Blood test to predict post-surgery death risk

New Delhi, June 6: A simple blood test may predict the risk of death from unexpected heart attacks after non-cardiac surgery and allow doctors to initiate appropriate precautions for patients at risk, a new study has suggested.

A team of doctors from Canada, India and other countries has found that post-surgery blood levels of a protein called troponin-T appear to predict the risk that patients will die from heart attacks within 30 days after surgery.

The findings, if confirmed through larger trials, could change clinical practice and reduce the risk of post-surgical death for tens of millions of patients who undergo non-cardiac surgery for anything — from fractures to tumours, from cosmetic procedures to transplants. The results of the study were published today in the Journal of the American Medical Association.

“We’re hoping a troponin-T value in patients who’ve undergone surgery becomes an alarm bell for doctors,” said Alben Sigamani, associate professor of pharmacology at the St John’s Medical College Hospital, Bangalore, a co-author of the study.

The study has shown that the higher the troponin-T value in the bloodstream of a patient measured within three days of a surgery, the greater is the risk that the patient will suffer a heart attack within four weeks.

“Troponin-T is a bio-marker released specifically by heart muscles when they’re injured. Any surgery leads to enormous stress on the heart and we believe troponin-T values reflect that damage,” Sigamani told The Telegraph.

Under standard medical practice, every patient who undergoes a planned surgical procedure is investigated for a history of diabetes, heart disease, and smoking. But such risk-prediction techniques don’t always work.

Research studies suggest that about 200 million patients worldwide have major non-cardiac surgery each year, and that up to 5 per cent, or one million, of these patients die from heart attacks within 30 days of their surgery.

The new study led by epidemiologist Philip J. Devereaux at McMaster University in Canada enrolled more than 15,000 patients from across North and South America, Europe, Asia, and Australia. All patients were above 45 years of age, had no history of heart disease and had undergone a non-cardiac surgery with a stay in hospital of at least 24 hours.

Sigamani and his colleagues from St John’s were co-authors of the research, having participated in the design and research analysis. But Indian doctors have adopted the same study protocol to launch an exclusively Indian study of post-surgical patients now under way at St John’s and the Christian Medical College, Ludhiana.

“We’ll need to further confirm these findings through rigorous studies that also take into account pre-surgical troponin-T,” Sigamani said. “We need objective and quantitative criteria to predict risk of unexpected death after successful surgery, and we’re hoping troponin-T may be such a tool.

Doctors believe surgery activates pathways of inflammation, stress and clotting that exposes the heart to injury. The study suggests that one in 25 patients with a troponin-T value of 0.02 ng/mL, and one in six patients with a troponin-T value of 0.30 ng/mL will die within 30 days of surgery.

“Given these results, worldwide more than 10 million adults may suffer a prognostically relevant heart injury after surgery every year,” Devereaux said through a press release issued by McMaster University.

Devereaux said that while there is “encouraging observational data” that aspirin and other drugs can save the lives of patients who suffer heart injury after surgery, clinical trials are needed to establish whether such interventions can reduce the risk of patients dying after surgery.