Blood Test Detects Heart Damage after Surgery

A simple blood test for high-sensitivity troponin T can identify damage to the heart after non-cardiac surgery, according to a new study.

Researchers at McMaster University conducted a prospective cohort study involving 21,842 patients aged 45 years or older from 23 Canadian hospitals scheduled for a range of non-cardiac, elective, urgent, and emergency surgeries. Measurements of high-sensitivity troponin T were taken in the first six to 12 hours after surgery, and on the following three days. The patients were then followed for up to 30 days after surgery, with all major complications recorded, including stroke, pulmonary embolism, sepsis, and bleeding.

Overall, 1.4% of patients died during the first 30 days after surgery. Using data from the blood assays, the researchers determined that patients with peak troponin T levels less than 5 ng/L had only a 0.1% percent risk of death within 30 days; by contrast, patients with peak troponin T levels between 20 and 64 ng/L had three-times the risk of death within 30 days. Risk of death after surgery continued to rise with higher peak troponin T levels. Patients with peak levels between 65 and 1000 ng/L had a 9.1% risk of dying within 30 days, while those with peak levels at or above 1000 ng/L had a 29.6% risk of 30-day mortality.

Data from 3,904 patients who sustained myocardial injury following surgery suggested that ischemic injury to cardiac tissue explained 24% of the deaths in the first 30 days after surgery; the vast majority of these patients experienced no symptoms of heart damage. The researchers added that observational data suggest that drugs such as aspirin or statins can decrease the risk of death in patients with ischemic heart damage after non-cardiac surgery. The study was presented at the American College of Cardiology (ACC) 66th annual scientific session, held during March 2017 in Washington (DC, USA).

“Where we're letting patients down is in post-operative management; that requires physicians to get more involved in post-operative care to make sure that patients benefit from these important surgical interventions,” said lead author and study presenter P.J. Devereaux, MD, PhD, director of cardiology at McMaster University. “Although the vast majority of patients undergoing surgery do well, if even a small proportion of patients are dying, that's a big deal because so many people have surgery.”

Cardiac troponin T (cTnT) and troponin I (cTnI) are regulatory proteins that control the calcium mediated interaction between actin and myosin. The measurement of serum cTnI and cTnT is superior in terms of sensitivity and specificity to cardiac muscle enzyme measurements in the identification of cardiac muscle damage, and is accepted as the standard biochemical marker for the diagnosis of myocardial infarct.