WASHINGTON — A new class of experimental medicines can dramatically lower cholesterol, raising hopes of a fresh option for people who can’t tolerate or don’t get enough help from Lipitor and other statin drugs that have been used for this for decades.

The first large studies of these drugs were presented at an American College of Cardiology conference in Washington over the weekend.

Several companies are developing these drugs, which are aimed at 70 million Americans and millions more worldwide who have high LDL or “bad” cholesterol, a major risk for heart disease.

Three studies of Amgen’s version of these drugs, called evolocumab, found it lowered LDL or “bad” cholesterol by 55 to 66 percent from baseline levels compared to others who took a fake drug, and by nearly that much when compared to Merck’s Zetia, another cholesterol medication.

As impressive as that is, it’s still just part of the picture. Doctors want evidence that the way these drugs lower cholesterol also will lead to fewer heart attacks and deaths, because that proof already exists for statins. New studies are under way to test this, but Amgen said it will seek approval for its drug this year based on cholesterol-lowering alone.