Early elevation in plasma high-sensitivity troponin T and morbidity after elective noncardiac surgery: prospective multicentre observational cohort study

Abstract

Background: Elevated high-sensitivity troponin (hsTnT) after noncardiac surgery is associated with higher mortality, but the temporal relationship between early elevated troponin and the later development of noncardiac morbidity remains unclear.

Methods: Prospective observational study of patients aged ≥45 yr undergoing major noncardiac surgery at four UK hospitals (two masked to hsTnT). The exposure of interest was early elevated troponin, as defined by hsTnT >99th centile (≥15 ng L^-1) within 24 h after surgery. The primary outcome was morbidity 72 h after surgery, defined by the Postoperative Morbidity Survey (POMS). Secondary outcomes were time to become morbidity-free and Clavien-Dindo ≥grade 3 complications.

Results: Early elevated troponin (median 21 ng L^-1 [16-32]) occurred in 992 of 4335 (22.9%) patients undergoing elective noncardiac surgery (mean [standard deviation, sd] age, 65 [11] yr; 2385 [54.9%] male). Noncardiac morbidity was more frequent in 494/992 (49.8%) patients with early elevated troponin compared with 1127/3343 (33.7%) patients with hsTnT <99th centile (odds ratio [OR]=1.95; 95% confidence interval [CI], 1.69-2.25). Patients with early elevated troponin had a higher risk of proven/suspected infectious morbidity (OR=1.54; 95% CI, 1.24-1.91) and critical care utilisation (OR=2.05; 95% CI, 1.73-2.43). Clavien-Dindo ≥grade 3 complications occurred in 167/992 (16.8%) patients with early elevated troponin, compared with 319/3343 (9.5%) patients with hsTnT <99th centile (OR=1.78; 95% CI, 1.48-2.14). Absence of early elevated troponin was associated with morbidity-free recovery (OR=0.44; 95% CI, 0.39-0.51).

Conclusions: Early elevated troponin within 24 h of elective noncardiac surgery precedes the subsequent development of noncardiac organ dysfunction and may help stratify levels of postoperative care in real time.

Keywords: cardiac; complications; myocardial injury; perioperative period; postoperative outcomes; surgery; troponin.

Fig 1

Patient flow diagram showing cases included in the primary analysis. RLH- Royal London Hospital; UCLH- University College London Hospital.

Fig 2

Time to become morbidity free within 7 days of surgery, in relation to early troponin increase. Kaplan–Meier plot showing time to become morbidity-free, stratified by early elevated troponin and troponin remaining <15 ng L⁻¹ status within 24 h of surgery. POMS-defined morbidity persisted for at least 7 days early elevated troponin (HR=1.35; 95% CI, 1.26–1.45; P<0.0001). Coloured numbers at risk for each category are matched to coloured lines shown in graph panel. CI, confidence interval; HR, hazard ratio; hsTnT, high-sensitivity troponin; POMS, Postoperative Morbidity Survey.

Fig 3

Critical care-free days. The risk of requiring intensive care was greater in patients with early elevated troponin 24 h after surgery (≥15 ng L⁻¹; early troponin), who experienced fewer postoperative days free of critical care (HR=1.15; 95% CI, 1.07–1.24; P<0.0001, by log-rank test). CI, confidence interval; HR, hazard ratio.

Fig 4

Unsupervised variable clustering analysis. (a) Hierarchical clustering for all patients, using Postoperative Morbidity Survey (POMS) domains scored on day 3 and troponin on day 1 dichotomised as early elevated troponin (≥15 ng L⁻¹) or within normal limits (<15 ng L⁻¹). The dendogram illustrates how various morbidities cluster in different groups of patients. (b) Variable similarity for POMS domains recorded on day 3 and troponin measured on day 1, dichotomised as early elevated troponin (≥15 ng L⁻¹) or within normal limits (<15 ng L⁻¹). Bright red shaded boxes indicate 100% association (i.e. correlation between same variable); lighter shading indicates weaker association.