Any decision to pull the drug from the market in Europe would be a blow to Merck's reputation, although the commercial impact would be limited.
Tredaptive, designed to raise "good" HDL cholesterol, did not do a better job at preventing heart attacks, deaths or strokes than traditional statin drugs that lower "bad" LDL cholesterol in the trial involving more than 25,000 patients.
A spokesman for the European Medicines Agency said experts at the London-based organization were studying the latest data on the drug and would issue a statement before the end of the week.
Merck said it no longer planned to seek regulatory approval for the drug in the United States and recommended that doctors did not start new patients on Tredaptive in countries where it is already available.
Bernstein analyst Tim Anderson noted that Tredaptive sales in Europe and other non-U.S. markets were running at only around $50 million a year, compared to overall Merck revenue of $47 billion.
(Reporting by Ben Hirschler; editing by Chris Wickham)