Links Between High Troponin Levels, Mortality Examined After Cardiac Surgery

PJ Devereaux, MD, PhD

New findings suggest levels of high-sensitivity troponin I after cardiac surgery associated with increased risk of death were substantially higher than levels currently recommended in detecting clinically important periprocedural myocardial injury.

In patients who underwent isolated coronary-artery bypass grafting (CABG) or aortic-valve replacement or repair (AVR), the threshold troponin level that was associated with a hazard ratio (HR) of more than 1.00 for death within 30 days was 5670 ng per liter (95% confidence interval [CI], 1045 - 8260). The level was noted to be 218 times the upper reference limit.

“We observed that the lowest troponin thresholds associated with an increased risk of death at 30 days after cardiac surgery were substantially higher than the levels that are currently recommended in consensus statements as the basis for diagnosis of perioperative myocardial infarction or clinically important perioperative myocardial injury,” wrote study author PJ Deveraux, MD, PhD, David Braley Research Institute, Hamilton General Hospital.

The Vascular Events in Surgery Patients Cohort Evaluation (VISION) Cardiac Surgery study examined clinical outcomes, with a primary objective of determining the relationship between postoperative high-sensitivity cardiac troponin I levels and the risk of death within 30 days after cardiac surgery.

Patients were recruited from a sample of 24 hospitals in 12 countries from May 2013 - April 2019. Criteria for eligibility included ≥18 years of age and underwent any cardiac surgical procedure, excluding an isolated pericardial window, pericardiectomy, or implantation of a pacemaker or defibrillator.

The high-sensitivity cardiac troponin I measurements (upper reference limit, 26 ng per liter; limit of detection, 1 to 2 ng per liter) were obtained before surgery, 3 to 12 hours after surgery, and on days 1, 2, and 3 after surgery. The primary outcome was death within 30 days after surgery.

Investigators obtained 30-day mortality data on 13,480 patients (97.2%) from the VISION study, with a mean age of 63.3 years. Further data show 70.9% of the patients were men, 29.3% had a history of myocardial infarction, and 70.2% were White.

In the first day after surgery, troponin was measured in 13,662 patients, with 13,316 patients (97.5%) having a peak troponin measurement of more than 260 ng per liter (>10 times the upper reference limit).

By 30 days after surgery 296 patients (2.1) had died and 399 patients (2.9%) had a major vascular complication. In multivariable analysis, the findings show an increased risk of death within 30 days associated with each 1-unit increase in the natural log of peak troponin measurement within 1 day after isolated CABG or AVR (adjusted HR, 1.62; 95% CI, 1.36 - 1.93)

Among patients who underwent other cardiac surgery, the lowest high-sensitivity cardiac surgery, the corresponding threshold troponin level was 12,981 ng per liter (95% CI, 2673 to 16,591). This level was noted to be 499 times the upper reference limit.

The study, “High-Sensitivity Troponin I after Cardiac Surgery and 30-Day Mortality,” was published online in the New England Journal of Medicine.