THURSDAY, April 28 (HealthDay News) -- Taking both Lipitor and the bone-strengthening drug Didronel reduces plaque buildup in the aorta better than Lipitor alone, a small Canadian study suggests.

While Lipitor is a statin that lowers cholesterol, Didronel (etidronate) belongs to a class of drugs called bisphosphonates, which are typically taken by people with osteoporosis.

"Calcified plaques in the abdominal aorta have been reported to be a risk factor for cardiovascular disease," said lead researcher Dr. Tetsuya Kawahara, from the University of Calgary in Alberta.

"Bisphosphonate plus statin combination therapy can be considered as the more effective therapeutic agents for atherosclerosis and cardiovascular disease than statin monotherapy in the near future," Kawahara said.

The results of the study were scheduled to be presented Thursday at the American Heart Association's Arteriosclerosis, Thrombosis and Vascular Biology 2011 Scientific Sessions in Chicago.

For the study, Kawahara's team randomly assigned 251 patients with high cholesterol to daily doses of Lipitor alone or in combination with Didronel.

After two years, the researchers had patients undergo an MRI to gauge the buildup of plaque in their aortas. The aorta is the large blood vessel that carries blood from the heart to other parts of the body.

The researchers found that patients in both groups had similar reductions in the wall thickness of the aorta in the chest.

However, in the part of the aorta that passes through the abdomen, those on combination therapy had a 12 percent reduction in aorta thickness, compared with a 1 percent reduction in those taking only Lipitor, Kawahara's group reported.

In addition, only 1 percent of those on combination therapy had a heart attack, cardiac bypass or died from heart problems, compared with 5 percent of those taking Lipitor alone. This difference was statistically significant, the researchers added.

While this combination of drugs might sound promising in further reducing the risks from heart disease, long-term use of bisphosphonates has been linked to a risk of atypical fractures of the thigh bone and also to an increased risk for stroke and irregular heartbeat in cancer patients.

Kawahara noted that the trial wasn't long enough to see if bisphosphonates had any of these effects. Moreover, not all bisphosphonates have the same effect on plaque buildup. Other commonly prescribed bisphosphonates include Fosamax (alendronate), Boniva (ibandronate) and Actonel (risedronate).

"Only etidronate and clodronate (Bonefos), which are first-generation bisphosphonates, might have this effect," Kawahara added. "So at this time, we cannot recommend that people take bisphosphonates solely for reduction of the atherosclerosis."

Dr. Gregg Fonarow, associate chief of cardiology at UCLA's David Geffen School of Medicine, said that "there is a biological link between bone and vascular calcification."

Bisphosphonates reduce bone resorption and fracture risk, but emerging new evidence suggested these drugs may have the potential to reduce the atherosclerotic process. Bisphosphonates have been shown to inhibit cholesterol production, inflammation and oxidative stress, he added.

"These preliminary findings, while intriguing, require replication in large-scale, prospective, randomized clinical trials," Fonarow said.

More information

For more information on atherosclerosis, visit the U.S. National Heart, Lung, and Blood Institute.