GRAND RAPIDS, MI – A study of 20 heart attack patients at Spectrum Health could ultimately lead to something long sought by cardiologists: A way to predict – and prevent – heart attacks.
The study by Dr. Ryan Madder found 19 of the 20 patients had a specific type of plaque blocking an artery – made up of a lipid, or cholesterol, core. In 17 of the patients, a very large lipid core was present, nearly wrapping around the inside of the artery.
His findings, published Wednesday, July 17, represent "a significant step forward" in the effort to identify the cause of heart attacks, said Dr. James Muller, a Boston cardiologist who developed the device used to examine the plaques.
“It is likely that the signature of a heart attack identified in the Spectrum Health study is present long before the event and could therefore be identified before a dangerous heart attack has occurred,” Muller said. “The Spectrum Health study will lead to large prospective studies of this possibility.”
Much is known about the risk factors for heart attacks – such as high blood pressure and high cholesterol levels. And despite medicines available to treat those risk factors, more than 1 million heart attacks occur every year in the U.S., said Madder, an interventional cardiologist at Spectrum Health.
“What is really sobering is that, of those 1 million heart attacks, we cannot predict a single one of them, despite all the testing we have available,” he said.
A heart attack usually occurs quickly after clot forms top of a plaque deposit.
This illustration shows, on the right, cross-sections of an artery. The yellow line nearly around the outside indicates the lipid plaque that nearly encircles the artery. The gray area indicates blockage. On the left are sections of artery, with the yellow spots indicating the presence of lipid deposits.
“We can’t predict the clot because it happens so suddenly,” Madder said. “But the lipid we think is in the artery well before a heart attack occurs.”
Previous research in autopsies has shown most major heart attacks are caused by the rupture of a lipid core plaque. Madder’s study is the first to document this in living patients.
The plaque was studied with near-infrared spectroscopy. Madder used a device that uses ultrasound to map the arteries and near-infrared light to examine the chemical makeup of the plaque. The device, called InfraredX, was created by Muller, a Nobel Prize winner. He visited Madder at Spectrum in 2012 after learning of preliminary findings from his study.
The plaques were studied after blood flow was established in the patient and before a stent was put in the artery.
Several steps lie ahead before the technique would become part of patient care. Madder is collaborating with Lund University in Sweden on a study enrolling 80 patients to validate his findings.
Further studies would be needed to see if the presence of lipid core plaques predicted heart attacks. If they did, researchers also would look into what treatments would be most effective in preventing them.
Madder's study is published online in the Cardiovascular Interventions Journal of the American College of Cardiology.
Madder discusses the study in the video below:
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