The findings are provocative, but need further validation from larger studies of both men and women, said two outside experts who reviewed the study for ABCNews.com. "This is an intriguing analysis," said Dr. Mark Einstein, head of the HPV Vaccine Clinic at Montefiore Medical Center in the Bronx, N.Y. "HPV is related to cancers -- but might be relevant in other diseases as well." He agreed with the study authors that people who test positive for HPV may have other risk factors for cardiovascular disease, like smoking. Einstein called it "too early to say" if HPV vaccination could protect the heart or influence more parents to have their children vaccinated.
Dr. Sharonne N. Hayes, director of the Mayo Clinic Women's Heart Clinic in Rochester, Minn., said the study deserved attention because it raised "important new biologically plausible connections between an infectious agent and coronary heart disease." However, Hayes tempered her enthusiasm by pointing out that the study doesn't rule out HPV infection as some kind of "intermediate marker" for cardiovascular disease when the "true risk" might come from an unidentified or unappreciated factor. Also, she said, there's a precedent for infectious agents that initially appeared related to cardiovascular disease risk not panning out when subjected to further scrutiny.
Dr. Diane Harper, director of the Gynecologic Cancer Prevention Research Group at the University of Missouri-Kansas City, offered unbridled criticism for the study, calling the association between HPV and atherosclerosis "biologically implausible."
"This is a classic study of correlation without causation," she told ABCNews.com. "It is unfortunate that it is being published in this form, as there are many assumptions that are incorrectly understood by these authors that make the likelihood of genital HPV infection a causative factor for CVD unlikely." HPV cannot damage the cells lining blood vessels, said Harper, a professor of obstetrics and gynecology as well as community and family medicine. HPV proteins only damage the p53 gene within cells that HPV directly infects, she said. Finally, she said: "There is no support for the statement that HPV vaccination may reduce CVD later in women's lives."
The study authors provided several caveats. Because women took their own vaginal swabs, HPV might have been under-recognized and the HPV-heart disease link underestimated, they said. Also, because the women in the study group self-reported heart attacks and strokes, the data might not fully reflect their cardiovascular problems.
Two HPV vaccines currently are on the market. Merck's Gardasil was designed to protect against two cancer-causing strains, HPV 16 and HPV 18, and two strains associated with genital warts, HPV 6 and HPV 11. GlaxoSmithKline's Cervarix protects against the two most important cancer strains HPV 16 and HPV 18, but also offers protection against three other cancer-causing strains, HPV 31, HPV 33 and HPV 45. Fujise and Kuo suggested that it might be worth re-evaluating HPV vaccine clinical trial data for the cardiac health of vaccine recipients. They also floated the idea of launching a prospective study to determine whether HPV vaccinations reduce cardiovascular disease.