Testing for Troponin T Can Spot Unrecognized Heart Injuries After Surgery

Measuring troponin T levels with a high-sensitivity troponin T assay can identify patients with heart damage after non-cardiac surgery whose lives could potentially be saved with timely treatment, according to results from the VISION study presented on March 19 at ACC.17 in Washington, DC.

The study enrolled 21,842 patients aged 45 years or older (41 percent were 65 years or older) from 23 hospitals in 13 countries. Patients with and without known heart or blood vessel disease were included. To obtain a broad sample of patients undergoing non-cardiac inpatient procedures, such as hip or knee replacements, researchers examined elective, urgent and emergency surgeries as well as procedures performed during the day, at night, on weekdays and on weekends. Measurements of high-sensitivity troponin T were taken in the first six to 12 hours after surgery and on the following three days.

Halfway through the study, researchers began measuring troponin T levels immediately before surgical procedures as well as post surgery. Patients were followed for up to 30 days after surgery and recorded all major complications, including stroke, pulmonary embolism, sepsis and bleeding. They adjusted the data for pre-operative and surgical variables previously shown to be associated with 30-day mortality, including age, active cancer, general surgery, urgent/emergent surgery, history of peripheral vascular disease, history of chronic obstructive pulmonary disease, recent high-risk coronary artery disease, history of stroke and neurosurgery.

Overall results showed 1.4 percent of patients died during the first 30 days after surgery. Using data from the assays, 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 than patients with lower troponin T measurements as well as a 3 percent absolute risk of 30-day mortality.

The risk of death after surgery rose with higher peak troponin T levels. Patients with peak levels between ≥65 and <1000 ng/L had a 9.1 percent risk of dying within 30 days, while those with peak levels at or above 1000 ng/L had a 29.6 percent risk of 30-day mortality. In patients whose troponin T levels were measured both before and after surgery, only 13.8 percent experienced peak levels before their procedure, suggesting that taking a baseline measurement is important to rule out a false indication of injury during or after surgery, said P.J. Devereaux, MD, PhD, director of cardiology at McMaster University in Hamilton, Canada, and lead author of the study.

Data from 3,904 patients who sustained myocardial injury after non-cardiac surgery suggested that ischemic injury to heart tissue after non-cardiac surgery explained 24 percent of deaths in the first 30 days after surgery. The vast majority of these patients experienced no symptoms of heart damage.

Researchers noted observational data suggesting that drugs such as aspirin or statins can decrease the risk of death in patients with ischemic heart damage after non-cardiac surgery.

"This is the first large international study to establish thresholds of high-sensitivity troponin T that are independently associated with death within 30 days after non-cardiac surgery. We found that approximately 18 percent of patients will sustain a heart injury after non-cardiac surgery, but without monitoring troponins, 93 percent of these will be missed," said Devereaux. "Our data show that unrecognized heart injuries may account for about one in four of the deaths that happen in the first 30 days after surgery." These findings suggest a need for physicians to get more involved in post-operative care to ensure patients benefit from these important surgical interventions.

A limitation of the study was that the researchers did not have pre-operative troponin measurements for about 60 percent of patients, making it difficult to clearly distinguish between patients with high pre-operative troponin T levels who developed ischemic injuries and those whose injuries were associated with high post-operative levels of troponin T. An international randomized controlled trial testing whether starting an anticoagulant based on troponin T levels after non-cardiac surgery can help prevent these post-operative cardiovascular deaths is in the works.

"The therapeutic implications of these associations are unknown," said Kim A. Eagle, MD, MACC, editor-in-chief of ACC.org. "Such biomarker measurement can only be justified in practice by completion of randomized trials that link treatment to the measures."

Clinical Topics: Anticoagulation Management, Dyslipidemia, Vascular Medicine, Atherosclerotic Disease (CAD/PAD), Nonstatins, Novel Agents, Statins

Keywords: ACC17, ACC Annual Scientific Session, Effect Modifier, Epidemiologic, Postoperative Period, Proportional Hazards Models, Risk, Troponin T, Anticoagulants, Aspirin, Biological Markers, Coronary Artery Disease, Heart Injuries, Hemorrhage, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Neoplasms, Neurosurgery, Peripheral Vascular Diseases, Pulmonary Disease, Chronic Obstructive, Pulmonary Embolism, Stroke, Troponin, Troponin T

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