Researchers have developed a new technique to identify the dangerous buildup of plaque in blood vessels that can lead to a serious heart attack. The procedure may someday save the lives of those who are most at risk.
Doctors know if someone is at high risk for a heart attack. Smoking, obesity, family history, high cholesterol - all these are considered important risk factors.
"Right now, our predictive tools are not good enough to understand who's at risk for developing an acute heart attack, which puts them at risk of sudden death and also future cardiac complications such as heart failure," noted Harvard University researcher Farouc Jaffer. He thought a better tool was needed, one that would identify the specific plaques that threaten the heart.
Plaque is composed of fat, cholesterol, and other material. If it stays encapsulated in the wall of an artery, it can cause the blood vessel to narrow. If the plaque breaks open, a blood clot can form. If the clot travels to the heart, it can cause a possibly-fatal heart attack. Using today's technology, doctors can't tell if or when that might happen.
Jaffer and his colleagues tested a new way to identify plaques before they cause trouble. In animal tests, they injected a dye called indocyanine green (ICG) into a vein. ICG is chemically attracted to cholesterol, and can be detected by a sensor that is threaded through the blood vessel, past the plaque.
"What we found was that all the ICG started to leave the blood and instead started to localize in the plaques themselves," he explained in a telephone interview. "As soon as we traversed the plaque - crossed the plaque - we would see a spike of signal, suggesting that ICG was actually depositing in these plaques."
This ICG-based procedure is invasive and not risk-free, so only people who are at high risk for heart attack would be likely to get it. Jaffer says a diagnostic technology that identifies dangerous but non-symptomatic plaques opens the way for preventing those plaques from rupturing. For example, Jaffer says doctors could insert a tiny metal scaffold called a stent inside the blood vessel.
"While you cannot stent every non-severe plaque because maybe 95-98 percent of them will never cause a heart attack, the ones that do we need to identify and try to stop because these are life-threatening events that can kill people, often way prematurely," added Jaffer.
Government regulators will have to approve the procedure before it is tried on human patients. But Farouc Jaffer points out that ICG dye has been used for other purposes since the 1950s, which should expedite regulatory approval.
A paper describing the imaging of plaques is published in the journal Science Translational Medicine.