Aggressively lowering high cholesterol can cut the risk of heart attack or stroke by about a third among people with clogged arteries, a new study says.

The results support updated guidelines that call for cutting “bad” LDL cholesterol levels to less than 55 mg/dL among people with heart disease driven by clogged and hardened arteries, researchers said.

Using drugs to get cholesterol down to that level reduced the rate of heart emergencies by 33%, researchers reported Saturday at an American College of Cardiology meeting in New Orleans.

“Targeting an LDL-C level of less than 55 mg/dL leads to a significantly lower three-year risk of major cardiovascular events compared with the conventional target of 70 mg/dL, without compromising safety,” lead researcher Dr. Byeong-Keuk Kim said in a news release. He’s director of cardiac catheterization and intervention at Severance Hospital at Yonsei University in Seoul, South Korea.

Guidelines have lowered the recommended LDL levels for people with clogged arteries from less than 70 mg/dL to less than 55 mg/dL, but the evidence supporting this move has been scanty, researchers said.

For this new study, researchers recruited more than 3,000 people (average age: 64) at 17 hospitals and clinics in South Korea. All had atherosclerotic cardiovascular disease (ASCVD), a type of heart disease caused by plaque buildup on artery walls.

Half were assigned to the lower cholesterol target and half to the higher target. Doctors used increasing doses of statins, as well as other drugs like ezetimibe and PCSK9 inhibitors, to help patients reach their assigned level.

After three years, those assigned the lower target had achieved a median 56 mg/dL level, and those with the higher target a median 66 mg/dL level. (Median means half were higher; half, lower.)

The team then tracked the patients to see how many died from heart disease, suffered a heart attack or stroke, or were hospitalized for chest pain.

After three years, about 6.6% of people in the lower-target group died or had heart problems, compared with 9.7% of those at the higher target – a 33% reduced risk for those who more aggressively lowered their cholesterol.

This benefit was driven primarily by a reduction in heart attacks and procedures for chest pain, researchers said.

“The consistency across the overall population and key subgroups suggests that the benefit of targeting LDL-C lower than 55 mg/dL is broadly applicable across the spectrum of patients with ASCVD and is not limited to specific patient subsets,” Kim said.

Results also showed that aggressive cholesterol lowering did not result in any added risk for patients.

The study comes shortly after the American College of Cardiology and American Heart Association updated guidelines to suggest lifelong screening and treatment for elevated cholesterol, starting with testing in childhood and cholesterol-lowering drugs prescribed as early as a person’s 30s.

The results were also published online March 28 in The New England Journal of Medicine.