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Blood test can predict post-surgery death risk: study

June 8, 2012 By CTVNews.ca Staff

A simple blood test given in the first three days after major surgery might help to identify which patients are at high risk of dying within one month, Canadian researchers have found.

The test has the potential to change how surgical patients are monitored and treated, doctors say, and could be coming soon to a hospital near you.

The test looks for something called Troponin T, an enzyme that is released by heart muscle when it’s injured.

Doctors commonly test for the protein when they suspect a patient has had a heart attack, but they don’t routinely test for it after a major surgery.

Researchers at McMaster University suspected that looking for the marker could help determine which surgery patients were at an elevated risk of death. To test their theory, they conducted a large study involving more than 15,000 patients from around the world.

All the patients had a Troponin T measurement daily during the first three days after surgery. Patients were then tracked for 30 days after surgery.

They found that the higher the Troponin T levels were in the first three days after surgery, the higher the risk of dying in the next week or two. The full results appear in JAMA, the the Journal of the American Medical Association.

Dr. P.J. Devereaux, the study’s principal investigator and an associate professor of medicine, clinical epidemiology and biostatistics at McMaster, says the good news is that they discovered they have a window of opportunity to try to correct heart problems. Most patients in the study did not die until an average of six or more days after their Troponin T blood test was flagged as elevated. That leaves hope that there is time to intervene with clot busters or cholesterol medications.

“At the moment, most heart injuries after surgery are missed, and we are grateful we will save lives doing this,” Devereaux told CTV News.

Patricia Semkow is one of those patients who could be helped by such a blood test.

The 71-year-old underwent surgery last fall for a fractured hip. Though she had no history of heart problems before the surgery, the stress of the operation triggered a small heart attack while she was in recovery.

Semkow’s abnormal Troponin test results tipped doctors off to her silent heart attack. She immediately had a second operation on her heart.

Devereaux says without that test, Semkow may not have survived the month after surgery.

“She had no signs of underlying heart disease, and unfortunately many patients like her would go home and die one or two weeks later,” he says.

Now, six months later, Semkow is back in her garden, feeling fortunate.

“I am lucky that I got a second chance to put more years on my life,” she says.

Devereaux’s team believes that many patients suffer small heart attacks after surgery, because the surgery itself activates inflammation and clotting that predispose their hearts to injury. The majority of these patients don’t experience chest pain, but those small attacks put their hearts under stress and leave them vulnerable to another larger attack.

“This study has substantial potential to change how patients are monitored after surgery,” Dr. Jean Rouleau, scientific director of the Institute for Circulatory and Respiratory Health of the Canadian Institutes of Health

Research, said in a statement.

The study was funded in part by the Canadian Institutes of Health Research and the Heart and Stroke

Foundation of Ontario.

From a report from CTV medical specialist Avis Favaro and producer Elizabeth St. Philip