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Latest research finds link that may explain what really triggers them

Photo by Darlene Antoine.

Researchers at the University of Ottawa Heart Institute have made a major breakthrough in the study of heart attacks.

The research team, led by Dr. Alexandre Stewart, has found a link between the protein PCSK9 and the onset of heart attacks. The protein had previously been associated with high levels of LDL cholesterol. LDL cholesterol is thought to contribute to the blockage of arteries through plaque formation, leading to heart disease and eventually heart attacks.

“We’ve known for a number of years now that mutations that inactivate this protein and prevent it from circulating in the blood are associated with reduced LDL cholesterol,” said Stewart, the principal investigator in the Ruddy Canadian Cardiovascular Genetics Centre, “but they also associate with a disproportionate reduction in the risk of heart attacks.”

The researchers questioned whether PCSK9 had a more direct link to the onset of heart attacks. They tested blood samples from patients participating in the Ottawa Heart Genomics Study. Stewart’s team found elevated levels of the protein in people who were having acute heart attacks.

“People who were having an acute heart attack had higher levels than people who had heart disease but hadn’t had a heart attack, or who had had a heart attack and gotten better,” he explained.

They then tested the blood samples of patients from Emory University in Atlanta, Ga., where they yielded the same results.

According to the Heart Institute, previous studies have shown that people with naturally lower levels of the protein have a significantly reduced risk of heart attacks—up to 90 per cent.

The Heart and Stroke Foundation estimates that there are 70,000 heart attacks in Canada every year, and the number of heart attack-related hospitalizations has grown steadily over the last decade. Statistics Canada reported that nearly 16,000 Canadians die of a heart attack each year.

Pharmaceutical companies have already invested in developing cholesterol-lowering drugs that block PCSK9.

“The potential market is estimated to be in the billions of dollars because they lower cholesterol in a manner that is independent of the widely prescribed statin drugs,” the Heart Institute said in a press release.

However, the researchers had difficulty getting their work published because it challenged previously held assumptions about PCSK9 and its association with cholesterol. They haven’t yet determined any causal relationship between the protein and heart attacks. “I don’t think we fully understand how this protein contributed to the risk of heart attacks,” said Stewart.

“People were sort of reticent to put out something that’s not entirely dogmatic.”

After two years, the peer-reviewed science journal PLOS One published their report Sept. 2.