Post-op Troponin Levels and Mortality

A new prospective study examining the relationship between postoperative troponin levels and mortality for noncardiac surgery patients found that there was a significant association between peak postoperative fourth-generation troponin T (TNT) measurement and 30-day mortality. The detailed results from the international cohort study were recently reported in the Journal of the American Medical Association [2012;307(21):2295-2305].

Each year, it is estimated that more than 1 million adults die within 30 days of noncardiac surgery. While some perioperative risk prediction models have been used to try to identify those patients that may have a greater mortality risk, the models have their limitations. Troponin measurement has been suggested as a possible predictor of mortality; however, according to the authors of this latest study, there is little information about its predictive value after noncardiac surgery.

In the VISION (Vascular Events in Noncardiac Surgery Patients Cohort Evaluation) study, researchers further investigated the role troponin measurement could have in identifying patients at a high mortality risk by evaluating whether peak fourth-generation TnT measurement had an association with 30-day mortality for 15,133 patients who underwent noncardiac surgery. As part of their analysis, researchers evaluated 24 preoperative variables as possible predictors of mortality.

To participate in the study, patients were required to be ≥45 years of age, have at least 1 overnight hospital stay after noncardiac surgery, and have received a general or regional anesthetic during the surgery.

Participating hospitals across 8 countries collected blood from study patients for a Roche 4th-generation Elecsys TnT assay 6 to 12 hours after surgery and were measured again on the first, second, and third day after surgery.

The most common type of surgery for participants was low-risk surgeries, accounting for 39.4% of the study population, followed by major orthopedic surgery and major general surgery.

Researchers identified the primary outcome of the VISION study as mortality at 30 days after surgery.

After analyzing the data, they found that at the 30-day mark postsurgery, there was a mortality rate of 1.9% (95% confidence interval [CI], 1.7%-2.1%) among study participants.

When researchers assessed multiple preoperative variables, they found that peak TnT values were the strongest predictor of 30-day mortality. Peak TnT threshold values of 0.02 ng/mL, 0.03 ng/mL, and 0.30 ng/mL were all found in a multivariable analysis to independently predict 30-day mortality.

Those patients who had peak TnT threshold values of ≥0.30 ng/mL had the highest 30-day mortality rate of 16.9%, followed by a mortality rate of 9.3% for those with peak TnT threshold values of 0.03-0.29 ng/mL. Patients with peak TnT threshold values of ≤0.01 ng/mL and those with values of 0.02 ng/nL had mortality rates of 1.0% and 4.0%, respectively.

Researchers also noted that the higher the peak TnT value, the shorter the median time to death. Those patients with TnT threshold values of ≥0.30 ng/mL had a median time to death of 6.5 days (interquartile range [IQR], 1.5-15 days, P=.01) compared with those with a value of 0.02 ng/mL who had a median time of death of 13.5 days (IQR, 8.5-20 days).

Researchers found, as part of a net reclassification improvement analysis, that monitoring TnT values in the initial days after surgery substantially improved 30-day mortality risk stratification compared to solely using preoperative risk factors.