Washington ? Tens of thousands of Americans face the type of heart valve replacement that Sen. Bob Graham underwent last week, open-heart surgery that is likely to increase dramatically as the population ages.

But what if a simple pill could slow the rusting of the aortic heart valve and let patients postpone, maybe even avoid, the surgery that is today’s only fix?

Scientists have uncovered tantalizing evidence that statins, those pills so popular to lower cholesterol, might do just that — and not through any cholesterol effect, but by a completely different action that suggests even patients with low cholesterol might benefit.

The aortic valve shunts oxygen-rich blood from the heart’s main pumping chamber to the rest of the body. It looks something like a rounded tulip, with three leaflets that open and close with each heartbeat.

But it can essentially start to rust shut and cause the heart to pump harder and harder to force blood through the narrowed opening. Eventually, patients with this “aortic stenosis” require open-heart surgery to replace the faulty valve or face life-threatening heart damage.

Aging is the biggest culprit, as with Graham, the 66-year-old Florida senator and possible Democratic presidential candidate whose aortic valve was replaced last week. Just as older people’s arteries harden, something sometimes scars the aortic valve’s tender leaflets. Calcium deposits build amid the leaflets, further narrowing and stiffening the opening.

Five in 10,000 Americans have significant aortic stenosis, and more than 20,000 aortic valves are replaced each year.

It’s highly successful surgery; even 90-year-olds can experience huge relief. But it’s a painful operation, with a 4 percent risk of death, one that will show dramatic increases as the baby boom generation ages. And while some patients qualify for biological replacements like pig or cow valves, many receive a mechanical heart valve that requires taking blood-thinners for the rest of their lives.

Hence the excitement about a possible pill.

Scientists at the Mayo Clinic tracked 156 people with aortic stenosis, including 38 who took statins, cholesterol-lowering drugs sold under such brand names as Lipitor and Pravachol. Initially, the researchers were disappointed: Patients’ cholesterol levels had no bearing on how quickly their aortic stenosis worsened.

Yet in almost four years, the statin users were half as likely to see their valves worsen. Other small studies have suggested a similar effect.

Within a year, Mayo hopes to begin a 1,000-patient experiment giving either statins or dummy pills to people whose aortic valves are going bad, in hopes of proving if the pills truly help.