Using modified magnetic resonance imaging (MRI) techniques, researchers at Johns Hopkins have been able to detect the early benefits of a cholesterol-lowering medication much sooner than before.
The researchers applied MRI to measure the success of simvastatin (Zocor), a widely used form of so-called statin therapy, in reducing plaque formation in patients with hardened and clogged arteries, or atherosclerosis. Reductions in plaque levels were detected within six months after therapy began. Traditionally, MRI has been unable to show results until one or two years after the onset of treatment.
The Hopkins findings, published in the journal Circulation online Oct. 11, should make it easier for physicians to monitor how well initial cholesterol-lowering therapy works for patients, especially those with advanced-stage cardiovascular disease in need of quick results.
The research also linked the early benefits of statins to their lipid-lowering actions, not to anti-inflammatory properties as some earlier studies suggested.
"Our study increases the likelihood that MRI could eventually be used as a predictive technology for determining which patients should be placed on statin therapy for atherosclerosis," said the study's lead author and cardiologist João Lima, M.D., associate professor of medicine and radiology at The Johns Hopkins University School of Medicine.
"Heart disease, especially atherosclerosis, is still the leading cause of death in the United States," added Lima. "While it has been proven that patients can benefit from even a short period of statin therapy, as early as 16 weeks, our abilities to harness modern technology for monitoring this condition - and tracking the effectiveness of our treatments - have not kept pace until now."
Cholesterol-lowering medications, which decrease lipid/fat levels in the blood, have been shown to reduce plaque formation by as much 30 percent to 40 percent, and death rates by as much as 30 percent. Increased plaque formation is part of atherosclerosis and consists of the buildup of fatty deposits - hardened by calcium particles - along the inside walls of arteries, making work more difficult for the body's blood vessels.
During the three-year study, the Hopkins team measured plaque levels in 29 patients on a cholesterol-lowering therapy for significant atherosclerosis. Using a standard MRI scanner, the researchers took two measurements of plaque formation. First, they measured calcium deposits at the start of therapy, to establish a baseline reading of plaque volume. Then, after six months, they took another reading to gauge if statin therapy and reduced levels of blood lipids were correlated to reduced plaque volume.
To improve upon standard imaging techniques, the Hopkins team amplified picture taking by placing a series of extra coil rings around the chest of each patient (the main electromagnetic coil ring gives MRI its distinct doughnut shape). To amplify the signal, or image, received by MRI, each patient swallowed an antenna, inserted through the nose and placed in the esophagus, or "food pipe," next to and directly in line with many of the main arteries, including the biggest artery on top of the heart, the aorta. Six different MRI images, each taken at different angles, were required to calculate plaque volume levels in each artery.
After six months of therapy with simvastatin (20-80 mg daily), plaque volume levels were significantly reduced by 9 percent, on average, from 3.3 cm3 to 2.9 cm3. The researchers were unable to determine how these results improved long-term survivability for patients. However, it is already known that cholesterol-lowering therapies can benefit patient outcomes as early as 16 weeks after therapy starts.