Levels of the protein can be measured in the blood
A protein in the blood has been found to be associated with the same increased risk of heart disease as high blood pressure and cholesterol.
Analysis of data from 79,000 people showed the protein, known as Lp-PLA2, also boosts the risk of stroke and early death, the Lancet reports.
Drugs against the protein, which is involved in inflammation in blood vessels, are already being developed.
But it remains to be seen whether such treatments cut rates of heart disease.
The UK researchers who led the international study said Lp-PLA2 is carried in the blood alongside LDL or "bad" cholesterol.
Although smoking, diabetes, high blood pressure, and high levels of bad cholesterol are known to cause coronary heart disease, they do not entirely explain its high incidence in the population.
This has prompted researchers to look for other factors that put people at risk of heart attacks and strokes.
Drugs which block Lp-PLA2 are of interest to researchers because studies had shown this protein is present in high levels in people with damaged arteries.
In fact two large trials are being done with one particular drug in people who already have heart disease.
Yet the extent of the link between the protein and the risk of heart disease and stroke has not been clear.
The results, which came from studies in people with and without heart disease, showed that higher levels of the protein were associated with stroke and early death.
And when they looked at heart disease specifically, they found the magnitude of the increased risk was similar to that found with higher blood pressure or bad cholesterol.
Study leader Dr Alex Thompson, an epidemiologist at the University of Cambridge, said there was a lot of interest in whether measuring levels of inflammatory markers, such as Lp-PLA2, could predict heart disease risk.
"What we need to do now is look at the extent of the link specifically in people who don't have a history of heart disease."
He added that a large trial looking following up heart attacks and strokes in people who had their Lp-PLA2 levels closely monitored would help determine if the test is something doctors should be using.
Professor Peter Weissberg, medical director at the British Heart Foundation, said the research suggests that Lp-PLA2 has a "significant role" in the progression of heart disease.
"These findings should stimulate research to find drugs that may reduce the levels of Lp-PLA2.
"The acid test will then be to find out if such drugs reduce the risk of heart attacks and strokes in large clinical trials."