"It might be a lifetime effect," said one study leader, Dr. Chris Packard of the University of Glasgow in Scotland.
Not only did original benefits of statins continue into late life, but researchers were surprised to see new ones become evident over time, he said.
The results are from the West of Scotland Coronary Prevention Trial, the first study ever to show that statins could prevent heart problems in people who had not yet developed clogged arteries but had high LDL, the bad type of cholesterol.
The watershed trial led to these drugs — sold as Lipitor, Crestor, Zocor and now in generic form — becoming a mainstay of treatment and one of the most prescribed medicines around the world.
The long-term results were discussed at an American Heart Association conference that ends Wednesday in Chicago.
The study, which started in 1989, involved about 6,600 Scottish men, ages 45 to 64, with high LDL — around 190, on average. Half were given the statin Pravachol and the rest, dummy pills. Five years later, there were 35 per cent fewer heart-related deaths and also fewer heart attacks in the statin group.
Once the study ended, the men went back to their regular doctors, and about one-third of both groups kept or started taking a statin. This means any differences seen years later probably is due to whether they took statins during the five-year study, Packard explained.
Scotland has national health care and good electronic medical records, so researchers were able to document what happened to more than 90 per cent of the men.
Twenty year after the study began, the risk of heart-related deaths was 27 per cent lower among the men who took Pravachol for those first five years rather than dummy pills.
The chance of dying from any cause was 13 per cent lower in the statin group at the 20-year mark, a benefit not seen earlier on.
"The big surprise" was a 31 per cent lower risk of heart failure in the group initially assigned to take the statin, Packard said. Heart failure occurs when a heart damaged from a heart attack or other cause gradually weakens over time and can't pump blood effectively.
Doctors have long suspected that the way statins work gives benefits beyond lowering cholesterol, and the heart failure result supports that theory, Packard said.
"This is another stone in the foundation supporting the value of preventive cardiology," said Dr. Sidney C. Smith Jr., a former Heart Association president from the University of North Carolina at Chapel Hill. Other factors might have played some role in how these men fared, but "nevertheless, a moderate-dose statin taken for primary prevention shows long-term benefit."
Cholesterol info: http://tinyurl.com/2dtc5vy
Heart facts: http://circ.ahajournals.org/content/127/1/e6
Marilynn Marchione can be followed at http://twitter.com/MMarchioneAP