Mildly Elevated Cardiac Troponin below the 99th-Percentile Upper Reference Limit after Noncardiac Surgery

Area of Science:

• Cardiology
• Perioperative Medicine
• Clinical Biochemistry

Background:

• Cardiac troponin I (cTn I) levels are crucial biomarkers in cardiovascular assessment.
• The prognostic significance of perioperative cTn I elevations below the 99th-percentile upper limit of normal (URL) in noncardiac surgery is not well-defined.
• This study addresses the association between minor cTn I elevations and mortality post-noncardiac surgery.

Purpose of the Study:

• To evaluate the association between postoperative cardiac troponin I (cTn I) levels within the 99th-percentile URL and 30-day mortality.
• To determine if a mild elevation of cTn I, above the limit of detection but below the 99th-percentile URL, impacts patient outcomes after noncardiac surgery.

Main Methods:

• A cohort of 5,312 patients undergoing noncardiac surgery was analyzed.
• Patients were categorized into two groups: no cTn I elevation (at limit of detection, 6 ng/L) and minor elevation (6 ng/L < cTn I < 40 ng/L).
• Propensity score-matching was employed to compare 30-day mortality between the groups, with cTn I values below the 99th-percentile URL.

Main Results:

• The minor elevation group (51.4%) exhibited significantly higher 30-day mortality compared to the no-elevation group (48.6%) post-propensity score-matching (2.3% vs. 0.5%).
• A hazard ratio of 4.30 (95% CI, 2.23-8.29; p<0.001) indicated a substantially increased risk of mortality in the minor elevation group.
• The estimated cutoff value for cTn I to predict 30-day mortality was 6 ng/L, with an area under the receiver operating characteristic curve of 0.657.

Conclusions:

• Mild elevation of cardiac troponin I (cTn I) within the 99th-percentile URL after noncardiac surgery is significantly associated with increased 30-day mortality.
• Even minor cTn I elevations warrant clinical attention as they may indicate heightened perioperative risk.
• The findings suggest that the 6 ng/L threshold for cTn I may serve as a predictor of short-term mortality in this patient population.