U.S. researchers say they have developed a blood test that can pinpoint people who are in imminent danger of a heart attack – giving doctors days or possibly a few weeks to take preventive action.
"We want to quickly move forward with the test because there is a real need for it," said Eric Topol, the principal investigator at the Scripps Translational Science Institute in San Diego, Ca.
Indeed, existing diagnostic tests have only a limited ability to predict who is most at risk.
The process of a heart attack usually begins with the rupture of plaque – or fatty deposit – inside a blood vessel. The debris can lead to the formation of a clot that blocks blood flow to the heart tissue, killing part of the organ.
Doctors are able to identify patients who have plaque deposits that partly obstruct blood vessels by using a combination of a treadmill stress test and imaging technology. But they can't say if or when any particular plaque deposit will burst open.
The new blood test, however, is able to detect impending danger. And, in particular, it can spot circulating endothelial cells (CEC) – or cells that are already breaking away from unstable plaque and floating freely through the blood stream.
"The rupturing of plaque typically takes place anywhere from a few days to two weeks before the actual heart attack," explained Dr. Topol.
"It's like a smouldering process. There is a segment of the artery that is quite inflamed. It's cracking and sloughing off cells that line the surface of the blood vessel. But it doesn't happen all at once."
At this early stage, some people will experience chest discomfort. Some of them may even seek help at a hospital emergency department. "They feel something is wrong; a small blood clot may have formed and dissolved on its own," said Dr. Topol. But unless there is already damage to the heart, an electrocardiogram and traditional blood tests won't indicate there is anything wrong. Patients are often released from hospital, only to suffer a full-blown heart attack in a few days or weeks.
"But, for the first time, we now have a test that can finally get at the underlying process and show there is a problem," said Dr. Topol. That means patients, who were once sent home without treatment, could be given anti-clotting drugs and other medications so they are potentially spared a devastating heart attack.
The test – details of which were released this week in the journal Science Translational Medicine – still needs to go through some refinement, said Dr. Topol.
He expects it will be ready for widespread use in about two years. (It would also need the approval of government regulators.)
With further advancements in medical technology, he believes the test could eventually serve as an early-warning monitor for patients who have cardiovascular disease. For instance, the test could be incorporated into a nano-sensor that's permanently implanted in a blood vessel.
"It could keep your blood under constant surveillance," he said. If it detects signs of plaque rupture, "it could send a message to your cellphone saying you're about to have a heart attack in the next week or two."