Troponin T Test Helps Assess Risk Following Noncardiac Surgery Reply

A new study in JAMA finds that postoperative Troponin T (TnT) tests can independently improve 30 day mortality risk assessment among patients who have had noncardiac surgery.

The VISION (Vascular Events in Noncardiac Surgery Patients Cohort Evaluation) study investigators evaluated the prognostic power of postoperative fourth-generation TnT testing in 15,133 patients. Overall mortality at 30 days was 1.9%.

11.6% of patients had peak TnT values greater than 0.02 ng/mL. These patients had an increased risk of death at 30 days:

  • TnT < 0.01: 1% mortality at 30 days
  • TnT 0.02 ng/mL: 4%, adjusted hazard ratio 2.41 (1.33-3.77)
  • TnT 0.03-0.29 ng/mL: 9.3%, HR 5.00 (3.72-6.76)
  • TnT > 0.30: 16.9%, HR 10.48 (6.25-16.62)
The VISION investigators reported that TnT was the strongest predictor of 30-day mortality. A population attributable risk analysis found that 41.8% of deaths were explained by elevated TnT levels. The findings suggest that postoperative patients with elevated TnT levels may benefit from aspirin and statin therapy, but this strategy has not been tested in clinical trials, the authors note. The investigators concluded that “clinical trials are needed to establish whether interventions can alter patients’ risk of death based on an elevated troponin measurement after surgery.”

Here is the press release from JAMA:

Biomarker Levels Associated With Increased Risk of Death Following Noncardiac Surgery

CHICAGO – Certain levels of the biomarker troponin T (a protein) measured in the first three days following noncardiac surgery are associated with an increased risk of death within 30 days, according to a study in the June 6 issue of JAMA.

“Worldwide more than 200 million adults have major noncardiac surgery annually. Despite benefits associated with surgery, major perioperative complications, including death, occur. More than 1 million adults worldwide will die within 30 days of noncardiac surgery each year. Perioperative risk estimation identifies patients who require more intensive monitoring and management in the postoperative period. Current preoperative risk prediction models for 30-day mortality have limitations,” according to background information in the article. Some research has suggested that monitoring troponin measurements after surgery may improve prediction of short-term mortality, although little is known about optimal troponin threshold(s) for predicting mortality after noncardiac surgery.

P.J. Devereaux. M.D., Ph.D., of McMaster University, Hamilton, Ontario, and colleagues with the VISION Study (Vascular Events in Noncardiac Surgery Patients Cohort Evaluation) assessed the relationship between the peak fourth-generation (a newer version of the laboratory test) troponin T (TnT) measurement after noncardiac surgery and 30-day mortality. The VISION study is evaluating major complications after noncardiac surgery; participating patients have TnT levels measured after surgery. For this analysis, patients were enrolled from August 2007 to January 2011. Eligible patients were aged 45 years and older and had at least an overnight hospital admission after having noncardiac surgery. Patients’ TnT levels were measured 6 to 12 hours after surgery and on days 1, 2, and 3 after surgery.

A total of 15,133 patients were included in this study. Approximately 1 in 4 patients (24.2 percent) were at least 75 years of age and 51.5 percent were women. The most common surgeries were major orthopedic surgery (20.4 percent), major general surgery (20.3 percent), and low-risk surgeries (39.4 percent). The 30-day mortality rate was 1.9 percent (282 deaths), with 26.6 percent of deaths occurring after hospital discharge (median [midpoint] time from discharge to death was 11.0 days). The researchers found that peak TnT values after noncardiac surgery proved the strongest predictors of 30-day mortality.

“Based on the identified peak TnT values, there were marked increases in the absolute risk of 30-day mortality (i.e., 1.0 percent for a TnT value 0.01 ng/mL [or less]; 4.0 percent for a value of 0.02 ng/mL; 9.3 percent for a value of 0.03-0.29 ng/mL; and 16.9 percent for a value 0.30 ng/mL [or greater]); 11.6 percent of patients had a prognostically relevant peak TnT value of at least 0.02 ng/mL. The higher the peak TnT value, the shorter the median time to death. Our net reclassification improvement analysis demonstrated that monitoring TnT values for the first 3 days after surgery substantially improved 30-day mortality risk stratification compared with assessment limited to preoperative risk factors.”

“Although no randomized controlled trial has established an effective treatment for patients with an elevated troponin measurement after noncardiac surgery, the prognosis of these patients may be modifiable,” the authors write.

“Our study demonstrates that prognostically relevant TnT measurements after surgery strongly predict who will die within 30 days of surgery. Although at present, troponin measurements are not commonly measured after noncardiac surgery, the simplicity of this test and its prognostic power suggest it may have substantial clinical utility. There is now a need for large randomized controlled trials to evaluate potential interventions to mitigate the high risk of death in patients who have an elevated troponin measurement after noncardiac surgery.”

(JAMA. 2012;307[21]:2295-2304)

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