SACHA PFEIFFER, HOST:
What doctors hoped would be the next big breakthrough in preventing heart attacks and strokes has failed its first big test. NPR health correspondent Rob Stein has the story.
ROB STEIN, BYLINE: Lots of people who seem to do everything right - low cholesterol and blood pressure, healthy diet, regular exercise - still get blindsided by a heart attack or stroke. Dr. Steven Nissen is a cardiologist at the Cleveland Clinic.
STEVEN NISSEN: That sort of patient we see very frequently, and we were really doing our best to try to find a way to help those patients.
STEIN: So Nissen and his colleagues decided to test a new class of drugs designed to lower a cholesterol-carrying particle found in the blood known as lipoprotein(a). Cardiologists call it Lp(a) (ph). High levels have been linked to an increased risk for heart attacks and strokes.
NISSEN: About 20% of the global population have elevated levels, and that's really more than a billion people. So it's a common disorder.
STEIN: The researchers gave more than 8,000 volunteers who already had heart disease either a placebo or a drug called pelacarsen. The drug, developed by Novartis, did slash Lp(a), but after five years, that didn't protect the patients from heart attacks and strokes.
NISSEN: I was shocked. I had high hopes for success. Cardiovascular disease is still the leading cause of death in developed countries. And so we really were hoping to find additional therapies that would reduce risk. And everyone thought that lipoprotein(a) was the most promising - very disappointing, terribly disappointing for all the patients that we see.
STEIN: The findings, which were presented at an American Heart Association meeting in Chicago Saturday and published by the New England Journal of Medicine, stunned other experts as well. Many thought Lp(a) drugs could be the next big thing in heart disease, possibly as big as cholesterol-lowering statins, which revolutionized the prevention of heart disease. Dr. Harlan Krumholz is a Yale University cardiologist.
HARLAN KRUMHOLZ: I think it's a big deal because the expectation was so high that this would end up being positive. And so it was really jarring to see this.
STEIN: Krumholz and others are now scratching their heads about what went wrong. It could turn out that high Lp(a) doesn't really cause heart attacks and strokes, but merely signals something else is going on. But many experts still think Lp(a) is the culprit and point to other possible reasons the study failed.
Dr. Roger Blumenthal is a cardiologist at Johns Hopkins.
ROGER BLUMENTHAL: Maybe you need to treat longer. You may need to treat earlier before people have advanced hardening of the arteries.
STEIN: The experimental drugs may only help people with higher levels or who don't already have their cholesterol and blood pressure under control, or maybe there's something about pelacarsen that doesn't do the trick, but other drugs might work. Dr. Karol Watson, a UCLA cardiologist, says scientists will pick through the details for clues.
KAROL WATSON: We tested one drug in one population. There are different drugs, different mechanisms, etc. The take-home message is the story's not over. It's kind of just starting.
STEIN: The results of other big studies testing three other Lp(a)-lowering drugs are expected to become available over the next few years. Rob Stein, NPR News.
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