Patients taking Pfizer Inc's cholesterol-lowering medicine Lipitor (atorvastatin calcium) experienced a significant reduction in the progression of atherosclerosis, or hardening of the arteries, compared to patients who received Pravachol (pravastatin), according to new data presented at the annual meeting of the American Heart Association.

The Reversing Atherosclerosis with Aggressive Lipid Lowering (REVERSAL) study followed 502 patients, who were diagnosed with coronary heart disease and required cardiac catheterization, or angiograms. Patients in the 18-month study had at least one arterial vessel with 20 percent or more constriction due to plaque build up. The study compared the effectiveness of Lipitor (80 mg/day) versus Pravachol (40 mg/day) in reducing plaque build-up. Lipitor-treated patients experienced a median 0.4 per cent reduction in total plaque volume, defined as all of the plaque present within a segment of a single artery-while patients who received Pravachol showed a significant increase in total plaque volume (2.7 per cent median).

"These results clearly show that aggressively lowering cholesterol levels with atorvastatin calcium stopped the progression of atherosclerosis," said Dr. Steve Nissen, medical director of the Cleveland Clinic Cardiovascular Coordinating Center and principal investigator of the REVERSAL study. "This study further demonstrates the benefits of aggressively managing cholesterol levels to reduce the risk of atherosclerosis."

Atherosclerosis, which is a leading cause of death from heart attack and stroke, occurs when there is a build-up of cholesterol-rich fatty areas called plaques in the arteries. The break-up and dispersal of these plaques can block the blood flow throughout the body, which can be fatal. It is estimated that atherosclerosis accounts for more than 75 per cent of all deaths from cardiovascular disease.

"The REVERSAL results reinforce the outstanding effectiveness of Lipitor in treating patients who have high cholesterol and signs of heart disease," said Dr. Joseph Feczko, Pfizer's executive vice president of global research and development and president of worldwide development. "These results provide important new information that will help physicians in treating the millions of patients who suffer from this devastating disease."

The average LDL-C or "bad" cholesterol levels of patients at the beginning of the study was 150 mg/dl-while accepted guidelines call for levels of <100 mg/dl. Prior to enrollment, study participants were not taking medication to treat their high cholesterol. Additionally, patients in the study had other heart disease risk factors, which may have included a history of diabetes, hypertension or a previous heart attack. Ninety-seven per cent of patients taking Lipitor reached their recommended LDL cholesterol goal levels compared to 67 per cent of Pravachol patients. The rates of elevated liver enzymes were low and similar in patients taking Lipitor 80 mg and Pravachol 40 mg. There were no reported cases of rare muscle problems associated with muscle breakdown.

Researchers used technology known as intravascular ultrasound, which is a three-dimensional method of imaging, to measure the total plaque volume in a cross-section of the artery wall over the length of the vessel. The total plaque volume of the patients was measured at the beginning and at the conclusion of the study.

Since the introduction of Lipitor seven years ago, its safety and effectiveness have been supported through an extensive clinical trial program, the Atorvastatin Landmark Program, with more than 400 ongoing and completed trials involving more than 80,000 patients. Lipitor is the leading cholesterol-lowering therapy in the world with more than 62 million patient years of experience.

Lipitor (atorvastatin calcium) is a prescription drug used with diet to lower cholesterol. Lipitor is not for everyone, including those with liver disease or possible liver problems, women who are nursing, pregnant, or may become pregnant. Lipitor is not indicated for the prevention of heart disease or heart attacks.

Patients who take Lipitor should tell their doctor about any unusual muscle pain or weakness. This could be a sign of serious side effects. Patients should also inform their doctor about any medications they are currently taking to avoid possible serious drug interactions. Prescribing physicians may do simple blood tests to monitor liver function before and during drug treatment. The most commonly reported side effects are gas, constipation, stomach pain and indigestion. They are usually mild and tend to go away.