The association between postoperative myocardial injury of unexplained aetiology after noncardiac surgery and sex and cancer on 1-yr survival: a retrospective, single-centre, observational cohort study

Abstract

Background

The aetiology of postoperative myocardial injury (PMI) is often unexplained, and the effect of sex and cancer surgery on prognosis in patients with PMI is unknown. We aimed to estimate the proportion of patients developing PMI of unknown aetiology and compare their prognosis with those with explained PMI, and to investigate the interaction with sex and cancer surgery.

Methods

This retrospective, single-centre, observational cohort study included patients aged ≥60 yr undergoing noncardiac surgery. Patients with PMI (defined as an elevated troponin concentration <72h after surgery) were categorised into five groups, based on the most likely aetiology of PMI: acute myocardial infarction (MI); extra-cardiac disease (acute or chronic renal failure, sepsis, pulmonary embolism, acute intracranial pathology, or all of the mentioned); known cardiac disease with regular follow-up; perioperative haemodynamic/respiratory events; and PMI of unexplained aetiology. The association between PMI group and 1-yr mortality, and between sex and cancer surgery, was estimated.

Results

Of 3885 patients, 823 (21%) had a diagnosis of PMI, of whom 32 (4%) had MI, 201 (24%) had extra-cardiac disease, 174 (21%) had known cardiac disease, 269 (33%) had haemodynamic/respiratory events, and 147 (18%) had PMI of unexplained aetiology. Like other patients with PMI, those with PMI of unexplained aetiology had an increased risk of 1-yr mortality (risk ratio 1.5, 95% confidence interval 1.1–2.1). PMI caused by MI or known cardiac disease occurred more often in men. Women more often had PMI owing to perioperative haemodynamic/respiratory factors. There was no interaction found between PMI and sex or cancer surgery on mortality risk.

Conclusions

In approximately half of the patients with a diagnosis of PMI, PMI aetiology was either related to perioperative haemodynamic/respiratory events or the aetiology was unexplained. These patients had an increased associated mortality risk. Women more often had PMI of likely haemodynamic/respiratory causes. Mortality risk in those with PMI was similar between sexes and between those undergoing cancer surgery vs non-cancer surgery.