Results

A primary search of the hospital information system identified 68 054 hospitalised adults undergoing noncardiac surgery between 2017 and 2022. Postoperative hs-cTnT was measured within 72 h in 6263 patients; among these, 1114 had hs-cTnT >50 ng L−1; 954 patients were eligible for analysis (Fig. 2).

Fig 2: Inclusion and exclusion. hs-cTnT, high-sensitivity cardiac troponin T.

Baseline characteristics of the total study cohort are presented in Table 1. The median age was 66 yr [55–74] and 66% were male; 32% of the procedures were elective. Vascular (19%), general (17%), and neurosurgery (16%) were the most frequent surgical specialties.

 | Overall (N=954) | Extra-cardiac (n=544) | Cardiac (n=410) | P-value
Age, y | 66 [55–74] | 63 [51–72] | 69 [61–75] | <0.001
Female | 329 (34.5) | 189 (34.7) | 140 (34.1) | 0.90
Elective | 304 (31.9) | 121 (22.3) | 183 (44.6) | <0.001
Troponin concentrations in ng L−1 | 109 [69–225] | 116 [71–230] | 95 [65–206] | 0.016
Surgical specialty
Ear-nose-throat | 35 (3.7) | 9 (1.7) | 26 (6.3) | <0.001
General surgery | 158 (16.6) | 80 (14.7) | 78 (19) | 0.11
Gynaecology | 11 (1.2) | 6 (1.1) | 5 (1.2) | 0.87
Neurosurgery | 151 (15.8) | 105 (19.3) | 46 (11.2) | 0.002
Orthopaedics | 42 (4.4) | 13 (2.4) | 29 (7.1) | <0.001
Other | 107 (11.2) | 57 (10.5) | 50 (12.2) | 0.43
Thoracic | 40 (4.2) | 20 (3.7) | 20 (4.9) | 0.37
Transplant | 87 (9.1) | 66 (12.1) | 21 (5.1) | <0.001
Trauma | 113 (11.8) | 92 (16.9) | 21 (5.1) | <0.001
Urology | 28 (2.9) | 14 (2.6) | 14 (3.4) | 0.45
Vascular | 182 (19) | 82 (15.1) | 100 (24.4) | 0.001
Comorbidities
Coronary artery disease | 217 (22.7) | 102 (18.8) | 115 (28.0) | 0.001
Myocardial infarction | 169 (17.7) | 83 (15.3) | 86 (21.0) | 0.027
Peripheral artery disease | 183 (19.2) | 82 (15.1) | 101 (24.6) | <0.001
Stroke/TIA | 120 (12.6) | 62 (11.4) | 58 (14.1) | 0.242
Chronic heart failure | 107 (11.2) | 52 (9.5) | 55 (13.4) | 0.078
Atrial fibrillation | 135 (14.2) | 73 (13.4) | 62 (15.1) | 0.514
Moderate/severe valvular disease | 77 (8.1) | 38 (7.0) | 39 (9.5) | 0.194
Diabetes mellitus (non-insulin) | 171 (17.9) | 95 (17.5) | 76 (18.5) | 0.732
Diabetes mellitus (insulin-dependent) | 80 (8.4) | 42 (7.7) | 38 (9.3) | 0.462
Chronic kidney disease | 240 (25.2) | 165 (30.3) | 75 (18.3) | <0.001
Hypertension | 393 (41.2) | 208 (38.2) | 185 (45.1) | 0.038
Chronic obstructive pulmonary disease | 116 (12.2) | 51 (9.4) | 65 (15.9) | 0.003
RCRI 0 | 212 (22.2) | 132 (24.3) | 80 (19.5) | 0.095
RCRI 1 | 385 (40.4) | 221 (40.6) | 164 (40) | 0.898
RCRI 2 | 212 (22.2) | 110 (20.2) | 102 (24.9) | 0.102
RCRI ≥3 | 145 (15.2) | 81 (14.9) | 64 (15.6) | 0.829
In-hospital mortality | 192 (20) | 129 (23.7) | 63 (15.4) | 0.002

Classification and reassessment

Results of the classification process are presented in Fig. 3. Myocardial injury was classified as extra-cardiac in 544 (57%) and cardiac in 410 patients (43%). Baseline characteristics according to myocardial injury aetiology are presented in Table 1. Patients with a cardiac cause were older and more frequently had a history of hypertension, coronary artery disease, myocardial infarction, peripheral arterial disease, and chronic obstructive pulmonary disease than patients with an extra-cardiac cause. Cardiac causes were more common after vascular, ear-nose-throat, and orthopaedic surgery, whereas extra-cardiac myocardial injury occurred more often after non-elective surgery, neurosurgery, trauma, and transplant surgery and in patients with chronic kidney disease.

Fig 3: Aetiologies of myocardial injury and in-hospital mortality by aetiology.

Across the overall cohort, the most frequent aetiological categories were type 2 myocardial injury with and without a documented trigger (35%; 22% and 13%, respectively), renal failure (21%), trauma (13%) and stroke (10%) (Fig. 3). Blinded reassessment yielded concordant classification in 739 patients, corresponding to 78% agreement (κ=0.55; 95% CI 0.50–0.60; P<0.001). Discrepancies occurred mainly within type 2 myocardial injury (Fig. 4).

Fig 4: Sankey diagram providing interobserver discrepancies.

In-hospital mortality

Overall in-hospital mortality in this high-risk cohort was 192 of 954 (20%). Mortality was 129 of 544 (24%) in extra-cardiac causes and 63 of 410 (15%) in cardiac causes (P=0.002). In extra-cardiac myocardial injury, the highest mortality was observed in stroke (46%) and sepsis (39%); in cardiac myocardial injury, the highest mortality was observed in acute heart failure (33%) and type 1 myocardial infarction (29%). In type 2 myocardial injury, mortality was 30 of 212 (14%) with a trigger and 15 of 119 (13%) without a trigger (P=0.82).

When accounting for time to event and discharge alive as competing risk, the 30-day cumulative incidence of in-hospital death was 20% in patients with extra-cardiac myocardial injury and 12% in those with cardiac myocardial injury (Gray’s test P<0.001) (Fig. 5). The corresponding cumulative incidence of discharge alive at 30 days was 56% and 72%, respectively (Gray’s test P<0.001). Multivariable logistic regression for in-hospital mortality in extra-cardiac and cardiac causes is presented in Supplement 2. Two sensitivity analyses were performed and are presented in Supplement 3: exclusion of patients with pre-existing chronic kidney disease and patients with hs-cTnT >50 ng L−1 measured at the enhanced perioperative care unit or after vascular surgery.

Fig 5: 30-day CIF of in-hospital mortality and discharge alive. Shading represents 95% confidence interval. CIF, cumulative incidence function.