The researchers screened the DNA of 26,000 people - 13,000 early heart attack patients and an equal number of healthy "controls".
They compared the results, looking for single-letter differences in the genetic code known as single-nucleotide polymorphisms (SNPs).
In nine regions of the genome, the complete set of chemical sequences written into DNA, these SNPs were found to be significantly associated with early heart attacks.
Patients with the most risk-associated variants were more than twice as likely to suffer an early heart attack as those with the fewest.
Professor Peter Weissberg, medical director at the British Heart Foundation, said: "These studies demonstrate the power of big international collaborations to unearth new clues on the causes of heart attacks.
"Our scientists are making excellent progress in this field but genetic testing to predict heart attack risk is still a long way off.
"Vital research is now trying to get to grips with how and why these genetic traits increase heart attack risk and whether new treatments can be devised to counteract them."
Early heart attacks run in families and can strike men under 50 and women under 60.
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