Cholesterol is essential to keep the body in working order. However, having high levels of “bad cholesterol,” called low-density lipoprotein (LDL), in the blood can cause fatty deposits to build up in the arteries. Eventually, this buildup results in the arteries narrowing and hardening (a condition called atherosclerosis), which leads to a greater risk of heart attack and stroke.

Statins are a commonly prescribed medicine that helps to lower harmful levels of LDL cholesterol to mitigate the risks of cardiovascular disease.

Types of statins approved for use in the United States include atorvastatin, fluvastatin, lovastatin, pravastatin, rosuvastatin, simvastatin, and pitavastatin. They all work in a similar way by blocking the enzyme in the liver – HMG-CoA reductase – that produces cholesterol.

Heart disease is the leading cause of death in the U.S. In 2013, almost 801,000 people in the country died from a stroke, heart disease, or other cardiovascular diseases.

Landmark studies exploring prevention of cardiovascular disease

Landmark studies have investigated the use of statins in secondary prevention of cardiovascular disease.

The Scandinavian Simvastatin Survival Study (4S) studied 4,444 people who had previously had a heart attack and high cholesterol. After a follow-up period of nearly 5.5 years, simvastatin was found to lower total cholesterol by 25 percent and LDL cholesterol by 35 percent. Few adverse effects were experienced.

In the placebo group, there were 256 deaths (12 percent) compared with 182 (8 percent) in the group taking simvastatin. Essentially, simvastatin reduced the risk of death by about one third. The 4S study concluded that “long-term simvastatin treatment is safe” and improved survival in people with cardiovascular disease.

The Cholesterol and Recurrent Events (CARE) trial studied 4,159 people with coronary heart disease and average cholesterol levels to examine the effect of lowering LDL levels on the occurrence of coronary events.

Reducing LDL cholesterol levels from average to low with pravastatin significantly reduced the number of recurring coronary events compared to the placebo group. During the 5-year follow-up, pravastatin lowered total cholesterol by 20 percent and LDL cholesterol by 28 percent.

Individuals treated with pravastatin were 24 percent less likely to die from cardiovascular heart disease or non-fatal heart attack and had a 31 percent decrease in risk of stroke. The CARE trial concluded that treatment with pravastatin reduces the burden of cardiovascular disease in individuals with a history of heart attack.

The Long-Term Intervention with Pravastatin in Ischemic Disease (LIPID) study investigated 9,014 people with a history of heart attack and a broad range of cholesterol levels. Researchers aimed to evaluate the effect of pravastatin on death from cardiovascular disease.

During the first 5 years of follow-up, pravastatin decreased total cholesterol by 18 percent and LDL cholesterol by 25 percent more than the placebo group. Individuals in the pravastatin group had a 24 percent reduced risk of death from coronary heart disease or non-fatal heart disease, were 29 percent less likely to have a heart attack, and received a 19 percent reduction in risk of stroke.

The LIPID study concluded that pravastatin is associated with a reduction in mortality from coronary heart disease and overall mortality in individuals who had previously had a heart attack.

Treatment guidelines to decrease high blood cholesterol

Trials have consistently demonstrated a clear correlation between reducing LDL cholesterol with statins and a decrease in cardiovascular risk. So why the controversy?

As the body of evidence evaluating statins has expanded, so too have the indications for the drug. Guidelines released in 2013 by the American College of Cardiology (ACC) and the American Heart Association (AHA) recommended that statin therapy might be beneficial for people in the following four groups:

• people with cardiovascular disease
• people who have high LDL cholesterol levels of 190 milligrams per deciliter or higher
• people aged 40 to 75 years with diabetes and LDL levels of 70-189 milligrams per deciliter
• people aged 40 to 75 years without diabetes, but with LDL cholesterol levels of 70-189 milligrams per deciliter and a predicted 10-year risk of cardiovascular disease of 7.5 percent or higher