By AMERICAN HEART ASSOCIATION NEWS

Coating heart stents with the erectile dysfunction drug Viagra, known by the generic name sildenafil, could one day reduce blood clots and re-narrowing of arteries, according to new research.

Stents prop open heart arteries to help restore blood flow to the heart, lowering the risk of a heart attack. Use of the small tube-shaped scaffolds is common, with more than 640,000 stent procedures in 2009.

But traditional bare metal stents can lead to restenosis — re-narrowing or blockage of a treated artery. Coating a stent with medicine can help prevent restenosis but may lead to blood clots near the stent.

In a series of laboratory and animal studies, researchers showed that sildenafil worked in two ways: It reduced blood platelet clumping by 30 percent in the lab, and in a rat study, it increased the action of an enzyme that prevents artery walls from thickening in response to an injury. Without sildenafil, the enzyme, called protein kinase G, would be less active, leading to more clumping of platelets and thickening of artery walls.

“This seems like a very interesting approach that could reduce both stent restenosis and stent thrombosis,” said Deepak L. Bhatt, M.D., executive director of interventional cardiovascular programs at Brigham and Women’s Hospital Heart & Vascular Center in Boston, who was not involved in the study.

“If validated in large, randomized human trials, this could be a major advance. But those large-scale trials would be necessary before getting too excited,” Bhatt said.

In addition to coating stents, the pill form of sildenafil may give patients another option, said lead study author Han-Mo Yang, M.D., Ph.D., an associate professor in the division of cardiology at Seoul National University Hospital in South Korea.

“If similar results are found in clinical trials, sildenafil could be an ideal drug for coating drug-eluting stents or to give orally after stent implantation,” Yang said in a news release. If found effective in preventing restenosis, “it could be used in the clinical setting right away because the drug is already used in the real world for other purposes,” he said.

Patients getting stents routinely take aspirin and other antiplatelet medications to prevent blood clots, although these also carry a higher risk of bleeding.

Sildenafil was originally developed as a high blood pressure drug, but researchers discovered one of its side effects was improving erectile dysfunction. It’s also used to treat pulmonary hypertension, a type of high blood pressure in the arteries that connect the heart to the lungs.

The study was presented Monday at the American Heart Association’s Basic Cardiovascular Sciences 2017 Scientific Sessions.