Both drugs lower levels of LDL cholesterol -- the bad cholesterol that can cause a build-up of blood-blocking plaque inside the arteries. Although Crestor caused a bigger drop in LDL cholesterol, the drugs tied when it came to reducing plaque.
"The good thing is that these are both effective drugs," said Stephen Nicholls, clinical director of the Cleveland Clinic Center for Cardiovascular Diagnostics and Prevention and lead author of the study published today in the New England Journal of Medicine.
Nicholls and his team studied more than 1,000 patients taking a daily dose of Lipitor (80 milligrams) or Crestor (40 milligrams). They used intravascular ultrasound to measure plaque inside patients' coronary arteries -- the vessels that supply oxygen-rich blood to the heart. And after two years, two-thirds of patients taking either drug had significantly less plaque.
"The takeaway message is that intensive treatment with cholesterol-lowering drugs is very successful at reducing coronary artery disease," said Dr. Aaron Kesselheim, assistant professor of medicine at Harvard Medical School, who was not involved in the study. "And there doesn't appear to be a substantial difference between the two drugs."
Because they are patented name brand drugs, Lipitor and Crestor can cost patients $160 per month. But the patent on Lipitor expires Nov. 30, opening the door for cheaper generic versions.
"We know from other research that lowering drug costs helps improve patient adherence," said Kesselheim, explaining that patients are more likely to fill their prescriptions when they can afford them. "Anything that helps patients stick to their prescription treatment plans is a good thing."
Using data from 2005 to 2008, the U.S. Centers for Disease Control and Prevention estimated that 25 percent of adults over age 45 used statins -- up from 2 percent in the mid-1990s. And between 1999 and 2007, deaths associated with heart disease declined by 28 percent.
Now even more people will have access to high-potency statins, as generic versions of Lipitor could cost 80 percent less. The cost of name brand Lipitor could also fall with the new competition.
"Generics will facilitate access to statins," said Nicholls. "And in light of the overwhelming body of evidence that statins are good medications, increased access is a positive outcome."
The patent on Crestor doesn't expire until 2016. But because its plaque-battling effects are on par with Lipitor's, some patients could make the switch.
"Lipitor and Crestor are both excellent, very potent statins," said Dr. Patrick McBride, professor of medicine and assistant director of preventive cardiology at the University of Wisconsin.
Although Crestor can lead to even lower LDL cholesterol levels, cost could tip the scale in favor of generic Lipitor.
"Price is going to be the issue," said McBride. "If it's $100 versus $5-to-$30, it's a no brainer. It would be a fairly rare patient that would need Crestor for its modest additional benefits."
Pfizer, the drug company that makes Lipitor, has reportedly offered large discounts to pharmacy benefit managers that block the use of generic versions of Lipitor, the New York Times reported Monday. Benefit managers serve as middlemen between drug companies and health insurance providers.
According to the Times, the co-pay for a 30-day supply of Lipitor will drop to $10 -- the same co-pay as generic versions.
"From a patient perspective, if the copay is the same because the manufacturer is giving a large discount then it's not a major concern," said McBride. "But if the cost of the plan goes up, that's a problem."
But the plan has some doctors crying foul.
"I'm not a pharmacy benefit manager, but it seems to me like it's a bare attempt to maintain some price elevation, some revenue flow from Lipitor sales for as long as possible," said Kesselheim, adding that generic statins are as effective as the brand name drugs. "Certainly there isn't any public health reason that pharmacy benefit managers should stick with brand name Lipitor."
In 2010, Lipitor earned Pfizer more than $5.3 billion in U.S. sales.
ABC News' Kim Carollo contributed to this report.