How Did a Heart Drug With So Much Promise Fall So Flat?

Until last Friday, cardiologists thought they were on the verge of a new frontier in treating heart disease.

Three companies were conducting large clinical trials on experimental drugs that slash levels of a blood protein, Lp(a), thought to cause heart attacks and stroke. Doctors were eagerly awaiting the results, hoping the drug could be as important as a statin.

When Novartis, the first company to complete its trial, announced its results, late Friday afternoon, after the markets closed, cardiologists were shocked. The drug could lower Lp(a) levels by 80 percent, but it did not prevent heart attacks and strokes. It had failed.

“There’s something we don’t understand here,” said Dr. John Alexander, a cardiologist at Duke.

Cardiologists regularly see patients who have had heart attacks even though their cholesterol and blood pressure levels are low. They do not have diabetes or obesity, and they do not smoke, either. All too often, though, they have high levels of Lp(a).

About 20 percent of Americans have elevated levels; people with the highest levels of the protein can have double or triple the risk of a heart attack.

So there was no question that Lp(a) was important. A drug to lower the level of the protein, cardiologists hoped, could provide a way for these patients to protect themselves.