risk," he said. "Our data show that if you take the pill for a long time you have accumulation of damage that gives you risk even after stopping."
Some physicians not involved with the research agreed that the results are intriguing.
"I think this is sort of a wake-up call for women and their physicians," said Dr. Jennifer Mieres, associate professor of medicine and director of nuclear cardiology at the New York University School of Medicine.
"It is a staggering statistic that there is a 20 to 30 percent increased risk in plaque formation in women who had used the pill for a decade, which becomes evident at a relatively young age," said Dr. Suzanne Steinbaum, director of Women and Heart Disease at the Lenox Hill Hospital's Heart and Vascular Institute in New York, N.Y.
"Certainly, like hormone replacement therapy recommendations are qualified in certain patients who are at risk for breast cancer, the recommendation for using the pill might need to be changed in those patients who are at risk for heart disease, and perhaps they should use another form of birth control," she said
However, not all heart physicians agreed that the findings broke new ground.
"If the author says it's the first shown cardio risk after discontinuation, I don't think that's true," said Dr. Camelia Davtyan, assistant professor of general internal medicine and health services research at the David Geffen School of Medicine at UCLA. Davtyan also cited the WISE study, which appeared to reach an entirely opposite conclusion.
Some other doctors were also hesitant to accept the findings as legitimate.
"It is new, unique data, and it definitely flies in the face of what we've been telling women based on past data," said Dr. Sharonne Hayes, director of the Women's Heart Clinic at Mayo Clinic in Rochester, Minn.
"It is a bit weak and needs to be replicated prospectively, or at least in other populations, since all -- and I mean decades of observational study -- say there is no increased risk of [heart-related] events with past use of [oral contraceptives]."
"Interpreting cross-sectional studies such as this one can be very complicated," said Dr. David Herrington, professor of medicine and cardiology at the Wake Forest University School of Medicine in Winston-Salem, N.C.
"These data are provocative and need to be confirmed or refuted in other cohorts, prospective data and clinical trials," he continued. "In isolation, these data do not provide enough evidence to make a general statement about the long term vascular effects of [oral contraceptive] use."
Most doctors -- Rietzschel included -- agreed women on the pill should not panic, as more data is needed before doctors can make recommendations based on this new evidence.